Compositions and methods for cross-linking structural proteins

Abstract

The present application provides compounds, compositions and methods for promoting photocrosslinking of structural proteins. In one example, the structural protein is collagen and is present in biological tissue. In one example, a pharmaceutical composition is provided that includes a compound of Formula (II): # imgabs0 # (Formula (II) wherein R6, R7, R8, and R9 are as described herein. In one example, a composition includes an organic solvent, such as a semi-fluorinated alkane solvent, a medium chain triglyceride solvent, or a combination thereof. Methods of using the compositions are also provided, and include medical applications in which known tissue crosslinking is beneficial. In one example, the disclosure provides a method of corneal crosslinking using the composition.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of the priority of U.S. Application No. 63 / 434,487, filed on Dec. 22, 2022, the content of the foregoing application being incorporated herein by reference in its entirety. Technical field

[0003] The present disclosure relates to pharmaceutical compositions comprising riboflavin or riboflavin derivatives, and methods for using such compositions to cross - link structural proteins such as, for example, collagen or keratin. Background art

[0004] Various biological tissues or structural proteins found in biological tissues can be modified by cross - linking. For example, corneal tissue in mammals can be modified by photo - cross - linking the structural protein collagen in the corneal tissue. Cross - linking of collagen in the cornea can stabilize pathogenic or degenerative eye conditions or correct vision defects. Riboflavin - 5 - phosphate has been used as a photosensitizer to promote photo - cross - linking of collagen in corneal tissue. Summary of the invention

[0005] The present disclosure relates to compositions and methods for cross - linking structural proteins such as collagen. In some embodiments, the structural protein can be present in biological tissue. In some embodiments, the tissue can be ex vivo or can be present in a subject such as a mammal.

[0006] The present disclosure is at least partially based on the recognition that certain riboflavin derivatives can be effective in promoting photo - cross - linking of structural proteins such as collagen. Without being bound by theory, it is believed that the riboflavin derivatives described herein can themselves act as (1) photosensitizers to promote photo - cross - linking of structural proteins such as collagen, and / or (2) can be converted into riboflavin within biological tissue and then act as a photosensitizer to promote photo - cross - linking of structural proteins. The present disclosure is also based on the recognition that the compositions and derivatives described herein can be useful at least in terms of stable formulations of photosensitizers and improved penetration and delivery of the compounds within biological tissue.

[0007] A non-limiting example of a tissue that can benefit from crosslinking of, for example, collagen is corneal tissue. Generally, from outside to inside, the cornea has a five-layer structure: (1) corneal epithelium, (2) Bowman's layer, (3) stroma, (4) Descemet's membrane, and (5) endothelium. In certain ocular conditions such as, for example, keratoconus, the stroma of the cornea can become thinner or liquefied, ultimately leading to bulging of the cornea and subsequent vision changes. Corneal crosslinking (CXL) is a procedure that can be used to crosslink the collagen fibrils within the stroma, thereby increasing the mechanical strength of the stroma, altering its shape, and / or providing relief of various ocular symptoms and treating or halting the progression of ocular diseases such as keratoconus.

[0008] The Dresden protocol (the original protocol developed for the procedure) remains the standard CXL protocol in use and generally involves de-epithelializing the cornea (removing at least a portion of the corneal epithelium), applying 0.1% riboflavin-5-phosphate in an aqueous solution, and applying UV radiation. See, for example, Wollensak G, Spoerl E, Seiler T. Riboflavin / ultraviolet-a–induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol 2003;135:620-627. One reason for de-epithelializing the cornea in this procedure is because riboflavin and riboflavin-5-phosphate are hydrophilic molecules that do not penetrate well through the tight structure of the corneal epithelium, thereby reducing the amount of promoter / photosensitizer that can reach the stroma of the cornea for the crosslinking procedure. The procedure typically takes 30 minutes and requires multiple re-applications of riboflavin or riboflavin-5-phosphate due to limitations such as poor penetration into corneal tissue and easy decomposition. In addition, while the procedure can provide success in improving corneal conditions, it is not without side effects and complications. The de-epithelialization procedure required to allow riboflavin to effectively penetrate into the cornea for crosslinking causes significant discomfort to the patient and results in slow recovery times and an opportunity for infection.

[0009] Various formulations have been attempted to improve the penetration of riboflavin into the stromal layer without de-epithelialization, but many of these formulations contain irritating or even damaging components, such as ionic agents, which can irritate or damage the tissues of the eye. In addition, while these components can improve riboflavin penetration, they do not alter the highly hydrophilic nature of riboflavin itself. Thus, even with additional components, the penetration efficiency of riboflavin is limited. Mechanical methods to avoid de-epithelialization have also been proposed, but these methods often require specialized equipment and operating skills. Further, riboflavin and riboflavin-5-phosphate are highly susceptible to photodegradation. There remains a need for improved compounds, compositions, and methods for corneal crosslinking and crosslinking of other biological tissues.

[0010] The present disclosure provides compositions including riboflavin or certain riboflavin derivatives that can be useful in the crosslinking of structural proteins, as well as methods for crosslinking structural proteins, including crosslinking of structural proteins in mammalian tissues. The compounds and compositions described herein provide improved photosensitizer / promoter stability and delivery. For example, in some embodiments, the compounds, compositions, and methods herein can provide enhanced penetration of epithelial tissues without including irritants such as preservatives or ionic agents, thus obviating the need for de-epithelialization of the cornea in corneal crosslinking procedures.

[0011] In one aspect, provided herein is a composition comprising:

[0012] A compound of formula I:

[0013]

[0014] Wherein:

[0015] R1, R2, and R3 are each independently selected from hydrogen or -C(O)R 5 ;

[0016] R4 is selected from hydrogen, -C(O)R 5 , phosphate, or a salt thereof; and

[0017] R5 is a straight-chain, branched-chain, or cyclic alkyl having 1 to 26 carbon atoms; and

[0018] A vehicle selected from medium-chain triglycerides (MCT), perfluorinated alkanes, or a combination thereof.

[0019] In this and other embodiments, formula I can optionally have the following characteristics. R1, R2, R3, and R4 can each independently be selected from hydrogen or -C(O)R 5 ; R5 can be a straight-chain, branched-chain, or cyclic alkyl having 1 to 26 carbon atoms; and at least one of R1, R2, R3, and R4 can be -C(O)R5 , at least two of R1, R2, R3 and R4 may be -C(O)R 5 , or at least three of R1, R2, R3 and R4 may be -C(O)R 5 . R1, R2, R3 and R4 may each independently be -C(O)R 5 ; and R5 may be a straight-chain, branched-chain or cyclic alkyl group having 1 to 26 carbon atoms. R1, R2, R3 and R4 may each independently be selected from hydrogen or -C(O)R5; at least one of R1, R2, R3 and R4 may be -C(O)R 5 , at least two of R1, R2, R3 and R4 may be -C(O)R 5 , or at least three of R1, R2, R3 and R4 may be -C(O)R 5 ; and R5 may be selected from straight-chain or branched-chain alkyl groups having 1 to 3 or 15 carbon atoms. R1, R2, R3 and R4 may each independently be -C(O)R5, and R5 may be selected from straight-chain or branched-chain alkyl groups having 1 to 3 or 15 carbon atoms. In some embodiments, the compound of formula I may be selected from riboflavin tetraacetate, riboflavin tetrapropionate, riboflavin tetrabutyrate, riboflavin tetrapalmitate or combinations thereof.

[0020] In these and other embodiments, the composition may optionally have the following characteristics. The MCT may be a triglyceride of fatty acids, and the fatty acids are selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid and combinations thereof. The semi-fluorinated alkane compound may have the formula RFRH or the formula RFRHRF; RF may be a perfluorinated hydrocarbon having 1 to 15 carbon atoms, and RH may be a non-fluorinated hydrocarbon having 1 to 15 carbon atoms. The semi-fluorinated alkane may be selected from perfluorobutylbutane (F4H4), perfluorobutylpentane (F4H5), perfluorobutylhexane (F4H6), perfluorohexylethane (F6H2), perfluorohexylbutane (F6H4), perfluorohexyl octane (F6H8) and perfluorohexyl decane (F6H10); preferably, perfluorohexylhexane (F6H6) and perfluorohexyl octane (F6H8). In some embodiments, the semi-fluorinated alkane may be perfluorohexyl octane (F6H8).

[0021] In these and other embodiments, the compound of Formula I may optionally be present in the composition(s) in an amount of from about 0.001% to about 1% (w / w), from about 0.01% to about 1% (w / w), from about 0.05% to about 0.5% (w / w), about 0.01% (w / w), 0.02% (w / w), 0.03% (w / w), 0.04% (w / w), 0.05% (w / w), 0.06% (w / w), 0.07% (w / w), 0.08% (w / w), 0.09% (w / w), 0.1% (w / w), 0.2% (w / w), 0.3% (w / w), 0.4% (w / w), 0.5% (w / w), 0.6% (w / w), 0.7% (w / w), 0.8% (w / w), 0.9% (w / w), or 1% (w / w).

[0022] In these and other embodiments, MCT may optionally be present in the composition(s) in an amount of from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0023] In these and other embodiments, the semi-fluorinated alkane may optionally be present in the composition(s) in an amount from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0024] In these and other embodiments, the composition(s) may have the following optional features. MCT may be present in an amount of about 1% (w / w) and SFA may be present in an amount of about 99% (w / w); MCT may be present in an amount of about 2% (w / w) and SFA may be present in an amount of about 98% (w / w); MCT may be present in an amount of about 5% (w / w) and SFA may be present in an amount of about 95% (w / w); MCT may be present in an amount of about 10% (w / w) and SFA may be present in an amount of about 90% (w / w); MCT may be present in an amount of about 15% (w / w) and SFA may be present in an amount of about 85% (w / w); MCT may be present in an amount of about 20% (w / w) and SFA may be present in an amount of about 80% (w / w); MCT may be present in an amount of about 25% (w / w) and SFA may be present in an amount of about 75% (w / w); MCT may be present in an amount of about 30% (w / w) and SFA may be present in an amount of about 70% (w / w); MCT may be present in an amount of about 35% (w / w) and SFA may be present in an amount of about 65% (w / w); MCT may be present in an amount of about 40% (w / w) and SFA may be present in an amount of about 60% (w / w); MCT may be present in an amount of about 45% (w / w) and SFA may be present in an amount of about 55% (w / w); MCT may be present in an amount of about 50% (w / w) and SFA may be present in an amount of about 50% (w / w); MCT may be present in an amount of about 55% (w / w) and SFA may be present in an amount of about 45% (w / w); MCT may be present in an amount of about 60% (w / w) and SFA may be present in an amount of about 40% (w / w); MCT may be present in an amount of about 65% (w / w) and SFA may be present in an amount of about 35% (w / w); MCT may be present in an amount of about 70% (w / w) and SFA may be present in an amount of about 30% (w / w); MCT may be present in an amount of about 75% (w / w) and SFA may be present in an amount of about 25% (w / w); MCT may be present in an amount of about 80% (w / w) and SFA may be present in an amount of about 20% (w / w); MCT may be present in an amount of about 85% (w / w) and SFA may be present in an amount of about 15% (w / w); MCT may be present in an amount of about 90% (w / w) and SFA may be present in an amount of about 10% (w / w); MCT may be present in an amount of about 95% (w / w) and SFA may be present in an amount of about 5% (w / w); MCT may be present in an amount of about 98% (w / w) and SFA may be present in an amount of about 2% (w / w); MCT may be present in an amount of about 99% (w / w) and SFA may be present in an amount of about 1% (w / w); MCT may be the only solvent and MCT may be present in an amount of about 99% (w / w); MCT may be the only solvent and MCT may be about 99.present in an amount of 5% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.6% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.7% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.8% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.9% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.5% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.6% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.7% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.8% (w / w), or wherein SFA can be the only solvent and SFA can be present in an amount of about 99.9% (w / w).

[0025] In these and other embodiments, the composition(s) can have the following optional features. The composition(s) can consist essentially of a compound of formula I and a solvent. The composition(s) can be an organic composition that is free of aqueous components. The composition(s) can be a topical composition or a topical ophthalmic composition, wherein the composition is a solution, suspension, or emulsion. The composition(s) can further include a viscosity enhancer. The composition(s) can be free of preservatives or free of eye irritants.

[0026] In another aspect, described herein is a method for crosslinking collagen in the cornea of a subject, which comprises: administering to at least a portion of the cornea of the subject a composition as described above; and irradiating at least a portion of the cornea of the subject with UV radiation or blue light.

[0027] In another aspect, described herein is a method for crosslinking collagen in the tissue of a subject, which comprises: administering to at least a portion of the cornea of the subject a composition as described above; and irradiating at least a portion of the cornea of the subject with UV radiation or blue light.

[0028] In another aspect, described herein is a method for crosslinking a structural protein, which comprises: contacting the structural protein or a biological tissue containing the structural protein with a composition as described above; and irradiating the structural protein or the tissue of the subject with UV radiation or blue light.

[0029] In these and other embodiments of the methods described herein, a structural protein or optionally collagen may be present in a biological tissue or may be present in or on a subject's body. The biological tissue may be ex vivo. The biological tissue may be in or on the subject's body. Contacting the structural protein or contacting the tissue may include administering a composition to a tissue within the subject's body. The tissue may be selected from a collagenous tissue, an epidermal tissue, or a keratinous tissue. The keratinous tissue is selected from hair or nails. The tissue may be selected from corneal tissue.

[0030] In these and other embodiments, the method(s) may have the following optional features. The subject may have a chemical burn or a disease selected from: keratoconus, thin cornea, keratitis, infectious keratitis including bacterial or fungal keratitis, corneal ulcer, bullous keratopathy, and other forms of corneal edema, corneal exfoliation, autoimmune diseases, cicatricial diseases such as ocular cicatricial pemphigoid, Stevens-Johnson syndrome, lupus erythematosus, rheumatoid arthritis, corneal ectasia including corneal ectasia occurring after laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), post-refractive ectasia, corneal degeneration, brittle cornea syndrome, Ehlers-Danlos syndrome type VI, corneal neovascularization, corneal melting including corneal melting in Boston type I keratoprosthesis, hyperopia, hyperopic astigmatism, myopia, astigmatism, myopic astigmatism, myopic regression, corneal disease, corneal astigmatism, unstable cornea, or pellucid marginal degeneration (PMD). The composition may be in the form of an eye drop, and the method may further include applying the eye drop to the subject's eye. The method may further include de-epithelializing at least a portion of the cornea. Crosslinking may be performed without de-epithelializing any portion of the cornea.

[0031] In another aspect, described herein is a method for crosslinking collagen in a subject's tissue, comprising: administering to the subject's tissue a compound of formula II:

[0032]

[0033] wherein:

[0034] R6, R7, R8, and R9 are each independently selected from hydrogen or -C(O)R5;

[0035] at least one of R6, R7, R8, and R9 is -C(O)R5; and

[0036] R5 is selected from straight-chain, branched-chain, or cyclic alkyl having 1 to 26 carbon atoms; and

[0037] Irradiate the tissue with UV radiation or blue light.

[0038] In another aspect, described herein is a method for crosslinking a structural protein, which comprises: contacting the structural protein or biological tissue containing the structural protein with a compound of Formula II:

[0039]

[0040] Wherein:

[0041] R6, R7, R8, and R9 are each independently selected from hydrogen or -C(O)R5;

[0042] At least one of R6, R7, R8, and R9 is -C(O)R5; and

[0043] R5 is selected from straight-chain, branched-chain, or cyclic alkyl groups having 1 to 26 carbon atoms; and

[0044] Irradiate the structural protein or tissue with UV radiation or blue light.

[0045] In these and other embodiments, Formula II may optionally have the following characteristics. R1, R2, R3, and R4 may each independently be selected from hydrogen or -C(O)R 5 ; R5 may be selected from straight-chain, branched-chain, or cyclic alkyl groups having 1 to 26 carbon atoms; and at least one of R1, R2, R3, and R4 may be -C(O)R 5 , at least two of R1, R2, R3, and R4 may be -C(O)R 5 , or at least three of R1, R2, R3, and R4 may be -C(O)R 5 . R1, R2, R3, and R4 may each independently be -C(O)R 5 ; and R5 may be selected from straight-chain, branched-chain, or cyclic alkyl groups having 1 to 26 carbon atoms. R1, R2, R3, and R4 may each independently be selected from hydrogen or -C(O)R5; at least one of R1, R2, R3, and R4 may be -C(O)R 5 , at least two of R1, R2, R3, and R4 may be -C(O)R 5 , or at least three of R1, R2, R3, and R4 may be -C(O)R 5 ; and R5 may be selected from straight-chain or branched-chain alkyl groups having 1 to 3 or 15 carbon atoms. R1, R2, R3, and R4 may each independently be -C(O)R5, and R5 may be selected from straight-chain or branched-chain alkyl groups having 1 to 3 or 15 carbon atoms. In some embodiments, the compound of Formula II may be selected from riboflavin tetraacetate, riboflavin tetrapropionate, riboflavin tetrabutyrate, riboflavin tetrapalmitate, or a combination thereof.

[0046] In these and other embodiments, the method may optionally have the following features. The structural protein may be selected from collagen, keratin, derivatives thereof, and combinations thereof. The structural protein may be present in biological tissue or may be present in or on the body of a subject. The biological tissue may be ex vivo. The biological tissue may be in or on the body of a subject. Contacting the structural protein or contacting the tissue may include administering a compound of Formula II to tissue within the body of a subject. The tissue may be selected from collagenous tissue, epidermal tissue, or keratinous tissue. The keratinous tissue may be selected from hair or nails. Administering a compound of Formula II to the tissue may include administering a composition comprising the compound of Formula II, and the composition may further comprise a solvent. The solvent may be selected from medium-chain triglycerides (MCTs), perfluorinated alkanes, or combinations thereof. The MCT may be a triglyceride of a fatty acid, and the fatty acid is selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid, and combinations thereof. The perfluorinated alkane compound may have the formula RFRH or the formula RFRHRF; RF may be a perfluorinated hydrocarbon having 1 to 15 carbon atoms, and RH may be a non-fluorinated hydrocarbon having 1 to 15 carbon atoms. The perfluorinated alkane may be selected from perfluorobutylbutane (F4H4), perfluorobutylpentane (F4H5), perfluorobutylhexane (F4H6), perfluorohexylethane (F6H2), perfluorohexylbutane (F6H4), perfluorohexyl octane (F6H8), and perfluorohexyl decane (F6H10); preferably, perfluorohexylhexane (F6H6) and perfluorohexyl octane (F6H8). The perfluorinated alkane may be perfluorohexyl octane (F6H8).

[0047] In these and other embodiments, the compound of Formula II may be present in the composition(s) in the following amounts: from about 0.001% to about 1% (w / w), from about 0.01% to about 1% (w / w), from about 0.05% to about 0.5% (w / w), about 0.01% (w / w), 0.02% (w / w), 0.03% (w / w), 0.04% (w / w), 0.05% (w / w), 0.06% (w / w), 0.07% (w / w), 0.08% (w / w), 0.09% (w / w), 0.1% (w / w), 0.2% (w / w), 0.3% (w / w), 0.4% (w / w), 0.5% (w / w), 0.6% (w / w), 0.7% (w / w), 0.8% (w / w), 0.9% (w / w), or 1% (w / w).

[0048] In these and other embodiments, MCT may optionally be present in the composition(s) in an amount from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0049] In these and other embodiments, the semi-fluorinated alkane may optionally be present in the composition(s) in an amount of from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0050] In these and other embodiments, the composition(s) may have the following optional features. MCT may be present in an amount of about 1% (w / w) and SFA may be present in an amount of about 99% (w / w); MCT may be present in an amount of about 2% (w / w) and SFA may be present in an amount of about 98% (w / w); MCT may be present in an amount of about 5% (w / w) and SFA may be present in an amount of about 95% (w / w); MCT may be present in an amount of about 10% (w / w) and SFA may be present in an amount of about 90% (w / w); MCT may be present in an amount of about 15% (w / w) and SFA may be present in an amount of about 85% (w / w); MCT may be present in an amount of about 20% (w / w) and SFA may be present in an amount of about 80% (w / w); MCT may be present in an amount of about 25% (w / w) and SFA may be present in an amount of about 75% (w / w); MCT may be present in an amount of about 30% (w / w) and SFA may be present in an amount of about 70% (w / w); MCT may be present in an amount of about 35% (w / w) and SFA may be present in an amount of about 65% (w / w); MCT may be present in an amount of about 40% (w / w) and SFA may be present in an amount of about 60% (w / w); MCT may be present in an amount of about 45% (w / w) and SFA may be present in an amount of about 55% (w / w); MCT may be present in an amount of about 50% (w / w) and SFA may be present in an amount of about 50% (w / w); MCT may be present in an amount of about 55% (w / w) and SFA may be present in an amount of about 45% (w / w); MCT may be present in an amount of about 60% (w / w) and SFA may be present in an amount of about 40% (w / w); MCT may be present in an amount of about 65% (w / w) and SFA may be present in an amount of about 35% (w / w); MCT may be present in an amount of about 70% (w / w) and SFA may be present in an amount of about 30% (w / w); MCT may be present in an amount of about 75% (w / w) and SFA may be present in an amount of about 25% (w / w); MCT may be present in an amount of about 80% (w / w) and SFA may be present in an amount of about 20% (w / w); MCT may be present in an amount of about 85% (w / w) and SFA may be present in an amount of about 15% (w / w); MCT may be present in an amount of about 90% (w / w) and SFA may be present in an amount of about 10% (w / w); MCT may be present in an amount of about 95% (w / w) and SFA may be present in an amount of about 5% (w / w); MCT may be present in an amount of about 98% (w / w) and SFA may be present in an amount of about 2% (w / w); MCT may be present in an amount of about 99% (w / w) and SFA may be present in an amount of about 1% (w / w); MCT may be the only solvent and MCT may be present in an amount of about 99% (w / w); MCT may be the only solvent and MCT may be about 99.be present in an amount of 5% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.6% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.7% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.8% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.9% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.5% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.6% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.7% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.8% (w / w), or wherein SFA can be the only solvent and SFA can be present in an amount of about 99.9% (w / w).

[0051] In these and other embodiments of the method(s), the composition(s) can have the following optional features. The composition(s) can consist essentially of a compound of Formula II and a solvent. The composition(s) can be an organic composition free of aqueous components. The composition(s) can be a topical composition or a topical ophthalmic composition. The composition(s) can be a solution, a suspension, or an emulsion. The composition(s) can further comprise a viscosity enhancer. The composition(s) can be free of preservatives or free of ophthalmic irritants.

[0052] In these and other embodiments, the method(s) may have the following optional features. The tissue may be corneal tissue. The subject may have a chemical burn or a disease selected from the following: keratoconus, thin cornea, keratitis, infectious keratitis including bacterial or fungal keratitis, corneal ulcer, bullous keratopathy and other forms of corneal edema, dellen, autoimmune disease, cicatricial disease such as ocular cicatricial pemphigoid, Stevens-Johnson syndrome, lupus erythematosus, rheumatoid arthritis, corneal ectasia including corneal ectasia occurring after laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), post-refractive corneal ectasia, corneal degeneration, brittle cornea syndrome, Ehlers-Danlos syndrome type VI, corneal neovascularization, corneal melting including corneal melting in Boston type I keratoprosthesis, hyperopia, hyperopic astigmatism, myopia, astigmatism, myopic astigmatism, myopic regression, corneal disease, corneal astigmatism, unstable cornea or pellucid marginal degeneration (PMD). The composition may be in the form of an eye drop, and the method may further comprise administering the eye drop to the eye of the subject. The method may further comprise de-epithelializing at least a portion of the cornea. Crosslinking may be performed without de-epithelializing any portion of the cornea.

[0053] In some embodiments, the compositions and methods provided herein may offer several advantages. First, in some embodiments of the compositions provided herein, riboflavin derivatives having variable hydrophobicity are included, allowing the skilled person to make adjustments to obtain optimal penetration, stability, and efficacy (compared to riboflavin or riboflavin 5-phosphate) for the intended use of the composition.

[0054] Second, in some embodiments of the compositions and methods provided herein, the compounds may better penetrate target tissues such as, for example, the corneal epithelium. This provides several additional advantages, which in some embodiments include improved crosslinking within the tissue, since the compounds can reach the intended structural proteins for crosslinking. Further, in some embodiments, increased penetration may result in using lower amounts or doses of the compound or composition, or fewer applications or shorter amounts of time to treat the tissue. Additionally, improved penetration may eliminate the need to de-epithelialize target tissues such as the corneal epithelium, thereby reducing patient pain and discomfort, as well as reducing healing time and minimizing the chance of infection.

[0055] Third, in some embodiments, the riboflavin derivative compounds described herein may exhibit greater stability than, for example, riboflavin or riboflavin 5-phosphate, thereby reducing the likelihood of an excess of free radicals being present in tissues. In some embodiments, this improved stability may permit the use of compositions that are free of preservatives or additional penetration enhancers or other irritants used in aqueous formulations to confer stability or enhance absorption through corneal tissue, thereby simplifying the composition and reducing the likelihood of irritation such as eye irritation or allergic reactions associated with the inclusion of such additives. In some embodiments of the riboflavin derivative compounds described herein, the compounds may be less susceptible to photodegradation than riboflavin or riboflavin 5-phosphate and still act as photosensitizers for the photocrosslinking of structural proteins such as collagen. Without being bound by theory, it is believed that in some embodiments, the compounds may act directly as photosensitizers or act as photosensitizers through an activity similar to that of a prodrug, wherein the compound enters a crosslinking environment (such as corneal tissue) and then is converted to ordinary riboflavin within the environment (such as the eye of a mammal). In either case, these embodiments may provide both enhanced penetration and the desired crosslinking activity.

[0056] Fourth, in some embodiments described herein, the compounds may be formulated into compositions that include organic solvents such as, for example, semi-fluorinated alkanes (SFA) and / or medium-chain triglycerides (MCT). In some embodiments, these formulations may permit an increase in the stability of the compounds and thus an increase in the stability of the formulation, the desired dose, and / or the lack of impurities.

[0057] Other features and advantages of the present application will be apparent from the following detailed description and the drawings, and from the claims. Detailed Description

[0058] Provided herein are compositions that can promote the photocrosslinking of structural proteins such as collagen, and methods for crosslinking structural proteins such as collagen and keratin using the compounds and compositions further described herein. In some embodiments, the structural proteins may be in a tissue or in or on the body of a subject such as a mammal, for example, a human.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Methods and materials for this application are described herein; other suitable methods and materials known in the art may also be used. The materials, methods, and examples are illustrative only and not intended to be limiting. All publications, patent applications, patents, sequences, database entries, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.

[0060] As used herein, the term "about" means "approximately" (e.g., plus or minus about 10% of the indicated value).

[0061] As used herein, the term "alkyl" refers to a saturated monovalent hydrocarbon moiety having a straight-chain or branched-chain portion or a combination thereof and containing a specified (e.g., 1 to 26) number of carbon atoms.

[0062] As used herein, the term "cycloalkyl" refers to a monovalent or divalent group of, for example, 3 to 8 carbon atoms derived from a saturated cyclic hydrocarbon. The cycloalkyl group can be monocyclic or polycyclic.

[0063] As used herein, the formula "H" represents a hydrogen atom.

[0064] As used herein, the formula "O" represents an oxygen atom.

[0065] As used herein, the formula "P" represents a phosphorus atom.

[0066] As used herein, the term "compound" means all stereoisomers, geometric isomers, tautomers, and isotopes of the described structure, including racemic mixtures. Unless otherwise specified, compounds herein identified by name or structure as a particular tautomeric form are intended to include other tautomeric forms.

[0067] As used herein, the term "contact" means bringing the indicated moieties together in an in vitro system or an in vivo system. For example, "contacting" an eye tissue with a compound of the invention includes administering the compound of the invention to an individual or patient (such as a human) having an eye tissue in need of treatment, and, for example, introducing the compound of the invention into a sample containing a cell preparation or a purified preparation containing eye tissue.

[0068] As used herein, the terms "individual", "patient", or "subject" used interchangeably refer to any animal, including mammals, preferably mice, rats, other rodents, rabbits, dogs, cats, pigs, cows, sheep, horses, or primates, and most preferably humans. In some embodiments, a human subject can be of any age, e.g., from 0 to 100 years old. As used herein, "pediatric subject" and "child" are used interchangeably and refer to a subject from 0 to 18 years old (e.g., 1, 2, 5, 10, 12, or 14 years old).

[0069] As used herein, the phrase "effective amount" or "therapeutically effective amount" means the amount of an active compound or agent that elicits a biological or pharmaceutical response in a tissue, system, animal, individual, or human sought by a researcher, veterinarian, medical doctor, or other clinician.

[0070] As used herein, the term "treating" or "treatment" means: 1) inhibiting a disease; e.g., inhibiting a disease, condition or disorder in an individual who is experiencing or displaying the pathology or symptomatology of the disease, condition or disorder (i.e., preventing further development of the pathology and / or symptomatology), or 2) alleviating a disease; e.g., alleviating a disease, condition or disorder in an individual who is experiencing or displaying the pathology or symptomatology of the disease, condition or disorder (i.e., reversing the pathology and / or symptomatology).

[0071] In some embodiments, provided herein are compositions comprising a compound having the general formula (I):

[0072]

[0073] In formula (I)

[0074] R1, R2, and R3 are each independently selected from hydrogen or -C(O)R 5 ;

[0075] R4 is selected from hydrogen, -C(O)R 5 , phosphate, or a salt thereof; and

[0076] R5 is a straight-chain, branched-chain or cyclic alkyl having 1 to 26 carbon atoms (e.g., methyl, ethyl, propyl, butyl, sec-butyl, and tert-butyl, etc.).

[0077] In some embodiments of formula (I), R1, R2, R3, and R4 are each independently selected from hydrogen or -C(O)R 5 . In some embodiments of formula (I), at least one of R1, R2, R3, and R4 is -C(O)R 5 , at least two of R1, R2, R3, and R4 are -C(O)R 5 , or at least three of R1, R2, R3, and R4 are -C(O)R 5 , or all of R1, R2, R3, and R4 are -C(O)R 5 . In some embodiments, each of R1, R2, R3, and R4 may be the same group or may have different groups.

[0078] In some embodiments of formula (I), R1, R2, R3, and R4 are each independently selected from hydrogen or -C(O)R 5 ; and at least one of R1, R2, R3, and R4 is -C(O)R 5 , at least two of R1, R2, R3, and R4 are -C(O)R 5, or at least three of R1, R2, R3, and R4 are -C(O)R 5 . In some embodiments, each of R1, R2, R3, and R4 is independently -C(O)R 5 .

[0079] In some embodiments of formula (I), each of R1, R2, R3, and R4 is independently selected from hydrogen or -C(O)R5; at least one of R1, R2, R3, and R4 is -C(O)R 5 , at least two of R1, R2, R3, and R4 are -C(O)R 5 , or at least three of R1, R2, R3, and R4 are -C(O)R 5 ; and R5 can be a straight-chain or branched-chain alkyl group having 1 or 3 carbon atoms.

[0080] In some embodiments, each of R1, R2, R3, and R4 is independently -C(O)R5, and R5 can be a straight-chain or branched-chain alkyl group having 1 or 3 carbon atoms. In some embodiments, exemplary compounds of formula (I) can include riboflavin, riboflavin-5-phosphate, riboflavin tetraacetate: (2R,3S,4S)-5-(7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl)pentane-1,2,3,4-tetrayl tetraacetate, riboflavin tetrapropionate: (2R,3S,4S)-5-(7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl)pentane-1,2,3,4-tetrayl tetrapropionate, riboflavin tetrabutyrate: (2R,3S,4S)-5-(7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl)pentane-1,2,3,4-tetrayl tetrabutyrate, riboflavin tetrapalmitate: (2R,3S,4S)-5-(7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl)pentane-1,2,3,4-tetrayl tetrapalmitate, or a combination thereof.

[0081] In some embodiments, the compound of formula (I) may be present in the composition in an amount from about 0.001% to about 1% (w / w), 0.001% to about 0.95% (w / w), 0.001% to about 0.9% (w / w), 0.001% to about 0.85% (w / w), 0.001% to about 0.8% (w / w), 0.001% to about 0.75% (w / w), 0.001% to about 0.7% (w / w), 0.001% to about 0.65% (w / w), 0.001% to about 0.6% (w / w), 0.001% to about 0.55% (w / w), 0.001% to about 0.5% (w / w), 0.001% to about 0.45% (w / w), 0.001% to about 0.4% (w / w), 0.001% to about 0.35% (w / w), 0.001% to about 0.3% (w / w), 0.001% to about 0.25% (w / w), 0.001% to about 0.2% (w / w), 0.001% to about 0.15% (w / w), 0.001% to about 0.1% (w / w), 0.001% to about 0.09% (w / w), 0.001% to about 0.08% (w / w), 0.001% to about 0.07% (w / w), 0.001% to about 0.06% (w / w), 0.001% to about 0.05% (w / w), 0.001% to about 0.04% (w / w), 0.001% to about 0.03% (w / w), 0.001% to about 0.02% (w / w), 0.001% to about 0.01% (w / w), from about 0.01% to about 1%, 0.01% to about 0.95% (w / w), 0.01% to about 0.9% (w / w), 0.01% to about 0.85% (w / w), 0.01% to about 0.8% (w / w), 0.01% to about 0.75% (w / w), 0.01% to about 0.7% (w / w), 0.01% to about 0.65% (w / w), 0.01% to about 0.6% (w / w), 0.01% to about 0.55% (w / w), 0.01% to about 0.5% (w / w), 0.01% to about 0.45% (w / w), 0.01% to about 0.4% (w / w), 0.01% to about 0.35% (w / w), 0.01% to about 0.3% (w / w), 0.01% to about 0.25% (w / w), 0.01% to about 0.2% (w / w), 0.01% to about 0.15% (w / w), 0.01% to about 0.1% (w / w), 0.01% to about 0.09% (w / w), 0.01% to about 0.08% (w / w), 0.01% to about 0.07% (w / w), 0.01% to about 0.06% (w / w), 0.01% to about 0.05% (w / w), 0.01% to about 0.04% (w / w), 0.01% to about 0.03% (w / w), from 0.01% to about 0.02% (w / w), from about 0.05% to about 0.5% (w / w), from about 0.05% to about 0.45% (w / w), from about 0.05% to about 0.4% (w / w), from about 0.05% to about 0.35% (w / w), from about 0.05% to about 0.3% (w / w), from about 0.05% to about 0.25% (w / w), from about 0.05% to about 0.2% (w / w), from about 0.05% to about 0.15% (w / w), from about 0.05% to about 0.1% (w / w), from about 0.05% to about 0.09% (w / w), from about 0.05% to about 0.08% (w / w), from about 0.05% to about 0.07% (w / w), from about 0.05% to about 0.06% (w / w), from about 0.06% to about 0.5% (w / w), from about 0.07% to about 0.5% (w / w), from about 0.08% to about 0.5% (w / w), from about 0.09% to about 0.5% (w / w), from about 0.1% to about 0.5% (w / w), from about 0.15% to about 0.5% (w / w), from about 0.2% to about 0.5% (w / w), from about 0.25% to about 0.5% (w / w), from about 0.3% to about 0.5% (w / w), from about 0.35% to about 0.5% (w / w), from about 0.4% to about 0.5% (w / w), from about 0.45% to about 0.5% (w / w), about 0.01% (w / w), 0.02% (w / w), 0.03% (w / w), 0.04% (w / w), 0.05% (w / w), 0.06% (w / w), 0.07% (w / w), 0.08% (w / w), 0.09% (w / w), 0.1% (w / w), 0.15% (w / w), 0.2% (w / w), 0.25% (w / w), 0.3% (w / w), 0.35% (w / w), 0.4% (w / w), 0.45% (w / w), 0.5% (w / w), 0.55% (w / w), 0.6% (w / w), 0.65% (w / w), 0.7% (w / w), 0.75% (w / w), 0.8% (w / w), 0.85% (w / w), 0.9% (w / w), 0.95% (w / w), or 1% (w / w).

[0082] In some embodiments, provided herein are compositions comprising a compound having the general formula (II):

[0083]

[0084] In formula (II)

[0085] R6, R7, R8, and R9 are each independently selected from hydrogen or -C(O)R5;

[0086] At least one of R6, R7, R8, and R9 is -C(O)R5; and

[0087] R5 is a straight-chain, branched-chain, or cyclic alkyl group having 1 to 26 carbon atoms.

[0088] In some embodiments of formula (II), at least one of R6, R7, R8, and R9, R6, R7, R8, and R9 is -C(O)R 5 , at least two of R6, R7, R8, and R9 are -C(O)R 5 , or at least three of R6, R7, R8, and R9 are -C(O)R 5 , or all of R6, R7, R8, and R9 are -C(O)R 5 . In some embodiments, each of R6, R7, R8, and R9 may be the same group or may have different groups.

[0089] In some embodiments of formula (II), R6, R7, R8, and R9 are each independently selected from hydrogen or -C(O)R 5 ; R5 is optionally selected from straight-chain, branched-chain, or cyclic alkyl groups having 1 to 26 carbon atoms; and at least two of R6, R7, R8, and R9 are -C(O)R 5 , or at least three of R6, R7, R8, and R9 are -C(O)R 5 .

[0090] In some embodiments of formula (II), R6, R7, R8, and R9 are each independently -C(O)R 5 ; and R5 is optionally selected from straight-chain, branched-chain, or cyclic alkyl groups having 1 to 26 carbon atoms.

[0091] In some embodiments of formula (II), R6, R7, R8, and R9 are each independently selected from hydrogen or -C(O)R5; at least two of R6, R7, R8, and R9 are -C(O)R 5 , or at least three of R6, R7, R8, and R9 are -C(O)R 5 ; and R5 is optionally selected from straight-chain or branched-chain alkyl groups having 1 or 3 carbon atoms.

[0092] In some embodiments of formula (II), R6, R7, R8, and R9 are each independently -C(O)R5, and R5 is optionally selected from straight-chain or branched-chain alkyl groups having 1 or 3 carbon atoms. In some embodiments, exemplary compounds of formula (II) may include riboflavin tetraacetate, riboflavin tetrapropionate, riboflavin tetrabutyrate, riboflavin tetrapalmitate, or combinations thereof.

[0093] In some embodiments, the compound of formula (II) may be present in the composition in an amount of from about 0.001% to about 1% (w / w), 0.001% to about 0.95% (w / w), 0.001% to about 0.9% (w / w), 0.001% to about 0.85% (w / w), 0.001% to about 0.8% (w / w), 0.001% to about 0.75% (w / w), 0.001% to about 0.7% (w / w), 0.001% to about 0.65% (w / w), 0.001% to about 0.6% (w / w), 0.001% to about 0.55% (w / w), 0.001% to about 0.5% (w / w), 0.001% to about 0.45% (w / w), 0.001% to about 0.4% (w / w), 0.001% to about 0.35% (w / w), 0.001% to about 0.3% (w / w), 0.001% to about 0.25% (w / w), 0.001% to about 0.2% (w / w), 0.001% to about 0.15% (w / w), 0.001% to about 0.1% (w / w), 0.001% to about 0.09% (w / w), 0.001% to about 0.08% (w / w), 0.001% to about 0.07% (w / w), 0.001% to about 0.06% (w / w), 0.001% to about 0.05% (w / w), 0.001% to about 0.04% (w / w), 0.001% to about 0.03% (w / w), 0.001% to about 0.02% (w / w), 0.001% to about 0.01% (w / w), from about 0.01% to about 1%, 0.01% to about 0.95% (w / w), 0.01% to about 0.9% (w / w), 0.01% to about 0.85% (w / w), 0.01% to about 0.8% (w / w), 0.01% to about 0.75% (w / w), 0.01% to about 0.7% (w / w), 0.01% to about 0.65% (w / w), 0.01% to about 0.6% (w / w), 0.01% to about 0.55% (w / w), 0.01% to about 0.5% (w / w), 0.01% to about 0.45% (w / w), 0.01% to about 0.4% (w / w), 0.01% to about 0.35% (w / w), 0.01% to about 0.3% (w / w), 0.01% to about 0.25% (w / w), 0.01% to about 0.2% (w / w), 0.01% to about 0.15% (w / w), 0.01% to about 0.1% (w / w), 0.01% to about 0.09% (w / w), 0.01% to about 0.08% (w / w), 0.01% to about 0.07% (w / w), 0.01% to about 0.06% (w / w), 0.01% to about 0.05% (w / w), 0.01% to about 0.04% (w / w), 0.01% to about 0.03% (w / w), from 0.01% to about 0.02% (w / w), from about 0.05% to about 0.5% (w / w), from about 0.05% to about 0.45% (w / w), from about 0.05% to about 0.4% (w / w), from about 0.05% to about 0.35% (w / w), from about 0.05% to about 0.3% (w / w), from about 0.05% to about 0.25% (w / w), from about 0.05% to about 0.2% (w / w), from about 0.05% to about 0.15% (w / w), from about 0.05% to about 0.1% (w / w), from about 0.05% to about 0.09% (w / w), from about 0.05% to about 0.08% (w / w), from about 0.05% to about 0.07% (w / w), from about 0.05% to about 0.06% (w / w), from about 0.06% to about 0.5% (w / w), from about 0.07% to about 0.5% (w / w), from about 0.08% to about 0.5% (w / w), from about 0.09% to about 0.5% (w / w), from about 0.1% to about 0.5% (w / w), from about 0.15% to about 0.5% (w / w), from about 0.2% to about 0.5% (w / w), from about 0.25% to about 0.5% (w / w), from about 0.3% to about 0.5% (w / w), from about 0.35% to about 0.5% (w / w), from about 0.4% to about 0.5% (w / w), from about 0.45% to about 0.5% (w / w), about 0.01% (w / w), 0.02% (w / w), 0.03% (w / w), 0.04% (w / w), 0.05% (w / w), 0.06% (w / w), 0.07% (w / w), 0.08% (w / w), 0.09% (w / w), 0.1% (w / w), 0.15% (w / w), 0.2% (w / w), 0.25% (w / w), 0.3% (w / w), 0.35% (w / w), 0.4% (w / w), 0.45% (w / w), 0.5% (w / w), 0.55% (w / w), 0.6% (w / w), 0.65% (w / w), 0.7% (w / w), 0.75% (w / w), 0.8% (w / w), 0.85% (w / w), 0.9% (w / w), 0.95% (w / w), or 1% (w / w).

[0094] The compounds of formula (I) or formula (II) and their salts may be in the form of solvates, which are included within the scope of the present invention. Such solvates include, for example, hydrates and alcoholates (such as ethanol solvates), etc. The compounds according to the present invention may exist in different polymorphic forms. Although not explicitly indicated in the above formulas, such forms are intended to be included within the scope of the present disclosure.

[0095] In some embodiments, a composition comprising a compound of formula (I), formula (II), or a combination thereof may be a pharmaceutical composition. In some embodiments of the pharmaceutical composition, the compounds disclosed herein (e.g., a compound of formula (I)) may be present in an effective amount (e.g., a therapeutically effective amount). The effective dose may vary depending on the disease being treated, the severity of the disease, the route of administration, the sex, age, and general health of the subject, the use of excipients, the likelihood of co-use with other therapeutic treatments (such as the use of other agents), and the judgment of the attending physician. For example, in some embodiments, in the case where the compositions described herein are used to treat a disease of the eye (such as keratoconus) of a patient, the attending physician may adjust the dose and dosing regimen based on the thickness or condition of the patient's cornea.

[0096] In some embodiments, the effective amount (e.g., in a systemic formulation) of a compound (e.g., a compound of formula (I) or a pharmaceutically acceptable salt thereof) may range, for example, from about 0.001 mg / kg to about 500 mg / kg (e.g., from about 0.001 mg / kg to about 200 mg / kg; from about 0.01 mg / kg to about 200 mg / kg; from about 0.01 mg / kg to about 150 mg / kg; from about 0.01 mg / kg to about 100 mg / kg; from about 0.01 mg / kg to about 50 mg / kg; from about 0.01 mg / kg to about 10 mg / kg; from about 0.01 mg / kg to about 5 mg / kg; from about 0.01 mg / kg to about 1 mg / kg; from about 0.01 mg / kg to about 0.5 mg / kg; from about 0.01 mg / kg to about 0.1 mg / kg; from about 0.1 mg / kg to about 200 mg / kg; from about 0.1 mg / kg to about 150 mg / kg; from about 0.1 mg / kg to about 100 mg / kg; from about 0.1 mg / kg to about 50 mg / kg; from about 0.1 mg / kg to about 10 mg / kg; from about 0.1 mg / kg to about 5 mg / kg; from about 0.1 mg / kg to about 2 mg / kg; from about 0.1 mg / kg to about 1 mg / kg; or from about 0.1 mg / kg to about 0.5 mg / kg). In some embodiments, the effective amount of the compound of formula (I) is about 0.1 mg / kg, about 0.5 mg / kg, about 1 mg / kg, about 2 mg / kg, or about 5 mg / kg.

[0097] In some embodiments, the dose may be administered on a daily basis (e.g., as a single dose or as two or more divided doses, such as once daily, twice daily, three times daily, or four times daily) or on a non-daily basis (e.g., every other day, every two days, every three days, once a week, twice a week, once every two weeks, once a month).

[0098] In some embodiments, the composition may include a solvent. The solvent may act as a carrier or solvent for one or more compounds of formula (I), one or more compounds of formula (II), or a combination thereof. In some embodiments, the composition may be in the form of a solution, suspension, or emulsion. In some embodiments, the compositions provided herein may consist essentially of one or more compounds of formula (I), one or more compounds of formula (II), or a combination thereof. In some embodiments, the composition may be an organic composition that is free of aqueous components.

[0099] In some embodiments, the solvent may be medium-chain triglyceride (MCT). Medium-chain triglyceride (MCT) is a triglyceride of fatty acids. The fatty acids have an aliphatic chain of 6-12 carbon atoms and may be, for example, caproic acid, caprylic acid, capric acid, and lauric acid. The MCT may be a single triglyceride or a mixture of triglycerides. Representative chemical structures of MCT are shown below:

[0100]

[0101] In some embodiments, the MCT may be a triglyceride of fatty acids, and the fatty acids may be selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid, and combinations thereof.

[0102] In some embodiments, MCT may be present in amounts of from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0103] In some embodiments, the solvent can be a semi-fluorinated alkane. A semi-fluorinated alkane is an amphiphilic liquid having two immiscible moieties (a hydrocarbon segment and a perfluorinated segment) covalently bonded. In one example, the partially fluorinated alkane compound useful in the formulations of the present disclosure has the formula CF3(CF2) m (CH2) n CH3. In some embodiments, m is an integer from 1 to 10, and n is an integer from 1 to 10. For example, m can be 1, 2, 3, 4, 5, or 6. In another example, n can be 1, 2, 3, 4, 5, or 6. Examples of semi-fluorinated alkanes include perfluorobutylbutane (F4H4), perfluorobutylpentane (F4H5), perfluorobutylhexane (F4H6), perfluorohexylethane (F6H2), perfluorohexylbutane (F6H4), perfluorohexyl octane (F6H8), and perfluorohexyl decane (F6H10), preferably, perfluorohexylhexane (F6H6) and perfluorohexyl octane (F6H8).

[0104] As an example, the structure of F6H8 is:

[0105]

[0106] In some embodiments, the semi-fluorinated alkane compound can have the formula RFRH or the formula RFRHRF; RF is a perfluorinated hydrocarbon having 1 to 15 carbon atoms, and RH is a non-fluorinated hydrocarbon having 1 to 15 carbon atoms.

[0107] In some embodiments, the concentration of the compound of formula (I) or formula (II) in the pharmaceutical composition comprising the partially fluorinated alkane solvent liquid can be from about 1 mg / mL to about 10 mg / mL. For example, the concentration can be about 1 mg / mL, about 2 mg / mL, about 3 mg / mL, about 4 mg / mL, about 5 mg / mL, about 6 mg / mL, or about 7 mg / mL. In one example, the composition comprising a semi-fluorinated alkane fluid as a pharmaceutically acceptable solvent can be a topical ophthalmic composition.

[0108] In some embodiments, the semi-fluorinated alkane can be present in the following amounts: from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0109] In some embodiments, the solvent can be a combination of one or more MCTs as described herein and one or more SFAs as described herein. In some embodiments, the MCT can be present in an amount of about 1% (w / w) and the SFA can be present in an amount of about 99% (w / w); the MCT can be present in an amount of about 2% (w / w) and the SFA can be present in an amount of about 98% (w / w); the MCT can be present in an amount of about 5% (w / w) and the SFA can be present in an amount of about 95% (w / w); the MCT can be present in an amount of about 10% (w / w) and the SFA can be present in an amount of about 90% (w / w); the MCT can be present in an amount of about 15% (w / w) and the SFA can be present in an amount of about 85% (w / w); the MCT can be present in an amount of about 20% (w / w) and the SFA can be present in an amount of about 80% (w / w); the MCT can be present in an amount of about 25% (w / w) and the SFA can be present in an amount of about 75% (w / w); the MCT can be present in an amount of about 30% (w / w) and the SFA can be present in an amount of about 70% (w / w); the MCT can be present in an amount of about 35% (w / w) and the SFA can be present in an amount of about 65% (w / w); the MCT can be present in an amount of about 40% (w / w) and the SFA can be present in an amount of about 60% (w / w); the MCT can be present in an amount of about 45% (w / w) and the SFA can be present in an amount of about 55% (w / w); the MCT can be present in an amount of about 50% (w / w) and the SFA can be present in an amount of about 50% (w / w); the MCT can be present in an amount of about 55% (w / w) and the SFA can be present in an amount of about 45% (w / w); the MCT can be present in an amount of about 60% (w / w) and the SFA can be present in an amount of about 40% (w / w); the MCT can be present in an amount of about 65% (w / w) and the SFA can be present in an amount of about 35% (w / w); the MCT can be present in an amount of about 70% (w / w) and the SFA can be present in an amount of about 30% (w / w); the MCT can be present in an amount of about 75% (w / w) and the SFA can be present in an amount of about 25% (w / w); the MCT can be present in an amount of about 80% (w / w) and the SFA can be present in an amount of about 20% (w / w); the MCT can be present in an amount of about 85% (w / w) and the SFA can be present in an amount of about 15% (w / w); the MCT can be present in an amount of about 90% (w / w) and the SFA can be present in an amount of about 10% (w / w); the MCT can be present in an amount of about 95% (w / w) and the SFA can be present in an amount of about 5% (w / w); the MCT can be present in an amount of about 98% (w / w) and the SFA can be present in an amount of about 2% (w / w); the MCT can be present in an amount of about 99% (w / w) and the SFA can be present in an amount of about 1% (w / w); the MCT can be the only solvent and the MCT can be present in an amount of about 99% (w / w); the MCT can be the only solvent and the MCT can be present in an amount of about 99.present in an amount of 5% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.6% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.7% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.8% (w / w); MCT can be the only solvent and MCT can be present in an amount of about 99.9% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.5% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.6% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.7% (w / w); SFA can be the only solvent and SFA can be present in an amount of about 99.8% (w / w); or SFA can be the only solvent and SFA can be present in an amount of about 99.9% (w / w).

[0110] The compositions disclosed herein can be pharmaceutical compositions comprising an effective amount of a compound of formula (I), formula (II), or a pharmaceutically acceptable salt thereof, or a combination thereof; and a pharmaceutically acceptable carrier or solvent as described herein. In some embodiments, the composition can be a topical composition. In some embodiments, the composition can be a topical ophthalmic composition.

[0111] The pharmaceutical composition can also include one or more additional therapeutic agents, excipients, or diluents, including but not limited to absorbents, anti-irritants, preservatives, antioxidants, colorants / pigments, emollients (moisturizers), emulsifiers, film-forming / holding agents, prescription drugs, surfactants / detergent cleaners, penetration enhancers, viscosity enhancers, and thickening agents.

[0112] The pharmaceutical compositions of the present application can include those compositions suitable for any acceptable route of administration. Suitable examples of acceptable routes of administration include topical, ophthalmic, topical ophthalmic, and injection, among others.

[0113] The compositions and formulations described herein can conveniently be in unit dosage form or in multiple dosage forms. In some embodiments, the compositions and formulations described herein can conveniently be in dosage form (unit or multiple) that can be used with or in an automated drug delivery device or protocol.

[0114] In some embodiments, the composition is prepared by uniformly and tightly associating a compound of formula (I) or formula (II) as disclosed herein with a liquid solvent as disclosed herein.

[0115] In some embodiments, the topical compositions of the present disclosure can be prepared and used in the form of an aerosol spray, cream, lotion, solid, liquid, dispersion, foam, oil, gel, hydrogel, lotion, mousse, ointment, pomade, or solution. In some embodiments, the composition is in any form commonly used in the fields of cosmetic and skin care formulations. In some embodiments, the topical composition can be in the form of a lotion. In some embodiments, the topical composition can be in an organic solution. In some embodiments, the composition can be in the form of an organic composition that does not contain aqueous components.

[0116] In some embodiments, the topical composition is an ophthalmic composition, for example, for intravitreal administration. Suitable examples of ophthalmic compositions include eye drops, suspensions, ointments, lotions, nanoemulsions, oils, gels, hydrogels, and solutions. Any of these ophthalmic compositions can be directly administered to the cornea using, for example, a plastic or latex applicator (such as a disposable applicator), an eye dropper, a glass pipette, or a rubber bulb. These compositions can contain, for example, a semi-fluorinated alkane liquid solvent as described above, or an MCT liquid solvent, or a combination thereof.

[0117] In some embodiments, the topical composition is a cosmetic composition, for example, for topical administration to, for example, epidermal tissue, nails, or hair. Suitable examples of cosmetic compositions include suspensions, ointments, lotions, nanoemulsions, oils, gels, creams, mousses, sprays, hydrogels, and solutions. Any of these cosmetic compositions can be directly administered to the skin, hair, or nails using, for example, a plastic or latex applicator (such as a disposable applicator), a dropper, a cotton or fabric applicator, a sponge, a glass pipette, or a rubber bulb. These compositions can contain, for example, a semi-fluorinated alkane liquid solvent as described above, or an MCT liquid solvent, or a combination thereof.

[0118] The present disclosure also includes, for example, a pharmaceutical kit useful in the treatment of the conditions, diseases, and disorders described herein, which includes one or more containers containing a pharmaceutical composition that includes a therapeutically effective amount of a compound of the present disclosure. If desired, such a kit can further include one or more of various conventional pharmaceutical kit components, such as, for example, a container having one or more pharmaceutically acceptable carriers, additional containers, etc. Instructions indicating the amount of the components to be administered, guidelines for administration, and / or guidelines for mixing the components (either as an insert or as a label) can also be included in the kit. The kit can optionally include additional therapeutic agents as described herein.

[0119] In some embodiments, the kit can contain a dispensing device pre-filled with the composition as described herein.

[0120] The present disclosure also provides methods for crosslinking structural proteins using the compounds and compositions described herein. Structural proteins that can be photocrosslinked using the compounds, compositions, or methods described herein can include any structural protein that can be photocrosslinked in the presence of a reactive oxygen promoter. Exemplary structural proteins include, but are not limited to, collagen and collagen derivatives, keratin and keratin derivatives, and elastin and elastin derivatives, among others. As used herein, "collagen" includes, but is not limited to, collagen fibers or fibrils. As used herein, "keratin" includes, but is not limited to, keratin fibers or fibrils.

[0121] In some embodiments, the method can include contacting a structural protein or a biological tissue comprising a structural protein with an effective amount of a compound of formula (I) or formula (II) or a combination thereof, or with an effective amount of a composition comprising formula (I) or formula (II) or a combination thereof; and irradiating the structural protein or the tissue comprising the structural protein.

[0122] In some embodiments, provided are methods for crosslinking collagen in a tissue of a subject. In some embodiments, the method can include administering to the tissue of the subject an effective amount of a compound of formula (I) or formula (II) or a combination thereof, or an effective amount of a composition comprising formula (I) or formula (II) or a combination thereof; and irradiating the tissue.

[0123] In some embodiments, the irradiation can include irradiating with UV light (e.g., UVA light) or with blue light. In some embodiments, contacting the structural protein or the biological tissue comprising the structural protein can include, but is not limited to, topically applying the compound or composition to the protein or tissue, immersing the protein or tissue in the composition, spraying the protein or tissue with the compound or composition, and injecting the compound or composition into the tissue or into a matrix comprising the structural protein. In some embodiments, contacting the structural protein or the biological tissue comprising the structural protein can include administering an effective amount of a compound of formula (I) or formula (II) or a combination thereof, or an effective amount of a composition comprising formula (I) or formula (II) or a combination thereof, to a tissue within the body of a subject.

[0124] An effective amount of a compound of formula (I) or formula (II) or a combination thereof, or an effective amount of a composition comprising formula (I) or formula (II) or a combination thereof, can be administered to various body tissues or biological tissues. In some embodiments, exemplary body tissues or biological tissues can include, but are not limited to, collagenous tissue, keratinous tissue, corneal tissue, epithelial tissue, epidermal tissue, pericardial tissue, skin, hair, or nails. In some embodiments, the tissue can be within or on the body of a subject. In some embodiments, the tissue can be ex vivo or in vitro. In some embodiments, the tissue can be bovine or porcine tissue.

[0125] Also provided herein are methods for treating an ocular disease or condition using the compounds, compositions, and methods described herein. In some embodiments, the ocular disease or condition can be related to the cornea or corneal tissue. Exemplary non-limiting ocular diseases that can be treated with the compounds, compositions, and methods described herein include chemical burns or diseases selected from the group consisting of keratoconus, thin cornea, keratitis, infectious keratitis including bacterial or fungal keratitis, corneal ulcer, bullous keratopathy, and other forms of corneal edema, corneal ectasia, autoimmune diseases, cicatricial diseases such as ocular cicatricial pemphigoid, Stevens-Johnson syndrome, lupus erythematosus, rheumatoid arthritis, corneal ectasia including corneal ectasia that occurs after laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), post-refractive corneal ectasia, corneal degeneration, brittle cornea syndrome, Ehlers-Danlos syndrome type VI, corneal neovascularization, corneal melting including corneal melting in Boston type I keratoprosthesis, hyperopia, hyperopic astigmatism, myopia, astigmatism, myopic astigmatism, myopic regression, corneal dystrophy, corneal astigmatism, unstable cornea, or pellucid marginal degeneration (PMD).

[0126] In some embodiments, provided is a method for administering to the eye and / or corneal tissue of a subject an effective amount of a compound of formula (I) or formula (II) or a combination thereof, or an effective amount of a composition comprising a compound of formula (I) or formula (II) or a combination thereof; and irradiating at least a portion of the eye and / or corneal tissue with, for example, UV light or blue light. In some embodiments, the compound of formula (I) or formula (II) or a combination thereof, or the composition comprising a compound of formula (I) or formula (II) or a combination thereof, can be in the form of an eye drop. In some embodiments, the method can further comprise applying the eye drop to the eye of the subject. In some embodiments, the method can further comprise de-epithelializing at least a portion of the cornea. In some embodiments, the crosslinking method can be performed without de-epithelializing any portion of the cornea.

[0127] In some embodiments, the compounds, compositions, and methods described herein may be useful for crosslinking structural proteins in vitro in biological tissues or other forms. Exemplary in vitro applications include, but are not limited to, compositions, biomaterials, biomatrices, and biological tissues for experimental or in vitro use, or biomaterials, tissues, hydrogels, and matrices for applications directed to wound healing, tissue regeneration, tissue engineering, or drug delivery, and compositions, biomatrices, and biological tissues, for example, intended for use in hydrogels, biological scaffolds, surgical implants, bioprosthetics, grafts, and transplants. Exemplary biomaterials include, but are not limited to, natural or synthetic variants of heart valves, corneal grafts, arterial prostheses, arterial grafts, wound healing matrices or grafts, skin grafts, vascular grafts, and transdermal drug delivery devices or patches, among others. In some embodiments, these biomaterials may also be photocrosslinked in or on the body of a subject using the compounds, compositions, and methods described herein, for example, during or after delivery of the biomaterial to the subject, such as by surgery or other delivery methods.

[0128] The invention will be further described in the following examples, which do not limit the scope of the invention.

[0129] It should be understood that although the invention has been described in connection with the detailed description thereof, the foregoing description is intended to be illustrative and not limiting of the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the appended claims.

[0130] Examples

[0131] Example 1a - Solubility of Riboflavin in Organic Solvents

[0132] The solubility of riboflavin was tested in medium-chain triglycerides (MCT), F6H8, or a mixture of MCT / F6H8 at 100 °C. Solubility was determined by HPLC according to the conditions outlined in Table 1.

[0133] Table 1. Chromatographic Conditions

[0134]

[0135] The results are shown in Table 1a below:

[0136] Table 1a. Solubility of Riboflavin in Organic Solvents

[0137]

[0138] Example 1b - Solubility of Riboflavin Tetrabutyrate in MCT, F6H8, or Mixed Solvents

[0139] The solubility of riboflavin tetrabutyrate (RTB) was tested at room temperature in medium-chain triglycerides (MCT), F6H8, or a mixture of MCT / F6H8, and in F6H8 at 100 °C. The solubility was analyzed as described in Example 1a.

[0140] The results are shown in Table 1b below:

[0141] Table 1b. Solubility of RTB in Organic Solvents

[0142]

[0143] Example 1c - Aqueous Solubility of Riboflavin Tetrabutyrate

[0144] The solubility of riboflavin tetrabutyrate (RTB) was tested in PBS solutions with or without 10% hydroxypropyl-β-cyclodextrin (HP-β-CD) as a solubilizer at different pH values. For each formulation, 5 mg of RTB was added to 5 mL of pH-adjusted PBS containing 10% HP-β-CD at 25 °C and mixed well. The solubility was analyzed as described in Example 1a. The results are shown in Table 1c below:

[0145] Table 1c. Saturated Aqueous Solubility of RTB

[0146]

[0147]

[0148] Example 2 - Stability of Riboflavin Tetrabutyrate in Organic Solvents

[0149] The stability of riboflavin tetrabutyrate (RTB) in various solvents was studied. Using a similar sample analysis method as described in Examples 1a - 1c, the stability of RTB in MCT, F6H8, and combined formulations was monitored at various temperatures. The results are summarized in Table 2 below.

[0150] Table 2. Stability of Riboflavin Tetrabutyrate in Organic Solvents

[0151]

[0152] Example 3a - Impurities from Riboflavin Tetrabutyrate in Aqueous Solution

[0153] The impurities present in PBS solutions containing riboflavin tetrabutyrate (RTB) with or without 10% hydroxypropyl-β-cyclodextrin (HP-β-CD) as a solubilizer at different pH values were studied. The impurities were determined using a similar sample analysis method as described in Examples 1a - 1c. The results are summarized in Table 3a below.

[0154] Table 3a. Impurities from riboflavin tetrabutyrate in aqueous solutions

[0155] Sample number HP-β-CD pH Riboflavin tetrabutyrate Other impurities Riboflavin YA1 10％ 5.0 96.28％ 2.94％ 0％ YA2 10％ 6.0 87.2％ 10.65％ 2.45％ YA3 10％ 7.0 88.58％ 9.39％ 2.03％ YA4 - 5.0 70.22％ 22.54％ 7.24％ YA5 - 6.0 71.90％ 20.58％ 7.52％ YA6 - 7.0 71.30％ 19.8％ 8.92％

[0156] Example 3b - Impurities from riboflavin tetrabutyrate in organic solvents

[0157] The impurities present in MCT, F6H8, or combinations containing riboflavin tetrabutyrate (RTB) at 25 °C were studied. The impurities were determined using a similar sample analysis method as described in Examples 1a - 1c. The results are summarized in Table 3b below.

[0158] Table 3b. Impurities from riboflavin tetrabutyrate in organic solvents

[0159]

[0160] Example 3 - In vitro study (Dresden method)

[0161] Based on Gregor Wollensak, Eberhard Spoerl, Theo Seiler. Riboflavin / ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. May 2003; 135(5):620 - 7.

[0162] Fresh porcine cadaver eyes with intact epithelium and clear corneas were retrieved from a local abattoir within 2 to 5 hours post-mortem. The eyes were mechanically de-epithelialized and the corneoscleral ring was removed with scissors. Using a self-made double-edged scalpel, 1 corneal strip with a width of 5.0 mm, a central corneal thickness of 850 μm, and a length of 14.0 mm including 1.0 mm of sclera at both ends was cut in a superior-inferior manner from the 12 o'clock position of the cornea (identified by its elliptical shape). Due to the natural thickness of the porcine cornea, only 1 corneal strip with clearly cut perpendicular edges could be properly prepared from each eye. Half of the corneas were treated with RTB-UVA irradiation and half were used as untreated controls. The central corneal thickness was determined in the eyes using an ultrasonic pachymeter (Pachette, Technomed).

[0163] Treatment

[0164] Starting 5 minutes before treatment, a 0.1% riboflavin tetrabutyrate (RTB) photosensitizer solution (10 mg riboflavin tetrabutyrate in 10 mL of MCT or F6H8 or a combination thereof) was dropped onto the treatment strip at 5-minute intervals and the MCT or F6H8 or combined solution was dropped onto the control strip. Ultraviolet A irradiation (370 nm) was applied using 2 double UVA diodes (Roithner Lasertechnik) at an irradiance of 3 mW / cm2 at a distance of 1.0 cm from the cornea for 30 minutes. This amounts to a dose of 5.4 J / cm2. The exposure parameters were selected according to the treatment protocol used for keratoconus patients. Three 1.3 V batteries were used as generators. Before treatment, the desired irradiance of 3 mW / cm2 was controlled with a calibrated UVA meter (LaserMate-Q, Laser2000) at a distance of 1.0 cm and adjusted with a potentiometer as needed.

[0165] Static stress-strain measurement

[0166] Porcine corneal strips were clamped horizontally at a distance of 8.0 mm between the jaws of a commercially available microcomputer-controlled biomaterial tester (Minimat, Rheometric Scientific GmbH). To include the physiological stress range, a prestress of 5×10 3 Pa (1 Pa = 1 N / m2) was used, which requires a force of 20 mN in porcine corneas. Then the strain was linearly increased at a rate of 1.5 mm min -1 −1, and the stress was measured up to 2×10 5 Pa. The stress-strain values were fitted by an exponential function σ = Aexp(B×ε) using the SPSS calculation program (SPSS GmbH Software, Munich). The Young's modulus (E) at 4%, 6%, and 8% strain was calculated as the gradient of the stress-strain plot (E = dσ / dε = A×B exp(B×ε)).

[0167] Statistical evaluation

[0168] Student's t-test was used to compare the stress data required for 4%, 6%, and 8% strain in treated and untreated corneas.

[0169] Result

[0170] Stress-strain curve

[0171] The stress-strain curve shows a typical exponential growth of a bio-viscoelastic solid. In porcine corneas, the stress using strain is greater in the treated corneas and smaller in the untreated corneas, corresponding to the increase in the treated corneas.

[0172] No epithelialization

[0173] Similar experiments were repeated on intact porcine eyes except that the corneas were not de-epithelialized. The RTB formulation in MCT or F6H8 was applied to half of the intact eyes and these eyes were treated with UVA radiation. After application and treatment, 1 corneal strip was retrieved from each treated and untreated eye according to the procedure described above. Corneal thickness and stress / strain measurements were obtained according to the procedure described above. In porcine corneas, the stress using strain is greater in the treated corneas and smaller in the untreated corneas, corresponding to the increase in the treated corneas.

[0174] Other embodiments

[0175] It should be understood that although the present invention has been described in connection with the detailed description of the invention, the foregoing description is intended to be illustrative and not to limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages and modifications are within the scope of the appended claims.

[0176] Embodiment 1 is a composition comprising:

[0177] A compound of formula I:

[0178]

[0179] Wherein:

[0180] R1, R2 and R3 are each independently selected from hydrogen or -C(O)R 5 ;

[0181] R4 is selected from hydrogen, -C(O)R 5 , phosphate, or a salt thereof; and

[0182] R5 is a straight-chain, branched-chain or cyclic alkyl having 1 to 26 carbon atoms; and

[0183] A solvent selected from medium-chain triglycerides (MCT), perfluorinated alkanes, or a combination thereof.

[0184] Embodiment 2 is the composition of Embodiment 1, wherein the MCT is a triglyceride of a fatty acid, and the fatty acid is selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid, and combinations thereof.

[0185] Embodiment 3 is a composition according to any one of Embodiments 1 or 2, wherein the semi-fluorinated alkane compound has the formula RFRH or the formula RFRHRF; RF is a perfluorinated hydrocarbon having 1 to 15 carbon atoms, and wherein RH is a non-fluorinated hydrocarbon having 1 to 15 carbon atoms.

[0186] Embodiment 4 is a composition according to any one of Embodiments 1 to 3, wherein the semi-fluorinated alkane is selected from perfluorobutylbutane (F4H4), perfluorobutylpentane (F4H5), perfluorobutylhexane (F4H6), perfluorohexylethane (F6H2), perfluorohexylbutane (F6H4), perfluorohexyl octane (F6H8), and perfluorohexyl decane (F6H10); preferably, perfluorohexylhexane (F6H6) and perfluorohexyl octane (F6H8).

[0187] Embodiment 5 is a composition according to any one of Embodiments 1 to 4, wherein the semi-fluorinated alkane is perfluorohexyl octane (F6H8).

[0188] Embodiment 6 is a composition according to any one of Embodiments 1 to 5, wherein the compound of formula I is present in an amount of from about 0.001% to about 1% (w / w), from about 0.01% to about 1% (w / w), from about 0.05% to about 0.5% (w / w), about 0.01% (w / w), 0.02% (w / w), 0.03% (w / w), 0.04% (w / w), 0.05% (w / w), 0.06% (w / w), 0.07% (w / w), 0.08% (w / w), 0.09% (w / w), 0.1% (w / w), 0.2% (w / w), 0.3% (w / w), 0.4% (w / w), 0.5% (w / w), 0.6% (w / w), 0.7% (w / w), 0.8% (w / w), 0.9% (w / w), or 1% (w / w).

[0189] Embodiment 7 is a composition according to any one of Embodiments 1 to 6, wherein the MCT is present in an amount of: from about 0% to about 99.9% (w / w), from about 0% to about 80% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0190] Embodiment 8 is a composition according to any one of Embodiments 1 to 7, wherein the semi-fluorinated alkane is present in an amount of from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0191] Embodiment 9 is a composition according to any one of Embodiments 1 to 8, wherein the MCT is present in an amount of about 1% (w / w) and the SFA is present in an amount of about 99% (w / w), wherein the MCT is present in an amount of about 2% (w / w) and the SFA is present in an amount of about 98% (w / w), wherein the MCT is present in an amount of about 5% (w / w) and the SFA is present in an amount of about 95% (w / w), wherein the MCT is present in an amount of about 10% (w / w) and the SFA is present in an amount of about 90% (w / w), wherein the MCT is present in an amount of about 15% (w / w) and the SFA is present in an amount of about 85% (w / w), wherein the MCT is present in an amount of about 20% (w / w) and the SFA is present in an amount of about 80% (w / w), wherein the MCT is present in an amount of about 25% (w / w) and the SFA is present in an amount of about 75% (w / w), wherein the MCT is present in an amount of about 30% (w / w) and the SFA is present in an amount of about 70% (w / w), wherein the MCT is present in an amount of about 35% (w / w) and the SFA is present in an amount of about 65% (w / w), wherein the MCT is present in an amount of about 40% (w / w) and the SFA is present in an amount of about 60% (w / w), wherein the MCT is present in an amount of about 45% (w / w) and the SFA is present in an amount of about 55% (w / w), wherein the MCT is present in an amount of about 50% (w / w) and the SFA is present in an amount of about 50% (w / w), wherein the MCT is present in an amount of about 55% (w / w) and the SFA is present in an amount of about 45% (w / w), wherein the MCT is present in an amount of about 60% (w / w) and the SFA is present in an amount of about 40% (w / w), wherein the MCT is present in an amount of about 65% (w / w) and the SFA is present in an amount of about 35% (w / w), wherein the MCT is present in an amount of about 70% (w / w) and the SFA is present in an amount of about 30% (w / w), wherein the MCT is present in an amount of about 75% (w / w) and the SFA is present in an amount of about 25% (w / w), wherein the MCT is present in an amount of about 80% (w / w) and the SFA is present in an amount of about 20% (w / w), wherein the MCT is present in an amount of about 85% (w / w) and the SFA is present in an amount of about 15% (w / w), wherein the MCT is present in an amount of about 90% (w / w) and the SFA is present in an amount of about 10% (w / w), wherein the MCT is present in an amount of about 95% (w / w) and the SFA is present in an amount of about 5% (w / w), wherein the MCT is present in an amount of about 98% (w / w) and the SFA is present in an amount of about 2% (w / w), wherein the MCT is present in an amount of about 99% (w / w) and the SFA is present in an amount of about 1% (w / w), wherein the MCT is the only solvent and the MCT is present in an amount of about 99% (w / w), wherein the MCT is the only solvent and the MCT is present in an amount of about 99.5% (w / w), wherein the MCT is the only solvent and the MCT is present in an amount of about 99.Present in an amount of 6% (w / w), wherein MCT is the only solvent and MCT is present in an amount of about 99.7% (w / w), wherein MCT is the only solvent and MCT is present in an amount of about 99.8% (w / w), wherein MCT is the only solvent and MCT is present in an amount of about 99.9% (w / w), wherein SFA is the only solvent and SFA is present in an amount of about 99% (w / w), wherein SFA is the only solvent and SFA is present in an amount of about 99.5% (w / w), wherein SFA is the only solvent and SFA is present in an amount of about 99.6% (w / w), wherein SFA is the only solvent and SFA is present in an amount of about 99.7% (w / w), wherein SFA is the only solvent and SFA is present in an amount of about 99.8% (w / w), or wherein SFA is the only solvent and SFA is present in an amount of about 99.9% (w / w).

[0192] Embodiment 10 is a composition according to any one of Embodiments 1 to 9, wherein:

[0193] R1, R2, R3 and R4 are each independently selected from hydrogen or -C(O)R 5 ;

[0194] R5 is a straight-chain, branched-chain or cyclic alkyl group having 1 to 26 carbon atoms; and

[0195] At least one of R1, R2, R3 and R4 is -C(O)R 5 , at least two of R1, R2, R3 and R4 are -C(O)R 5 , or at least three of R1, R2, R3 and R4 are -C(O)R 5 .

[0196] Embodiment 11 is a composition according to any one of Embodiments 1 to 10, wherein:

[0197] R1, R2, R3 and R4 are each independently -C(O)R 5 ; and

[0198] R5 is a straight-chain, branched-chain or cyclic alkyl group having 1 to 26 carbon atoms.

[0199] Embodiment 12 is a composition according to any one of Embodiments 1 to 11, wherein:

[0200] R1, R2, R3 and R4 are each independently selected from hydrogen or -C(O)R5;

[0201] At least one of R1, R2, R3 and R4 is -C(O)R 5 , at least two of R1, R2, R3 and R4 are -C(O)R 5or at least three of R1, R2, R3 and R4 are -C(O)R 5 ; and

[0202] R5 is selected from straight-chain or branched-chain alkyl groups having 1 to 3 or 15 carbon atoms.

[0203] Embodiment 13 is a composition according to any one of Embodiments 1 to 12, wherein R1, R2, R3 and R4 are each independently -C(O)R5, and wherein R5 is selected from straight-chain or branched-chain alkyl groups having 1 to 3 or 15 carbon atoms.

[0204] Embodiment 14 is a composition according to any one of Embodiments 1 to 12, wherein the compound of Formula I is selected from riboflavin tetraacetate, riboflavin tetrapropionate, riboflavin tetrabutyrate, riboflavin tetrapalmitate, or a combination thereof.

[0205] Embodiment 15 is a composition according to any one of Embodiments 1 to 14, wherein the composition consists essentially of a compound of Formula I and a solvent.

[0206] Embodiment 16 is a composition according to any one of Embodiments 1 to 15, wherein the composition is an organic composition that does not contain an aqueous component.

[0207] Embodiment 17 is a composition according to any one of Embodiments 1 to 16, wherein the composition is a topical composition or a topical ophthalmic composition, and wherein the composition is a solution, a suspension, or an emulsion.

[0208] Embodiment 18 is a composition according to any one of Embodiments 1 to 17, wherein the composition further comprises a viscosity enhancer.

[0209] Embodiment 19 is a method for crosslinking collagen in a tissue of a subject, comprising:

[0210] administering a compound of Formula II to the tissue of the subject:

[0211]

[0212] wherein:

[0213] R6, R7, R8 and R9 are each independently selected from hydrogen or -C(O)R5;

[0214] at least one of R6, R7, R8 and R9 is -C(O)R5; and

[0215] R5 is selected from straight-chain, branched-chain or cyclic alkyl groups having 1 to 26 carbon atoms; and

[0216] irradiating the tissue with UV radiation or blue light.

[0217] Embodiment 20 is a method for crosslinking a structural protein, which comprises:

[0218] contacting a structural protein or a biological tissue containing a structural protein with a compound of Formula II:

[0219]

[0220] wherein:

[0221] R6, R7, R8 and R9 are each independently selected from hydrogen or -C(O)R5;

[0222] at least one of R6, R7, R8 and R9 is -C(O)R5; and

[0223] R5 is selected from straight-chain, branched-chain or cyclic alkyl having 1 to 26 carbon atoms; and

[0224] irradiating the structural protein or tissue with UV radiation or blue light.

[0225] Embodiment 21 is the method of any one of Embodiments 19 or 20, wherein for Formula II:

[0226] R1, R2, R3 and R4 are each independently selected from hydrogen or -C(O)R 5 ;

[0227] R5 is selected from straight-chain, branched-chain or cyclic alkyl having 1 to 26 carbon atoms; and

[0228] at least one of R1, R2, R3 and R4 is -C(O)R 5 , at least two of R1, R2, R3 and R4 are -C(O)R 5 , or at least three of R1, R2, R3 and R4 are -C(O)R 5 .

[0229] Embodiment 22 is the method of any one of Embodiments 19 to 21, wherein:

[0230] R1, R2, R3 and R4 are each independently -C(O)R 5 ; and

[0231] R5 is selected from straight-chain, branched-chain or cyclic alkyl having 1 to 26 carbon atoms.

[0232] Embodiment 23 is the method of any one of Embodiments 19 to 21, wherein:

[0233] R1, R2, R3 and R4 are each independently selected from hydrogen or -C(O)R5;

[0234] at least one of R1, R2, R3 and R4 is -C(O)R5 , at least two of R1, R2, R3 and R4 are -C(O)R 5 , or at least three of R1, R2, R3 and R4 are -C(O)R 5 ; and

[0235] R5 is selected from straight-chain or branched-chain alkyl groups having 1 to 3 or 15 carbon atoms.

[0236] Embodiment 24 is the method of any one of Embodiments 19 to 23, wherein R1, R2, R3 and R4 are each independently -C(O)R5, and wherein R5 is selected from straight-chain or branched-chain alkyl groups having 1 to 3 or 15 carbon atoms.

[0237] Embodiment 25 is the method of any one of Embodiments 19 to 23, wherein the compound of Formula II is selected from riboflavin tetraacetate, riboflavin tetrapropionate, riboflavin tetrabutyrate, riboflavin tetrapalmitate, or a combination thereof.

[0238] Embodiment 26 is the method of any one of Embodiments 19 to 25, wherein the structural protein is selected from collagen, keratin, derivatives thereof, and combinations thereof.

[0239] Embodiment 27 is the method of any one of Embodiments 19 to 26, wherein the structural protein is present in a biological tissue or in or on the body of a subject.

[0240] Embodiment 28 is the method of any one of Embodiments 19 to 27, wherein the biological tissue is ex vivo.

[0241] Embodiment 29 is the method of any one of Embodiments 19 to 27, wherein the biological tissue is in or on the body of a subject.

[0242] Embodiment 30 is the method of any one of Embodiments 19 to 29, wherein contacting the structural protein or contacting the tissue comprises administering the compound of Formula II to a tissue within the body of a subject.

[0243] Embodiment 31 is the method of any one of Embodiments 19 to 30, wherein the tissue is selected from collagenous tissue, epidermal tissue, keratinous tissue, or a combination thereof.

[0244] Embodiment 32 is the method of Claim 31, wherein the keratinous tissue is selected from hair or nails.

[0245] Embodiment 33 is the method of any one of Embodiments 19 to 32, wherein administering the compound of Formula II to the tissue comprises administering a composition comprising the compound of Formula II, and wherein the composition further comprises a solvent.

[0246] Embodiment 34 is the method of claim 33, wherein the solvent is selected from medium-chain triglycerides (MCTs), perfluorinated alkanes, or combinations thereof.

[0247] Embodiment 35 is the method of claim 34, wherein the MCT is a triglyceride of fatty acids, and the fatty acids are selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid, and combinations thereof.

[0248] Embodiment 36 is the method of any one of embodiments 34 or 35, wherein the perfluorinated alkane compound has the formula RFRH or the formula RFRHRF; RF is a perfluorinated hydrocarbon having 1 to 15 carbon atoms, and wherein RH is a non-fluorinated hydrocarbon having 1 to 15 carbon atoms.

[0249] Embodiment 37 is the method of any one of embodiments 34 to 36, wherein the perfluorinated alkane is selected from perfluorobutylbutane (F4H4), perfluorobutylpentane (F4H5), perfluorobutylhexane (F4H6), perfluorohexylethane (F6H2), perfluorohexylbutane (F6H4), perfluorohexyl octane (F6H8), and perfluorohexyl decane (F6H10); preferably, perfluorohexylhexane (F6H6) and perfluorohexyl octane (F6H8).

[0250] Embodiment 38 is the composition of any one of embodiments 34 to 37, wherein the perfluorinated alkane is perfluorohexyl octane (F6H8).

[0251] Embodiment 39 is the method of any one of embodiments 33 to 38, wherein the compound of formula II is present in an amount of from about 0.001% to about 1% (w / w), from about 0.01% to about 1% (w / w), from about 0.05% to about 0.5% (w / w), about 0.01% (w / w), 0.02% (w / w), 0.03% (w / w), 0.04% (w / w), 0.05% (w / w), 0.06% (w / w), 0.07% (w / w), 0.08% (w / w), 0.09% (w / w), 0.1% (w / w), 0.2% (w / w), 0.3% (w / w), 0.4% (w / w), 0.5% (w / w), 0.6% (w / w), 0.7% (w / w), 0.8% (w / w), 0.9% (w / w), or 1% (w / w).

[0252] Embodiment 40 is the method of any one of Embodiments 34 to 39, wherein the MCT is present in an amount of: from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0253] Embodiment 41 is the method of any one of Embodiments 34 to 40, wherein the semi-fluorinated alkane is present in an amount of from about 0% to about 99.9% (w / w), from about 0.1% to about 99.9% (w / w), from about 0.1% to about 30% (w / w), from about 1% to about 25% (w / w), from about 1% to about 20% (w / w), from about 5% to about 20% (w / w), from about 5% to about 15% (w / w), from about 10% to about 99.9% (w / w), from about 20% to about 99.9% (w / w), from about 30% to about 99.9% (w / w), from about 40% to about 99.9% (w / w), from about 50% to about 99.9% (w / w), from about 60% to about 99.9% (w / w), from about 65% to about 99.9% (w / w), from about 70% to about 99.9% (w / w), from about 75% to about 99.9% (w / w), from about 80% to about 99.9% (w / w), from about 85% to about 99.9% (w / w), from about 90% to about 99.9% (w / w), from about 95% to about 99.9% (w / w), from about 98% to about 99.9% (w / w), from about 20% to about 80% (w / w), from about 20% to about 70% (w / w), from about 20% to about 60% (w / w), from about 20% to about 50% (w / w), from about 20% to about 40% (w / w), from about 20% to about 30% (w / w), from about 30% to about 80% (w / w), from about 40% to about 80% (w / w), from about 50% to about 80% (w / w), from about 60% to about 80% (w / w), from about 70% to about 80% (w / w), about 99.9% (w / w), about 99% (w / w), about 98% (w / w), about 97% (w / w), about 96% (w / w), about 95% (w / w), about 94% (w / w), about 93% (w / w), about 92% (w / w), about 91% (w / w), about 90% (w / w), about 85% (w / w), about 80% (w / w), about 75% (w / w), about 70% (w / w), about 65% (w / w), about 60% (w / w), about 55% (w / w), about 50% (w / w), about 45% (w / w), about 40% (w / w), about 35% (w / w), about 30% (w / w), about 25% (w / w), about 20% (w / w), about 15% (w / w), about 10% (w / w), about 9% (w / w), about 8% (w / w), about 7% (w / w), about 6% (w / w), about 5% (w / w), about 4% (w / w), about 3% (w / w), about 2% (w / w), about 1% (w / w), about 0.5% (w / w), or about 0.1% (w / w).

[0254] Embodiment 42 is the method of any one of Embodiments 34 to 41, wherein the MCT is present in an amount of about 1% (w / w) and the SFA is present in an amount of about 99% (w / w), wherein the MCT is present in an amount of about 2% (w / w) and the SFA is present in an amount of about 98% (w / w), wherein the MCT is present in an amount of about 5% (w / w) and the SFA is present in an amount of about 95% (w / w), wherein the MCT is present in an amount of about 10% (w / w) and the SFA is present in an amount of about 90% (w / w), wherein the MCT is present in an amount of about 15% (w / w) and the SFA is present in an amount of about 85% (w / w), wherein the MCT is present in an amount of about 20% (w / w) and the SFA is present in an amount of about 80% (w / w), wherein the MCT is present in an amount of about 25% (w / w) and the SFA is present in an amount of about 75% (w / w), wherein the MCT is present in an amount of about 30% (w / w) and the SFA is present in an amount of about 70% (w / w), wherein the MCT is present in an amount of about 35% (w / w) and the SFA is present in an amount of about 65% (w / w), wherein the MCT is present in an amount of about 40% (w / w) and the SFA is present in an amount of about 60% (w / w), wherein the MCT is present in an amount of about 45% (w / w) and the SFA is present in an amount of about 55% (w / w), wherein the MCT is present in an amount of about 50% (w / w) and the SFA is present in an amount of about 50% (w / w), wherein the MCT is present in an amount of about 55% (w / w) and the SFA is present in an amount of about 45% (w / w), wherein the MCT is present in an amount of about 60% (w / w) and the SFA is present in an amount of about 40% (w / w), wherein the MCT is present in an amount of about 65% (w / w) and the SFA is present in an amount of about 35% (w / w), wherein the MCT is present in an amount of about 70% (w / w) and the SFA is present in an amount of about 30% (w / w), wherein the MCT is present in an amount of about 75% (w / w) and the SFA is present in an amount of about 25% (w / w), wherein the MCT is present in an amount of about 80% (w / w) and the SFA is present in an amount of about 20% (w / w), wherein the MCT is present in an amount of about 85% (w / w) and the SFA is present in an amount of about 15% (w / w), wherein the MCT is present in an amount of about 90% (w / w) and the SFA is present in an amount of about 10% (w / w), wherein the MCT is present in an amount of about 95% (w / w) and the SFA is present in an amount of about 5% (w / w), wherein the MCT is present in an amount of about 98% (w / w) and the SFA is present in an amount of about 2% (w / w), wherein the MCT is present in an amount of about 99% (w / w) and the SFA is present in an amount of about 1% (w / w), wherein the MCT is the only solvent and the MCT is present in an amount of about 99% (w / w), wherein the MCT is the only solvent and the MCT is present in an amount of about 99.5% (w / w), wherein the MCT is the only solvent and the MCT is present in an amount of about 99.Present in an amount of 6% (w / w), where MCT is the only solvent and MCT is present in an amount of about 99.7% (w / w), where MCT is the only solvent and MCT is present in an amount of about 99.8% (w / w), where MCT is the only solvent and MCT is present in an amount of about 99.9% (w / w), where SFA is the only solvent and SFA is present in an amount of about 99% (w / w), where SFA is the only solvent and SFA is present in an amount of about 99.5% (w / w), where SFA is the only solvent and SFA is present in an amount of about 99.6% (w / w), where SFA is the only solvent and SFA is present in an amount of about 99.7% (w / w), where SFA is the only solvent and SFA is present in an amount of about 99.8% (w / w), or where SFA is the only solvent and SFA is present in an amount of about 99.9% (w / w).

[0255] Embodiment 43 is the method of any one of embodiments 33 to 42, wherein the composition consists essentially of a compound of formula II and a solvent.

[0256] Embodiment 44 is the method of any one of embodiments 33 to 43, wherein the composition is an organic composition free of aqueous components.

[0257] Embodiment 45 is the method of any one of embodiments 43 to 44, wherein the composition is a topical composition or a topical ocular composition, and wherein the composition is a solution, suspension or emulsion.

[0258] Embodiment 46 is the method of any one of embodiments 19 to 31 or 33 to 45, wherein the tissue is corneal tissue.

[0259] Embodiment 47 is the method of claim 46, wherein the subject has a chemical burn or a disease selected from: keratoconus, thin cornea, keratitis, infectious keratitis including bacterial or fungal keratitis, corneal ulcer, bullous keratopathy and other forms of corneal edema, corneal dehiscence, autoimmune diseases, cicatricial diseases such as ocular cicatricial pemphigoid, Stevens-Johnson syndrome, lupus erythematosus, rheumatoid arthritis, corneal ectasia including corneal ectasia occurring after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), post-refractive corneal ectasia, corneal degeneration, brittle cornea syndrome, Ehlers-Danlos syndrome type VI, corneal neovascularization, corneal melting including corneal melting in Boston keratoprosthesis type I, hyperopia, hyperopic astigmatism, myopia, astigmatism, myopic astigmatism, myopic regression, corneal disease, corneal astigmatism, unstable cornea or pellucid marginal degeneration (PMD).

[0260] Embodiment 48 is the method of any one of embodiments 46 to 47, wherein the composition is in the form of an eye drop, and the method further comprises applying the eye drop to the eye of a subject.

[0261] Embodiment 49 is the method of any one of embodiments 46 to 48, which further comprises de-epithelializing at least a portion of the cornea.

[0262] Embodiment 50 is the method of any one of embodiments 46 to 48, wherein the crosslinking is performed without de-epithelializing any part of the cornea.

[0263] Embodiment 51 is a method for crosslinking collagen in a subject's tissue, which comprises:

[0264] administering the composition of any one of embodiments 1 to 18 to the subject's tissue; and

[0265] irradiating the subject's tissue with UV radiation or blue light.

[0266] Embodiment 52 is a method for crosslinking a structural protein, which comprises:

[0267] contacting the structural protein or a biological tissue containing the structural protein with the composition of any one of embodiments 1 to 18; and

[0268] irradiating the structural protein or the subject's tissue with UV radiation or blue light.

[0269] Embodiment 53 is the method of any one of embodiments 51 to 52, wherein the structural protein is present in a biological tissue or in or on the body of the subject.

[0270] Embodiment 54 is the method of any one of embodiments 51 to 53, wherein the biological tissue is ex vivo.

[0271] Embodiment 55 is the method of any one of embodiments 51 to 53, wherein the biological tissue is in or on the body of the subject.

[0272] Embodiment 56 is the method of any one of embodiments 51 to 55, wherein contacting the structural protein or contacting the tissue comprises administering the composition to the tissue in the body of the subject.

[0273] Embodiment 57 is the method of any one of embodiments 51 to 56, wherein the tissue is selected from collagenous tissue, epidermal tissue or keratinous tissue.

[0274] Embodiment 58 is the method of claim 57, wherein the keratinous tissue is selected from hair or nails.

[0275] Embodiment 59 is the method of any one of Embodiments 51 to 56, wherein the tissue is corneal tissue.

[0276] Embodiment 60 is the method of Claim 59, wherein the subject has a chemical burn or a disease selected from the following: keratoconus, thin cornea, keratitis, infectious keratitis including bacterial or fungal keratitis, corneal ulcer, bullous keratopathy and other forms of corneal edema, corneal dehiscence, autoimmune diseases, cicatricial diseases such as ocular cicatricial pemphigoid, Stevens-Johnson syndrome, lupus erythematosus, rheumatoid arthritis, corneal ectasia including corneal ectasia occurring after laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), post-refractive corneal ectasia, corneal degeneration, brittle cornea syndrome, Ehlers-Danlos syndrome type VI, corneal neovascularization, corneal melting including corneal melting in Boston type I artificial cornea, hyperopia, hyperopic astigmatism, myopia, astigmatism, myopic astigmatism, myopic regression, corneal disease, corneal astigmatism, unstable cornea or pellucid marginal degeneration (PMD).

[0277] Embodiment 61 is the method of any one of Embodiments 59 to 60, wherein the composition is in the form of an eye drop, and the method further comprises applying the eye drop to the eye of the subject.

[0278] Embodiment 62 is the method of any one of Embodiments 59 to 61, which further comprises de-epithelializing at least a part of the cornea.

[0279] Embodiment 63 is the method of any one of Embodiments 59 to 61, wherein the crosslinking is carried out without de-epithelializing any part of the cornea.

[0280] Embodiment 64 is a method for crosslinking collagen in the cornea of a subject, comprising:

[0281] administering to at least a part of the cornea of the subject the composition of any one of Embodiments 1 to 18; and

[0282] irradiating at least a part of the cornea of the subject with UV radiation or blue light.

[0283] Embodiment 65 is the method of claim 64, wherein the subject has a chemical burn or a disease selected from the following: keratoconus, thin cornea, keratitis, infectious keratitis including bacterial or fungal keratitis, corneal ulcer, bullous keratopathy and other forms of corneal edema, corneal epithelial detachment, autoimmune diseases, cicatricial diseases such as ocular cicatricial pemphigoid, Stevens-Johnson syndrome, lupus erythematosus, rheumatoid arthritis, corneal ectasia including corneal ectasia occurring after laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), post-refractive corneal ectasia, corneal degeneration, brittle cornea syndrome, Ehlers-Danlos syndrome type VI, corneal neovascularization, corneal melting including corneal melting in Boston type I keratoprosthesis, hyperopia, hyperopic astigmatism, myopia, astigmatism, myopic astigmatism, myopic regression, corneal disease, corneal astigmatism, unstable cornea or pellucid marginal degeneration (PMD).

[0284] Embodiment 66 is the method of any one of embodiments 64 to 65, wherein the composition is in the form of an eye drop, and the method further comprises applying the eye drop to the eye of the subject.

[0285] Embodiment 67 is the method of any one of embodiments 64 to 66, which further comprises de-epithelializing at least a part of the cornea.

[0286] Embodiment 68 is the method of any one of embodiments 64 to 66, wherein the crosslinking is carried out without de-epithelializing any part of the cornea.

[0287] Embodiment 69 is the composition of any one of embodiments 1 to 18, or the method of any one of embodiments 33 to 63 or 64 to 69, wherein the composition does not contain preservatives or does not contain ocular irritants.

Claims

1. A composition, comprising: A compound of formula I: Wherein: R1, R2, and R3 are each independently selected from hydrogen or -C(O)R 5 ; R4 is selected from hydrogen, -C(O)R 5 , phosphate, or a salt thereof; and R5 is a straight-chain, branched-chain or cyclic alkyl group having 1 to 26 carbon atoms; and A solvent selected from medium-chain triglycerides (MCTs), perfluorinated alkanes or combinations thereof.

2. The composition according to claim 1, wherein the MCT is a triglyceride of fatty acids, and the fatty acids are selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid and combinations thereof.

3. The composition according to any one of claims 1 to 2, wherein the perfluorinated alkane is selected from perfluorobutylbutane (F4H4), perfluorobutylpentane (F4H5), perfluorobutylhexane (F4H6), perfluorohexylethane (F6H2), perfluorohexylbutane (F6H4), perfluorohexyl octane (F6H8) and perfluorohexyl decane (F6H10); preferably, perfluorohexylhexane (F6H6) and perfluorohexyl octane (F6H8).

4. The composition according to any one of claims 1 to 3, wherein the compound of formula I is present in an amount from about 0.001% to about 1% (w / w), the MCT is present in an amount from about 0.1% to about 99.9% (w / w), and the perfluorinated alkane is present in an amount from about 0.1% to about 99.9% (w / w).

5. The composition according to any one of claims 1 to 4, wherein: R1, R2, R3, and R4 are each independently selected from hydrogen or -C(O)R 5 ; R5 is a straight-chain, branched-chain or cyclic alkyl group having 1 to 26 carbon atoms; and At least one of R1, R2, R3, and R4 is -C(O)R 5 , at least two of R1, R2, R3, and R4 are -C(O)R 5 , or at least three of R1, R2, R3, and R4 are -C(O)R 5 .

6. The composition according to any one of claims 1 to 5, wherein the compound of formula I is selected from riboflavin tetraacetate, riboflavin tetrapropionate, riboflavin tetrabutyrate, riboflavin tetrapalmitate or combinations thereof.

7. The composition according to any one of claims 1 to 6, wherein the composition consists essentially of the compound of formula I and the solvent.

8. The composition according to any one of claims 1 to 7, wherein the composition is an organic composition free of aqueous components.

9. A method for crosslinking collagen in a tissue of a subject, comprising: Administering to the tissue of the subject the composition according to any one of claims 1 to 8, or administering to the tissue of the subject a compound of formula II: Wherein: R6, R7, R8 and R9 are each independently selected from hydrogen or -C(O)R5; At least one of R6, R7, R8 and R9 is -C(O)R5; and R5 is selected from straight-chain, branched-chain or cyclic alkyl groups having 1 to 26 carbon atoms; and Irradiating the tissue with UV radiation or blue light.

10. A method for crosslinking a structural protein, comprising: Contacting the structural protein or a biological tissue containing the structural protein with the composition according to any one of claims 1 to 8, or contacting the structural protein or a biological tissue containing the structural protein with a compound of formula II: Wherein: R6, R7, R8 and R9 are each independently selected from hydrogen or -C(O)R5; At least one of R6, R7, R8 and R9 is -C(O)R5; and R5 is selected from straight-chain, branched-chain or cyclic alkyl groups having 1 to 26 carbon atoms; and Irradiate the structural protein or the tissue with UV radiation or blue light.

11. The method according to claim 10, wherein the structural protein is selected from collagen, keratin, derivatives thereof, and combinations thereof.

12. The method according to any one of claims 9 or 10, wherein the tissue is selected from collagenous tissue, epidermal tissue, or keratinous tissue.

13. The method according to any one of claims 9 to 12, wherein the tissue is corneal tissue.

14. The method according to claim 13, wherein the subject has a chemical burn or a disease selected from the following: keratoconus, thin cornea, keratitis, infectious keratitis including bacterial or fungal keratitis, corneal ulcer, bullous keratopathy and other forms of corneal edema, corneal exfoliation, autoimmune diseases, cicatricial diseases such as ocular cicatricial pemphigoid, Stevens-Johnson syndrome, lupus erythematosus, rheumatoid arthritis, corneal ectasia including corneal ectasia occurring after laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), post-refractive corneal ectasia, corneal degeneration, brittle cornea syndrome, Ehlers-Danlos syndrome type VI, corneal neovascularization, corneal melting including corneal melting in Boston type I artificial cornea, hyperopia, hyperopic astigmatism, myopia, astigmatism, myopic astigmatism, myopic regression, corneal disease, corneal astigmatism, unstable cornea, or pellucid marginal degeneration (PMD).

15. The method according to any one of claims 13 to 14, further comprising de-epithelializing at least a portion of the cornea.

16. The method according to any one of claims 13 to 14, wherein the crosslinking is performed without de-epithelializing any part of the cornea.

17. A method for crosslinking collagen in a subject's cornea, comprising: administering to at least a portion of the subject's cornea the composition according to any one of claims 1 to 8; and irradiating at least a portion of the subject's cornea with UV radiation or blue light.

18. The method according to claim 17, wherein the subject has a chemical burn or a disease selected from the following: keratoconus, thin cornea, keratitis, infectious keratitis including bacterial or fungal keratitis, corneal ulcer, bullous keratopathy and other forms of corneal edema, corneal exfoliation, autoimmune diseases, cicatricial diseases such as ocular cicatricial pemphigoid, Stevens-Johnson syndrome, lupus erythematosus, rheumatoid arthritis, corneal ectasia including corneal ectasia occurring after laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), post-refractive corneal ectasia, corneal degeneration, brittle cornea syndrome, Ehlers-Danlos syndrome type VI, corneal neovascularization, corneal melting including corneal melting in Boston type I artificial cornea, hyperopia, hyperopic astigmatism, myopia, astigmatism, myopic astigmatism, myopic regression, corneal disease, corneal astigmatism, unstable cornea, or pellucid marginal degeneration (PMD).

19. The method according to any one of claims 17 to 18, further comprising de-epithelializing at least a portion of the cornea.

20. The method according to any one of claims 17 to 18, wherein the crosslinking is performed without de-epithelializing any portion of the cornea.

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