Contrast agents for imaging collagen and fibrin

Abstract

This disclosure relates to fibrin and collagen-specific imaging agents containing metal oxide nanoparticles. TIFF2026510425000134.tif81128

Description

[Technical Field]

[0001] Cross-reference with related applications This application claims priority under U.S. Provisional Application No. 63 / 488,642, filed on 6 March 2023, which is incorporated herein by reference in its entirety.

[0002] Technical field This disclosure relates to fibrin and collagen-specific imaging agents containing metal oxide nanoparticles. [Background technology]

[0003] background Diagnostic imaging techniques such as magnetic resonance imaging (MRI), X-ray imaging, radiopharmaceutical imaging, ultraviolet-visible-infrared imaging, and ultrasound are frequently used in medical diagnosis. Complexes of paramagnetic metal oxide ions (e.g., gadolinium oxide, iron oxide, manganese oxide) with ligands are widely used to enhance and improve imaging contrast. Small metal oxide particles can be used to aid in the renal excretion and extravasation of metal oxide-ligand complexes into interstitial tissue after acquisition of diagnostic images. [Overview of the project]

[0004] overview This application describes fibrin and collagen-specific imaging agents containing extremely small metal oxide nanoparticles, as well as pharmaceutical compositions containing the imaging agents described herein. This specification also provides methods for imaging fibrin and collagen in mammals.

[0005] All publications, patents, and patent applications referenced herein are incorporated by reference to the same extent as any individual publication, patent, or patent application is specifically and individually indicated as being incorporated by reference. To the extent that any publications and patents or patent applications incorporated by reference conflict with any disclosures contained herein, this specification is intended to supersede and / or take precedence over such conflicting material.

[0006] Other features and advantages of this disclosure will become apparent from the following detailed description and figures, as well as from the claims. [Brief explanation of the drawing]

[0007] [Figure 1] The structure of SNIO-CBP is shown. [Figure 2] The SAXS profile of SNIO-CBP in the q range corresponding to the 1 nanometer range in real space is shown; the scattering profile is fitted to a spherical particle with a log-normal distribution and an average diameter of 1.47 nm. [Figure 3] The gel filtration chromatogram of SNIO-CBP is shown, indicating the size, purity, and hydrodynamic diameter of SNIO-CBP. [Figure 4] The gel filtration chromatograms of SNIO-CBP incubated with FBS and FBS alone are shown, demonstrating the minimal degree of nonspecific binding of SNIO-CBP in plasma. Red and orange peaks: binding products; lower peak: native species in FBS. [Figure 5] This shows the binding affinity of SNIO-CBP to human type I collagen. [Figure 6] This shows the T1-weighted MRI test of SNIO-CBP clearance in normal mice (intravenous injection, based on CBP concentration of 2 nmol / g). [Figure 7]This study compares SNIO-CBP (2 nmol / g CBP) and CM-101 (5 nmol / g CBP) in mice treated with CCl4 or olive oil vehicle (OO) for 12 weeks, showing similar contrast-to-noise ratios in the liver (n=6 in each group). Representative microscopic images of adjacent liver tissue from CCl4 (disease) and OO (control) mice, stained with Sirius Red and Prussian Blue, show the presence of fibrosis in CCl4 mice and the accumulation of SNIO-CBP in the fibrotic zone. [Figure 8] This report shows MR imaging of hepatic fibrosis in a non-alcoholic steatohepatitis model mouse using SNIO-CBP (2 nmol / g CBP). Mice fed a choline-deficient, L-amino acid-restricted high-fat diet (CDAHFD) for 14 weeks (n=6) functioned as the disease group. Mice fed a standard solid diet (SD, n=6) for 14 weeks were used as a control. Significantly enhanced liver signaling was observed in the CDAHFD group imaged with SNIO-CBP. Corresponding liver histological examination revealed fibrosis and probe retention in the disease group. [Figure 9] A schematic diagram of nanoparticle synthesis is shown. [Figure 10] This shows the zeta potential of SNIO-CBP. [Figure 11] This demonstrates the stability of SNIO-CBP. [Figure 12] This shows the binding affinity of SNIO-CBP to type I collagen. [Figure 13] This shows the longitudinal relaxation ability (r1). [Figure 14] This shows the pharmacokinetics of SNIO-CBP in normal mice. [Figure 15] This shows a model of CCl4-induced liver fibrosis. [Figure 16] Ex vivo characterization (CCl4 model) is shown. [Figure 17] It presents with diet-induced liver fibrosis. [Modes for carrying out the invention]

[0008] Detailed explanation Collagen is a type of extracellular matrix protein that accounts for approximately 30% of the body's total protein and contributes to the structure of tendons, bones, and connective tissue. Abnormal accumulation of collagen in various organs can lead to fibrosis, such as myocardial fibrosis, heart failure, non-alcoholic steatohepatitis (NASH), cirrhosis, and primary biliary cirrhosis, among other debilitating conditions; vascular or thoracic injuries; collagen-induced arthritis; muscular dystrophy; scleroderma; Dupuytren's disease; and rheumatoid arthritis. Fibrin is a fibrous protein derived from the soluble plasma protein fibrinogen. Fibrin is a major component of blood clots and is present in all thrombi, regardless of their stage or location in the body. Due to their high specificity and sensitivity, both fibrin and collagen-binding compounds can be used in diagnostic imaging.

[0009] This specification provides protein-binding imaging agents having paramagnetic metal oxide ions and ligands for enhancing image contrast and assisting analysis. These imaging agents utilize paramagnetic metal oxide ions with smaller particle sizes while still producing high-resolution images, allowing for easy excretion from the patient.

[0010] definition Commonly used chemical abbreviations not expressly defined in this disclosure can be found in The American Chemical Society Style Guide, Second Edition, American Chemical Society, Washington, DC (1997); “2001 Guidelines for Authors” J. Org. Chem. 66(1), 24A (2001); and “A Short Guide to Abbreviations and Their Use in Peptide Science” J. Peptide Sci. 5, 465-471 (1999).

[0011] As used herein, the term "peptide" refers to an amino acid chain with a length of approximately 2 to 25 amino acid residues. All peptide sequences herein are written from the N-terminus to the C-terminus. In any of the peptides described herein that contain two or more cysteine ​​residues, it is understood that the cysteine ​​residues may form one or more disulfide bonds under non-reducing conditions. The formation of disulfide bonds may result in the construction of a cyclic peptide.

[0012] As used herein, the terms “natural” or “naturally occurring” amino acids refer to one of the 20 most common amino acids found in nature. Natural amino acids that have been modified to provide a label for detection purposes (e.g., a radioactive label, an optical label, or a dye) are considered natural amino acids. Natural L amino acids are referred to by their standard one-letter or three-letter abbreviations. D amino acids are referred to using the convention of lowercase for their standard one-letter abbreviations and the convention of the prefix “D-” for their standard three-letter abbreviations.

[0013] As used herein, the terms “target binding” and “binding” refer to non-covalent interactions of a peptide or composition within a target. These non-covalent interactions are independent of each other and may include, in particular, hydrophobic, hydrophilic, dipole-dipole, π-stacking, hydrogen bonding, electrostatic association, and / or Lewis acid-base interactions. Binding affinity to a target is defined by the equilibrium dissociation constant “K” for the target under a defined set of conditions. d It can be expressed in the phrase "".

[0014] As used herein, the term “relaxation ability” refers to the increase in magnetic resonance imaging (MRI) amount 1 / T1 or 1 / T2 per millimolar (mM) concentration of a paramagnetic ion, contrast agent, or compound, where T1 is the longitudinal relaxation time or spin-lattice relaxation time of a water proton or other imaging or spectroscopic nucleus (including protons in molecules other than water), and T2 is the transverse relaxation time or spin-spin relaxation time. Relaxation ability is mM -1 s -1It is expressed in units of [unit].

[0015] As used herein, the term “purified” means a peptide or compound that has been isolated from naturally occurring organic molecules that normally accompany it, or, in the case of chemically synthesized molecules, isolated from other organic molecules present during the chemical synthesis. Typically, a polypeptide or compound is considered “purified” if, by dry weight, it contains no other proteins or organic molecules by at least 70% (e.g., at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%). The terms “purified” and “isolated” are used interchangeably herein.

[0016] Where a numerical value is stated as a range, it will be understood that such disclosure includes all possible subranges within that range, and any specific numerical values ​​that fall within that range, regardless of whether specific numerical values ​​or specific subranges are explicitly stated.

[0017] Collagen-binding imaging agent In this specification, Formula I: [NP]-[C] m -[L] n -[CP] o (I) An imaging agent or a pharmaceutically acceptable salt thereof is provided. In the formula, NP is a nanoparticle metal oxide core containing iron oxide, manganese oxide, or gadolinium oxide; C is a metal oxide bond ligand; L is the linker part; CP is a collagen-binding peptide; n is an integer selected from 0 to 10; and m and o are integers independently selected from 1 to 5.

[0018] In some embodiments of the imaging agent of formula I, n is 0, n is 1, n is 2, n is 3, n is 4, or n is 5. In some embodiments of the imaging agent of formula I, m is 1 or m is 2. In some embodiments of the imaging agent of formula I, o is 1 or o is 2.

[0019] In some embodiments of the imaging agent of formula I, NP is a nanoparticle metal oxide containing iron oxide. In some embodiments of the imaging agent of formula I, NP is a nanoparticle metal oxide containing manganese oxide. In some embodiments of the imaging agent of formula I, NP is a nanoparticle metal oxide core containing gadolinium oxide. In some embodiments of the imaging agent of formula I, NP is a nanoparticle metal oxide core containing iron oxide, manganese oxide, gadolinium oxide, or a combination thereof. For example, the nanoparticle core may contain iron oxide and manganese oxide. For example, the nanoparticle core may contain iron oxide and gadolinium oxide. For example, the nanoparticle core may contain manganese oxide and gadolinium oxide. For example, the nanoparticle core may contain iron oxide, manganese oxide, and gadolinium oxide.

[0020] In some embodiments of the imaging agent of Formula I, the nanoparticle metal oxide core contains about 5 to about 200 metal ions. Examples include about 5 to about 175, about 5 to about 150, about 5 to about 125, about 5 to about 100, about 5 to about 75, about 5 to about 50, about 5 to about 25, or about 5 to about 10 metal ions. In some embodiments, the nanoparticle metal oxide core contains about 10 to about 200, about 25 to about 200, about 50 to about 200, about 75 to about 200, about 100 to about 200, about 125 to about 200, about 150 to about 200, or about 175 to about 200 metal ions. In some embodiments, the nanoparticle metal oxide core contains about 5 to about 15, about 10 to about 15, about 10 to about 20, about 10 to about 25, about 10 to about 30, about 10 to about 35, about 10 to about 40, about 10 to about 45, about 10 to about 50, about 25 to about 50, about 50 to about 100, about 75 to about 100, about 100 to about 125, about 125 to about 150, or about 150 to about 175 metal ions.

[0021] In some embodiments, the nanoparticle metal oxide cores have a diameter of approximately 2.0 to 10.0 nm. Examples include diameters of approximately 2.0 to 9.0, 2.0 to 8.0, 2.0 to 7.5, 2.0 to 7.0, 2.0 to 6.5, 2.0 to 6.0, 2.0 to 5.5, 2.0 to 5.0, 2.0 to 4.5, 2.0 to 3.5, or 2.0 to 3.0 nm. In some embodiments, the nanoparticle metal oxide core has a diameter of approximately 2.5 to 10.0 nm, 3.0 to 10.0 nm, 3.5 to 10.0 nm, 4.0 to 10.0 nm, 4.5 to 10.0 nm, 5.0 to 10.0 nm, 5.5 to 10.0 nm, 6.0 to 10.0 nm, 6.5 to 10.0 nm, 7.0 to 10.0 nm, 7.5 to 10.0 nm, 8.0 to 10.0 nm, 8.5 to 10.0 nm, or 9.0 to 10.0 nm. In some embodiments, the nanoparticle metal oxide core has a diameter of approximately 3.0 to 5.0 nm. Examples include diameters of approximately 3.0 to 4.8 nm, 3.0 to 4.5 nm, 3.0 to 4.2 nm, 3.0 to 4.0 nm, or 3.0 to 3.8 nm. Examples also include diameters of approximately 3.2 to 5.0 nm, 3.5 to 5.0 nm, 3.8 to 5.0 nm, 4.0 to 5.0 nm, or 4.2 to 5.0 nm. In some embodiments, the nanoparticle metal oxide core has a diameter of approximately 3.4 to 4.5 nm.

[0022] In some embodiments, the nanoparticle metal oxide core has a diameter of approximately 0.5 to 1.5 nm. In some embodiments, the nanoparticle metal oxide core has a diameter of approximately 1.0 nm.

[0023] In some embodiments, the hydrodynamic size of the coated nanoparticle metal oxide core is from about 2.0 to about 25 nm in diameter. By way of example, the diameter can be from about 2.0 to about 23, about 2.0 to about 21, about 2.0 to about 20, about 2.0 to about 18, about 2.0 to about 15, about 2.0 to about 12, about 2.0 to about 10, about 2.0 to about 8, about 2.0 to about 6, or about 2.0 to about 4 nm. In some embodiments, the hydrodynamic size of the coated nanoparticle metal oxide core is from about 2.5 to about 25, about 3.0 to about 25, about 3.5 to about 25, about 4.0 to about 25, about 4.5 to about 25, about 5.0 to about 25, about 5.0 to about 25, about 5.5 to about 25, about 6.0 to about 25, about 6.5 to about 25, about 7.0 to about 25, about 8.0 to about 25, about 8.5 to about 25, about 9.0 to about 25, about 9.5 to about 25, about 10 to about 25, about 12 to about 25, about 15 to about 25, about 17 to about 25, about 20 to about 25, or about 22 to about 25 nm in diameter. In some embodiments, the hydrodynamic size of the coated nanoparticle metal oxide core is from about 2.9 to about 21 nm in diameter.

[0024] In some embodiments of the imaging agent of Formula I, the metal oxide binding ligand is benzenediol or hydroxycarboxylic acid. In some embodiments of the imaging agent of Formula I, the metal oxide binding ligand is benzenediol. In some embodiments of the imaging agent of Formula I, the metal oxide binding ligand is hydroxycarboxylic acid.

[0025] In some embodiments of the imaging agent of Formula I, the benzenediol has the formula: TIFF2026510425000002.tif14128, and wherein X and Y are independently CR 8 and N; R 1 is -CH2CH2COOH, -CH2CH2NH2, -CH2CH2SH, -(CH2CH2O) x N3-, -(CH2CH2O) x C≡C-, -(CH2CH2O) x SCN-, -(CH2CH2O) x SH-, and Selected from the group consisting of TIFF2026510425000003.tif9128; x is an integer selected from 1 to 9; R 2 is H or an electron-withdrawing group; and R 8 The group is selected from the group consisting of H and C1-C6 alkyl groups.

[0026] In some embodiments of the imaging agent of formula I, benzenediol is of formula: It has TIFF2026510425000004.tif17128, In the formula, X and Y are independently CR 8 and selected from N; R 1 -CH2CH2COO-, -CH2CH2NH-, -CH2CH2S-, -(CH2CH2O) x N3-, -(CH2CH2O) x C≡C-, -(CH2CH2O) x SCN-, -(CH2CH2O) x SH-, Selected from the group consisting of TIFF2026510425000005.tif9128, -CH2CH2NHC(=O)-, and -CH2CH2C(=O)NH-; x is an integer selected from 1 to 9; R 2 is H or an electron-withdrawing group; and R 8 It is selected from the group consisting of H and C1-C6 alkyl groups, During the ceremony, TIFF2026510425000006.tif6128 shows the bonding sites of a specified group to a nanoparticle metal oxide core.

[0027] In some embodiments of the imaging agent of formula I, R 1 This is -CH2CH2NHC(=O)- or -CH2CH2C(=O)NH-.

[0028] In some embodiments of the imaging agent of formula I, benzenediol is, TIFF2026510425000007.tif21129, and in the formula, TIFF2026510425000008.tif4128 shows the bond points of the specified group to the linker.

[0029] In some embodiments of the imaging agent of formula I, X is CR 8 And here R 8 X is selected from the group consisting of H and C1-C6 alkyl groups. For example, X may be CH, CMe, and CET. In some embodiments of the imaging agent of formula I, X is N.

[0030] In some embodiments of the imaging agent of formula I, R 2 H is H.

[0031] In some embodiments of the imaging agent of formula I, R 2 It is an electron-withdrawing group. For example, R 2 This can be -NO2, -SO3H, -SO3Na, -CF3, -SO2CF3, or -CN.

[0032] In some embodiments of the imaging agent of formula I, Y is CR 8 And here R 8 Y is selected from the group consisting of H and C1-C6 alkyl groups. For example, Y may be CH, CMe, and CEt. In some embodiments of the imaging agent of formula I, Y is N.

[0033] In some embodiments of the imaging agent of formula I, the hydroxycarboxylic acid is an α-hydroxycarboxylic acid. For example, the hydroxycarboxylic acid may be lactic acid or glycolic acid. In some embodiments of the imaging agent of formula I, the hydroxycarboxylic acid is a β-hydroxycarboxylic acid. For example, the hydroxycarboxylic acid may be tropic acid or citrate.

[0034] In some embodiments of the imaging agent of formula I, the hydroxycarboxylic acid is of formula: Having TIFF2026510425000009.tif22128 or a pharmaceutically acceptable salt thereof, In the formula, p is an integer selected from 1 to 4. R 3 H, -(CH2) q C(O)- and -(CH2) q Selected from the group consisting of NH-, q is an integer selected from 1 to 5.

[0035] In some embodiments of the imaging agent of formula I, the hydroxycarboxylic acid is of formula: It has TIFF2026510425000010.tif30128, and in the formula, TIFF2026510425000011.tif6128 shows the bonding sites of a specified group to a nanoparticle metal oxide core.

[0036] In some embodiments of the imaging agent of formula I, R 3 is, -(CH2) q C(O)- or -(CH2) q It is NH-.

[0037] In some embodiments of the imaging agent of formula I, the hydroxycarboxylic acid is TIFF2026510425000012.tif31128, and in the formula, TIFF2026510425000013.tif4128 shows the bond points of the specified group to the linker.

[0038] In some embodiments of the imaging agent of Formula I, the linker portion has a molecular weight of about 200 to about 800 amu. Examples include about 200 to about 750, about 200 to about 700, about 200 to about 650, about 200 to about 600, about 200 to about 550, about 200 to about 500, about 200 to about 450, about 200 to about 400, about 200 to about 350, about 200 to about 300, or about 200 to about 250 amu. In some embodiments of the imaging agent of formula I, the linker has a molecular weight of about 250 to about 800, about 300 to about 800, about 350 to about 800, about 400 to about 800, about 450 to about 800, about 500 to about 800, about 550 to about 800, about 600 to about 800, about 650 to about 800, about 700 to about 800, or about 750 to about 800 amu. In some embodiments of the imaging agent of formula I, the linker portion has a molecular weight of about 250 to about 600, about 300 to about 650, about 350 to about 700, or about 400 to about 750 amu.

[0039] In some embodiments of the imaging agent of formula I, the linker portion is -NHCH(R 4 )CO-, -NH(CH2) s C(O)-, -NHCH2CH2OCH2CH2CH2C(O)-, -NHCH2CH2OCH2CH2OCH2CH2C(O)-, NHCH2C6H4CH2NH-, -NH(CH2) t NH-, -NHCH2OCH2NH-, -NHCH2CH2OCH2CH2NH-, -NHCH2CH2OCH2CH2OCH2CH2NH-, -N3(CH2CH2O) u C(O)-, -C≡C(CH2CH2O) u C(O)-, -SCN(CH2CH2O) u C(O)-, -SH(CH2CH2O) u C(O)-, Selected from the group consisting of TIFF2026510425000014.tif21128; Here, s is an integer selected from 1 to 6; R 4 These are amino acid side chains; t is an integer selected from 2 to 6; u is an integer selected from 2 to 10; and Linkers can be read from right to left or left to right; During the ceremony, TIFF2026510425000015.tif3128 shows the binding sites of a specified group to a collagen-binding peptide.

[0040] In some embodiments of the imaging agent of formula I, the linker portion is selected from the group consisting of -CH2CH2OC(=O)-, -CH2CH2OCH2CH2OC(=O)-, -CH2CH2O(CH2CH2O)2C(=O)-, -CH2CH2O(CH2CH2O)3C(=O)-, -CH2CH2O(CH2CH2O)4C(=O)-, and -CH2CH2O(CH2CH2O)5C(=O)-.

[0041] In some embodiments of the imaging agent of formula I, the linker portion is selected from the group consisting of -CH2CH2O-, -CH2CH2OCH2CH2O-, -CH2CH2O(CH2CH2O)2-, -CH2CH2O(CH2CH2O)3-, -CH2CH2O(CH2CH2O)4-, and -CH2CH2O(CH2CH2O)5-.

[0042] In some embodiments of the imaging agent of formula I, the linker portion is The image agent of formula I is TIFF2026510425000016.tif14128. In some embodiments of the imaging agent of formula I, the collagen-binding peptide is about 2 to about 25 amino acid residues long. Examples include about 2 to about 23, about 2 to about 20, about 2 to about 18, about 2 to about 15, about 2 to about 12, about 2 to about 10, about 2 to about 8, about 2 to about 5, or about 2 to about 4 amino acid residues long. In some embodiments of the imaging agent of formula I, the collagen-binding peptide is about 5 to about 25, about 8 to about 25, about 10 to about 25, about 12 to about 25, about 15 to about 25, about 18 to about 25, about 20 to about 25, or about 22 to about 25 amino acid residues long. In some embodiments of the imaging agent of Formula I, the collagen-binding peptide has an amino acid residue length of about 5 to about 10, about 5 to about 15, about 10 to about 12, about 10 to about 15, about 10 to about 20, about 15 to about 18, or about 15 to about 20.

[0043] In some embodiments of the imaging agent of formula I, the collagen-binding peptide is: It has TIFF2026510425000017.tif31133.

[0044] In some embodiments of the imaging agent of formula I, the imaging agent is of formula: It has TIFF2026510425000018.tif114160TIFF2026510425000019.tif49160, During the ceremony, TIFF2026510425000020.tif10128 is a nanoparticle metal oxide core containing iron oxide, manganese oxide, gadolinium oxide, or a combination thereof; X and Y are independently selected from CH and N; R 2 It is selected from the group consisting of -H, -NO2, -CF3, -SO3H, -SO3Na, and -CHCHSO3Na; and n is an integer selected from 1 to 6.

[0045] In some embodiments of the imaging agent of formula I, the imaging agent further comprises an additional metal oxide bond ligand. In some embodiments, the additional metal oxide bond ligand is TIFF2026510425000021.tif19128, and in the formula, TIFF2026510425000022.tif6128 shows the bonding sites of a specified group to a nanoparticle metal oxide core.

[0046] In some embodiments, the metal oxide ligands and additional metal oxide ligands cover approximately 1–10%, 10–20%, 20–30%, 30–40%, 40–50%, 50–60%, 60–70%, 70–80%, 80–90%, or 90–100% of the surface of the nanoparticle metal oxide core. In some embodiments, the metal oxide ligands cover approximately 1–10%, 10–20%, 20–30%, 30–40%, 40–50%, 50–60%, 60–70%, 70–80%, 80–90%, or 90–100% of the surface of the nanoparticle metal oxide core. In some embodiments, the additional metal oxide-bonding ligands cover approximately 1–10%, 10–20%, 20–30%, 30–40%, 40–50%, 50–60%, 60–70%, 70–80%, 80–90%, or 90–100% of the surface of the nanoparticle metal oxide core.

[0047] In some embodiments, the ratio of metal oxide-bonding ligands to additional metal oxide-bonding ligands on the surface of the nanoparticle metal oxide core is approximately 1:1, 1:5, 1:10, 1:15, 1:20, 20:1, 15:1, 10:1, or 5:1. In some embodiments, the ratio is approximately 1.1. In some embodiments, the ratio is approximately 1.5. In some embodiments, the ratio is approximately 1.10. In some embodiments, the ratio is approximately 1.15. In some embodiments, the ratio is approximately 1.20. In some embodiments, the ratio is approximately 20:1. In some embodiments, the ratio is approximately 15:1. In some embodiments, the ratio is approximately 10:1. In some embodiments, the ratio is approximately 5:1.

[0048] In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is CH, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is CH, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is CH, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is CH, and R 2 It is -CHCHSO3Na.

[0049] In some embodiments, the nanoparticle metal oxide core is iron oxide, X is N, Y is CH, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is N, Y is CH, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is N, Y is CH, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is N, Y is CH, and R 2 It is -CHCHSO3Na.

[0050] In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is N, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is N, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is N, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is N, and R 2 It is -CHCHSO3Na.

[0051] In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is CH, Y is CH, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is CH, Y is CH, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is CH, Y is CH, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is CH, Y is CH, and R 2 It is -CHCHSO3Na.

[0052] In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is N, Y is CH, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is N, Y is CH, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is N, Y is CH, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is N, Y is CH, and R 2 It is -CHCHSO3Na.

[0053] In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is CH, Y is N, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is CH, Y is N, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is CH, Y is N, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, X is CH, Y is N, and R 2 It is -CHCHSO3Na.

[0054] In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is CH, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is CH, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is CH, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, X is CH, Y is CH, and R 2 It is -CHCHSO3Na.

[0055] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, where X is N, Y is CH, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, where X is N, Y is CH, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, X is N, Y is CH, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, where X is N, Y is CH, and R 2 It is -CHCHSO3Na.

[0056] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, where X is CH, Y is N, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, X is CH, Y is N, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, X is CH, Y is N, and R 2is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, X is CH, Y is N, and R 2 is -CHCHSO3Na.

[0057] In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is lactic acid, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is lactic acid, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is lactic acid, and R 2 y is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is lactic acid, and R 2 is -CHCHSO3Na.

[0058] In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is glycolic acid, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is glycolic acid, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is glycolic acid, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is glycolic acid, and R 2 is -CHCHSO3Na. <00,00722>

[0059] In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is citric acid, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is citric acid, and R 2is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is citric acid, R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is citric acid, R 2 is -CHCHSO3Na.

[0060] In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is TIFF2026510425000023.tif22128, p is an integer selected from 1 to 4, R 3 is H, R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is TIFF2026510425000024.tif23128, p is an integer selected from 1 to 4, R 3 is H, R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is TIFF2026510425000025.tif23128, p is an integer selected from 1 to 4, R 3 is H, R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is TIFF2026510425000026.tif23128, p is an integer selected from 1 to 4, R 3 is H, R 2 is -CHCHSO3Na.

[0061] In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is TIFF2026510425000027.tif22128, p is an integer selected from 1 to 4, R 3 is -(CH2)q C(O)-, where q is an integer selected from 0 to 5, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000028.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000029.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000030.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 It is -CHCHSO3Na.

[0062] In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000031.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000032.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2)q NH-, where q is an integer selected from 0 to 5, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000033.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000034.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 It is -CHCHSO3Na.

[0063] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is lactic acid, 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, the hydroxycarboxylic acid is lactic acid, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, the hydroxycarboxylic acid is lactic acid, and R 2 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is lactic acid. 2 It is -CHCHSO3Na.

[0064] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is glycolic acid, 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is glycolic acid, R 2is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is glycolic acid, R 2 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is glycolic acid. 2 It is -CHCHSO3Na.

[0065] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is citric acid, 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, the hydroxycarboxylic acid is citric acid, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, the hydroxycarboxylic acid is citric acid, and R 2 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is citric acid. 2 It is -CHCHSO3Na.

[0066] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000035.tif23128, where p is an integer selected from 1 to 4, and R 3 H is R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000036.tif23128, where p is an integer selected from 1 to 4, and R 3 H is R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000037.tif23128, where p is an integer selected from 1 to 4, and R3 H is R 2 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000038.tif23128, where p is an integer selected from 1 to 4, and R 3 H is R 2 It is -CHCHSO3Na.

[0067] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000039.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000040.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000041.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000042.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) qC(O)-, where q is an integer selected from 0 to 5, and R 2 It is -CHCHSO3Na.

[0068] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000043.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000044.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000045.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000046.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 It is -CHCHSO3Na.

[0069] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is lactic acid, 2is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, the hydroxycarboxylic acid is lactic acid, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, the hydroxycarboxylic acid is lactic acid, and R 2 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is lactic acid. 2 It is -CHCHSO3Na.

[0070] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is glycolic acid, R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is glycolic acid, R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is glycolic acid, R 2 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is glycolic acid. 2 It is -CHCHSO3Na.

[0071] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is citric acid, 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is citric acid, R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, the hydroxycarboxylic acid is citrate, and R 2 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is citric acid. 2 It is -CHCHSO3Na.

[0072] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000047.tif23128, where p is an integer selected from 1 to 4, and R 3 H is R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000048.tif23128, where p is an integer selected from 1 to 4, and R 3 H is R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000049.tif23128, where p is an integer selected from 1 to 4, and R 3 H is R 2 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000050.tif23128, where p is an integer selected from 1 to 4, and R 3 H is R 2 It is -CHCHSO3Na.

[0073] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000051.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000052.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000053.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000054.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q C(O)-, where q is an integer selected from 0 to 5, and R 2 It is -CHCHSO3Na.

[0074] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000055.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000056.tif23128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000057.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000058.tif22128, where p is an integer selected from 1 to 4, and R 3 ha-(CH2) q NH-, where q is an integer selected from 0 to 5, and R 2 It is -CHCHSO3Na.

[0075] Collagen-binding imaging agent The collagen-binding peptides described herein have affinity for extracellular matrix proteins, including type I collagen, from humans and other animals. Collagen is an extracellular matrix protein that is particularly useful to target. For example, collagen I and III are the most abundant components of the extracellular matrix in cardiomyocyte tissue, accounting for more than 90% of total cardiomyocyte collagen and approximately 5% of the dry cardiomyocyte weight. The ratio of collagen I to collagen III in cardiomyocytes is approximately 2:1, and their total concentration in the extracellular matrix is ​​approximately 100 μM. Human type I collagen is a two-chain trimer with a stoichiometric ratio of [α1(I)]2[α2(I)], characterized by a repeating GXY sequence motif in which X is most frequently proline and Y is more frequently hydroxyproline. In some embodiments, the compounds described herein may have affinity for human, rat, and / or canine type I collagen.

[0076] In some embodiments, the compounds described herein include collagen-binding peptides directly linked to one or more metal oxide-linked ligands. In some embodiments, the compounds described herein include collagen-binding peptides indirectly linked to one or more metal oxide-linked ligands via linking portions. Peptides useful for inclusion in the compounds and compositions described herein include the natural and non-natural amino acid L-4,4'-biphenylalanine (Bip). Peptides can be synthesized according to standard synthetic methods, such as those disclosed in WO 01 / 09188 and WO 01 / 08712. Many different protecting groups of amino acids suitable for immediate use in solid-phase synthesis of peptides are commercially available.

[0077] Peptides can be assayed for affinity to suitable extracellular matrix proteins by methods disclosed in WO 01 / 09188 and WO 01 / 08712, as well as by methods described below. For example, peptides can be screened for binding to extracellular matrix proteins by methods well known in the art, including pull-down assays, equilibrium dialysis, affinity chromatography, and inhibition or substitution of probes bound to matrix proteins. For example, peptides can be evaluated for their ability to bind to collagen, such as dried type I collagen from humans, rats, or dogs. In some embodiments, collagen-binding peptides can bind to human collagen with dissociation constants of less than 25 μM, less than 10 μM, less than 5 μM, less than 1 μM, or less than 100 nM. In some embodiments, collagen-binding peptides can bind to rat collagen with dissociation constants of less than 25 μM, less than 10 μM, less than 5 μM, less than 1 μM, or less than 100 nM. In some embodiments, collagen-binding peptides can bind to canine collagen with dissociation constants of less than 25 μM, less than 10 μM, less than 5 μM, less than 1 μM, or less than 100 nM.

[0078] Peptides can be synthesized directly using conventional techniques, including solid-phase peptide synthesis and solution-phase synthesis. See, for example, Stewart et al., Solid-Phase peptide Synthesis (1989), WH Freeman Co., San Francisco; Merrifield, J. Am. Chem. Soc., 1963 85:2149-2145; and Bodanszky and Bodanszky, The Practice of Peptide Synthesis (1984), Springer-Verlag, New York. Peptides can also be prepared or purchased commercially. Automated peptide synthesizers, such as those manufactured by Perkin-Elmer Applied Biosystems, can also be used.

[0079] Collagen-binding peptides can be purified once isolated or synthesized by chemical or recombinant techniques. For purification purposes, alkylated silica columns (e.g., C4, C8, or C4) can be used. 18 There are many standard methods that can be employed, including reverse-phase high-pressure liquid chromatography (RP-HPLC) using silica. For example, a gradient mobile phase of increasing organic contents, such as acetonitrile in aqueous buffer, is commonly used to achieve purification. In some embodiments, the mobile phase may also contain a small amount of trifluoroacetic acid. Ion exchange chromatography can also be used to separate peptides based on their charge. The purity of collagen-bound peptides can be determined by various methods, including the identification of major large peaks in HPLC. In some embodiments, the peptide produces a single peak that is at least 95% of the input material to the HPLC column. In some embodiments, the peptide produces a single peak that is at least 97%, at least 98%, at least 99%, or even 99.5% of the input material to the HPLC column.

[0080] MR compounds can exhibit high relaxation ability as a result of binding to collagen, which can lead to better image resolution. In some embodiments, the increase in relaxation ability upon binding is 1.5 times or more (e.g., at least 2, 3, 4, 5, 6, 7, 8, 9, or 10 times increase in relaxation ability). For example, target-directed MR compounds can increase the relaxation ability upon binding by 7-8 times, 9-10 times, or even more than 10 times. In some embodiments, the relaxation ability is measured using an NMR spectrometer. In some embodiments, the relaxation ability of the MRI compound at 20 MHz and 37°C is at least 8 mM per paramagnetic metal ion. -1 s -1 (For example, at least 10, 15, 20, 25, 30, 35, 40, or 60 mM per paramagnetic metal ion) -1 s -1 In some embodiments, the MR compound is 60 mM at 20 MHz and 37°C. -1 s -1 It has super relaxation capabilities.

[0081] As described herein, targeted MR compounds can be selectively taken up by body sites where collagen concentrations are higher compared to other sites. The selectivity of targeted substance uptake can be determined by comparing its uptake by the myocardium with that by the blood. The selectivity of targeted compounds can also be demonstrated by using MRI and observing the enhancement of the myocardial signal compared to the blood signal.

[0082] Fibrin-binding imaging agent In this specification, Equation II: [NP]-[C] a -[L] b -[FP] c (II) An imaging agent or a pharmaceutically acceptable salt thereof is provided. In the formula, NP is a nanoparticle metal oxide core containing iron oxide, manganese oxide, or gadolinium oxide; C is a metal oxide bond ligand; L is the linker part; FP is a fibrin-binding peptide; b is an integer selected from 0 to 10; and a and c are integers independently selected from 1 to 5.

[0083] In some embodiments of the imaging agent of formula II, a is 0, a is 1, a is 2, a is 3, a is 4, or a is 5. In some embodiments of the imaging agent of formula II, b is 1 or b is 2. In some embodiments of the imaging agent of formula II, c is 1 or c is 2.

[0084] In some embodiments of the imaging agent of formula II, NP is a nanoparticle metal oxide containing iron oxide. In some embodiments of the imaging agent of formula II, NP is a nanoparticle metal oxide containing manganese oxide. In some embodiments of the imaging agent of formula II, NP is a nanoparticle metal oxide core containing gadolinium oxide. In some embodiments of the imaging agent of formula II, NP is a nanoparticle metal oxide core containing iron oxide, manganese oxide, gadolinium oxide, or a combination thereof. For example, the nanoparticle core may contain iron oxide and manganese oxide. For example, the nanoparticle core may contain iron oxide and gadolinium oxide. For example, the nanoparticle core may contain manganese oxide and gadolinium oxide. For example, the nanoparticle core may contain iron oxide, manganese oxide, and gadolinium oxide.

[0085] In some embodiments of the imaging agent of Formula II, the nanoparticle metal oxide core contains about 5 to about 200 metal ions. Examples include about 5 to about 175, about 5 to about 150, about 5 to about 125, about 5 to about 100, about 5 to about 75, about 5 to about 50, about 5 to about 25, or about 5 to about 10 metal ions. In some embodiments, the nanoparticle metal oxide core contains about 10 to about 200, about 25 to about 200, about 50 to about 200, about 75 to about 200, about 100 to about 200, about 125 to about 200, about 150 to about 200, or about 175 to about 200 metal ions. In some embodiments, the nanoparticle metal oxide core contains about 5 and about 15, about 10 and about 15, about 10 and about 20, about 10 and about 25, about 10 and about 30, about 10 and about 35, about 10 and about 40, about 10 and about 45, about 10 and about 50, about 25 and about 50, about 50 and about 100, about 75 and about 100, about 100 and about 125, about 125 to about 150, or about 150 to about 175 metal ions.

[0086] In some embodiments, the nanoparticle metal oxide cores have a diameter of approximately 2.0 to 10.0 nm. Examples include diameters of approximately 2.0 to 9.0, 2.0 to 8.0, 2.0 to 7.5, 2.0 to 7.0, 2.0 to 6.5, 2.0 to 6.0, 2.0 to 5.5, 2.0 to 5.0, 2.0 to 4.5, 2.0 to 3.5, or 2.0 to 3.0 nm. In some embodiments, the nanoparticle metal oxide core has a diameter of approximately 2.5 to 10.0 nm, 3.0 to 10.0 nm, 3.5 to 10.0 nm, 4.0 to 10.0 nm, 4.5 to 10.0 nm, 5.0 to 10.0 nm, 5.5 to 10.0 nm, 6.0 to 10.0 nm, 6.5 to 10.0 nm, 7.0 to 10.0 nm, 7.5 to 10.0 nm, 8.0 to 10.0 nm, 8.5 to 10.0 nm, or 9.0 to 10.0 nm. In some embodiments, the nanoparticle metal oxide core has a diameter of approximately 3.0 to 5.0 nm. Examples include diameters of approximately 3.0 to 4.8 nm, 3.0 to 4.5 nm, 3.0 to 4.2 nm, 3.0 to 4.0 nm, or 3.0 to 3.8 nm. Examples also include diameters of approximately 3.2 to 5.0 nm, 3.5 to 5.0 nm, 3.8 to 5.0 nm, 4.0 to 5.0 nm, or 4.2 to 5.0 nm. In some embodiments, the nanoparticle metal oxide core has a diameter of approximately 3.4 to 4.5 nm.

[0087] In some embodiments, the hydrodynamic size of the coated nanoparticle metal oxide core is approximately 2.0 to 25 nm in diameter. Examples include diameters of approximately 2.0 to 23, 2.0 to 21, 2.0 to 20, 2.0 to 18, 2.0 to 15, 2.0 to 12, 2.0 to 10, 2.0 to 8, 2.0 to 6, or 2.0 to 4 nm. In some embodiments, the hydrodynamic size of the coated nanoparticle metal oxide core is approximately 2.5–25, 3.0–25, 3.5–25, 4.0–25, 4.5–25, 5.0–25, 5.0–25, 5.5–25, 6.0–25, 6.5–25, 7.0–25, 8.0–25, 8.5–25, 9.0–25, 9.5–25, 10–25, 12–25, 15–25, 17–25, 20–25, or 22–25 nm in diameter. In some embodiments, the hydrodynamic size of the coated nanoparticle metal oxide core is approximately 2.9–21 nm in diameter.

[0088] In some embodiments of the imaging agent of formula II, the metal oxide ligand is a benzenediol or a hydroxycarboxylic acid.

[0089] In some embodiments of the imaging agent of formula II, benzenediol is of formula: It has TIFF2026510425000059.tif14128, In the formula, A and B are independently CR 9 and selected from N; R 5 -CH2CH2COOH, -CH2CH2NH2, -CH2CH2SH, -(CH2CH2O) d N3-, -(CH2CH2O) d C≡C-, -(CH2CH2O) d SCN-, -(CH2CH2O) d SH-, and Selected from the group consisting of TIFF2026510425000060.tif9128; d is an integer selected from 1 to 9; R 6 is H or an electron-withdrawing group; and R 9 The group is selected from the group consisting of H and C1-C6 alkyl groups.

[0090] In some embodiments of the imaging agent of formula II, benzenediol is of formula: It has TIFF2026510425000061.tif17128, In the formula, A and B are independently CR 8 and selected from N; R 5 -CH2CH2COO-, -CH2CH2NH-, -CH2CH2S-, -(CH2CH2O) x N3-, -(CH2CH2O) x C≡C-, -(CH2CH2O) x SCN-, -(CH2CH2O) x SH-, Selected from the group consisting of TIFF2026510425000062.tif9128, -CH2CH2NHC(=O)-, and -CH2CH2C(=O)NH-; d is an integer selected from 1 to 9; R 6 is H or an electron-withdrawing group; and R 9 It is selected from the group consisting of H and C1-C6 alkyl groups, During the ceremony, TIFF2026510425000063.tif6128 shows the bonding sites of a specified group to a nanoparticle metal oxide core.

[0091] In some embodiments of the imaging agent of formula II, R 5 This is -CH2CH2NHC(=O)- or -CH2CH2C(=O)NH-.

[0092] In some embodiments of the imaging agent of Formula II, the benzenediol is TIFF2026510425000064.tif21128, wherein TIFF2026510425000065.tif4128 indicates the binding point of the specified group to the linker.

[0093] In some embodiments of the imaging agent of Formula II, X is CR 9 where R 9 is selected from the group consisting of H and C1-C6 alkyl. For example, X can be CH, CMe, and CEt. In some embodiments of the imaging agent of Formula II, X is N.

[0094] In some embodiments of the imaging agent of Formula II, R 6 is H.

[0095] In some embodiments of the imaging agent of Formula II, R 6 is an electron-withdrawing group. For example, R 6 can be -NO2, -SO3H, -SO3Na, -CF3, -SO2CF3, or -CN.

[0096] In some embodiments of the imaging agent of Formula II, the hydroxycarboxylic acid is an α-hydroxycarboxylic acid. For example, the hydroxycarboxylic acid can be lactic acid or glycolic acid. In some embodiments of the imaging agent of Formula II, the hydroxycarboxylic acid is a β-hydroxycarboxylic acid. For example, the hydroxycarboxylic acid can be tropic acid or citric acid.

[0097] In some embodiments of the imaging agent of Formula II, the hydroxycarboxylic acid has the formula: TIFF2026510425000066.tif22128 or a pharmaceutically acceptable salt thereof, where e is an integer selected from 1-4, R 7 is H, -(CH2) f C(O)-, and -(CH2)f selected from the group consisting of NH- f is an integer selected from 0 to 5.

[0098] In some embodiments of the imaging agent of Formula II, the hydroxycarboxylic acid has the formula: TIFF2026510425000067.tif30128, wherein TIFF2026510425000068.tif6128 indicates the binding point of the designated group to the nanoparticle metal oxide core.

[0099] In some embodiments of the imaging agent of Formula II, R 7 is -(CH2) f C(O)- or -(CH2) f NH-.

[0100] In some embodiments of the imaging agent of Formula II, the hydroxycarboxylic acid is TIFF2026510425000069.tif31128, wherein TIFF2026510425000070.tif4128 indicates the binding point of the designated group to the linker.

[0101] In some embodiments of the imaging agent of Formula II, the linker portion has a molecular weight of about 200 to about 800 amu. Examples include about 200 to about 750, about 200 to about 700, about 200 to about 650, about 200 to about 600, about 200 to about 550, about 200 to about 500, about 200 to about 450, about 200 to about 400, about 200 to about 350, about 200 to about 300, or about 200 to about 250 amu. In some embodiments of the imaging agent of formula II, the linker has a molecular weight of approximately 250 to approximately 800, approximately 300 to approximately 800, approximately 350 to approximately 800, approximately 400 to approximately 800, approximately 450 to approximately 800, approximately 500 to approximately 800, approximately 550 to approximately 800, approximately 600 to approximately 800, approximately 650 to approximately 800, approximately 700 to approximately 800, or approximately 750 to approximately 800 amu. In some embodiments of the imaging agent of formula II, the linker portion has a molecular weight of approximately 250 to approximately 600, approximately 300 to approximately 650, approximately 350 to approximately 700, or approximately 400 to approximately 750 amu.

[0102] In some embodiments of the imaging agent of formula II, the linker portion is -NHCH(R 4 )CO-, -NH(CH2) g C(O)-, NHCH2CH2OCH2CH2CH2C(O)-, -NHCH2CH2OCH2CH2OCH2CH2C(O)-, NHCH2C6H4CH2NH-, -NH(CH2) h NH-, -NHCH2OCH2NH-, -NHCH2CH2OCH2CH2NH-, -NHCH2CH2OCH2CH2OCH2CH2NH-, -N3(CH2CH2O) i C(O)-, -C≡C(CH2CH2O) i C(O)-, -SCN(CH2CH2O) i C(O)-, -SH(CH2CH2O) i C(O)-, Selected from the group consisting of TIFF2026510425000071.tif20128; Here, g is an integer selected from 1 to 6; R 4 These are amino acid side chains; h is an integer selected from 2 to 6; i is an integer selected from 2 to 10; and Linkers can be read from right to left or left to right; During the ceremony, TIFF2026510425000072.tif3128 shows the binding sites of the specified group to the fibrin-binding peptide.

[0103] In some embodiments of the imaging agent of formula II, the linker portion is selected from the group consisting of -CH2CH2OC(=O)-, -CH2CH2OCH2CH2OC(=O)-, -CH2CH2O(CH2CH2O)2C(=O)-, -CH2CH2O(CH2CH2O)3C(=O)-, -CH2CH2O(CH2CH2O)4C(=O)-, and -CH2CH2O(CH2CH2O)5C(=O)-.

[0104] In some embodiments of the imaging agent of formula II, the linker portion is selected from the group consisting of -CH2CH2O-, -CH2CH2OCH2CH2O-, -CH2CH2O(CH2CH2O)2-, -CH2CH2O(CH2CH2O)3-, -CH2CH2O(CH2CH2O)4-, and -CH2CH2O(CH2CH2O)5-.

[0105] In some embodiments of the imaging agent of formula II, the linker portion is The filename is TIFF2026510425000073.tif14128.

[0106] In some embodiments of the imaging agent of Formula II, the fibrin-binding peptide is approximately 2 to approximately 25 amino acid residues long. Examples include approximately 2 to approximately 23, approximately 2 to approximately 20, approximately 2 to approximately 18, approximately 2 to approximately 15, approximately 2 to approximately 12, approximately 2 to approximately 10, approximately 2 to approximately 8, approximately 2 to approximately 5, or approximately 2 to approximately 4 amino acid residues long. In some embodiments of the imaging agent of Formula II, the fibrin-binding peptide is approximately 5 to approximately 25, approximately 8 to approximately 25, approximately 10 to approximately 25, approximately 12 to approximately 25, approximately 15 to approximately 25, approximately 18 to approximately 25, approximately 20 to approximately 25, or approximately 22 to approximately 25 amino acid residues long. In some embodiments of the imaging agent of formula II, the fibrin-binding peptide has an amino acid residue length of approximately 5–10, 5–15, 10–12, 10–15, 10–20, 15–18, or 15–20.

[0107] In some embodiments of the imaging agent of formula II, the fibrin-binding peptide is of formula: It has TIFF2026510425000074.tif43142, In the formula, X 1 teeth, Selected from the group consisting of TIFF2026510425000075.tif19128; X 2 teeth, Selected from the group consisting of TIFF2026510425000076.tif13128; X 3 It is selected from the group consisting of H and OH; X 4 It is selected from the group consisting of H, I, Br, and Cl; X 5 It is selected from the group consisting of H and CH2COOH; X 6 teeth, Selected from the group consisting of TIFF2026510425000077.tif19128; and X 7 It is selected from the group consisting of CH2CH2C(O)NH2 and CH2CH(CH3)2; During the ceremony, TIFF2026510425000078.tif3128 indicates the binding site of the specified group to the fibrin-binding peptide.

[0108] In some embodiments of the imaging agent of Formula II, the imaging agent has the formula: TIFF2026510425000079.tif72165, and wherein TIFF2026510425000080.tif10128 is a nanoparticle of iron oxide, manganese oxide, or gadolinium oxide; A and B are independently selected from CH and N; R 6 is selected from the group consisting of -H, -NO2, -CF3, -SO3H, -SO3Na, -CHCHSO3Na; and n is an integer selected from 1 to 6.

[0109] In some embodiments of the imaging agent of Formula II, the imaging agent further comprises an additional metal oxide binding ligand. In some embodiments, the additional metal oxide binding ligand is TIFF on2026510425000081.tif19128, wherein TIFF2026510425000082.tif6128 indicates the binding site of the specified group to the nanoparticle metal oxide core.

[0110] In some embodiments, the metal oxide ligands and additional metal oxide ligands cover approximately 1–10%, 10–20%, 20–30%, 30–40%, 40–50%, 50–60%, 60–70%, 70–80%, 80–90%, or 90–100% of the surface of the nanoparticle metal oxide core. In some embodiments, the metal oxide ligands cover approximately 1–10%, 10–20%, 20–30%, 30–40%, 40–50%, 50–60%, 60–70%, 70–80%, 80–90%, or 90–100% of the surface of the nanoparticle metal oxide core. In some embodiments, the additional metal oxide-bonding ligands cover approximately 1–10%, 10–20%, 20–30%, 30–40%, 40–50%, 50–60%, 60–70%, 70–80%, 80–90%, or 90–100% of the surface of the nanoparticle metal oxide core.

[0111] In some embodiments, the ratio of metal oxide-bonding ligands to additional metal oxide-bonding ligands on the surface of the nanoparticle metal oxide core is approximately 1:1, 1:5, 1:10, 1:15, 1:20, 20:1, 15:1, 10:1, or 5:1. In some embodiments, the ratio is approximately 1.1. In some embodiments, the ratio is approximately 1.5. In some embodiments, the ratio is approximately 1.10. In some embodiments, the ratio is approximately 1.15. In some embodiments, the ratio is approximately 1.20. In some embodiments, the ratio is approximately 20:1. In some embodiments, the ratio is approximately 15:1. In some embodiments, the ratio is approximately 10:1. In some embodiments, the ratio is approximately 5:1.

[0112] In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is CH, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is CH, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is CH, and R 6is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is CH, and R 6 It is -CHCHSO3Na.

[0113] In some embodiments, the nanoparticle metal oxide core is iron oxide, A is N, B is CH, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is N, B is CH, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is N, B is CH, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is N, B is CH, and R 6 It is -CHCHSO3Na.

[0114] In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is N, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is N, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is N, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is N, and R 6 It is -CHCHSO3Na.

[0115] In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is CH, B is CH, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is CH, B is CH, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is CH, B is CH, and R6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is CH, B is CH, and R 6 It is -CHCHSO3Na.

[0116] In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is N, B is CH, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is N, B is CH, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is N, B is CH, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is N, B is CH, and R 6 It is -CHCHSO3Na.

[0117] In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is CH, B is N, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is CH, B is N, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is CH, B is N, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, A is CH, B is N, and R 6 It is -CHCHSO3Na.

[0118] In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is CH, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is CH, and R 6is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is CH, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, A is CH, B is CH, and R 6 It is -CHCHSO3Na.

[0119] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, A is N, B is CH, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, A is N, B is CH, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, A is N, B is CH, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, A is N, B is CH, and R 6 It is -CHCHSO3Na.

[0120] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, A is CH, B is N, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, A is CH, B is N, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, A is CH, B is N, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, A is CH, B is N, and R 6 It is -CHCHSO3Na.

[0121] In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is lactic acid, 6is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is lactic acid, R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, the hydroxycarboxylic acid is lactic acid, and R 6 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is lactic acid. 6 It is -CHCHSO3Na.

[0122] In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is glycolic acid, 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is glycolic acid, R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is glycolic acid, R 6 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is glycolic acid. 6 It is -CHCHSO3Na.

[0123] In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is citric acid, 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is citric acid, R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is citric acid, R 6 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is citric acid. 6 It is -CHCHSO3Na.

[0124] In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000083.tif22128, where e is an integer selected from 1 to 4, and R 7 H is R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000084.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000085.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000086.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 It is -CHCHSO3Na.

[0125] In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000087.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000088.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) fC(O)-, where f is an integer selected from 0 to 5, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000089.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000090.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 It is -CHCHSO3Na.

[0126] In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000091.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000092.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000093.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) fNH-, where f is an integer selected from 0 to 5, and R 6 is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is iron oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000094.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 It is -CHCHSO3Na.

[0127] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is lactic acid, 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, the hydroxycarboxylic acid is lactic acid, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, the hydroxycarboxylic acid is lactic acid, and R 6 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is lactic acid. 6 It is -CHCHSO3Na.

[0128] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is glycolic acid, 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is glycolic acid, R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is glycolic acid, R 6 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is glycolic acid. 6 It is -CHCHSO3Na.

[0129] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is citric acid, 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, the hydroxycarboxylic acid is citric acid, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, the hydroxycarboxylic acid is citric acid, and R 6 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is citric acid. 6 It is -CHCHSO3Na.

[0130] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000095.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000096.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000097.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000098.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6It is -CHCHSO3Na.

[0131] In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000099.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000100.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000101.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000102.tif23128, where p is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 It is -CHCHSO3Na.

[0132] In some embodiments, the nanoparticle metal oxide core is manganese oxide. Hydroxycarboxylic acids The filename is TIFF2026510425000103.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000104.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000105.tif24128, where p is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is manganese oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000106.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 It is -CHCHSO3Na.

[0133] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is lactic acid, 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, the hydroxycarboxylic acid is lactic acid, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, the hydroxycarboxylic acid is lactic acid, and R 6R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is lactic acid. 6 It is -CHCHSO3Na.

[0134] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is glycolic acid, R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is glycolic acid, R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is glycolic acid, R 6 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is glycolic acid. 6 It is -CHCHSO3Na.

[0135] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is citric acid, 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is citric acid, R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, the hydroxycarboxylic acid is citrate, and R 6 R is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is citric acid. 6 It is -CHCHSO3Na.

[0136] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000107.tif23128, where e is an integer selected from 1 to 4, and R7 H is R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000108.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000109.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000110.tif23128, where e is an integer selected from 1 to 4, and R 7 H is R 6 It is -CHCHSO3Na.

[0137] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000111.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000112.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000113.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000114.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f C(O)-, where f is an integer selected from 0 to 5, and R 6 It is -CHCHSO3Na.

[0138] In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000115.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 is -NO2. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000116.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 is -CF3. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000117.tif22128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6The is selected from the group consisting of -SO3H and -SO3Na. In some embodiments, the nanoparticle metal oxide core is gadolinium oxide, and the hydroxycarboxylic acid is The filename is TIFF2026510425000118.tif23128, where e is an integer selected from 1 to 4, and R 7 ha-(CH2) f NH-, where f is an integer selected from 0 to 5, and R 6 It is -CHCHSO3Na.

[0139] Fibrin-binding imaging agent The fibrin-binding peptides described herein have affinity for fibrin in mammals (e.g., thrombi, solid tumors, and atherosclerotic plaques). Any peptide capable of binding to fibrin may be used. For example, peptides disclosed in WO 2008 / 071679, U.S. Patents 6,984,373, 6,991,775, and 7,238,341, and U.S. Patent Application No. 2005 / 0261472 may be used.

[0140] The ability of a peptide to bind to fibrin can be evaluated using known methodologies. For example, the affinity of a peptide to fibrin can be assessed using a fibrin DD(E) fragment, which contains 55 kD (fragment E) and 190 kD (fragment DD) subunits. The DD(E) fragment can be biotinylated and immobilized on a solid support (e.g., a multiwell plate) via avidin. The peptide can then be incubated with the immobilized DD(E) fragment in a suitable buffer, and binding can be detected using known methodologies. See, for example, WO 2001 / 09188.

[0141] Binding can also be evaluated by plasma-derived clot assays (see, e.g., Overoye-Chan et al. J. Am. Chem. Soc. 2008130:6025-39). In this specification, a known concentration of the peptide is incubated in plasma (human or other species), and thrombin is added to induce clot formation. The clot is separated from the serum, and the concentration of the peptide ([peptide]free) in the serum is measured (e.g., by HPLC, or by fluorescence if the peptide is labeled with a fluorophore, or by radioactivity if it is labeled with a radionuclide). The concentration of fibrin-bound peptide ([peptide]bound) is calculated by subtraction ([peptide]bound = [peptide]total - [peptide]free).

[0142] Binding can also be evaluated by a dry fibrin assay. In this specification, purified fibrinogen (2.5 mg / mL; 7 μM fibrin) was coagulated using thrombin and dried into a thin film in the wells of a microtiter plate. The resulting clot binds to the plate without protein loss. The clot is rehydrated with a buffer containing a known concentration of peptide. After incubation at 37°C for 2 hours, the concentration of peptide ([peptide]free) in the supernatant is measured (e.g., by HPLC, or by fluorescence if the peptide is labeled with a fluorophore, or by radioactivity if it is labeled with a radionuclide). The concentration of fibrin-bound peptide ([peptide]bound) is calculated by subtraction ([peptide]bound = [peptide]total - [peptide]free). The fibrin bond dissociation constant (Kd) can be determined by fitting a plot of [peptide] binding versus [peptide] release to a stoichiometric model (see, e.g., Nair et al., Angew. Chem. Int. Ed. 2008 47:4918-21) or an equivalent binding site model (see, e.g., Overoye-Chan et al. J. Am. Chem. Soc. 2008 130:6025-39).

[0143] Peptides can be synthesized directly using conventional techniques, including solid-phase peptide synthesis and solution-phase synthesis. See, for example, Stewart et al., Solid-Phase peptide Synthesis (1989), WH Freeman Co., San Francisco; Merrifield, J. Am. Chem. Soc., 1963 85:2149-2145; Bodanszky and Bodanszky, The Practice of Peptide Synthesis (1984), Springer-Verlag, New York. Peptides may be prepared or purchased commercially. Automated peptide synthesizers, such as those manufactured by Perkin-Elmer Applied Biosystems, can also be used.

[0144] In some embodiments, fibrin-binding peptides are purified once isolated or synthesized by chemical or recombinant techniques. For purification purposes, alkylated silica columns (e.g., C4, C8, or C4) are used. 18 There are many standard methods that can be employed, including reverse-phase high-pressure liquid chromatography (RP-HPLC) using silica. For example, a gradient mobile phase of increasing organic contents, which is acetonitrile in aqueous buffer and usually contains a small amount of trifluoroacetic acid, is commonly used to achieve purification. Ion exchange chromatography can also be used to separate peptides based on their charge. The purity of fibrin-bound peptides can be determined in various ways, including the identification of major large peaks in HPLC. In some embodiments, the peptide produces a single peak that is at least 95% of the input material to the HPLC column. In some embodiments, the peptide produces a single peak that is at least 97%, at least 98%, at least 99%, or at least 99.5% of the input material to the HPLC column.

[0145] pharmaceutically acceptable derivatives and compositions In some embodiments, the imaging agents of the present disclosure can be formulated as pharmaceutical compositions according to routine procedures. In some embodiments, the pharmaceutical composition comprises a compound of formula I or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient. In some embodiments, the pharmaceutical composition comprises a compound of formula II or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient.

[0146] When used herein, imaging agents may include pharmaceutically acceptable derivatives thereof. "Pharmacologically acceptable" means that the compound or composition can be administered to an animal without unacceptable adverse effects. "Pharmacologically acceptable derivative" means any pharmaceutically acceptable salt, ester, salt of an ester, or other derivative of an imaging agent of this disclosure that can provide the imaging agent or its active metabolite or residue (directly or indirectly) when administered to a recipient.

[0147] Other derivatives include those that improve the bioavailability of imaging agents when such compounds are administered to mammals (for example, by enabling orally administered compounds to be more readily absorbed into the bloodstream), or those that enhance the delivery of the parent compound to biological compartments (e.g., the brain or lymphatic system), thereby increasing exposure to the parent species.

[0148] The pharmaceutically acceptable salts of the imaging agents of this disclosure include counterions derived from pharmaceutically acceptable inorganic and organic acids and bases known in the art, such as alkali metal and alkaline earth metal cations; sodium; primary, secondary, and tertiary amines such as ethanolamine, diethanolamine, morpholine, glucamine, N,N-dimethylglucamine, and N-methylglucamine; and amino acids such as lysine, arginine, and ornithine.

[0149] The pharmaceutical compositions described herein can be administered by any route, including both oral and parenteral administration. Parenteral administration includes, but is not limited to, subcutaneous, intravenous, intra-arterial, interstitial, intrathecal, and intracavitary administration. When administration is intravenous, the pharmaceutical composition may be administered as a bolus, as two or more temporally separated terminations, or as an infusion of a constant or non-linear flow rate. Thus, the compositions of this disclosure can be formulated for any route of administration.

[0150] Typically, compositions for intravenous administration are solutions in sterile isotonic aqueous buffer. If necessary, the composition may also include solubilizers, stabilizers, and local anesthetics such as lidocaine to relieve pain at the injection site. Compositions for intravenous administration may also contain 80 mmol of sucrose. In some embodiments, the components are supplied, for example, separately in a kit or mixed together in a unit dosage form, as, for example, a dry lyophilized powder or a water-free concentrate. Compositions can be stored in sealed containers such as ampoules or sachets indicating the amount of activator in active units. When the composition is administered by infusion, it can be prepared using infusion bottles containing sterile pharmaceutical-grade "water for injection," saline, or other suitable intravenous fluid. When the composition is administered by injection, ampoules of sterile water for injection or saline may be prepared so that the components can be mixed before administration. The pharmaceutical compositions of this disclosure comprise the imaging agents described herein and their pharmaceutically acceptable salts, together with any pharmaceutically acceptable components, excipients, carriers, adjuvants, or vehicles.

[0151] In some embodiments, the compositions of the Disclosure are administered to a patient in the form of an injectable composition. In some embodiments, the method of administering the compound is parenteral, meaning intravenous, intraarterial, intrathecal, interstitial, or intraluminal. The pharmaceutical compositions of the Disclosure may be administered to animals, including humans, in a manner similar to other diagnostic or therapeutic agents. The dosage and mode of administration depend on a variety of factors, including age, weight, sex, patient condition, and genetic factors, and are ultimately determined by a healthcare professional after imaging studies described herein, followed by empirical decisions to vary the dosage.

[0152] Methods for imaging collagen In some embodiments, a method for imaging collagen in a mammal includes the steps of: administering an effective amount of an imaging agent of formula I or a pharmaceutically acceptable salt thereof to a mammal; acquiring an image of the mammal's collagen using nuclear imaging techniques and acquiring an image of the mammal using magnetic resonance imaging; and superimposing the images to identify the location of collagen within an anatomical image of the mammal.

[0153] In some embodiments of methods for imaging collagen, images of mammalian collagen using nuclear imaging techniques and images of mammals using magnetic resonance imaging are acquired simultaneously. In some embodiments of methods for imaging collagen, images of mammalian collagen using nuclear imaging techniques are acquired first, and images of mammals using magnetic resonance imaging are acquired second. In some embodiments of methods for imaging collagen, images of mammals using magnetic resonance imaging are acquired first, and images of mammalian collagen using nuclear imaging techniques are acquired second.

[0154] In some embodiments, a method for imaging collagen in a mammal includes the steps of: administering an effective amount of an imaging agent of formula I or a pharmaceutically acceptable salt thereof to a mammal; then acquiring an image of the mammal's collagen using nuclear imaging techniques and an image of the mammal using computed tomography; and then superimposing the images to identify the location of collagen within an anatomical image of the mammal.

[0155] In some embodiments of methods for imaging collagen, images of mammalian collagen using nuclear imaging techniques and images of mammalian collagen using computed tomography are acquired simultaneously. In some embodiments of methods for imaging collagen, images of mammalian collagen using nuclear imaging techniques are acquired first, and images of mammalian collagen using computed tomography are acquired second. In some embodiments of methods for imaging collagen, images of mammalian collagen using computed tomography are acquired first, and images of mammalian collagen using nuclear imaging techniques are acquired second.

[0156] In some embodiments of the methods for imaging collagen, the nuclear imaging technique is single-photon emission, computed tomography, or a combination thereof. In some embodiments of the methods for imaging collagen, the mammal is human. In some embodiments of the methods for imaging collagen, the mammal is rat. In some embodiments of the methods for imaging collagen, the mammal is dog.

[0157] In some embodiments of a method for imaging collagen, the method further includes the step of administering an effective amount of a second imaging agent to a mammal. In some embodiments, this second imaging agent does not target collagen.

[0158] In some embodiments, the second imaging agent includes an MRI imaging agent. In some embodiments, the second imaging agent is an MRI imaging agent. Examples include gadoteridol, gadopentetate, gadobenate, gadoxetic acid, gadodiamide, gadobercetamide, and gadophosbecet; or CT imaging agents selected from the group consisting of iopamidol, iohexol, ioxiran, iopromide, iodixanol, ioxagrate, metrizoate, and diatrizoate.

[0159] Methods for imaging fibrin In some embodiments, a method for imaging fibrin in a mammal includes the steps of: administering an effective amount of an imaging agent of formula I or a pharmaceutically acceptable salt thereof to a mammal; acquiring an image of the mammal's fibrin using nuclear imaging techniques and acquiring an image of the mammal using magnetic resonance imaging; and superimposing the images to identify the location of fibrin within an anatomical image of the mammal.

[0160] In some embodiments of methods for imaging fibrin, images of mammalian fibrin using nuclear imaging techniques and images of mammalian fibrin using magnetic resonance imaging are acquired simultaneously. In some embodiments of methods for imaging fibrin, images of mammalian fibrin using nuclear imaging techniques are acquired first, and images of mammalian fibrin using magnetic resonance imaging are acquired second. In some embodiments of methods for imaging fibrin, images of mammalian fibrin using magnetic resonance imaging are acquired first, and images of mammalian fibrin using nuclear imaging techniques are acquired second.

[0161] In some embodiments, a method for imaging fibrin in a mammal includes the steps of: administering an effective amount of an imaging agent of formula I or a pharmaceutically acceptable salt thereof to a mammal; then acquiring an image of the mammal's fibrin using nuclear imaging techniques and an image of the mammal using computed tomography; and then superimposing the images to identify the location of fibrin within an anatomical image of the mammal.

[0162] In some embodiments of methods for imaging fibrin, images of mammalian fibrin using nuclear imaging techniques and images of mammalian fibrin using computed tomography are acquired simultaneously. In some embodiments of methods for imaging fibrin, images of mammalian fibrin using nuclear imaging techniques are acquired first, followed by images of mammalian fibrin using computed tomography. In some embodiments of methods for imaging fibrin, images of mammalian fibrin using computed tomography are acquired first, followed by images of mammalian fibrin using nuclear imaging techniques.

[0163] In some aspects of methods for imaging fibrin, the nuclear imaging technique is single-photon emission, computed tomography, or a combination thereof.

[0164] In some embodiments of the method for imaging fibrin, the mammal is human. In some embodiments of the method for imaging fibrin, the mammal is rat. In some embodiments of the method for imaging fibrin, the mammal is dog.

[0165] In some embodiments of a method for imaging fibrin, the method further includes the step of administering an effective amount of a second imaging agent to a mammal. In some embodiments, this second imaging agent does not target fibrin.

[0166] In some embodiments, the second imaging agent includes an MRI imaging agent. In some embodiments, the second imaging agent is an MRI imaging agent. Examples include gadoteridol, gadopentetate, gadovenate, gadoxetate, gadodiamide, gadobercetamide, and gadophosbecet; or CT imaging agents selected from the group consisting of iopamidol, iohexol, ioxiran, iopromide, iodixanol, ioxagrate, metrizoate, and diatrizoate.

[0167] Image overlay Image overlay can be performed by various means known in the art. See, for example, U.S. Patents 7,412,279; 7,110,616; 6,898,331; 6,549,798; and 5,672,877; Rudd, J.HF. et al., J. Nucl. Med. 2008 49(6): 871-878; Slomka, PJ et al., J. Nucl. Med. 2009 50: 1621-1630; and Jupp, B. and O'Brien, TJ, Epilepsia 2007 49: 82-89. In some embodiments, first and second image datasets can be overlaid to determine the presence of collagen or fibrin in mammals. For example, the first and second image datasets can be combined to generate a third dataset containing images of collagen or fibrin targets and images of the anatomical regions where the collagen or fibrin is located. This third dataset can indicate the location of collagen or fibrin, if present, within a mammal. If desired, this third dataset may be displayed on a display device to indicate the location of stationary targets within the vascular system. This third dataset may also indicate the size of stationary targets within a mammal. [Examples]

[0168] The present disclosure is further illustrated by the following embodiments, which do not limit the scope of the present disclosure as set forth in the appended claims.

[0169] Example 1: Miniature Fe with citric acid coating using microwave irradiation x O y Nanoparticle synthesis Citrate-coated iron oxide nanoparticles were synthesized according to a known procedure (Pellico et al., Langmuir 2017, 33, 10239-10247). The nanoparticle size and coating thickness were controlled by varying the reaction temperature. The size of the iron oxide cores varied from 3.4 to 4.5 nm in diameter. The hydrodynamic size of the citrate-coated nanoparticles varied from 2.9 to 21 nm in diameter.

[0170] Hydrazine monohydrate was added to a mixture of FeCl3·6H2O in water and trisodium citrate. This mixture was treated with microwave irradiation and heated at 240W for 10 minutes with stirring. The temperature ranged from 60 to 140°C. After the reaction was complete, the resulting nanoparticles were purified by gel filtration chromatography (PD10).

[0171] Example 2: Miniature Fe with catechol-based coating x O y Nanoparticle synthesis Iron oxide nanoparticles coated with catechol-based metal oxide ligands were synthesized according to a known procedure (Wei et al. Nano Lett. 2012, 22, 22-25). Iron oxide particles were first synthesized with an oleic acid surface, and the catechol derivatives were synthesized separately.

[0172] Catechol derivatives To a solution of 3-(3,4-dihydroxyphenyl)propanoic acid in dichloromethane, N-hydroxysuccinimide (NHS) and N,N'-dicyclohexylcarbodiimide (DCC) were added. The resulting NHS ester in dichloromethane was treated with an amino-based bifunctional linking moiety and N,N'-diisopropylethylamine (DIPEA) to obtain catechol derivatives.

[0173] Iron oxide nanoparticles coated with an oleic acid ligand in ethanol were treated with 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MEAA). MEAA was used as an intermediate ligand to facilitate ligand exchange for the formation of final particles and to improve the solubility of the iron oxide particles in DMF / DI water. The intermediate MEAA-based particles were treated with a solution of catechol derivatives in DMF / DI water, precipitated, and then purified by dialysis to obtain iron oxide nanoparticles coated with catechol-based metal oxide-bonded ligands.

[0174] To obtain iron oxide particles coated with structurally different catechols that can be used for further derivatization, a similar procedure was performed using mixtures of separate catechol-based compounds in pre-calculated ratios.

[0175] Example 3: Superparamagnetic iron oxide nanoparticles (SPIONs) have been studied for their applications in T2-weighted MRI due to their larger r2 / r1 ratio compared to Gd(III). However, the high r2 / r1 ratio also leads to significant signal loss for SPIONs in positive-contrast T1-weighted images. In addition, most SPIONs circulate in the bloodstream for extended periods and / or accumulate in the liver due to their large size (over 10 nm) and their phagocytosis by macrophages. As a result, targeted imaging with SPIONs requires several hours to several days for sufficient probe accumulation at the target and background washout, and targeted imaging of the liver is hindered by high background signaling. Single-nanometer iron oxide (SNIO) nanoparticles have been shown to be a powerful probe for in vivo T1-weighted imaging due to their rapid blood clearance and low liver uptake. SNIOCBP is a type I collagen-binding peptide-functionalized SNIO nanoparticle for the detection of hepatic fibrosis, which is the result of viral hepatitis B or C infection, autoimmune diseases, and biliary tract diseases, or most chronic liver injuries, including alcoholic and non-alcoholic steatohepatitis. TIFF2026510425000120.tif35148

[0176] SNIO-CBP was prepared by conjugation of alkyne-functionalized SNIO (SNIO-alkyne) and type I collagen-binding peptide CBP-azide via a copper-catalyzed alkyne-azide reaction (Figure 1). Small-angle X-ray scattering (SAXS) confirmed that the average diameter of the iron oxide core of SNIOCBP was 1.5 nm (Figure 2). Gel filtration chromatography showed an average hydrodynamic diameter of 3.8 nm (Figure 3). SNIO-CBP had a zeta potential close to zero and showed minimal nonspecific binding in plasma after incubation with fetal bovine serum (FBS) (Figure 4). 56Fe ICP-MS and L-amino acid quantification determined the SNIO / CBP ratio to be 1 / 1.2. SNIO-CBP exhibited a dissociation constant of 23.2 μM upon binding to type I collagen (Figure 5). The longitudinal relaxation ability (r1) of SNIO-CBP was 1.41 T and 4.5 s at 37°C. -1 (mM Fe) -1 , or 145 s -1 (mM peptide) -1 It was measured as follows.

[0177] Dynamic T1-weighted MRI after intravenous administration (2 nmol / g based on CBP concentration) showed immediate blood pool enhancement with a serum elimination half-life of 5.7 minutes, followed by rapid renal excretion. Importantly, SNIO-CBP showed only transient, slight hepatic enhancement consistent with extracellular distribution and renal clearance (Figure 6). Next, we investigated the ability of SNIO-CBP to detect hepatic fibrosis in two different mouse models: a CCl4-induced hepatic fibrosis model and a choline-deficient, L-amino acid-restricted high-fat diet (CDAHFD) model. SNIO-CBP-enhanced T1-weighted MRI was able to specifically and robustly detect hepatic fibrosis in both toxin-induced (Figure 7) and diet-induced (Figure 8) mouse models. Changes in ΔCNR in fibrous liver due to SNIO-CBP were well consistent with increased hydroxyproline content and elevated collagen proportional area (CPA) in the liver. Prussian blue staining showed the localization of SNIO-CBP in fibrous regions. Importantly, in detecting hepatic fibrosis in CCl4 mice, the sensitivity of SNIO-CBP was compared with CM-101, a CBP-modified gadolinium-based contrast agent. We found that SNIO-CBP produced comparable fibrous liver enhancement to CM-101, even at 2.5 times lower doses, demonstrating the higher sensitivity of gadolinium-free SNIO-CBP.

[0178] SNIO-CBP was shown to possess ideal properties as a targeted T1-weighted contrast agent, including good affinity for type I collagen, minimal nonspecific binding to plasma biomolecules, rapid blood elimination, and minimal nonspecific liver enhancement. These properties enabled rapid (within minutes post-injection) detection and quantification of hepatic fibrosis with higher sensitivity than state-of-the-art Gd-based probes in two different mouse models. In summary, SNIO-CBP is a promising candidate as a gadolinium-free contrast agent for highly sensitive detection of hepatic fibrosis.

[0179] Other embodiments While this disclosure has been described in conjunction with its detailed description, it should be understood that the foregoing description is intended to illustrate, and not limit, the scope of this disclosure as defined by the attached claims. Other aspects, advantages, and modifications are included in the attached claims.

Claims

1. Imaging agent of formula I, or a pharmaceutically acceptable salt thereof: [NP]-[C] m -[L] n -[CP] o (I) In the formula, NP is a nanoparticle metal oxide core containing iron oxide, manganese oxide, or gadolinium oxide; C is a metal oxide bond ligand; L is the linker part; CP is a collagen-binding peptide; n is an integer selected from 0 to 10; and m and o are integers independently selected from 1 to 5.

2. The imaging agent according to claim 1, wherein the nanoparticle metal oxide core contains about 5 to about 200 metal ions.

3. The imaging agent according to claim 2, wherein the nanoparticle metal oxide core contains about 5 to about 100 metal ions.

4. The imaging agent according to claim 3, wherein the nanoparticle metal oxide core contains about 10 to about 50 metal ions.

5. The imaging agent according to any one of claims 1 to 4, wherein the nanoparticle metal oxide core contains iron oxide.

6. The imaging agent according to any one of claims 1 to 4, wherein the nanoparticle metal oxide core comprises manganese oxide.

7. The imaging agent according to any one of claims 1 to 4, wherein the nanoparticle metal oxide core comprises gadolinium oxide.

8. The imaging agent according to any one of claims 1 to 7, wherein the metal oxide bond ligand is selected from benzenediol or hydroxycarboxylic acid.

9. The aforementioned benzenediol is given by formula: It has, In the formula, X and Y are independently selected from CH and N; R 1 が、-CH 2 CH 2 COOH、-CH 2 CH 2 NH 2 、-CH 2 CH 2 SH、-(CH 2 CH 2 ABOUT) x N 3 -、-(CH 2 CH 2 ABOUT) x C≡C-、-(CH 2 CH 2 ABOUT) x SCN-、-(CH 2 CH 2 ABOUT) x SH-、および Selected from; x is an integer selected from 1 to 9; and R 2 However, H or an electron-withdrawing group, The imaging agent according to claim 8.

10. R 2 However, -NO 2 , -SO 3 H, -SO 3 Na and -CF 3 The imaging agent according to claim 9, wherein the electron-withdrawing group is selected from the group consisting of the following.

11. The imaging agent according to claim 8, wherein the metal oxide bond ligand is an α-hydroxycarboxylic acid.

12. The imaging agent according to claim 11, wherein the α-hydroxycarboxylic acid is selected from lactic acid or glycolic acid.

13. Hydroxycarboxylic acid, formula: or having a pharmaceutically acceptable salt thereof, In the formula, p is an integer selected from 1 to 4. R 3 H, -(CH 2 ) q C(O)-, and -(CH 2 ) q Selected from the group consisting of NH-, q is an integer selected from 1 to 5. The imaging agent according to claim 8.

14. The imaging agent according to any one of claims 1 to 13, wherein the linker, when present, has a molecular weight of about 200 to about 800 amu.

15. The imaging agent according to claim 14, wherein the linker has a molecular weight of about 250 to about 600 amu.

16. Each linker is independently -NHCH(R 4 )CO-, -NH(CH 2 ) s C(O)-, -NHCH 2 CH 2 OCH 2 CH 2 CH 2 C(O)-, -NHCH 2 CH 2 OCH 2 CH 2 OCH​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ Selected from the group consisting of; Here, s is an integer selected from 1 to 6; R 4 However, it is an amino acid side chain; and t is an integer selected from 2 to 6; and u is an integer selected from 2 to 10. The imaging agent according to claim 15.

17. The imaging agent according to any one of claims 1 to 16, wherein the collagen-binding peptide has a length of about 2 to about 25 amino acid residues.

18. The imaging agent according to claim 17, wherein the collagen-binding peptide has a length of about 10 to about 20 amino acid residues.

19. Collagen-binding peptide, formula: The imaging agent according to claim 18, having the following characteristics.

20. Imaging agent of formula II, or a pharmaceutically acceptable salt thereof: [NP]-[C] a -[L] b -[FP] c (II) In the formula, NP is a nanoparticle metal oxide core containing iron oxide, manganese oxide, or gadolinium oxide; C is a metal oxide bond ligand; L is the linker part; FP is a fibrin-bound peptide; b is an integer selected from 0 to 10; and a and c are each integers independently selected from 1 to 5.

21. The imaging agent according to claim 20, wherein the nanoparticle metal oxide core contains about 5 to about 200 metal ions.

22. The imaging agent according to claim 21, wherein the nanoparticle metal oxide core contains about 5 to about 100 metal ions.

23. The imaging agent according to claim 22, wherein the nanoparticle metal oxide core contains about 10 to about 50 metal ions.

24. The imaging agent according to any one of claims 20 to 23, wherein the nanoparticle metal oxide core contains iron oxide.

25. The imaging agent according to any one of claims 20 to 23, wherein the nanoparticle metal oxide core comprises manganese oxide.

26. The imaging agent according to any one of claims 20 to 23, wherein the nanoparticle metal oxide core comprises gadolinium oxide.

27. The imaging agent according to any one of claims 20 to 26, wherein the metal oxide bond ligand is selected from benzenediol or hydroxycarboxylic acid.

28. The aforementioned benzenediol is given by formula: It has, In the formula, A and B are independently selected from CH and N; R 5 が、-CH 2 CH 2 COOH、-CH 2 CH 2 NH 2 、-CH 2 CH 2 SH、-(CH 2 CH 2 ABOUT) d N 3 -、-(CH 2 CH 2 ABOUT) d C≡C-、-(CH 2 CH 2 ABOUT) d SCN-、-(CH 2 CH 2 ABOUT) d SH-、および Selected from the group consisting of; d is an integer selected from 1 to 9; and R 6 However, H or an electron-withdrawing group, The imaging agent according to claim 27.

29. R 6 However, -NO 2 , -SO 3 H, -SO 3 Na and -CF 3 The imaging agent according to claim 28, wherein the electron-withdrawing group is selected from the group consisting of the following.

30. The imaging agent according to claim 27, wherein the metal oxide bond ligand is an α-hydroxycarboxylic acid.

31. The imaging agent according to claim 30, wherein the α-hydroxycarboxylic acid is selected from lactic acid or glycolic acid.

32. The aforementioned hydroxycarboxylic acid is given by formula: or having a pharmaceutically acceptable salt thereof, In the formula, e is an integer selected from 1 to 4. R 7 H, -(CH 2 ) f C(O)-, and -(CH 2 ) f Selected from NH-, f is an integer selected from 1 to 5. The imaging agent according to claim 27.

33. The imaging agent according to any one of claims 20 to 32, wherein, if the linker is present, it has a molecular weight of about 200 to about 800 amu.

34. The imaging agent according to claim 33, wherein the linker has a molecular weight of about 250 to about 600 amu.

35. The linker is independently -NHCH(R)CO-, -NH(CH 2 ) g C(O)-, -NHCH 2 CH 2 OCH 2 CH 2 CH 2 C(O)-, -NHCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 C(O)-, NHCH 2 C 6 H 4 CH<了 2 NH-, -NH(CH 2 ) h NH-, -NHCH 2 OCH 2 NH-, -NHCH 2 CH 2 OCH 2 CH 2 NH-, -NHCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 NH-, -N 3 (CH 2 CH 2 O) i C(O)-, -C≡C(CH 2 CH 2 O) i C(O)-, -SCN(CH 2 CH 2 O) i C(O)-, -SH(CH 2 CH 2 O) i C(O)-, It should be noted that there may be some inaccuracies in the translation due to the unclear nature of the original text in some parts. It is recommended to double-check with the original context for a more accurate understanding. Selected from the group consisting of; Here, g is an integer selected from 1 to 6; R is any amino acid side chain; and h is an integer selected from 2 to 6; and i is an integer selected from 2 to 10. The imaging agent according to claim 34.

36. The imaging agent according to any one of claims 20 to 35, wherein the fibrin-binding peptide has a length of 2 to 25 amino acid residues.

37. The imaging agent according to claim 36, wherein the fibrin-binding peptide has a length of about 10 to 20 amino acid residues.

38. The fibrin-binding peptide has the formula: It has, In the formula, X 1 but, Selected from the group consisting of; X 2 but, Selected from the group consisting of; X 3 However, selected from the group consisting of H and OH; X 4 However, it is selected from the group consisting of H, I, Br, and Cl; X 5 However, H and CH 2 Selected from the group consisting of COOH; X 6 but, Selected from the group consisting of; and X 7 However, CH 2 CH 2 C(O)NH 2 and CH 2 CH(CH 3 ) 2 Selected from the group consisting of, The imaging agent according to claim 37.

39. A pharmaceutical composition comprising a compound of formula I or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient.

40. A pharmaceutical composition comprising a compound of formula II or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient.

41. A method for imaging collagen in mammals, (a) The step of administering an effective amount of the imaging agent of formula I or a pharmaceutically acceptable salt thereof to the mammal; (b) A step of obtaining an image of the collagen of the mammal using nuclear imaging technology; (c) the step of obtaining anatomical images of the mammal using magnetic resonance imaging or computed tomography; and (d) The process of overlaying the images from steps (b) and (c) in order to locate the image of collagen within the anatomical image of the mammal. The method, including the method described above.

42. The method according to claim 41, wherein the nuclear imaging technique is selected from single-photon emission computed tomography and positron emission tomography.

43. The method according to claim 41, wherein images of steps (b) and (c) are acquired simultaneously.

44. The method according to claim 41, further comprising the step of administering an effective amount of a second imaging agent to the mammal, wherein the second imaging agent does not target collagen.

45. The method according to claim 44, wherein the second imaging agent is an MRI imaging agent selected from the group consisting of gadoteridol, gadopentetate, gadobenate, gadoxetic acid, gadodiamide, gadobercetamide, and gadophosbecet; or a CT imaging agent selected from the group consisting of iopamidol, iohexol, ioxiran, iopromide, iodixanol, ioxagrate, metrizoate, and diatrizoate.

46. A method for imaging fibrin in mammals, (a) The step of administering an effective amount of the imaging agent of formula II or a pharmaceutically acceptable salt thereof to the mammal; (b) A step of obtaining an image of the fibrin of the mammal using nuclear imaging techniques; (c) the step of obtaining anatomical images of the mammal using magnetic resonance imaging or computed tomography; and (d) The process of overlaying the images from steps (b) and (c) in order to locate the fibrin image within the anatomical image of the mammal. The method, including the method described above.

47. The method according to claim 46, wherein the nuclear imaging technique is selected from single-photon emission computed tomography and positron emission tomography.

48. The method according to claim 46, wherein images of steps (b) and (c) are acquired simultaneously.

49. The method according to claim 46, further comprising the step of administering an effective amount of a second imaging agent to the mammal, wherein the second imaging agent does not target fibrin.

50. The method according to claim 49, wherein the second imaging agent is an MRI imaging agent selected from the group consisting of gadoteridol, gadopentetate, gadvenate, gadoxetic acid, gadodiamide, gadversetamide, and gadophosbecet; or a CT imaging agent selected from the group consisting of iopamidol, iohexol, ioxiran, iopromide, iodixanol, ioxagrate, metrizoate, and diatrizoate.

Images