Biodegradability Test Kit

Abstract

A biodegradable test kit and method for making the biodegradable test kit includes a first shaped body section and a second shaped body section configured for attachment to the first shaped body section to hold a test strip between the first and second shaped body sections, the first and second shaped body sections comprising from about 50 to about 99.5 weight percent polyhydroxyalkanoate.

Description

[Technical Field]

[0001] Related Applications This application claims priority to U.S. Provisional Application No. 63 / 483,027, filed February 4, 2023, which is currently pending.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to biodegradable test kits, and in particular to biodegradable cartridges for biological and chemical test kits. [Background technology]

[0003] Test kits are often used for chemical and biological testing of water and food, as well as testing for monoclonal or polyclonal labeled antibodies, such as for pregnancy testing, drug testing, and virus testing. The test kits can be used to determine whether toxic or harmful chemicals are present in food, water samples, air, blood, or environmental surfaces. Test kits typically include an absorbent test strip held within a cartridge body structure. The test kit includes an inlet for applying a chemical reagent that is absorbed by the test strip. Because a wide variety of chemicals can be used with the test kit, the test kit is typically made of plastic or other elastic materials. However, conventional test kits are typically not biodegradable. Therefore, the test kits do not degrade over time and therefore cannot be buried at the site of use after testing is completed. Therefore, there is a need for test kits made of biodegradable materials so that the test kits can be disposed of at the site of use and rapidly degrade over time.

[0004] In view of the above, there is provided a biodegradable test kit comprising a first shaped body section and a second shaped body section configured for attachment to the first shaped body section to hold a test strip between the first and second shaped body sections, wherein the first and second shaped body sections comprise from about 50 to about 99.5 weight percent polyhydroxyalkanoate.

[0005] In some embodiments, the polyhydroxyalkanoate is selected from the group consisting of hydroxalkanoate homopolymers, copolymers, terpolymers, and mixtures thereof. In other embodiments, the polyhydroxyalkanoate comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate. In some embodiments, the polyhydroxyalkanoate comprises a terpolymer made from about 75 to about 99.9 mole percent monomer residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent monomer residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent monomer residues of a third 3-hydroxyalkanoate having 5 to 12 carbon atoms.

[0006] In some embodiments, the first and second shaped body sections comprise a major amount of polyhydroxyalkanoate and a minor amount of one or more additional biodegradable polymers selected from the group consisting of polycaprolactone, polylactic acid, polybutylene succinate, polybutylene succinate-co-butylene adipate, polybutylene adipate terephthalate, other biodegradable polymers, and mixtures thereof.

[0007] In some embodiments, the first and second shaped body sections are biodegradable as determined by ASTM D5988.

[0008] In another embodiment, a method for making a biodegradable test kit is provided. The method includes molding first and second body sections of the biodegradable test kit from about 50 to about 99.5 weight percent polyhydroxyalkanoate. A test indicator strip is attached to one of the first and second body sections, and the first and second body sections are attached to each other such that the test strip is between the first and second body sections.

[0009] A particular advantage of the disclosed embodiments is that the test kits can be disposed of after use by burying them in the ground so that they decompose over time. Thus, there is no need to collect used biodegradable test kits and transport used test kits to a disposal area. Other benefits and advantages of the disclosed embodiments can become apparent by reference to the drawings and detailed description thereof. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an exploded view of a biodegradable test kit showing a first shaped body section and a second shaped body section made from a biodegradable polymer, and a test trip for use with the biodegradable test kit. [Figure 2] 10 is an illustration of a test kit as defined in claim 1, wherein a test strip is disposed in a second shaped body section of the test kit. [Figure 3] FIG. 1 is a plan view of another test kit having a body section made from a biodegradable polymer in accordance with the present disclosure. [Figure 4] FIG. 1 is a plan view of another test kit having a body section made from a biodegradable polymer in accordance with the present disclosure. [Figure 5] FIG. 1 is a top perspective view of a microwell plate made from a biodegradable polymer according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present disclosure addresses the need for test kits that are disposable and have improved biodegradability and / or compostability.

[0012] As used herein, "ASTM" means American Society for Testing and Materials.

[0013] As used herein, "alkyl" means a saturated carbon-containing chain which may be straight or branched, substituted (mono- or poly-) or unsubstituted.

[0014] As used herein, "alkenyl" means a carbon-containing chain that can be monounsaturated (i.e., one double bond in the chain) or polyunsaturated (i.e., two or more double bonds in the chain), and can be straight or branched, substituted (monovalent or polyvalent) or unsubstituted.

[0015] As used herein, "PHA" means a poly(hydroxyalkanoate) as described herein having random monomer repeat units of the formula: [ka] In the formula, R1 is CH3 and C3 to C 19 R is selected from the group consisting of alkyl groups. 1 is CH 3 The monomer units are from about 75 to about 99 mole percent of the polymer.

[0016] As used herein, "P3HB" means poly-(3-hydroxybutyrate).

[0017] As used herein, "P3HHx" means poly(3-hydroxyhexanoate).

[0018] As used herein, "biodegradable" means the ability of a compound to be completely broken down by microorganisms and / or natural environmental factors, ultimately to CO2 and water or biomass, according to ASTM D5511 (anaerobic and aerobic environments), ASTM 5988 (soil environments), ASTM D5271 (freshwater environments), or ASTM D6691 (marine environments). Biodegradability can also be determined using ASTM D6868 and European EN 13432.

[0019] As used herein, "compostable" means a material that meets the following three requirements: (1) the material can be processed in a solid waste composting facility; (2) when so processed, the material becomes ultimate compost; and (3) when the compost is used in soil, the material will ultimately biodegrade in the soil in accordance with ASTM D6400 for industrial and domestic compostability.

[0020] All copolymer composition ratios listed herein refer to molar ratios unless specifically indicated otherwise.

[0021] Unless otherwise specified, all molecular weights referred to herein are weight average molecular weights as determined in accordance with ASTM D5296.

[0022] According to embodiments of the present disclosure, test kits are provided having a molded body section made from a biodegradable polymer. In some embodiments, the test kits include an absorbent test strip affixed to the molded body section and used with various reagents to provide colorimetric test results. For example, a rapid antigen test developed for lipopolysaccharide (LPS, specifically the lipid A component) present in the cell walls of Gram-negative bacteria uses a collected sample. Thus, the rapid antigen test may include a dipstick similar to an HCG pregnancy test, or may include a well into which the sample is placed, after which reagents are added to the well. In other embodiments, the test kit includes a solid molded surface onto which antibodies or immune markers, proteins, or fluorescent markers can be absorbed or incorporated.

[0023] 1 and 2 illustrate a rapid test device 10 that can be used for various applications, such as rapid Covid testing, and includes a first shaped body section 12, a second shaped body section 14, and an absorbent test strip 16 made of nitrocellulose material enclosed between the first and second body sections 12, 14. A test sample is applied to a sample well 18 so that it is absorbed by the test strip 16 and provides a positive or negative indication in a window 20 of the first body section. An immunochromatographic lateral flow assay will detect antigens present in the sample being tested using highly sensitive antibodies. Specific and control antibodies are immobilized on the test strip 16 as two distinct lines. The test line (T) region will contain a monoclonal anti-lipid A antibody, and the control line (C) region will contain a polyclonal control antibody. Polyclonal and monoclonal anti-lipid A antibodies conjugated with red colloidal gold particles are used to detect the lipid A antigen. When testing a solid sample, the sample is mixed in a buffer solution, which is then applied to the sample well 18 of the test device 10. If lipid A antigen is present, it will bind to the antibody-gold conjugate, forming an immune complex. The immune complex will then migrate across the test strip 16 via capillary action toward the test line. The immune complex will then bind to the anti-lipid A antibody at the test line (T), forming a visible red line indicating antigen detection. If lipid A antigen is not detected in the sample, no color will appear at the test line (T). If the sample being tested is liquid, no buffer solution is used, and the sample is dropped directly onto the sample well 18. The control (C) line is used for procedural control and should appear regardless of the test results. The appearance of the control line (C) helps ensure that the test is being performed properly and that the test results are valid. According to an embodiment of the present disclosure, first shaped body section 12 and second shaped body section 14 are made of a biodegradable polymer, as described in more detail below, resulting in a device that can be implanted in place and has an estimated degradation time of 90 to 120 days.In some embodiments, the test kits are made from biodegradable polymers described herein and can be recycled rather than biodegraded.

[0024] 3 and 4 illustrate other test kits having body sections made of biodegradable polymers. In FIG. 3, test kit 30 includes a first molded body section 32 hingedly connected to a second molded body section 34. A test strip holder 36 is provided in second molded body section 36 for holding an absorbent test strip. A sample hole 38 is provided in second molded body section 34 for applying the sample to be tested to the test strip. FIG. 4 illustrates a pregnancy test kit 40 having a molded body section made from a biodegradable polymer as described herein. Other embodiments that may use the biodegradable polymers described herein may include a microwell plate 50 ( FIG. 5 ) having 96 or 394 microwells therein, or any other solid molded device surface to which antibodies or immune markers, proteins, or fluorescent markers may be absorbed or incorporated.

[0025] For all of the test kits described herein, the biodegradable polymer used is one that is resistant to the chemicals and solvents used with the test kit. In one embodiment of the present disclosure, at least about 50 mol % but less than 100%, more preferably at least about 60 mol %, more preferably at least about 70 mol %, and more preferably at least about 75-98 mol % of the monomer repeat units of the biodegradable polymer contain a CH group as R 1 as.

[0026] In another embodiment, a minority of the monomer repeat units have an R group selected from alkyl groups containing 3 to 19 carbon atoms. 1 Thus, the polymer has about 0 to about 30 mol %, preferably about 1 to about 25 mol %, more specifically about 2 to about 10 mol % of C3 to C6 19 The alkyl group is R 1 The monomer may contain repeating units as follows:

[0027] According to certain embodiments, the shaped body sections described above are preferably composed of at least 50 weight percent polyhydroxyalkanoate (PHA). In some embodiments, the PHA polymer is a copolymer comprising about 94 to about 98 mole percent 3-hydroxybutyrate repeat units and about 2 to about 6 mole percent 3-hydroxyhexanoate repeat units.

[0028] Different forms of polyhydroxyalkanoate can be used to make the shaped body section of the biodegradable test kit described above. Generally, the substrate polyhydroxyalkanoate can be either a homopolymer, copolymer, or terpolymer. In some embodiments, the polyhydroxyalkanoate is preferably poly-3-hydroxybutyrate-co-3-hydroxyhexanoate ("P(3HB-co-3HH)"). x In another embodiment, the prehydroxyalkanoate preferably comprises a terpolymer made from about 75 to about 99.9 mole percent monomer residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent monomer residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent monomer residues of a third 3-hydroxyalkanoate having 5 to 12 carbon atoms.

[0029] In some embodiments, the shaped body section of the biodegradable test kit may also include at least one additional biodegradable polymer selected from the group consisting of polycaprolactone, polylactic acid, polybutylene succinate, polybutylene succinate-co-butylene adipate, polybutylene adipate terephthalate, and mixtures thereof.

[0030] Synthesis of biodegradable PHA The biological synthesis of the biodegradable PHAs described herein can be carried out by fermentation with suitable organisms (natural or genetically engineered) using appropriate feedstocks (single or multi-component). Biological synthesis can also be carried out using bacterial species genetically engineered to express the copolymer of interest (see U.S. Pat. No. 5,650,555, incorporated herein by reference).

[0031] Melting temperature Preferably, the biodegradable PHA of the present disclosure has a melting temperature (T) of about 30°C to about 170°C, more preferably about 90°C to about 165°C, and even more preferably about 130°C to about 160°C. m )

[0032] Molded body classification According to the present disclosure, biodegradable test kits are formed from a resin containing a polymer or copolymer material (e.g., a PHA) that is injection molded into a desired shape. Injection molding of thermoplastic resins is a multi-step process in which a PHA formulation is heated until molten, then forced into a closed mold to form a shape, and finally solidified by cooling. The body section of the test kit described above can be made by modifying the PHA with melt strength enhancers, chain extenders, and other processing aids. During the injection molding process, the PHA formulation can be heated to a temperature ranging from about 135°C to about 205°C. Care must be taken to avoid overheating the PHA formulation during the molding process to prevent thermal degradation of the polymer.

[0033] PHAs according to the present disclosure may contain about 40 to 99 weight percent poly(hydroxyalkanoate) copolymer and about 1 to about 60 weight percent polymer modifier. In some embodiments, the poly(hydroxyalkanoate) copolymer is poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB-co-P3HH). xIn other embodiments, the PHA composition comprises from about 1.0 to about 15.0 weight percent of at least one poly(hydroxyalkanoate) comprising from about 25 to about 50 mole percent of a poly(hydroxyalkanoate) selected from the group consisting of poly(hydroxyhexanoate), poly(hydroxyoctanoate), poly(hydroxydecanoate), and mixtures thereof.

[0034] In some embodiments, the PHA formulation used to make the biodegradable test kit may contain from about 0.5 weight percent to about 15 weight percent of at least one plasticizer selected from the group consisting of sebacate, citrate, fatty esters of adipic, succinic, and glucaric acid, lactate, alkyl diesters, citrate, alkyl methyl esters, dibenzoate, propylene carbonate, caprolactone diols having a number average molecular weight of 200 to 10,000 g / mole, polyethylene glycols having a number average molecular weight of 400 to 10,000 g / mole, esters of vegetable oils, long chain alkyl acids, adipate, glycerol, isosorbide derivatives, or mixtures thereof.

[0035] In other embodiments, the PHA formulation may comprise from about 0.1 weight percent to about 10 weight percent, or from about 0.1 to about 20 weight percent, of at least one nucleating agent selected from sulfur, erythritol, pentaerythritol, dipentaerythritol, inositol, stearates, sorbitol, mannitol, polyester waxes, compounds having a 2:1:2:1 crystal structure chemical structure, boron nitride, and mixtures thereof.

[0036] In certain preferred embodiments, the PHA formulation may comprise from about 0.1 to about 3 weight percent of a nucleating agent selected from boron nitride or pentaerythritol, more preferably from about 0.3 to about 1.5 weight percent of boron nitride or pentaerythritol. Furthermore, when boron nitride is used as the nucleating agent, the PHA formulation may also comprise from about 1 to about 5 weight percent of a poly(hydroxybutyrate) homopolymer in addition to the poly(hydroxyalkanoate) copolymer.

[0037] In some embodiments, the PHA formulation preferably comprises about 0 to about 1 weight percent, e.g., about 1 to about 0.5 weight percent, of a melt strength enhancer / rheology modifier. The melt strength enhancer may be selected from the group consisting of, for example, multifunctional epoxides, epoxy-functional styrene-acrylic polymers, organic peroxides such as di-t-butyl peroxide, oxazolines, carbodiimides, and mixtures thereof.

[0038] Without being bound by theory, it is believed that this additive acts as a crosslinking agent to increase the melt strength of the PHA formulation. Alternatively, in some cases, the amount of melt strength enhancer is about 0.05 to about 3 weight percent. More preferred melt strength enhancers include organic peroxides, epoxides, and carbodiimides, preferably in an amount of about 0.05 to about 0.2 weight percent of the PHA formulation. In some embodiments, the PHA formulation contains unsaturated monomer units in the polymer to enable crosslinking of the polymer without the use of a melt strength enhancer / rheology modifier compound.

[0039] In some embodiments, the PHA formulation may include one or more performance-enhancing polymers selected from poly(lactic acid), poly(caprolactone), poly(ethylene sebacate), poly(butylene succinate), and poly(butylene succinate-co-adipate), as well as copolymers and blends thereof. The performance-enhancing polymer may be present in the formulation in a range of about 1 to about 60 weight percent. In some embodiments, about 0.1 to about 15 weight percent polylactic acid fiber is included in the polymer formulation for structural support of the container made from the polymer formulation.

[0040] In some embodiments, the polymer formulation comprises from about 0.1 to about 5 weight percent of a reheating agent, such as carbon black or another infrared-absorbing material, hi other embodiments, the polymer comprises from about 0.1 to about 20 weight percent (preferably from about 0.1 to about 10 weight percent) of a filler selected from calcium carbonate, talc, starch, zinc oxide, neutral alumina, and mixtures thereof.

[0041] The foregoing description of preferred embodiments of the present disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments have been chosen and described to provide the best illustration of the principles of the disclosure and its practical application, and to thereby enable those skilled in the art to utilize the disclosure in various embodiments and with various modifications that are suitable for the particular uses contemplated. All such modifications and variations are within the scope of the disclosure, as determined by the appended claims, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

1. 1. A biodegradable test kit comprising: a first shaped body section; and a second shaped body section configured to attach to the first shaped body section to hold a test strip between the first and second shaped body sections, wherein the first and second shaped body sections comprise from about 50 to about 99.5 weight percent polyhydroxyalkanoate.

2. 10. The biodegradable test kit of claim 1, wherein the polyhydroxyalkanoate is selected from the group consisting of hydroxalkanoate homopolymers, copolymers, terpolymers, and mixtures thereof.

3. 2. The biodegradable test kit of claim 1, wherein the polyhydroxyalkanoate comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate.

4. 10. The biodegradable test kit of claim 1, wherein the plyhydroxyalkanoate comprises a terpolymer made from about 75 to about 99.9 mole percent monomer residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent monomer residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent monomer residues of a third 3-hydroxyalkanoate having 5 to 12 carbon atoms.

5. 10. The biodegradable test kit of claim 1, wherein the first and second shaped body sections comprise a major amount of polyhydroxyalkanoate and a minor amount of one or more additional biodegradable polymers selected from the group consisting of polycaprolactone, polylactic acid, polybutylene succinate, polybutylene succinate-co-butylene adipate, polybutylene adipate terephthalate, other biodegradable polymers, and mixtures thereof.

6. 10. The biodegradability test kit of claim 1, wherein said first and second shaped body sections are biodegradable as determined by ASTM D5988.

7. 1. A method for making a biodegradable test kit, comprising: molding first and second body sections of the biodegradable test kit from about 50 to about 99.5 weight percent polyhydroxyalkanoate; attaching a test indicator strip to one of the first and second body sections; and attaching the first and second body sections to one another such that the test strip is between the first and second body sections.

8. 8. The method of claim 7, wherein the polyhydroxyalkanoate is selected from the group consisting of hydroxalkanoate homopolymers, copolymers, terpolymers, and mixtures thereof.

9. The method of claim 7, wherein the polyhydroxyalkanoate comprises poly-3-hydroxybutyrate-co-3-hydroxyhexanoate.

10. 8. The method of claim 7, wherein the plyhydroxyalkanoate comprises a terpolymer made from about 75 to about 99.9 mole percent monomer residues of 3-hydroxybutyrate, about 0.1 to about 25 mole percent monomer residues of 3-hydroxyhexanoate, and about 0.1 to about 25 mole percent monomer residues of a third 3-hydroxyalkanoate having 5 to 12 carbon atoms.

11. 8. The method of claim 7, wherein the first and second body sections comprise a major amount of polyhydroxyalkanoate and a minor amount of one or more additional biodegradable polymers selected from the group consisting of polycaprolactone, polylactic acid, polybutylene succinate, polybutylene succinate-co-butylene adipate, polybutylene adipate terephthalate, and mixtures thereof.

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