WO2008095148A2

WO2008095148A2 - Methods and compositions for generation of reactive oxygen species

Info

Publication number: WO2008095148A2
Application number: PCT/US2008/052732
Authority: WO
Inventors: Ali Zendedel Haghighi
Original assignee: Sunstorm Research Corporation
Priority date: 2007-01-31
Filing date: 2008-01-31
Publication date: 2008-08-07
Also published as: WO2008095148A3

Abstract

Methods, compositions and articles of manufacture for the generation of reactive oxygen species are provided. These embodiments utilize the ability of a flavin- containing compound, such as riboflavin, to produce peroxide in the presence of a suitable light source. In some embodiments, a multivalent metal cation that can catalyze a Fenton or Fenton-type reaction may be used to produce additional reactive oxygen species. These techniques find application in the oxidation of surfaces, crosslinking of materials, and in sterilization techniques, including the purification of solutions including water.

Description

METHODS AND COMPOSITIONS FOR GENERATION OF REACTIVE

OXYGEN SPECIES

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.

60/921,490, filed Jan. 31, 2007, which is hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to methods, articles and compositions for the generation of reactive oxygen species and their use in various oxidative, purification and crosslinking applications.

BACKGROUND OF THE INVENTION

Hydrogen peroxide has been used in a variety of applications, including for bleaching, disinfection, and as a polymerization initiator. Hydrogen peroxide has been used to sterilize human tissue, and to sterilize materials that come in contact with human tissue, including medical implements and medical devices, including contact lenses.

Hydrogen peroxide is typically provided in solution at a concentration of 1-30%.

However, the inherently reactive nature of the solutions requires careful handling. When used in methods for sterilizing contact lenses, for example, there is substantial risk that hydrogen peroxide can be directly administered to the eye, either through inadvertent use of an incorrect container, or from incomplete inactivation of peroxide in the solution.

Furthermore, peroxide solution are unstable and decrease in reactivity with time, thereby raising the possibility of inadequate sterilization. It has been demonstrated that exposure of riboflavin to UV results in the formation of oxygen free radicals (oxygen anions). Generation of free radicals by UV- exposed riboflavin occurs at a constant rate and stops after the removal of the light source. This method has been used in studies where the production of oxygen free radicals is needed at a constant rate, and also as a polymerization initiator, for example of poly-acrylamide gels used in electrophoretic methods. However, riboflavin-generated reactive oxygen species are not known to have been used in bleaching and disinfection methods. Nor are Fenton or Fenton-type reactions known to have been employed in such embodiments.

There is a need in the art for methods of oxidizing and/or sterilizing substances using reactive oxygen species that are safer than known techniques, and that employ solutions and materials that are safer to produce and store than those used in known techniques. There is a further need for compositions and articles of manufacture useful for such methods.

SUMMARY OF THE INVENTION

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts the oxidation of orthophenylenediamine (OPD) by riboflavin in the presence, but not the absence, of a light source. Exposure to ultraviolet light (UV) for 30 minutes resulted in oxidation of OPD from its colorless reduced state to its red oxidized state.

Figure 2 characterizes the oxidizing ability of UV- exposed Riboflavin at 0.1 g/1 in comparison to 50% H₂O₂. At that concentration, H₂O₂ is very corrosive. UV- exposure of Riboflavin for 30 minutes produced approximately 57% of the oxidized OPD produced by 50% H₂O₂.

Figure 3 depicts the calibration of the oxidizing ability of riboflavin with that of hydrogen peroxide. Because hydrogen peroxide is typically used in teeth- whitening products in the range of 15-20%, a comparison of the UV-exposed Riboflavin oxidation was made to that of H₂O₂ at 3.125-25%. The level of OPD oxidized by UV-exposed riboflavin in 15 minutes was similar to that oxidized by H₂O₂ at 15-20%.

Figure 4 depicts the results of tests to determine the ability of riboflavin to produce reactive oxygen species when deposited on a matrix. Riboflavin was loaded onto Cavilink beads, which were then tested for their oxidizing ability, which results from incorporated riboflavin. Polyvinyl alcohol (PVA)-beads showed the best levels of oxidizing ability.

DETAILED DESCRIPTION OF THE INVENTION

The disclosed embodiments of the invention employ a riboflavin for the generation of reactive oxygen species, including hydrogen peroxide and free radicals derived therefrom. Like other free radicals, the half-life of oxygen free radicals is on the order of milliseconds. Hence, the generated oxygen free radicals very quickly oxidize any material in its vicinity. Thus, methods and articles are provided which are useful for oxidative reactions, including bleaching application, sterilization, and purification.

In some embodiments of the invention, a polyvalent metal cation is employed that can react with hydrogen peroxide in a Fenton or Fenton-type reaction. In the Fenton reaction, the two oxidation states of iron react with hydrogen peroxide molecules in a disproportionation cycle. Iron(II) is oxidized by hydrogen peroxide to Iron(III), producing a hydroxyl radical and a hydroxyl anion. Iron(III) is then reduced by hydrogen peroxide to iron(II), producing a peroxide radical and a proton.

(1) Fe²⁺ + H₂O₂ → Fe³⁺ + OH- + OH^"

(2) Fe³⁺ + H₂O₂ → Fe²⁺ + OOH- + H⁺ Iron thus acts catalytically to produce two radicals and water from two molecules of hydrogen peroxide. The radicals thus produced can then engage in secondary reactions. Similar Fenton-type reactions can be performed by metal cations exhibiting multiple oxidation states, for example copper, zinc, and manganese. Before the present invention is described in further detail, it is to be understood that this invention is not limited to the particular methodology, devices, solutions or apparatuses described, as such methods, devices, solutions or apparatuses can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

Use of the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a riboflavin" includes a plurality of riboflavins, reference to "a reactive oxygen species" includes a plurality of such species, reference to "a matrix" includes a plurality of matrices, and the like. Additionally, use of specific plural references, such as "two," "three," etc., read on larger numbers of the same subject unless the context clearly dictates otherwise.

Terms such as "connected," "attached," "linked" and conjugated are used interchangeably herein and encompass direct as well as indirect connection, attachment, linkage or conjugation unless the context clearly dictates otherwise. Where a range of values is recited, it is to be understood that each intervening integer value, and each fraction thereof, between the recited upper and lower limits of that range is also specifically disclosed, along with each subrange between such values. The upper and lower limits of any range can independently be included in or excluded from the range, and each range where either, neither or both limits are included is also encompassed within the invention. Where a value being discussed has inherent limits, for example where a component can be present at a concentration of from 0 to 100%, or where the pH of an aqueous solution can range from 1 to 14, those inherent limits are specifically disclosed. Where a value is explicitly recited, it is to be understood that values which are about the same quantity or amount as the recited value are also within the scope of the invention, as are ranges based thereon. Where a combination is disclosed, each subcombination of the elements of that combination is also specifically disclosed and is within the scope of the invention. Conversely, where different elements or groups of elements are disclosed, combinations thereof are also disclosed. Where any element of an invention is disclosed as having a plurality of alternatives, examples of that invention in which each alternative is excluded singly or in any combination with the other alternatives are also hereby disclosed; more than one element of an invention can have such exclusions, and all combinations of elements having such exclusions are hereby disclosed.

Unless defined otherwise or the context clearly dictates otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods and materials are now described.

All publications mentioned herein are hereby incorporated by reference for the purpose of disclosing and describing the particular materials and methodologies for which the reference was cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.

DEFINITIONS

In describing the present invention, the following terms will be employed, and are intended to be defined as indicated below.

By "reactive oxygen species" is meant a species containing one or more oxygen atoms that is in an unstable form which can react with other substances and oxidize them. Exemplary reactive oxygen species include hydrogen peroxide, hydroxide radicals, and hyperoxide radicals.

By "riboflavin" is meant any flavin compound or analog thereof comprising a flavin moiety capable of oxidizing water to hydrogen peroxide when activated by a light source of an appropriate wavelength. The term "riboflavin" includes the natural chemical riboflavin, also known as vitamin B2, as well as chemical analogs of riboflavin which are also capable of producing one or more oxygen free radicals upon application of a light source of appropriated wavelength. Analogs of riboflavin are known in the art; see for example Wallace and Holmlund, J. Nutrition 110:2113-2116, 1980; Otto et al, PNAS 78(l):266-269, 1981; Lambooy, Riboflavin (Rivlin, R.S., ed.) pp. 303-367, Plenum Press, New York, 1975; Lambooy, J. Med. Chem 21:301-303, 1978; Lambooy, Arch. Biochem. Biophys. 117, 120-124, 1966; Lambooy, J. Nutr. 74:2466-472, 1961. Also encompassed are conjugated forms comprising a flavin moiety, for example flavin adenine dinucleotide and flavin mononucleotide. Also included are solubilized versions of such compounds, for example derivatives including polar, charged, or other groups which improve solubility in predominantly aqueous media or compositions comprising a predominantly aqueous phase. An example of a solubilized form of riboflavin is riboflavin-5'- phosphate.

By "multivalent metal cation" is meant any metal cation that can exist in multiple oxidation states and which can catalyze a Fenton or Fenton-type reaction. Particular metal cations of interest include transition metals, i.e., those elements in the d-block of the periodic table. Particular transition metals of interest include copper, iron, manganese, zinc, nickel, chromium, cobalt, and cadmium. Mixtures of metals and/or metal ions can be used. Of particular interest are iron, zinc, magnesium, and copper. The metal cations may be provided in particular oxidation states or as mixtures of oxidation states. Exemplary metal cations include Cu(II), Cr(III), Co(II), Fe(III), Mn(II), Ni(II), Cd(II), Zn(II), or a mixture thereof. The transition metal(s), when used, are preferably used at levels or in a manner which minimizes any toxicity. Some metal cations which by themselves do not produce oxidizing species at a significant rate may increase the rate of production of oxidizing species when used in combination with others. Forms of the metals of interest include salt forms, particularly those salt forms exhibiting aqueous solubility.

"Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not. Methods, compositions and articles of manufacture are provided which utilize riboflavin and a light source for the production of reactive oxygen species. Also provided are methods, compositions and articles further utilizing one or more transition metals capable of performing a Fenton or Fenton-type reaction.

The techniques can be used for a variety of applications in which oxidation is used, for example in bleaching and/or disinfecting reactions. These applications include such diverse areas as teeth whitening, wound healing, disinfection, and water treatment. These applications can also include wound repair and for cross-linking of extracellular matrix.

As compared to other bleaching or disinfecting procedures involving oxidizing materials, use of UV-exposed riboflavin is a safer alternative to the existing methods, where either hydrogen peroxide or bleach is used. The methods described herein avoid the dangerous storage and transport of peroxides, and permit localized generation of peroxides and other active oxygen species at the point of use. The techniques described herein may reduce exposure to ultraviolet light in a variety of settings.

Reagents may be provided in dry form or in solution, alone or in combination, in lotions, creams, pharmaceutical compositions, and any other form useful for storing the reagents or for carrying out any of the methods described. In use, the reagents are present in an amount sufficient to produce the desired quantity of reactive oxygen species. Similarly, in use, the reagents are contacted with a light source of a type and in an amount sufficient to do so. In some instances, the reagents described herein may be provided in and/or attached to a matrix. In such instances, the toxicity of the reagent(s) can be less important, as the matrix can be removed (e.g., rinsed away) upon completion of the desired reaction.

Solutions comprising the riboflavin(s) and optional transition metal(s) are also provided, as are excited solutions comprising such materials which have been contacted with a light source to initiate the production of reactive oxygen species by the reagent(s). The solution may be provided in a darkened or light-tight vessel. Solutions and pharmaceutical compositions may comprise one or more buffers, carriers, diluents or excipients, in addition to the reagent(s) of interest. The reagents can be provided in lotions or creams, including hand lotions and wrinkle creams.

In some embodiments, portable water purification devices are provided comprising one or more reagent(s) able to produce reactive oxygen species upon introduction of light. Such devices may be transparent, at least in part, and may use sunlight as a light source. Such devices are envisioned to be particularly useful in remote or wilderness settings, e.g., camping, in rescue situations, or in any environment in which fresh water and /or electricity are not readily available. In some embodiments, the purification device can be provided as a personal backpack.

METHODS OF THE INVENTION

Method of generating reactive oxygen species to oxidize a substance are provided. The methods comprise providing a solution comprising a riboflavin, contacting the solution with the substance, and contacting the solution with a light source that excites the riboflavin to produce one or more reactive oxygen species and oxidize the surface. The substance to be oxidized can be any substance desired to be oxidized, whether for disinfection, sterilization or crosslinking. Exemplary substances include teeth, dentures, a wound, medical implements, contact lenses, or solutions, including water. The methods optionally utilize a multivalent metal cation of a type and in an amount capable of acting in a Fenton-type reaction upon excitation of the riboflavin.

Light sources useful for activating the riboflavin include those capable of outputting ultraviolet light of a frequency and in an amount to create sufficient reactive oxygen species for the desired application. The light source can be a lamp, LED, laser, or a combination of sources. The light source may be filtered so as to produce a restricted wavelength or set of wavelengths of interest. In some cases, sunlight may be used as the light source. The light source may be focused, concentrated, or amplified.

Also provided are methods for decreasing the use of ultraviolet light for the generation of reactive oxygen species, for example reducing the exposure of tissue to ultraviolet light. Riboflavin is currently used for the crosslinking of collagen in living tissue, to improve the healing of the cornea during laser eye surgery. Such procedure typically applies ultraviolet light directly to the eye on the order of 30 minutes. Use of transition metal(s) in concert with riboflavin decreases the need for exposure of the eye to ultraviolet light. Since solutions comprising a riboflavin and a suitable metal continue to produce reactive oxygen species even after the ultraviolet light source has been removed, in some embodiments the need for contacting tissue with a light source can be significantly reduced or even eliminated.

ARTICLES OF MANUFACTURE

Articles of manufacture are provided comprising one or more riboflavin(s) and/or one or more transition metals capable of carrying out a Fenton or Fenton-type reaction. These include water purification devices, either portable or large scale. The reagents may be provided in solution, in a form capable of dissolution, and may be carried by a matrix (e.g., rods, beads, particles, etc.), or bound to a matrix.

The articles of manufacture provided by the invention may be light tight (e.g., a vial containing reagent(s) to be added to another container that can be exposed to a light source), may contain one or more regions capable of being exposed to a light source to initiate the desired reaction, or may be transparent to permit light to react freely with the article. The articles may also be provided in a light-tight shipping and/or storing container, particularly where the article is itself transparent. The articles may be of a large volume such that they are not readily portable, or may be smaller devices permitting portable use of their capabilities.

A water purification device as provided by the invention comprises one or more water input(s) and one or more water output(s); in some embodiments, one orifice may be used as the water input and output. The device further comprises a matrix located within a purification chamber in fluid communication with the liquid input, and a riboflavin retained within the matrix. The device also comprises a a light activating region in optical communication with the riboflavin, as well as a liquid output in fluid communication with the purification chamber.

The device may optionally comprise one or more water storage compartments, which may be a water input reservoir(s), a purified water output reservoir(s), which optionally may be light tight. The water input(s) and water output(s) can be as simple as a port or tube for introducing water into and recovering water from the purification device. The device may optionally incorporate one or more water storage compartments connected to the water input and/or the water output. Thus the device may be provided in a format useful for either instant purification, or for purification for later use. The device may be provided in a portable format, for example in a backpack form, or integrated with a water bottle.

The device comprises a light activating region in optical communication with the riboflavin. The light activating region may comprise one or more transparent regions suitable for permitting external light to activate the riboflavin. The light activating region may comprise a physical light source in the device, for example an LED with an associate power supply (e.g., physical such as a crank generator, a battery, a solar cell, an electronic cable for connecting to a power grid, etc.).

The purification device may optionally incorporate one or more filters useful for water purification.

In some embodiments, a purification device is provided with a light source, a matrix comprising one or more riboflavins and optional transition metal(s) loaded onto or attached to the matrix, and a vessel (e.g., a column) for containing the matrix which has at least one region in which the light source can contact the matrix and initiate the desired reaction. The vessel may contain a transparent region (e.g., a transparent column wall) for permitting the light source to contact the matrix. Useful matrices include any porous material which can retain one or more reaction components and contact a solution to be oxidized. Exemplary matrices include columns, particles, and beads. Exemplary beads of interest include those described in U.S. Pats. Nos. 5,583,162, 5,653,922, 5,760,097, 5,863,957, 6,048,908, 6,100,306, and 6,218,440.

Purification devices as provided herein, including a personal backpack, may comprise a replaceable cartridge comprising one or more surfaces which permits light of the desired wavelength(s) to pass through its outer surface and to act on the riboflavin(s) and optional transition metal carried within a matrix. When the cartridge loses its potency for sterilization, it can be removed and replaced. Such devices may include or be used in conjunction with one or more filtration devices, examples of which are known in the art, to purify the solution of interest (e.g., water).

Also provided are machines that can contact a solution comprising one or more riboflavins and one or more transition metals with ultraviolet light, and apply the solution to a tissue, either simultaneously or sequentially, and methods of performing such techniques. Such machines and methods can completely eliminate the need to contact living tissue with a damaging ultraviolet light source.

Similarly, in concert with the methods of sterilizing a surface such as a contact lens as described herein, contact lens sterilization devices are provided. The devices employ a light activating region, and one or more receptacles for retaining the contact lens(es). The light activating region may be a transparent portion of the receptacle which permits external activation of a light source. Alternatively, an internal light source, such as a lamp or LED, may be utilized as a light activating region. The light activating region can apply light to the receptacle, which holds a riboflavin, a contact lens, and optionally a multivalent metal cation as described herein.

Also provided are wound healing devices comprising one or more riboflavins and optionally one or more transition metals as described. The wound healing devices may take the form of a bandage or wound covering, and may contain a transparent region permitting light suitable for excitation of the riboflavin to pass through.

KITS

Kits for performing the desired method(s) are also provided, and comprise a container for holding the components of the kit, one or more vessels containing one or more riboflavin(s), and optionally one or more vessels containing one or more transition metals. The reagents may independently be in liquid or solid form. The reagents may be provided in mixtures. One or more of the reagents may be provided in a matrix, and may be loaded onto or bound to the matrix. A light source may optionally be provided in the kit.

Instructions for using the kit to perform a method of the invention can be provided with the container, and can be provided in any fixed medium. The instructions may be located inside the container or outside the container, and may be printed on the interior or exterior of any surface forming the container.

EXAMPLES

The following examples are set forth so as to provide those of ordinary skill in the art with a complete description of how to make and use the present invention, and are not intended to limit the scope of what is regarded as the invention. Efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperature, etc.) but some experimental error and deviation should be accounted for. Unless otherwise indicated, parts are parts by weight, temperature is degree centigrade and pressure is at or near atmospheric, and all materials are commercially available.

The following examples were performed using a handheld ultraviolet lamp as a light source (VWR Model UVGL-55, Mineralight Lamp, Multiband UV 254/365 nm used on the 254 nm setting, 115V, 60 Hz, 0.16 Amps). Although 254 nm setting was used as the excitation wavelength, any wavelength capable of exciting the riboflavin(s) being used to a degree sufficient to produce the desired amount of reactive oxygen species can be used. In some cases it may be desirable to use longer excitation wavelengths (e.g., 300-400 nm) to decrease UV exposure and damage.

Copper is used as an exemplary transition metal in the examples below, although any suitable transition metal can similarly be used. The copper concentration in the examples below is in the range of 0.2 to 0.8 mM, made from CuSO4 ' 5H20, although the concentration of transition metal used can be adapted to the particular implementation being used, and may fall outside this range.

The beads described below include Cavilink beads (polystyrene), s-beads (sulfonated beads), and PVA-beads (polyvinylalcohol derivatized beads).

Similar tooth whitening model experiments can be performed using stained objects rather than the OPD as demonstrated, for example tea-stained portions of materials such as paper cups. The concentration of ingredients used to bleach such objects can be adjusted to provide similar levels of oxidation to existing products. Example 1. Demonstration of the oxidizing ability of light-activated riboflavin

Riboflavin at O.lg/1 was added to a solution of orthophenylenediamine (OPD), and either exposed to UV for 30 minutes or kept in the dark for the same period of time. Reduced OPD is a colorless solution. However, upon oxidation it develops a red color which has an absorbance at 439 nm. As shown in Figure 1, while riboflavin in the dark did not result in any significant oxidized OPD, the same riboflavin solution caused oxidation of about 0.15 mg/ml OPD when exposed to UV for 30 minutes.

Example 2. Comparison of riboflavin-induced oxidation with H₂O₂

The oxidizing ability of UV- exposed Riboflavin (0.1 g/1) was compared to that of H₂O₂ (50%), a very strong oxidizer. At that concentration, H₂O₂ is very corrosive. OPD solution was again used as an indicator of oxidation. As shown in Figure 2, UV- exposure of Riboflavin for 30 minutes produced approximately 57% of the oxidized OPD produced by 50% H₂O₂.

Example 3. Calibration of the oxidizing ability of riboflavin

Because the H₂O₂ concentration used in teeth- whitening products is typically in the range of 15-20%, a comparison of the UV-exposed Riboflavin oxidation was made to that of H₂O₂ at 3.125-25%. As shown in Figure 3, a level of OPD oxidized by UV- exposed Riboflavin in 15 minutes was similar to that oxidized by H₂O₂ at 15-20%. Adjustment of reaction conditions can achieve different levels of peroxide-equivalent oxidation.

Example 4. Loading of riboflavin on a matrix

Riboflavin was loaded onto Cavilink beads (Sunstorm Research Corp, Los Gatos, CA). 0.1 g of beads were mixed with riboflavin at O.lg/1 for 2 hr, and were then filtered and dried overnight. The beads were then tested for their oxidizing ability, which results from incorporated riboflavin. PVA-beads showed the best results (Figure 4).

Example 5. Oxidation in the presence and absence of a light source using metals Solutions comprising riboflavin with and without a polyvalent metal cation were tested to determine the requirement for continued light exposure for the generation of reactive oxygen species. While the oxidizing effect of riboflavin was stopped after removal of the activating UV source, the presence of a metal such as copper in the mixture continued the oxidizing reaction even after UV exposure was halted. This permits activation of the riboflavin by a light source prior to contact with a substance to be oxidization, thereby permitting applications which lessen or remove entirely exposure to the ultraviolet light source.

Although the invention has been described in some detail with reference to the preferred embodiments, those of skill in the art will realize, in light of the teachings herein, that certain changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the invention is limited only by the claims.

Claims

CLAIMSWhat is claimed is:

1. A method of generating reactive oxygen species to oxidize a substance, comprising: providing a solution comprising a riboflavin; contacting the solution with the substance; and contacting the solution with a light source that excites the riboflavin to produce one or more reactive oxygen species and oxidize the surface.

2. The method of claim 1, where the substance is a tooth or a denture.

3. The method of claim 1, where the substance is a wound.

4. The method of claim 1, where the substance is a medical implement.

5. The method of claim 1, where the substance is a contact lens.

6. The method of claim 1, where the substance is a solution.

7. The method of claim 1, wherein the solution further comprises a multivalent metal cation of a type and in an amount capable of acting in a Fenton-type reaction upon excitation of the riboflavin.

8. The method of claim 7, wherein the multivalent metal cation is a transition metal.

9. The method of claim 7, wherein the multivalent metal cation is selected from copper, iron, manganese, zinc, nickel, chromium, cobalt, cadmium, a mixture of any thereof, and a mixture of ionic forms of any thereof.

10. The method of claim 7, wherein the multivalent metal cation is selected from iron, zinc, magnesium, copper, a mixture of any thereof, and a mixture of ionic forms of any thereof.

11. The method of claim 1, wherein the light source is selected from sunlight, a lamp, and a light emitting device (LED).

12. A purification device comprising: a liquid input; a matrix located within a purification chamber in fluid communication with the liquid input; a riboflavin retained within the matrix; a light activating region in optical communication with the riboflavin; and a liquid output in fluid communication with the purification chamber.

13. The purification device of claim 12, further comprising one or more water storage compartments in fluid communication with the liquid input or the liquid output.

14. The purification device of claim 13, further comprising a water storage compartment for storing the purified water.

15. The purification device of claim 12, wherein the device is portable.

16. The purification device of claim 15, wherein the device is a backpack.

17. The purification device of claim 12, wherein the light activating region comprises a transparent region permitting external light to enter and activate the riboflavin.

18. The purification device of claim 12, wherein the light activating region comprises an LED.

19. The purification device of claim 12, further comprising a multivalent metal cation capable of performing a Fenton-type reaction.

20. The purification device of claim 19, wherein the cation is retained within a matrix, which may be the same matrix as the riboflavin or a different matrix.

21. The purification device of claim 12, wherein the purification chamber comprises a vessel/column that contains the matrix.

22. The purification device of claim 12, wherein the purification chamber comprises a vessel that contains the matrix.

23. The purification device of claim 22, wherein the vessel is replaceable.

24. The purification device of claim 12, wherein the light activating region is a light source attached to the device.

25. The purification device of claim 12, wherein the light activating region is a transparent region permitting entrance of external light to activate the riboflavin.

26. The purification device of claim 12, wherein the device further comprises a filter.

27. A method of crosslinking an extracellular matrix, comprising: providing a riboflavin in a solution; providing a polyvalent metal cation in the solution that is capable of performing a Fenton-type reaction; contacting the solution with a light source that excites the riboflavin and produces reactive oxygen species; wherein the solution contacts a tissue comprising an extracellular matrix while reactive oxygen species are present.

28. The method of claim 27, wherein the riboflavin is excited while the solution is in contact with the tissue.

29. The method of claim 27, wherein the riboflavin is excited in the solution prior to the solution contacting the tissue, and the solution is placed in contact with the tissue while reactive oxygen species are still present.

30. Use of a riboflavin and a polyvalent metal cation for the production of a medicament for the oxidation of a substance.

31. A wound healing device, comprising: a wound covering; a riboflavin attached to or deposited on the wound covering; and a light activating region.

32. A kit comprising: a riboflavin disposed within a matrix; a transition metal; and a container for holding the components of the kit.

33. The kit of claim 32, further comprising a light source capable of exciting the riboflavin.