PHOTOINITIATING POLYMERISABLE COMPOSITION

Abstract

The present invention provides a method of producing a visual marking on the exterior of a human or animal body. There is also provided a method of forming a polymer within a human or animal body. The resultant polymer generally has an electrical conductivity of 10.sup.10 S/cm or more.

Claims

1. A method of producing a visual marking on the exterior of a human or animal body comprising: implanting a composition at a site in the human or animal body 1 cm or less from the exterior of the human or animal body wherein the composition comprises a polymerisable precursor and a photo-initiator wherein the photo-initiator causes the polymerisable precursor to polymerise where the photo-initiator is in its excited state, illuminating the site with electromagnetic radiation having a wavelength of 400 to 1600 nm, wherein absorption of two or more photons of the electromagnetic radiation excites the photo-initiator causing initiation of polymerisation of the polymerisable precursor to form a polymer within the human or animal body, wherein the polymer is visible on the exterior of the human or animal body and wherein the resultant polymer has an electrical conductivity of 10.sup.10 S/cm or more.

2. The method as claimed in claim 1 wherein the resultant polymer shows more than one colour on the exterior of the human or animal body.

3. The method as claimed in claim 1 wherein the visual marking is in the form of a tattoo.

4. The method as claimed in claim 1 wherein the composition is injected into the lower surfaces of the skin of the human or animal body and the visual marking may grow out as the skin is shed.

5. The method as claimed in claim 1 wherein the composition is injected under the skin of the human or animal body, to provide a permanent visual marking.

6. The method as claimed in claim 1 wherein the polymer is in the form of a solid, gel, paste or foam; generally a solid, hydrogel or plastics material.

7. The method as claimed in claim 1 wherein, the dimensions of the polymer formed (width, length, thickness) are at least 1 nm, typically at least 100 nm.

8. The method as claimed in claim 1 wherein the two or more photons are from intersecting photon beams.

9. The method as claimed claim 1 wherein the composition includes second photo-initiatable functional moieties which become excited at a second wavelength different to the first wavelength wherein the polymer may be dis-assembled through illumination of the site with electromagnetic radiation having the second wavelength, wherein absorption of two or more photons of the electromagnetic radiation causes the second photo-initiatable functional moieties on the polymer to become excited and dis-assemble the polymer.

10. The method as claimed in claim 9 wherein the second wavelength is at least 200 nm higher or lower than the first wavelength.

11. The method as claimed in claim 1 wherein the composition includes a visual indicator which alters upon polymerisation of the polymerisable precursor, wherein the visual indicator is visible in the polymerisable precursor but not in the polymer, or the visual indicator is visible in the polymer but not the polymerisable precursor.

12. The method as claimed in claim 1 wherein the composition has a viscosity of from 1 centipoise to 250,000 centipoise.

13. The method as claimed in claim 1, wherein the polymerisable precursor comprises, consists or consists essentially of monomers having at least one olefinic bond, oligomers having at least one olefinic bond, polymers having at least one olefinic bond, olefins, halogenated olefins, acrylates, methacrylates, pyrroles, acrylamides, bisacrylamides, styrenes, epoxides, cyclohexeneoxide, amino acids, peptides, proteins, fatty acids, lipids, nucleotides, oligonucleotides, synthetic nucleotide analogues, nucleic acids, sugars, carbohydrates, cytokines, hormones, receptors, growth factors, drugs, and mixtures thereof.

14. The method as claimed in claim 1 wherein the resultant polymer comprises, consists or consists essentially of one or more of the group consisting of poly(fluorene)s, polyphenylenes, polypyrenes, polyazulenes, polynaphthalenes, Poly(acetylene)s, Poly(p-phenylene vinylene), poly(pyrrole)s, polycarbazoles, polyindoles, polyazepines, poly(thiophene)s, poly(3,4-ethylenedioxythiophene), poly(p-phenylene sulfide) and polyanilines.

15. The method as claimed in claim 1 wherein the composition is in the form of a buffered aqueous based composition comprising pyrrole, a photo-initiator (generally irgacure) and a dye.

Description

[0129] The present invention will now be described by way of example only, with reference to the accompanying Figures, in which:

[0130] FIG. 1 provides a schematic representation of the manufacture of a subcutaneous structure according to the present invention. (not to scale);

[0131] FIG. 2 provides a schematic representation of assembly and disassembly of polymers according to the present invention;

[0132] FIG. 3 is a halftone rendering of a photograph of a polymeric structure printed into vertebrate tissue.

[0133] FIG. 1 shows schematically and not to scale the manufacture of a subcutaneous device according to the present invention. A first photon beam (101) and a second photon beam (103) pass from outside (105) tissue, through the surface (107) of tissue, into the interior of tissue (109). Previously a region of precursor material (111) has been placed into the tissue (109). The photon beams cause polymerisation of precursor monomers at the point of intersection (115), and when the beams are moved, this point (115) moves and a polymerised structure (113) results.

[0134] FIG. 2 shows schematically assembly and disassembly of polymers according to the present invention. Each square block (201) represents a monomer unit that has polymerized via a multi-photon polymerisation reaction creating a bond (203) to a neighbouring monomer unit (201). In this embodiment each monomer also comprises a suitably designed moiety (205; represented by a triangle), via which a second multi-photon process may disassemble the polymer when required.

[0135] A composition of the present invention, was provided including pyrrole as the polymerisable precursor and irgacure as the photo-initiator. The composition was injected under the skin of a chicken breast. The external surface of the chicken breast was illuminated with two laser beams, and at the location of intersection, the photo-initiator was excited causing localised polymerisation of the pyrrole to form polypyrrole. The lasers were used to controllably initiate polymerisation in a targeted manner. The polypyrrole is shown in FIG. 3 as the dark lines which read I heart Chemistry.

[0136] Various modifications and variations of the described aspects of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes of carrying out the invention which are obvious to those skilled in the relevant fields are intended to be within the scope of the following claims.