Removable tattoo ink and the use thereof
Provided is a removable tattoo ink that is composed of colored micro-particles that create permanent tissue markings, such as tattoos. The micro-particles include an inner core housing a bio-absorbable chromophore and an outer shell, which includes polystyrene sulfonate and polyallylamine hydrochloride and is designed for rupture with ultrasonic energy. The micro-particles can be implanted in the tissue of a subject, for example to create a tattoo and ruptured in situ by the application of ultrasonic energy to remove the tattoo. Also provided are methods of making the colored micro-particles.
1. A removable tattoo ink, comprising colored micro-particles, wherein the micro-particles, comprise:
an internal core, comprising one or more bio-absorbable chromophores,
wherein the one or more bio-absorbable chromophores are water-soluble dyes, water-soluble pigments, or water-soluble drugs; and
an outer shell, consisting of at least one layer of polystyrene sulfonate (PSS) and at least one layer of polyallylamine hydrochloride (PAH); and
wherein the micro-particles further comprise a coating over the outer shell, wherein the coating comprises polystyrene;
wherein the polystyrene coating and outer shell are rupturable by the application of ultrasonic energy.
2. The removable tattoo ink of claim 1 , wherein the outer shell, consists of between 2 and 10 optionally alternating layers of polystyrene sulfonate (PSS) and polyallylamine hydrochloride (PAH).
3. The removable tattoo ink of claim 1 , wherein the inner layer consists of polystyrene sulfonate or polyallylamine hydrochloride, and/or the outer layer consists of polyallylamine hydrochloride or polystyrene sulfonate.
4. The removable tattoo ink of claim 1 , wherein the outer shell and/or coating is substantially visibly transparent such that the chromophore is detectable through the outer shell and/or coating.
5. The removable tattoo ink of claim 1 , wherein the micro-particles range in size from 0.1 μm to 100 μm.
6. The removable tattoo ink of claim 1 , wherein the micro-particle is suspended in a liquid carrier.
7. The removable tattoo ink of claim 6 , wherein the carrier comprises alcohol, water, or glycerin, or any combination thereof.
8. The removable tattoo ink of claim 1 , wherein the chromophore comprises a chromophore selected from:
the group consisting of phthalocyanine dyes, cyanine dyes, and pyrylium dyes;
the group consisting of water soluble forms of rifampin, β-carotene, tetracycline, indocyanine green, Evan's blue, and methylene blue;
the group consisting of FD&C Blue No. 2, FD&C Blue No. 1, FD&C Green No. 3, FD&C Red No. 3, FD&C Red No. 40, FD&C Yellow No. 5, and FD&C Yellow No. 6, or a combination thereof;
the group consisting of water soluble forms of copper sulfate, Cu(NH 3 ) 2+ , MnO 4 , NiCl 2 , CrO 4 , and Cr 2 O7 2− , or a combination thereof.
9. A method of applying a tissue marking, the method comprising:
providing the removable tattoo ink of claim 1 ; and
implanting the ink into a tissue of a subject, thereby forming a tissue marking.
10. A method for rendering undetectable a tissue marking implanted in tissue, comprising subjecting a tissue marking formed from the removable tattoo ink of claim 1 to ultrasonic energy, for an intensity and duration sufficient to disrupt the micro-particles of the removable tattoo ink, thereby rendering undetectable the tissue marking implanted in tissue.
11. A method of making a removable tattoo ink, comprising:
forming an internal core, comprising one or more bio-absorbable chromophores, wherein the one or more bio-absorbable chromophores are water-soluble dyes, water-soluble pigments, or water-soluble drugs; and one or more salts with low water solubility; and
coating the internal core with at least one layer of polystyrene sulfonate (PSS) and at least one layer of polyallylamine hydrochloride (PAH), thereby forming an outer shell; and
coating the surface of the outer shell with polystyrene.
12. The method of claim 11 , further comprising, removing the one or more salts with low water solubility, such that the inner core is substantially the one or more bio-absorbable chromophores.
13. The method of claim 11 , wherein forming the internal core comprises mixing in solution the one or more bio-absorbable chromophores, CaCl 2 and Na 2 CO 3 , to form the internal core comprising CaCO 3 and the one or more bio-absorbable chromophores and removing the residual NaCl.
14. The method of claim 13 , wherein coating the internal core with at least one layer of polystyrene sulfonate comprises contacting the internal core comprising CaCO 3 and the one or more bio-absorbable chromophores with a solution comprising polystyrene sulfonate (PSS).
15. The method of claim 13 , wherein coating the internal core with at least one layer of polyallylamine hydrochloride comprises contacting the internal core comprising CaCO 3 and the one or more bio-absorbable chromophores with a solution comprising polyallylamine hydrochloride (PAH).
16. The method of claim 13 , further comprising removing the CaCO 3 present in the internal core with a metal chelation agent.
17. The method of claim 16 , wherein the metal chelation agent comprises EDTA.