Phenolic coatings and methods of making and using same
A method of making a facile, surface-independent, polyphenol coating is disclosed. In general, the method includes contacting at least a portion of the substrate to be coated with an aqueous solution containing one or more salts and one or more nitrogen-free phenolic compounds. Substrates of all kinds may be used, and compounds used to make the coating may include epigallocatechin-3-gallate (EGCG), epigallocatechin (EGC) and epicatechin-3-gallate (ECG), tannic acid, gallic acid, pyrogallol, and/or other nitrogen-free phenolic compounds. The coating made using the method, methods of using the coating, and kits comprising the coating precursors are also disclosed.
1. A Method of forming a coating on a substrate surface, the method comprising contacting at least a portion of the substrate surface with an aqueous saline solution, comprising at least one salt selected from the group consisting of NaCl, MgCl2, CaCl2, CuCl2 with NaCl, ZnCl2 with NaCl and any combination thereof and an effective amount of one or more natural or synthetic polyphenols, pyrogallol, or gallic acid, wherein the polyphenols are selected from the group consisting of epigallocatechin-3-gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), tannic acid, those extracted from green tea leaves, those extracted from cacao beans, those extracted from dark chocolate and those extracted from red wine, comprising 1) preparing the aqueous saline solution comprising the one or more polyphenols, pyrogallol, or gallic acid, and 2) applying the aqueous saline solution to the substrate; wherein the pH and the salt concentration are such that a coating forms on the substrate surface, which has a thickness greater that a coating formed under identical conditions, in the absence of the salt, further comprising the step of contacting the resulting coating with a reactive moiety, whereby the reactive moiety reacts with and becomes bound to the coating.
2. The method of claim 1 , wherein the solution comprises NaCl.
3. The method of claim 1 , wherein the solution is basic.
4. The method of claim 3 , wherein the pH of the solution is about 7.8.
5. The method of claim 1 , wherein the substrate surface is selected from the group consisting of titanium dioxide, silica, gold, polycarbonate, polysulfone, polytetrafluoroethylene, polystyrene, and stainless steel.
6. The method of claim 1 , wherein the reactive moiety comprises a nucleophile or a metal ion.
7. The method of claim 6 , wherein the metal ion is silver ion.
8. The method of claim 1 , wherein the reactive moiety comprises silver ion (Ag+), and elemental silver becomes bound to the coating.
9. The method of claim 8 , further comprising contacting the resulting coating with an alkanethiol, whereby the coating becomes superhydrophobic.
10. The method of claim 6 , wherein the nucleophile is comprised of a protein or an amine- or thiol-functionalized polymer.
11. A coating on a surface substrate as produced by the method of claim 1 .
12. A method of removing metal ions from a liquid, comprising contacting the liquid with the coating of claim 11 , whereby at least some of the metal ions in the sample are captured by the coating and removed from the liquid.
13. The method of claim 12 , wherein the metal ion is silver.