Antibacterial and anti-biofouling coating on hydroxyapatite surface based on peptide-modified tannic acid.

Hydroxyapatite-based implant is widely used in the fields of artificial teeth and bones. However, the problem of microbial communities on hydroxyapatite surfaces remain a great challenge. In order to inhibit bacterial adhesion and activity in a long term, a salivary acquired pellicle (SAP) bioinspired tannic acid (SAP3-TA) is synthesized and characterized. The SAP inspired peptide sequence DDDEEK has a good adsorption performance on the surface of hydroxyapatite (HA). Tannic acid (TA) is a natural polyphenolic compound that can be extracted from green tea, and it has been proved to have an effective antibacterial property. After the coating of SAP3-TA on HA slices, the water contact angle is decreased to 14.2° and the HA surface becomes super-hydrophilic. The hydrophilic surface can prevent proteins adhesion and further inhibit the adhesion of bacteria. In this work, Streptococcus mutans (S. mutans) and bovine serum albumin (BSA) are used as models to prove the antibacterial and anti-biofouling properties of SAP3-TA coating on HA surface, respectively. SAP3-TA also shows low cytotoxicity to MG63 cells in the MTT test. All these results indicate that the SAP3-TA can be used as a potential antibacterial and anti-biofouling coating for hydroxyapatite-based implants.

Bioinspired Peptide-Decorated Tannic Acid for in Situ Remineralization of Tooth Enamel: In Vitro and in Vivo Evaluation.

Tooth enamel can be eroded by the local cariogenic bacteria in plaque or nonbacterial factors in the oral environment. The damage is irreversible in most situations. For the etched human tooth enamel to be restored in situ, a salivary-acquired pellicle (SAP) bioinspired tannic acid (SAP-TA) is synthesized. Statherin is one of the SAP proteins that can selectively adsorb onto enamel surface. Peptide sequence DDDEEKC is a bioinspired sequence of statherin and has the adsorption capacity of hydroxyapatite (HAP). TA has abundant polyphenol groups that can grasp Ca2+ in saliva to induce the regeneration of HAP crystal. Hence, SAP-TA not only enhances the binding force at the interface of remineralization but also mimics the biomineralization process of tooth enamel. Moreover, ferric ion can coordinate with SAP-TA to form a compact coating that increases the adsorbed amounts of SAP-TA on tooth enamel. Compared with SAP-TA alone, the etched enamels treated with SAP-TA/Fe(III) have a better remineralization effect and mechanical properties (surface microhardness recovery >80% and binding force of 64.85 N) when being incubated in artificial saliva for 2 weeks. In vivo remineralization performance is evaluated in a classical rat caries model. The polarizing microscope and micro-CT results show that SAP-TA/Fe(III) has a good effect on the remineralization process in a real oral environment, indicating that it is a promising repair material for in situ remineralization of enamel.