Evaluation of the long-term antibiofilm effect of a surface coating with dual functionality of antibacterial and protein-repellent effects.

The provision of antibacterial properties to resinous restorative/reconstructive materials by incorporating polymerizable bactericides such as 12-methacryloyloxydodecylpyridinium bromide (MDPB) has been attempted. Previously, MDPB was combined with 2-methacryloyloxyethyl phosphorylcholine (MPC) to fabricate a copolymer coating to increase antibacterial effectiveness by protein repelling. In this study, we assessed the longevity of the protein-repelling, antibacterial, and antibiofilm effects of the MDPB-MPC copolymer. After 28 days of water immersion, MPC-containing copolymers exhibited lower adsorption of bovine serum albumin and salivary proteins; after 24 h of incubation, MDPB-containing copolymers demonstrated antibacterial effects against Streptococcus mutans. The copolymer containing both MDPB and MPC showed thinner biofilm formation with a higher percentage of membrane-compromised bacteria than control. The results were consistent with those before aging, indicating the long-lasting antibacterial, protein-repellent, and antibiofilm effects of this copolymer. The durable copolymer developed in this study can be applied to dental resins to control bacteria in the oral environment.

Development of novel surface coating composed of MDPB and MPC with dual functionality of antibacterial activity and protein repellency.

Resin-based reconstructive/restorative materials with antibacterial effects are potentially useful for preventing dental and oral diseases. To this end, the immobilization of an antibacterial component on the surface of a resin by incorporating polymerizable bactericide such as a quaternary ammonium compound-monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) is an effective technique. However, the effectiveness of immobilized bactericide is reduced by salivary protein coverage. We address this issue by utilizing 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, which exhibits protein repellency, with MDPB to fabricate a novel copolymer, which served as a surface coating on a methacrylate-based resin. This coating provided a more hydrophilic surface than that provided by MDPB coating and reduced the adsorption of bovine serum albumin and salivary protein. To evaluate bacterial growth on the contact surface, Streptococcus mutans suspension was placed on the coated specimen. After 24-h incubation, MDPB/MPC copolymer exhibited killing effects against S. mutans. Moreover, confocal laser scanning microscopy and scanning electron microscopy were used to evaluate biofilm formation after 48-h incubation in S. mutans suspension, which revealed sparse biofilm and dead bacteria in biofilm on the surface coated with MDPB/MPC. Overall, the proposed surface coating on dental resins exhibited protein-repellent ability and inhibitory effects against bacteria and oral biofilms.

Thermally Assisted Generation of Protein-Poly(ethylene sodium phosphate) Conjugates with High Mineral Affinity.

Protein therapeutics has recently attracted interest in various medical treatments. However, the structure and function preservation in proteins under physiological conditions is still an important issue and reliable immobilization techniques are required. In this study, the thermally assisted complexation of proteins with amphiphilic polyphosphoesters is proposed as a new methodology for their durability improvement. Amphiphilic cholesterol-terminated poly(ethylene sodium phosphate) (CH-PEP·Na) was synthesized via the organocatalytic ring-opening polymerization of 2-methoxy-2-oxo-1,3,2-dioxaphospholane initiated by cholesterol as the hydrophobic molecule and followed by demethylation and neutralization. For the protein nanocarrier preparation, a complex of the amphiphilic CH-PEP·Na with bovine serum albumin (BSA) was formed through the hydrophobic interactions between the lipophilic moieties of the protein and the cholesteryl groups of the CH-PEP·Na chains, which were induced by thermal treatment at 90 °C. The resulting complex size ranged between 27 and 51 nm, as confirmed by dynamic light scattering. The complexes dispersed in an aqueous medium exhibited a high stability in size for up to 1 month of storage. CH-PEP·Na efficiently inhibited the thermal aggregation and sedimentation of BSA, unlike poly(ethylene sodium phosphate) (PEP·Na) and cholesterol-terminated poly(ethylene glycol) (CH-PEG). In addition, CH-PEP·Na was able to protect the complexed BSA against proteolytic digestion and the BSA-CH-PEP·Na complexes well adsorbed onto hydroxyapatite even in the presence of BSA (5.5 g/dL). Hence, thermally induced protein-CH-PEP·Na complexes can be a potential tool for the development of bone and dental applications.

Cascade post-polymerization modification of single pentafluorophenyl ester-bearing homopolymer as a facile route to redox-responsive nanogels.

Poly(pentafluorophenyl methacrylate) (PPFPMA) was first subjected to post-polymerization modification with oligo(ethylene glycol) methyl ether amine (OEG-NH2) and yielded poly(pentafluorophenyl methacrylate)-co-poly(oligo(ethylene glycol methacrylamide)), PPFPMA-co-POEGMAM. These amphiphilic random copolymers can self-assemble into micellar nanoparticles in water having sizes less than 100nm. By tandemly reacting the pentafluorophenyl (PFP) groups in the copolymeric nanoparticles with a dithiol crosslinker, cystamine, redox-responsive nanogels can be formed. The last step of post functionalization with isopropylamine was introduced in order to remove the remaining PFP groups in the nanogels. Stepwise post functionalization can be monitored by FTIR and 19F NMR spectroscopy. Release of a model hydrophobic drug, nile red (NR) from the nanogels, simultaneously encapsulated during micelles formation, can be accelerated in the presence of glutathione (GSH) especially at 37°C. Results from cytocompatibility evaluation suggested that these developed redox-responsive nanogels strongly possessed a potential for applications in controlled delivery.