Compare the physicochemical properties of engineered polymer-functionalized silver nanoparticles and evaluate their biological properties against Porphyromonas gingivalis

Abstract

Background: Nano silver (AgNPs) is a broad-spectrum antibacterial nanomaterial and many polymer-functionalized AgNPs (P-AgNPs) have been developed to optimize the biological properties of AgNPs and some possess good potential for commercial application. However, no horizontal study compares the differences in physicochemical and biological properties among various P-AgNPs, and provides evidence for the selection of polymer and optimization of AgNPs. Methods: Two AgNPs with similar nano-size but opposite surface charges were synthesized and functionalized by seven polymers. Their physicochemical properties were detected by UV-Vis, DLS, TEM and ICP-OES. Their biological properties against Porphyromonas gingivalis and human gingival fibroblast were investigated by MIC determination, time-dependent antibacterial assay, antibiofilm activity, and cell viability assay. Silver diamine fluoride (SDF), AgNO3 and metronidazole were used as the positive controls.Results: Comparative analysis found that there was no significant difference between P-AgNPs and AgNPs in nano-size and surface charge. For antibacterial property, in negatively charged AgNPs, only polyvinylpyrrolidone (PVP)-functionalized AgNPs-1 showed significant lower MIC values than AgNPs-1 (0.79 vs 4.72 μg/ml). In positively charged AgNPs, the MIC values of all P-AgNPs (0.34-4.37 μg/ml) were lower than AgNPs-2 (13.89 μg/ml), especially the PVP- and Pluronic127-AgNPs-2 (1.75 and 0.34 μg/ml). For antibiofilm property, the PVP-AgNPs-1 (7.86 μg/ml, P=0.002) and all P-AgNPs-2 (3.425-31.14 μg/ml, P<0.001) showed great antibiofilm effect against Porphyromonas gingivalis biofilm at 5* to 10* MIC level. For cytotoxicity, all negatively charged AgNPs and PVP-AgNPs-2 showed no cytotoxicity at MIC level, but significant cytotoxicity was detected at 2.5*-10* MIC levels. Conclusions: Polymer functionalization only minimally alters the physical properties of AgNPs, but modifies their surface chemical property, which is closely related to their biological property. The antibacterial and antibiofilm properties and cytotoxicity of AgNPs can be significantly optimized to varying degrees by some polymer functionalization, especially using PVP. However, none of the AgNPs studied has low cytotoxicity at the antibiofilm concentration levels.