Compare the physicochemical and biological properties of engineered polymer-functionalized silver nanoparticles

Abstract

<p><strong>Objectives</strong>: To compare the difference of physicochemical and biological properties among engineered polymer-functionalized silver nanoparticles (P-AgNPs).<br><strong>Methods</strong>: AgNPs with similar nanosize and opposite surface charges were synthesized and functionalized by seven polymers with different molecular weights (PEG, PVP, Pluronic^TM). Their physical properties were detected by UV-Vis, DLS, TEM, and ICP. Their antibacterial and antibiofilm capability against <em>Porphyromonas gingivalis</em> (<em>P.g</em>), and their cytotoxicity on human gingival fibroblast were investigated by MIC determination, time-dependent antibacterial assay, live-dead staining assay, and cell viability assay. Silver diamine fluoride (SDF), AgNO_3, and metronidazole were used as the positive controls.<br><strong>Results</strong>: We successfully synthesized spherical, 15-25 nm of negatively/positively charged AgNPs (AgNPs-1/2). The hydrated nanosize of P-AgNPs detected by DLS was 50-200 nm, but TEM images showed that the size of P-AgNPs remains 15-40 nm. There is no alteration in surface charge. For antibacterial property, in negatively charged AgNPs, only PVP-functionalized AgNPs showed significant lower MIC values than AgNPs-1 (0.79 μg/ml vs 4.72 μg/ml). In positively charged AgNPs, the MIC value of all P-AgNPs (0.34-4.37 μg/ml) was lower than AgNPs-2 (13.89 μg/ml), especially PVP- and F127-functionalized AgNPs (1.75 and 0.34 μg/ml). For antibiofilm property, the PVP-functionalized AgNPs-1 (7.86 μg/ml, P=0.002) and all positively charged P-AgNPs (3.425-31.14 μg/ml, P<0.001) showed great antibiofilm effect against P.g biofilm at 5*-10* MIC level. For cytotoxicity, all negatively charged AgNPs and PVP- and F127-functionalized AgNPs-2 showed no cytotoxicity at MIC level, but significant cytotoxicity was detected at 2.5*-10* MIC levels.<br><strong>Conclusions</strong>: Polymer functionalization doesn’t significantly alter the physical properties of AgNPs, including nanosize and surface charge, but it modifies the surface chemical property of AgNPs, which are closely related to their biological property. The antibacterial and antibiofilm properties of AgNPs can be significantly optimized by the functionalization of some polymers, especially PVP. However, the cytotoxicity does not improve with the reduction in MIC value.<br></p>