Nanosynthesis of silver-calcium glycerophosphate: Promising association against oral pathogens

Abstract

Nanobiomaterials combining remineralization and antimicrobial abilities would bring important benefits to control dental caries. This study aimed to produce nanocompounds containing calcium glycerophosphate (CaGP) and silver nanoparticles (AgNP) by varying the reducing agent of silver nitrate (sodium borohydride (B) or sodium citrate (C)), the concentration of silver (1% or 10%), and the CaGP forms (nano or commercial), and analyze its characterization and antimicrobial activity against ATCC Candida albicans (10231) and Streptococcus mutans (25175) by the microdilution method. Controls of AgNP were produced and silver ions (Ag+) were quantified in all of the samples. X-ray diffraction, UV-Vis, and scanning electron microscopy (SEM) analysis demonstrated AgNP associated with CaGP. Ag+ ions were considerably higher in AgCaGP/C. C. albicans was susceptible to nanocompounds produced with both reducing agents, regardless of Ag concentration and CaGP form, being Ag10%CaGP-N/C the most effective compound (19.5-39.0 μg Ag mL-1). While for S. mutans, the effectiveness was observed only for AgCaGP reduced by citrate, also presenting Ag10%CaGP-N the highest effectiveness (156.2-312.5 μg Ag mL-1). Notably, CaGP enhanced the silver antimicrobial potential in about two-and eight-fold against C. albicans and S. mutans when compared with the AgNP controls (from 7.8 to 3.9 and from 250 to 31.2 μg Ag mL-1, respectively). The synthesis that was used in this study promoted the formation of AgNP associated with CaGP, and although the use of sodium borohydride (B) resulted in a pronounced reduction of Ag+, the composite AgCaGP/B was less effective against the microorganisms that were tested.