Green synthesis of silver nanoparticles by reduced glycated casein adducts: Assessment of their antibacterial and antioxidant activity against Streptococcus mutans

•The reduced glycated casein adducts were applied for the synthesis of silver nanoparticles (AgNPs).•Different spectroscopic techniques and microscopic assessment were applied for characterization of the AgNPs.•The nanoparticles demonstrate size ranges between 30 and 60 nm and indicate almost spherical morphology.•The AgNPs reveal reasonable antibacterial properties against cariogenic bacterium Streptococcus mutans.•Reduced glycated casein adducts are novel source of biomaterials for efficient production of antibacterial AgNPs.

IntroductionDue to their effective antibacterial and antiviral activity and lower tendency to develop resistance, silver nanoparticles (AgNPs) have recently gained much attention. In the current study, we report an economically green route for the synthesis of biocompatible AgNPs, employing reduced glycated adducts of whole casein fraction (gWCF) as reducing/capping agents.MethodsDifferent spectroscopic techniques and microscopic assessment were used to characterize AgNPs and their antimicrobial properties to investigate their effects against cariogenic bacterium Streptococcus mutans (S. mutans).ResultsAccording to the UV–vis spectroscopic results, generation of AgNPs from silver ions was significantly more efficient in the presence of gWCF than WCF, explaining with the variation in their antioxidant powers, as indicated in this study. The results of salt induced aggregation of AgNPs and those of FTIR analysis provide an indication on coating of AgNPs with these acidic and amphiphilic proteins. Also, dynamic light scattering analysis suggests that AgNPs produced by either WCF or gWCF demonstrate the size ranges between 30 and 60 nm. Moreover, microscopic analysis indicates almost spherical morphology for the produced AgNPs. Furthermore, the difference in the antibacterial properties against S. mutans of these two types of AgNPs can be explained with their size variations and/or with differences in the physicochemical properties of their coating agents.ConclusionIn spite of slightly higher antibacterial activity and lower size ranges of AgNPs produced in the presence of WCF, this study may suggest reduced glycated casein adducts as a novel and important source of biomaterials for the economic and efficient production of relatively stable AgNPs.

Graphical abstractWhole casein fraction (WCF) was extensively glycated under reducing condition. The bio reduction of silver ions by reducing power of WCF and its glycated counterpart (gWCF) results in formation of almost spherical AgNPs, displaying promising antibacterial properties against S. mutans. The generation of AgNPs was significantly more efficient with gWCF than WCF.Figure optionsDownload full-size imageDownload high-quality image (143 K)Download as PowerPoint slide