Thermo-responsive nanoarrays of silver nanoparticle, silicate nanoplatelet and PNiPAAm for the antimicrobial applications

The ternary nanohybrids of silver nanoparticles (AgNPs) in combination with silicate nanoplatelets (NSP) and thermally sensitive poly(N-isopropylacrylamide)(PNiPAAm) were fabricated for antibacterial applications. PNiPAAm were chemically grafted on the NSP by atom-transfer radical polymerization (ATRP) via polymerizing N-isopropylacrylamide monomers with sol-gel linkers (BBTES). The nanoparticles of AgNPs then were adsorbed on NSP-PNiPAAm nanosheets through in situ reduction reaction of AgNO3 in aqueous dispersion. The particle sizes of AgNPs were estimated to be 7-12 nm in diameter with different composition ratios of AgNPs to NSP-PNiPAAm, evaluated by transmission electron microscope (TEM). The nanohybrids of AgNP/NSP-PNiPAAm exhibited the unique property of lowest critical solution temperature (LCST) at 32 degrees C. The thermo-responsive antibacterial efficacy of the ternary nanohybrids was demonstrated by Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli) at lower than the LCST (28 C) and higher than the LCST (37 degrees C). The result show that the great antibacterial ability was observed in the hydrophilic bacteria (B. subtilis) at 28 degrees C. In contrast, the excellent antibacterial ability was found in the hydrophobic bacteria (E. coli) at 37 degrees C, due to the surface energy modulation of AgNP/NSP-PNiPAAm. The tailoring of silver-containing ternary nanohybrids allow the new antibacterial nanomaterials to selectively affect the surface of bacteria by varying temperature. (C) 2017 Elsevier B.V. All rights reserved.