In situ silver nanoparticle formation embedded into a photopolymerized hydrogel with biocide properties

Abstract

In situ nanoparticle formation embedded into hydrogel matrix, acting as container and stabilizer for nanoparticle reaction was the focus in this research; this method was realized using AgNO3 (0.75 and 1.0 M) as silver source for nanoparticle formation; also, monomers (HEMA), cross-linker agents (DEGDMA) and a photoinitiator (Irgacure 651) were used for the hydrogel synthesis. For the reduction of Ag+ → Ag0, the reaction mixture was irradiated with an UV lamp at 365 nm for 30 min; parallel to this process, the hydrogel photopolymerization occurs. All these systems were studied by Infrared and Raman Spectroscopy, optical studies: UV/Vis absorption, thermal studies: differential scanning calorimetry and thermogravimetric analysis, X-ray diffraction, fluorescence X-ray spectroscopy and transmission electronic microscopy. Characterization techniques are capable to detect the presence of non-agglomerated silver nanoparticles homogeneously distributed in all the systems. X-Ray photoemission spectroscopy establishes the presence of Ag0 and Ag+ as mixture in the synthesized composite. Quantitative assays show that the sample Ag_Hg3-89.5 % (1.0 M) presents an important biocide property, by reducing 99.9 % of bacterium Escherichia coli ATCC 25922 as compared with the alone hydrogel used as control. GRAPHICAL ABSTRACT: The embedding of silver nanoparticles homogenously distributed and stabilized into the hydrogel matrix was realized in situ using a photoinitiator during the synthesis. In figures it is possible to observe different conformations of hydrogel/silver nanoparticle composites, so the non-organic nanoparticles seem to be confined in the organic polymer matrix, forming a bunch. TEM analysis shows spherical nanoparticles with diameters around 22–37 nm. Biocide tests show that this compound could be utilized as E. coli bactericide with remarkable results. [Figure not available: see fulltext.].