OICC Press Journal of Nanostructure in Chemistry 2193-8865 4 4 (December 2015) 2014 09 18 In situ silver nanoparticle formation embedded into a photopolymerized hydrogel with biocide properties 10.1007/s40097-014-0125-y EN Carmen Mabel González Henríquez Chemistry Department, Metropolitan Technological University, Santiago, 7800002, CL Guadalupe del Carmen Pizarro Guerra Chemistry Department, Metropolitan Technological University, Santiago, 7800002, CL Mauricio Alejandro Sarabia Vallejos Physics Institute, Pontifical Catholic University of Chile, Santiago, 7820436, CL Susana Dennis Rojas de la Fuente Physics Institute, Pontifical Catholic University of Chile, Santiago, 7820436, CL María Teresa Ulloa Flores Microbioloy and Mycology Program, ICBM, Medicine Faculty, University of Chile, Santiago, 8380453, CL Lina María Rivas Jimenez Microbioloy and Mycology Program, ICBM, Medicine Faculty, University of Chile, Santiago, 8380453, CL Journal Article 2014 09 18 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 AgNO 3 (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 +  → Ag 0 , 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 Ag 0 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.