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Silver nanoparticles (AgNPs) possess antibacterial properties and exhibit cytoprotective activity toward HIV-1-infected cells. AgNPs also promotes the acceleration of delayed wound healing and faster diabetic wound healing [1]. In this work AgNPs were synthesized onto microcrystalline cellulose (MCC) and onto a modified microcrystalline cellulose (MMCC). For MCC-Ag nanocomposite obtention the MCC was impregnated with aqueous silver nitrate solution containing polyvinylpyrrolidone (PVP), during 24 h. In a second stage the silver (Ag) impregnated cellulose was immersed in a basic solution of PVP and then hydroxylamine (H) or ascorbic acid (AA) was added until complete silver reduction. The MMCC-Ag nanocomposite was obtained in the same manner except that MCC was treated with a solution of NaOH 5% before the impregnation with Ag+. Cellulosic materials were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), photoacoustic spectroscopy in the ultraviolet-visible region (PAS), scanning electron microscopy (SEM) and antibacterial test. The FTIR spectra of MCC-Ag and MMCC-Ag samples showed only characteristic bands of cellulose. The x-ray diffractograms showed characteristic peaks of the cubic Ag phase at 2Ө= 38, 1 [crystallographic plane (111)][2]. AgNPs with average size of 10-25 nm were obtained. Treatment with 5% NaOH of the MCC caused a decrease in the crystallinity of the cellulose. Reducing agents also affected the crystallinity of the samples. The PAS spectroscopy exhibits maximum absorption intensity in the region of 400 nm, which is characteristic of Ag. SEM micrographs …