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Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5–12 nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus . [ABSTRACT FROM AUTHOR]

Highlights: [•] Carboxymethyl cellulose (CMC) was oxidized to form dialdehyde CMC (DCMC). [•] Guanidine hydrochloride (GH) was grafted onto the DCMC to obtain DCMC-GH. [•] The coating of DCMC-GH onto paper resulted in the improvement of paper strength. [•] The DCMC-GH-coated paper exhibited excellent antimicrobial activities. [Copyright &y& Elsevier]

Abstract: We report on the synthesis of cellulose paper bearing a cationic porphyrin, designed for antimicrobial applications. Tricationic porphyrin has been covalently grafted on paper, without previous chemical modification of the cellulosic support, using 1,3,5-triazine derivative as linker. The obtained porphyrin-grafted paper was characterized by infrared (ATR-FTIR), UV–visible and diffuse reflectance UV–vis (DRUV) spectroscopies to confirm the triazine linkage. Thermogravimetric analysis (TGA) was used to investigate thermal properties of grafted paper. Antimicrobial activity of porphyrin–cellulose material was tested under visible light irradiation against Staphylococcus aureus and Escherichia coli. The two bacterial strains deposited on the resulting photosensitizing filter paper are efficiently killed after illumination. [Copyright &y& Elsevier]

Abstract: A silver nanoparticle colloid was prepared by a modified Tollens method using d-glucose as the reduction agent. The obtained nanoparticles were used for the modification of pine, linter and recycled cellulose fibers. Although the silver contents were relatively low (0.05–0.13wt.%), the cellulose-sheets prepared from the modified fibers show improved mechanical and viscoelastic properties. The tensile index (strength) increased with up to 30% in comparison to the index of the sheets obtained from the untreated fibers. The influence of the nanoparticles on the viscoelastic properties of the cellulose sheets was investigated by dynamic mechanical analysis (DMA) in the temperature range from −120 to 20°C and with a force frequency of 100Hz. A broad relaxation transition positioned at −80°C was observed in the loss modulus spectrum of all the cellulose sheets, while the Ag-modified sheets exhibited higher storage moduli values in the whole temperature range. The antimicrobial activity tests show that the pine, silver and recycled cellulose fiber sheets with silver nanoparticles can be successfully employed to prevent the viability and growth of the common pathogens Staphylococcus aureus, Escherichia coli and Candida albicans. [Copyright &y& Elsevier]

Abstract: Chitosan–guanidine complexes were prepared by reacting chitosan and polyhexamethylene guanidine hydrochloride or crosslinked polyhexamethylene guanidine hydrochloride in the presence of sodium tripolyphosphate as a crosslinking agent. The complexes, used as functional additives for paper, synergistically improved wet-strength and antimicrobial activities. In comparison with the control sample, the wet/dry strength ratio of hand-sheets treated with the complexes was increased from 2.65% up to 23.3%. The MIC values of the chitosan–PHGH and chitosan–PHGHE complexes against Escherichia coli were 15.6 and 31.2μgmL−1, respectively, thus demonstrating excellent antimicrobial activity. Hand-sheets treated with the complexes exhibited antibacterial activity against E. coli and Staphylococcus aureus. The release of the guanidine polymers included in the complexes was dynamically monitored using UV and the results showed the amount released exceeded 80%. Atomic force microscopy images indicated that the antimicrobial mechanism of the complexes was likely due to membrane damage. [Copyright &y& Elsevier]

Abstract: Antimicrobial papers were prepared by coating paper with soy protein isolate (SPI) solution as inclusion matrix of carvacrol, an antimicrobial agent. Addition of carvacrol (30% w/w of SPI) to SPI solution (10% w/v) prepared at 25°C induced soy protein aggregates and viscosity decrease. Heat treatment (50, 70, 90°C) of SPI solutions and carvacrol addition improved homogeneity reduced particles size and increased viscosity of solutions. The aggregated structure of SPI in the presence of carvacrol at 25°C may play the role of a trapping structure leading to low carvacrol losses during coating and drying process of paper (9.6% against 37% after heat treatment at 90°C) and to lower release rates specially the first three days (0.04g/m2/day and 0.31g/m2/day when SPI coating solutions were prepared at 25 and 90°C, respectively). Regardless of the heat treatments received by the SPI solutions, residual carvacrol quantities in the coated papers after 50 days ranged between 0.6 and 0.7g/m2. [Copyright &y& Elsevier]