Chitosan/carboxymethyl cellulose wound dressings supplemented with biologically synthesized silver nanoparticles from the ligninolytic fungus Anamorphous Bjerkandera sp. R1.

Chitosan (CHI) and carboxymethyl cellulose (CMC) are naturally sourced materials with excellent physical, chemical, and biological properties, which make them a promising tool for the development of different medical devices. In this research, CHI-CMC wound dressings were manufactured, by using different colloidal suspensions of silver nanoparticles (AgNPs) synthesized from the ligninolytic fungus Anamorphous Bjerkandera sp. R1, called CS and SN. Transmission electron microscopy (TEM), UV-Vis spectroscopy, and dynamic light scattering (DLS) analysis were used to characterize AgNPs. The wound dressings were characterized, by scanning electron microscopy (SEM), optical microscopy and their mechanical, antimicrobial, and biological properties were evaluated. The results of the different characterizations revealed the formation of spherical AgNPs with a mean size between 10 and 70 nm for the different mixtures worked. The mechanical properties of CHI-CMS-AgNPs doped with CS and SN suspensions showed superior mechanical properties with respect to CHI-CMC wound dressings. Compared to the latter, CHI-CMC-AgNPs wound dressings yielded better antibacterial activity against the pathogen Escherichia coli. In biological assays, it was observed that manufactured CHI-CMC-AgNPs wound dressings were not toxic when in contact with human skin fibroblasts (Detroit). This study, then, suggests that this type of wound dressings with a chitosan matrix and carboxymethyl cellulose doped with biologically synthesized nanoparticles from the fungus Bjerkandera sp., may be an ideal alternative for the manufacture of new wound dressings.

Synthesis of silver nanoparticles using white-rot fungus Anamorphous Bjerkandera sp. R1: influence of silver nitrate concentration and fungus growth time.

Currently, silver nanoparticles (AgNPs) constitute an interesting field of study in medicine, catalysis, optics, among others. For this reason, it has been necessary to develop new methodologies that allow a more efficient production of AgNPs with better antimicrobial and biological properties. In this research growth time effects Anamorphous Bjerkandera sp. R1 and the silver nitrate (AgNO3) concentration over AgNPs synthesis were studied. Through the protocol used in this work, it was found that the action of the capping proteins on the surface of the mycelium played a determining role in the reduction of the Ag+ ion to Ag0 nanoparticles producing a particle size that oscillated between 10 and 100 nm. The progress of the reaction was monitored using visible UV-Vis spectroscopy and the synthesized AgNPs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared radiation (FTIR) spectroscopy. The best synthetic properties were found at 1 mM of AgNO3 concentration, growth time of 8 days, and reaction time of 144 h. Nanometals obtention from microorganisms could be considered as a new method of synthesis, due to reducing abilities of metal ions through its enzymatic system and represents low-cost synthesis that reduces the generation of harmful toxic wastes.