Interdisciplinary approach to synthesis, stability and antimicrobial activity of silver nanoparticles.

Introduction: Chronic wounds are an increasing problem for health care all over the world. New treatment options for this illness are desired, especially antimicrobial agents. Silver nanoparticles (AgNPs) can be a potential substance that may be used in treatment of chronic wounds due to the growing antibiotic resistance. Aim: To synthetize silver nanoparticles that are stable, pure and effective against bacteria. Material and methods: The synthesis was conducted with chemical methods using different coating factors. The antistaphylococcal properties were analysed with the microdilution method to determine minimal inhibition concentrations (MIC) value. AgNPs were purified by dialysis. Moreover, keratinocyte cytotoxic properties of AgNPs were also assessed. Results: A method of synthesizing stable and efficient AgNPs has been developed. The type of the coating substance has a significant effect on AgNPs antimicrobial properties. Most of the silver nanoparticles, synthesized based on literature data, turned out to be durable during a few hours. This study has proven that depending on the coating factor, AgNPs stability ranges from 4 weeks to even 12 months. Unfortunately, the type of the stabilizer used also affects the cytotoxicity of AgNPs. It has been shown that dialysis is a substance purification method that is cheap, simple and easy to apply when dealing with high volume solutions. Conclusions: AgNPs could be an alternative to widely used antibiotics and disinfectants. Nevertheless, the introduction of those substances to health care requires detailed long-term research not only in the field of safe use, yet also durability and purity of AgNPs solutions used.

Partial Inhibition of Calcineurin Activity by Rcn2 as a Potential Remedy for Vps13 Deficiency.

Regulation of calcineurin, a Ca2+/calmodulin-regulated phosphatase, is important for the nervous system, and its abnormal activity is associated with various pathologies, including neurodegenerative disorders. In yeast cells lacking the VPS13 gene (vps13Δ), a model of VPS13-linked neurological diseases, we recently demonstrated that calcineurin is activated, and its downregulation reduces the negative effects associated with vps13Δ mutation. Here, we show that overexpression of the RCN2 gene, which encodes a negative regulator of calcineurin, is beneficial for vps13Δ cells. We studied the molecular mechanism underlying this effect through site-directed mutagenesis of RCN2. The interaction of the resulting Rcn2 variants with a MAPK kinase, Slt2, and subunits of calcineurin was tested. We show that Rcn2 binds preferentially to Cmp2, one of two alternative catalytic subunits of calcineurin, and partially inhibits calcineurin. Rcn2 ability to bind to and reduce the activity of calcineurin was important for the suppression. The binding of Rcn2 to Cmp2 requires two motifs in Rcn2: the previously characterized C-terminal motif and a new N-terminal motif that was discovered in this study. Altogether, our findings can help to better understand calcineurin regulation and to develop new therapeutic strategies against neurodegenerative diseases based on modulation of the activity of selected calcineurin isoforms.