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This work describes the synthesis and characterization of noncytotoxic nanocomposites either colloidal or as films exhibiting high antibacterial activity. The biocompatible and biodegradable polymer chitosan was used as reducing and stabilizing agent for the synthesis of gold nanoparticles embedded in it. Herein, for the first time, three different chitosan grades varying in the average molecular weight and deacetylation degree (DD) were used with an optimized gold precursor concentration. Several factors were analyzed in order to obtain antimicrobial but not cytotoxic nanocomposite materials. Films based on chitosan with medium molecular weight and the highest DD exhibited the highest antibacterial activity against biofilm forming strains of Staphylococcus aureus and Pseudomonas aeruginosa. The resulting nanocomposites did not show any cytotoxicity against mammalian somatic and tumoral cells. They produced a disruptive effect on the bacteria wall while their internalization was hindered on the eukaryotic cells. This selectivity and safety make them potentially applicable as antimicrobial coatings in the biomedical field.

In this work different variables have been analyzed in order to optimize the bactericidal properties of chitosan films loaded with silver nanoparticles. The goal was to achieve complete elimination of antibiotic resistant and biofilm forming strains of Staphylococcus aureus after short contact times. The films were produced by solution casting using chitosan as both a stabilizing and reducing agent for the in situ synthesis of embedded silver nanoparticles. We have applied an innovative approach: the influence of the chitosan molecular weight and its deacetylation degree (DD) were analyzed together with the influence of the bacterial concentration and contact time. The best results were obtained with high DD chitosan where a fast reduction was favored; leading to smaller nanoparticles (nucleation is promoted), and a sufficiently high polymer viscosity prevented the resulting nanoparticles from undesired agglomeration. In addition, for the first time, potential detachment of the silver nanoparticles from the films was evaluated and neglected, demonstrating that uncontrolled release of silver nanoparticles from the chitosan films is prevented. The influence of the ionic silver released from the films, silver loading, nanoparticle sizes, contact, and initial number of bacteria was also analyzed to elucidate the mechanism responsible for the strong bactericidal action observed.

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Novel half-sandwich iridium(III) complexes with aminomethyl(diphenyl)phosphine derived from fluoroloquinolones (IrPCp, IrPSf, IrPLm, IrPNr) were being studied as possible anticancer chemotherapeutics with potency higher than that of the other well-known metal-based...

The synthesis of stable copper nanoparticles (CuNPs) has been carried out in the presence of green chemicals such as chitosan, sodium phosphinate, and ascorbic acid. The colloidal stability of the copper nanoparticles has been evaluated for a period of one month. No further aggregation or significant changes in the overall oxidation state of the resulting nanoparticles has been detected, thereby proving the viability of this one‐step synthesis method. In addition, different control experiments have shown that the presence of the three reactants is necessary to obtain stable copper nanoparticles for periods of time longer than one week. The use of chitosan as a natural polymer with stabilizing properties enables its application in the biomedical field owing to its demonstrated biocompatibility, biodegradability, and lack of toxicity. Sodium phosphinate acts as a co‐reducing agent and the ascorbic acid prevents the formation of copper sub‐oxides owing to its antioxidant properties.

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We describe the synthetic pathway to produce efficient bactericidal, fungicidal and non-cytotoxic chitosan–ascorbic acid–silver composites as solid films.