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.
We describe the synthetic pathway to produce efficient bactericidal, fungicidal and non-cytotoxic chitosan–ascorbic acid–silver composites as solid films.
The ability of pathogenic bacteria to develop resistance mechanisms to avoid the antimicrobial potential of antibiotics has become an increasing problem for the healthcare system. The search for more effective and selective antimicrobial materials, though not harmful to mammalian cells, seems imperative. Herein we propose the use of gold-chitosan nanocomposites as effective bactericidal materials avoiding damage to human cells. Nanocomposites were obtained by taking advantage of the reductive and stabilizing action of chitosan solutions on two different gold precursor concentrations. The resulting nanocomposites were added at different final concentrations to a coculture model formed by Gram-positive (Staphylococcus aureus) or Gram-negative (Escherichia coli) bacteria and human macrophages. Gold-chitosan colloids exhibited superior bactericidal ability against both bacterial models without showing cytotoxicity on human cells at the concentrations tested. Morphological and in vitro viability studies supported the feasibility of the infection model here described to test novel bactericidal nanomaterials. Flow cytometry and scanning electron microscopy analyses pointed to the disruption of the bacterial wall as the lethal mechanism. Data obtained in the present study suggest that gold-chitosan nanocomposites are powerful and promising nanomaterials for reducing bacteria-associated infections, respecting the integrity of mammalian cells, and displaying high selectivity against the studied bacteria.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.