Designing, preparation and evaluation of the antimicrobial activity of biomaterials based on chitosan modified with silver nanoparticles.

Chitosan was chemically modified through a four-step procedure. First, the amino groups of chitosan have reacted with benzaldehyde (Derivative 1); second, hydroxyl groups on C6 of Derivative 1 have reacted with epichlorohydrin (Derivative 2); third, the epoxy groups of Derivative 2 have reacted with 4-aminosalicylic acid (Derivative 3); and fourth, benzaldehyde moieties of Derivative 3 have been removed to retrieve the amino groups (Derivative 4). For further modification, three nano-biocomposites were synthesized via impregnating three different concentrations of silver nanoparticles inside Derivative 4. These derivatives and Derivative 4/AgNP composites were structurally identified using elemental analysis, FTIR, XPS, 1H NMR, XRD, SEM, EDS and TEM techniques. These derivatives and Derivative 4/AgNP composites have superior antimicrobial activities than virgin chitosan. Some of them have inhibition zone analogous or superior than the utilized reference drugs. Cytotoxic activity of Derivative 4 and Derivative 4/AgNPs-5 composite indicated that these materials are safe on normal human cells. Accordingly, combinations between chitosan and functional groups derived from the different modifiers in addition to AgNPs within a single structure have extraordinarily enhanced the efficiency of chitosan. It might be deemed as a path to attain promising frameworks which are taken as proper competitors for antimicrobial materials in biomedical fields.