Effect of zinc oxide micro- and nanoparticles on cytotoxicity, antimicrobial activity and mechanical properties of apatite-polymer osteoplastic material.

This work is devoted to the comparison of the physical and biological properties of synthesized osteoplastic composites with an experimentally determined content (375 µg/g) of the micro (ZnOMPs) and nano (ZnONPs) particles, immobilized in Hydroxyapatite-Alginate-Chitosan matrix (HA-Alg-CS). ZnONPs show pronounced antimicrobial activity against E.coli ATCC 25922 and S. aureus ATCC 25923, while ZnOMPs only in the CS presence. Composites containing ZnONPs/MPs do not have a toxic effect on bone-forming cells - osteoblasts, preserving their ability to biomineralization. ZnOMPs and ZnONPs to varying degrees, but significantly affect composites' swelling, porosity, shape stability, and prolong vitamin D3 release for 120h, compared to Control. Composites do not demonstrate unwanted "burst release." ZnONPs/MPs increase Youngs' modulus of the HA-Alg matrix, namely 348 â†’ 419 MPa (ZnOMPs), 348 â†’ 646 MPa (ZnONPs), and weaken the plastic (irreversible) deformations. The compressive strength of HA-Alg and HA-Alg/CS matrixes containing ZnONPs (178 MPa and 251 MPa, respectively) is in the range of values for native cortical bone (170-193 MPa). Biocompatibility and lack of toxic effect give both composites a perspective for osteoplastic application, but composites doped with ZnONPs are more attractive.

Low-frequency ultrasound increase effectiveness of silver nanoparticles in a purulent wound model.

Bacterial biofilm formation and antibiotic resistance are the main factors of surgical wound complications. Traditional treatments in some cases cannot provide complete bacterial eradication and new therapeutic approaches should be developed to overcome antibiotic resistance. Silver nanoparticles (AgNPs) can be the first choice for bacteria treatment but their clinical application is limited due to toxic effects. Combination of AgNPs with the low-frequency ultrasound (US) treatment expected to decrease toxicity and leads to the facilitation of wound healing. In current research we investigated the antibacterial activity of AgNPs per se and in combination with low-frequency US, assessed the cytotoxicity of AgNPs on human dermal fibroblasts and finally, wound healing was evaluated in purulent wound model (96 white laboratory rats) applying AgNPs and US as a treatment strategy. Our results demonstrate no toxic effect of AgNPs in minimum inhibitory concentrations and show increasing their antibacterial effectiveness after US application. The combination of low-frequency US and AgNPs provides reduction of the inflammatory reaction, microorganism elimination and leads to facilitation of new tissue formation with complete epithelization. All effects were significant over the Chlorhexidine treatment, monotherapy with AgNPs or US. Advanced effectiveness of complex therapy opens new perspectives for clinical application of AgNPs solution accompanied by US.