Nano-Antimicrobial Solutions Using Synthetic-Natural Hybrid Designs

Abstract

Nanotechnology potential in antimicrobial therapy is increasingly demonstrated by various data. Results reveal antibacterial properties, comparable to that of conventional antibiotics. Working on parallel experiments, researchers continue to bring evidence demonstrating age-old-recognized antibacterial properties of various natural components of plant and animal origin. Later years brought an increasing trend for combining synthetic and natural composition in new constructs. The tendency aims to bring more on different essential aspects, such as active substance release, improvement of antibacterial effect, and up-regulation of the mechanisms at the structure-cell interface. Present chap ter structures the up-to-date achievements in the field, including the concept of design, biological effects, benefits, mechanisms, and limitations of the field. Also, expected future research directions are to be discussed. The a performed using followed of log (active different 15, 30 and 24 h) paint additive with the generation of nanoparticles (partially covered with silver) by means of flame spray pyrolysis, followed by powder dispersion through stirring and sonication. Characterization of obtained product included specific surface area assessment, transmission electron microscopy analyzes, x-ray fluorescence testing, and dynamic light scattering measurements, demonstrating the structure, conformation, and dimensions of nanoparticles included in the product. Testing of antimicrobial effect was performed using a standardized method (ISO 22196:2011, modeled by Japanese standard JIS Z 2801:2000). In brief, survival counts were estimated after spreading of different concentrations of ZnO-Ag nanopowder (0.1, 0.2, 0.3, and 0.4%) and ZnO nanopowder on solidified plates containing 10 9 colony forming units of each of the microorganism (tryptone soy agar, 0.6% (W/v) yeast extract, nutrient agar). Results showed significant antimicrobial effect against Salmonella spp. , Bacillus subtilis, and Pseudomonas spp. with an inhibition zone of >5 mm silver and gold nanoparticles who demonstrated no antimicrobial effect. The results demonstrate the enhancing of antimicrobial properties due to green synthesis protocol [25]. Intracellular synthesis of gold nanoparticles by using a special strain of Rhodococcus species was reported. Experimental protocol included isolation of Rhodococcus sp., maintenance (potato-dextrose agar slants), monthly subculturing, and preservation. Mycelia were produced by growing of actinomycete in MGYP medium, separation (centrifugation 200 rpm, 27°C, 96 h), and wash ing. Gold nanoparticles were isolated by resuspension of mycelia in aqueous HAuCl 4 solution (10 − 3 M). Successful biotransformation was certified by UV-VIS spectra, TEM, and XRD analyzes [26 ]. Also, Bacillus licheniformis has been successfully used for synthesis of silver nanocrystals. Isolation of bacteria (collection, incubation 37°C, 48 h) and characterization of isolates were followed by addition of AgNO 3 (1 mM) solution to 2 g wet biomass previously inoculated with bacterial isolate [27]. For another report, the synthesis was carried out by using fungal strains, such as Fusarium acuminatum . After isolation from infected ginger and characterization of extract, fabrication of biomass was carried out (incubation of fungal culture at 28°C in potato sucrose broth, inoculation onto flasks, agitation, and filtration). Synthesis was carried out by mixing AgNO 3 solution with the filtrate for a final concentration of 1 mM, followed by 2 h incubation. Such nanoconstructs, resulted from mycosynthesis and validated by UV-VIS and TEM analysis, demonstrated efficiency against S. aureus (17 mm inhibition), S. epidermidis , S. typhi , or E. coli (10 mm) in the exact mentioned order (from high-est to lowest efficiency) [ 28]. nano-SiO 2 composite was reported to exert a good antimicrobial against S. aureus as well E. , and the authors demonstrate the synergic action of all included components in the structure as being responsible for improved effect [ Another biofilm-destructive solution was that of polysaccharide-bound silver nanoparticles. Green synthesis of caboxy-methyl-tamarind, polysaccharide-capped silver nanoparticles was performed, and the newly designed construct has demonstrated inhibitory effects against E. coli and B. subtilis growth. The obtained effect could be efficient against bacterial biofilm formation and consolidation [ 50].