Abstract:The bringing human populations to cities and increasing urban living and creation of quick human progress in agriculture and industry have caused a lot of pollution. One of the main concerns that exist today is the identification and elimination of environmental pollution. The environmental pollution through heavy metals has become one of the biggest issues facing human societies today. There are several methods to identify such contaminations, but the use of nanobiosensors is the best method. Biosensors are divided to different types according to how the signals are transmitted, such as optical, magnetic, etc. In addition, nanobiosensors identify biologically pathogens such as bacteria, viruses and the like with high accuracy and sensitivity. In addition to identifying heavy metals and environmental contaminants, nanobiosensors have replaced time-consuming and expensive methods. The yeast biosensors are a good example of these biosensors. Considering all the results and activities carried out, designing and researching on the construction of new nanosensors, monitoring and caring for more human activities can have desirable results. پرونده مقاله

Chitosan is one of the natural biopolymer. Despite its importance, the characterization and extraction processes of this essential biopolymer are yet enigmatic. In this study, we developed an analytical procedure for the extraction of chitin and chitosan from the aquatic beetles’ shells (Hydraenidae family). The commercial chitosan and isolated chitosan, obtained during our experiment were analyzed by XRD, EDX, SEM, FT-IR, TGA, and UV-vis DRS techniques. Our results indicate 38% chitin and 23.5% chitosan segregated from the aquatic beetles’ shells. The ratio of protein residues to the wet weight (RWW) of the segregated chitosan was about 24%. FT-IR analysis attested that the isolated chitosan from the aquatic beetles’ shells was identical to the commercial chitosan. The EDX analysis does not reveal any impurities or the used precursor's characterized peaks, confirming high purity percentage of the segregated chitosan. Furthermore, according to the SEM images the segregated chitosan has smooth surface with amorphous property. Ultimately, the antibacterial activities of isolated chitosan were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria to assess their potential antibacterial applications. The results showed that the isolated chitosan from the aquatic beetles represented an outstanding performance in against the studied bacteria. پرونده مقاله