Design And Synthesis Of Green Nanostructures And Their Applications

Official URL: https://risc01.sabanciuniv.edu/record=b3205845

Advances in nanoscience have paved the way for new research fields in green chemistry. Nanostructures with various sizes, shapes, and modifications have considerable potential in many sensing, antimicrobial and plasmonic applications due to their superior mechanical and antimicrobial properties. In recent years, effective manufacturing of pure nanocrystals with a narrow size distribution in a matrix has been very challenging. Also, it is highly crucial to get their full potential for advanced applications. This thesis mainly focuses on the design and synthesis of nanostructures and the evaluation of their applications. In this thesis, nanostructures with narrowly distributed nanoparticles having antimicrobial features were synthesized using various synthesis methods. The practical synthesis of silver nanoparticles was achieved through the reduction of silver nitrate solution using an algal source, Chlorella vulgaris, as the reducing as well as the stabilizing agent. The energy required for this synthesis was supplied by microwave radiation. The silver nanoparticles with high stability (a zeta potential of −17mV), a hydrodynamic size distribution of 1–50 nm, and a mostly spherical shape were obtained through a 10-min process. Antibacterial features of the produced silver nanoparticles were verified against those of Salmonella enterica subsp. enterica serovar typhimurium and Staphylococcus aureus. Also, A long-lasting nanocomposite manufacturing challenge was, for the first time, overcome by our microwave-powered fluidic system. The effect of microwave power, flow rate, and concentration of the reagents were systematically studied. The nylon-6 nanocomposite bearing evenly distributed silver nanoparticles with a mean size of ∼2.59 ± 0.639 nm were manufactured continuously in ∼2 min at ∼50–55 °C using a green solvent, formic acid. Given the small-sized silver nanoparticles in the microwave fluidic-manufactured nanocomposites, the antibacterial activity tests with Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa show superior activity compared to that of the large silver nanoparticle-bearing (∼50 nm) nanocomposites produced in a fluidic system which has convectional heating. Furthermore, a microwave-promoted flow system was successfully employed for in-situ, continuous manufacturing of polyamide 11 and cellulose acetate nanocomposites having copper/copper oxide nanoparticles with a mean diameter of less than 10 nm and narrow size distribution. No copper/copper oxide nanoparticle formation occurred under almost identical experimental conditions in the microwave-batch system. The experimental parameters, including microwave power, polymer concentration, metal salt concentration, and flow rate, were fully optimized, and reproducibility was tested. These experiments proved that the above-mentioned green nanostructures which have been synthesized using environmentally friendly, time-saving, and scalable techniques have the potential to exhibit high efficiency for antimicrobial applications.