Green Synthesis and Characterization of Silver Nanoparticles Using Ginkgo Biloba Laf Extract

A facile, effective and green method using Ginkgo Biloba leaf extract was applied and optimized for the preparation of well dispersed silver nanoparticles. In the method, Ginkgo Biloba leaf extract was employed as both stabilizing and reducing agent without the addition of a toxic agent. 0.1 % silver nitrate solution (w/v) was used silver source. The synthesized silver nanoparticles were investigated and examined by UV-vis absorption spectroscopy (UV-vis), Scanning electron microscope (SEM), Transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and Dynamic light scattering (DLS). The formation of silver nanoparticles was found by a change of color from light yellow to red, which was further proved by absorbance peak at 456 nm in UV-vis spectroscopy. The prepared nanoparticles are global in shape, highly crystalline in nature with a narrow distribution from 10 nm to 40 nm. The silver nanoparticles were capped with extracts, which prevented them from agglomeration and oxidation. Different parameters affecting the generation performance of silver nanoparticles, such as time, amount of silver nitrate and extract were investigated. The results demonstrate that these reaction parameters play important roles in the synthesis of silver nanoparticles

Analysis of Synonymous Codon Usage Patterns in Seven Different Species

We used large samples of expressed sequence tags to characterize the patterns of codon usage bias (CUB) in seven different Citrus species and to analyze their evolutionary effect on selection and base composition. We found that A- and T-ending codons are predominant in Citrus species. Next, we identified 21 codons for 18 different amino acids that were considered preferred codons in all seven species. We then performed correspondence analysis and constructed plots for the effective number of codons (ENCs) to analyze synonymous codon usage. Multiple regression analysis showed that gene expression in each species had a constant influence on the frequency of optional codons (FOP). Base composition differences between the proportions were large. Finally, positive selection was detected during the evolutionary process of the different Citrus species. Overall, our results suggest that codon usages were the result of positive selection. Codon usage variation among Citrus genes is influenced by translational selection, mutational bias, and gene length. CUB is strongly affected by selection pressure at the translational level, and gene length plays only a minor role. One possible explanation for this is that the selection-mediated codon bias is consistently strong in Citrus , which is one of the most widely cultivated fruit trees

Functionalizing DNA nanostructures with natural cationic amino acids

Complexing self-assembled DNA nanostructures with various functional guest species is the key to unlocking new and exciting biomedical applications. Cationic guest species not only induce magnesium-free DNA to self-assemble into defined structures but also endow the final complex nanomaterials with new properties. Herein, we propose a novel strategy that employs naturally occurring cationic amino acids to induce DNA self-assembly into defined nanostructures. Natural l-arginine and l-lysine can readily induce the assembly of tile-based DNA nanotubes and DNA origami sheets in a magnesium-free manner. The self-assembly processes are demonstrated to be pH- and concentration-dependent and are achieved at constant temperatures. Moreover, the assembled DNA/amino acid complex nanomaterials are stable at a physiological temperature of 37 °C. Substituting l-arginine with its D form enhances its serum stability. Further preliminary examination of this complex nanomaterial platform for biomedical applications indicates that DNA/amino acids exhibit distinct cellular uptake behaviors compared with their magnesium-assembled counterparts. The nanomaterial mainly clusters around the cell membrane and might be utilized to manipulate molecular events on the membrane. Our study suggests that the properties of DNA nanostructures can be tuned by complexing them with customized guest molecules for a designed application. The strategy proposed herein might be promising to advance the biomedical applications of DNA nanostructures