Antibacterial Activity of Green-Synthesized Silver Nanoparticles Using <em>Areca catechu</em> Extract against Antibiotic-Resistant Bacteria

In this work, the antibacterial activity of silver nanoparticles (AgNPs) synthesized using Areca catechu extracts against three species of antibiotic-susceptible and three species of resistant bacteria was investigated. The effects of this plant were more promising when compared with other medicinal plants tested. The hydrothermal extract of Areca catechu was mixed with silver nitrate to synthesize AgNPs. The synthesized particle characteristics were analyzed by UV–Vis spectrophotometry, scanning electron microscopy (SEM), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FT-IR). Minimum inhibitory concentration and minimum bactericidal concentration tests were conducted to confirm antibacterial activity and the results showed that AgNPs synthesized using Areca catechu extracts effectively inhibited the growth of bacterial species. Moreover, the SEM images of the bacterial species treated with AgNPs synthesized with Areca catechu extracts showed that clusters of AgNPs were attached to the surface of the bacterial cell wall, which could induce destruction of the cell membranes. The results suggest that AgNPs synthesized with Areca catechu extracts have the potential to treat antibiotic-resistant bacteria known as the major cause of nosocomial infections

Synthesis of echogenic liposomes for sonoporation

Ultrasound contrast agents (UCAs), which are groups of engineered microbubbles, have been recently studied for drug delivery applications, since the cavitation of bubbles can increase the temporary permeability of nearby cells. However, the internal volume of UCAs is generally filled with gas, hence loading drug molecules into UCAs is limited. In this study, an echogenic liposome with a liquid and gas core is proposed as an alternative carrier of genetic material for ultrasound-mediated drug delivery. The structure of the synthesized echogenic liposome was analysed via transmission electron microscopy and confocal microscopy with fluorescent labels. The protection of siRNA by the echogenic liposomes was also verified by exposure to RNase. The results indicate that at least 10% of the total siRNA used in the experiment was successfully protected by the proposed echogenic liposome. Additionally, the release of siRNA from the liposomes could be successfully achieved with 1 W/cm(2) ultrasound sonication at 1 MHz; parameters low enough to be used in generic ultrasound therapeutic systems. Although further studies to clarify the responses to incident ultrasound fields and to quantitatively analyse the internal liquid volume for drug loading are required, the proposed echogenic liposome has great potential for ultrasound-mediated gene delivery.N