No abstract

Interest in biogenic silver nanoparticles (AgNPs) is steadily increasing due to the costeffective, easy, and environmentally friendly way in which they are synthesized. Synthesis using polychaete (Marphysa moribidii) extract as a reducing agent is particularly new and has the potential of being applied in various industries. However, biogenic AgNPs require synthesis optimization to increase their stability, yield, and characteristics. To meet these requirements, several synthesis parameters (such as polychaete size (body width), silver nitrate (AgNO3) concentration, pH of polychaete crude extract, and the temperature during pre-incubation) and storage conditions were optimized in this study. The optimized conditions for obtaining high yield and stable AgNPs were polychaetes with a body width of 6-8 mm, 1 mM AgNO3 with polychaete crude extract of pH 9, preheated at 90°C for 15 min before incubation at 30°C (150 rpm) for 24 hours, and stored at 4°C for long-term stability. The formation of AgNPs was confirmed through observation of a color transition (from pinkish to yellowish-brown) and analysis of UV-Vis spectra (between 398 and 400 nm). Scanning electron microscopy and transmission electron microscopy revealed the formation of spherical AgNPs with an average size of approximately 40.19 nm. Further, the optimized AgNPs demonstrated high storage stability for up to 6 months without any agglomeration. It is believed that these parameters are eminently suitable for the production of stable biosynthesized AgNPs.

The emergence of technology to produce nanoparticles (1 nm – 100 nm in size) has drawn significant researchers’ interests. Nanoparticles can boost the antimicrobial, catalytic, optical, and electrical conductivity properties, which cannot be achieved by their corresponding bulk. Among other noble metal nanoparticles, silver nanoparticles (AgNPs) have attained a special emphasis in the industry due to their superior physical, chemical, and biological properties, closely linked to their shapes, sizes, and morphologies. Proper knowledge of these NPs is essential to maximise the potential of biosynthesised AgNPs in various applications while mitigating risks to humans and the environment. This paper aims to critically review the global consumption of AgNPs and compare the AgNPs synthesis between conventional methods (physical and chemical) and current trend method (biological). Related work, advantages, and drawbacks are also highlighted. Pertinently, this review extensively discusses the current application of AgNPs in various fields. Lastly, the challenges and prospects of biosynthesised AgNPs, including application safety, oxidation, and stability, commercialisation, and sustainability of resources towards a green environment, were discussed.

Recently, a remarkable scientific interest in the inhalation therapy for respiratory disease was spiked attributed to the growing prevalence of asthma, chronic obstructive pulmonary disease (COPD), and coronavirus disease 2019 (COVID-19) pandemic. A pressurized metered-dose inhaler (pMDI) is the best option by providing fast and efficient symptomatic relief within the lung. However, the rapid development of new inhalation devices could be critical in this competitive environment, and optimizing the inhalation devices could be costly and time-consuming. Therefore, the computational fluid dynamic (CFD) approach was used to shorten the development time. In this study, response surface methodology (RSM) in ANSYS version 19.2 was introduced to discover the optimal design for the actuator nozzle to increase the performance of pMDI. Three (3) parameters (orifice diameter, length, and actuator angle) were optimized, and the best design was selected according to the analysis of particle tracking. The analysis of spray plume was also conducted and compared to analyze the spray plume characteristic produced by three designs. The result showed that RSM generated three (3) models for the new design of the actuator nozzle (Design A, Design B, and Design C). Among three (3) designs, actuator nozzle design C showed the highest injection particle number (232457) and the only one that produced maximum particles velocity magnitude in the acceptable ranges (35.67m/s). All three designs showed a similar pattern as maximum particle velocity magnitude decreased along the axial length until they match the air velocity (0.03-0.04 m/s). Furthermore, the spray plume length, angle, and width were observed to increase linearly with the decreasing maximum particle velocity magnitude. Thus, this study suggested that design C might have the potential as a new actuator nozzle to develop future pMDI to relieve the respiratory condition.