The purpose of this work is to single-pot biosynthesize silver nanoparticles (AgNPs) using the extract from mesocarp and endocarp of durian rind under photo-irradiation. Without adding chemical substance, flavonoids, phenolic compounds and glucose dissolved in the extract served as the reducing agent; while proteins acted as the particle-stabilizing agent in the formation of AgNPs. The synthesis parameters i.e. light intensity, exposure duration, and pH value directly associated with the nucleation, growth, and aggregation of nanoparticles. The amount of synthesized AgNPs increased with increasing visible light intensity and exposure duration, while the size and stability of nanoparticles were decided by pH value adjustment. The size of synthesized AgNPs decreased when the pH value increased, on the contrary, the size increased when the pH value decreased. Under the optimized synthesis conditions (visible light intensity of 13,430 lx and pH value of 8.5), approximately 99% of silver ions was reduced to the spherical AgNPs with the mean diameter of 11.4 ± 3.2 nm within 5 min. The AgNPs remained uniformly dispersed in de-ionized water at no less than six months. The present environmental-friendly method is facile, rapid, and cost effective for the large scale preparation of AgNPs. The obtained AgNPs synthesized under optimum conditions could be applied for use in various fields such as antimicrobial activity, biosensors, and catalysis in the near future.

In magnetic head recording storage, Al2O3 film was deposited onto Al2O3-TiC substrate, as insulating and protection layers, using RF diode sputtering. Pure Al2O3 (99.5%) with a dimension of 43.2cm × 43.2cm × 2.0cm was used as a sputtering target. The base pressure for all depositions was 1 × 10-6 m Torr and the deposition time was 12.2min. The target sputtering power and substrate bias voltage were varied from 4 to 8kW and 80 to 180V, respectively. The surface morphology of Al2O3 films was investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). It was found that the roughness of deposited Al2O3 films depends on sputtering power. SEM cross-sectional image clearly showed good adhesion between substrate and Al2O3 film. The mechanical properties, including elastic modulus and hardness, of Al2O3 films were performed on nanoindentator. The results showed that both elastic and hardness of Al2O3 films increased with the increase of target sputtering power

Urinary tract infections, especially catheter-associated urinary tract infections (CAUTIs), are the most common type of nosocomial infections. Patients with chronic indwelling urinary catheters have a higher risk of infection due to biofilm formation on the urinary catheter surface. Therefore, in this work, a novel, cost-effective antimicrobial urinary catheter was developed using green technology. Silver nanoparticles (AgNPs) synthesized from Mon Thong durian rind waste were used as an antimicrobial agent for the prevention of infection. Flavonoids, phenolic compounds, and glucose extracted from durian rind were used as a reducing agent to reduce the Ag⁺ dissolved in AgNO₃ solution to form non-aggregated AgNPs under light irradiation. The AgNPs were simultaneously synthesized and coated on the inner and outer surfaces of silicone indwelling urinary catheters using the dip coating method. The results showed that the antimicrobial urinary catheter fabricated using a 0.3 mM AgNO₃ concentration and 48 h coating time gave the highest antibacterial activity. The as-prepared spherical AgNPs with an average diameter of 9.1 ± 0.4 nm formed on catheter surfaces in a monolayer approximately 1.3 µm thick corresponding to a 0.712 mg/cm² silver content. The AgNP layer was found to damage and almost completely inhibit the growth of Escherichia coli cells with antibacterial activity by 91%, equivalent to the commercial, high-price antimicrobial urinary catheter. The cumulative amount of silver released from the coated catheter through artificial urine over 10 days was about 0.040 µg/mL, which is less than the silver content that causes tissue and organ toxicity at 44 µg/mL. Thus, we concluded that the developed antimicrobial urinary catheter was useful in reducing the risk of infectious complications in patients with indwelling catheters.

Crystals of hydroxyapatite (HAp) were grown on silk fibers using simulated body fluid (SBF) at a temperature of 37°C. Two different conditions of silk thread were investigated for efficiency of inducing HAp: i) with sericin protein and ii) without sericin protein. Effect of simulated body fluid (SBF) concentrations at 1.0 × SBF and 1.5 × SBF and sericin protein on HAp growth was discussed. The results showed that HAp was successfully crystallized on silk from both 1.0 × SBF and 1.5 × SBF concentrations. The crystal size obtained from the 1.5 × SBF concentration was larger than that of the 1.0 × SBF concentration. However, it was found that the 1.5 × SBF offered less number of the crystals per unit area than that of the 1.0 × SBF. The physical and chemical compositions of HAp were characterized by XRD, SEM and optical microscopy. This study may be very useful for many applications, especially in biomedical and material science