Green synthesis and stabilization of silver nanoparticles using Lysimachia foenum-graecum Hance extract and their antibacterial activity

The Lysimachia foenumgraecum Hance extract (LHE) was used for silver nanoparticles (AgNPs) synthesis. In this study, the herbal plant of Lysimachia foenumgraecum Hance (LH) was extracted with deionized water and we are the first to successfully use LHE as reducing and stabilizing agents for the green synthesis of AgNPs. The concentration of LHE used in this study was in the range of 0.003 to 1.0 wt%. Aqueous colloidal solutions of AgNPs reduced and stabilized by LHE show long-term stability due to the steric stabilization effect. This can be confirmed by zeta potential measurements which afforded values approximately of 0 mV, indicating the steric stability of AgNPs colloidal solutions synthesized by LHE. Furthermore, the obtained AgNPs colloidal solutions show superior antibacterial effect to gram-positive bacteria (Staphylococcus aureus) comparing to Chloramphenicol (positive control). AgNPs with LHE 0.003 wt% affords the highest antibacterial effect to S. aureus showing an inhibition zone diameter of 19.08 ± 0.67 mm; which is superior to Chloramphenicol.

A UCN@mSiO2@cross-linked lipid with high steric stability as a NIR remote controlled-release nanocarrier for photodynamic therapy

In clinics, the application of photodynamic therapy (PDT) in deep tissue is severely constrained by the limited penetration depth of visible light that was used for activating the photosensitizer (PS).

Poly (Vinyl Alcohol) in Fabrication of PLA Micro- and Nanoparticles Using Emulsion and Solvent Evaporation Technique

Poly (vinyl alcohol) (PVAL) was a common stabilizing agent used in formulate polymeric drug encapsulated micro-/nanoparticles. In preparing poly (lactic acid) (PLA) micro-/nanoparticles by emulsion and solvent evaporation (ESE) technique, the particle size and distribution have shown dependent on PVAL concentration. The focused of this project was to investigate the PVAL function in relation to significant changes in particle size. These studies were relatively important, as it was the basic studies of material usage in ESE fabricating process. The function of PVAL as, either surfactant that able to reduce interfacial tension or stabilizer to provide steric stability was further investigated by measuring the interfacial tension (IFT) of two liquids and zeta potential of the particles. As PVAL concentration increased, the reduction of IFT was only pronounced at the early stage of PVAL incorporation from 16.02 m N/m (absence of PVAL) to 2.0 m N/m (presence of 1 % PVAL), while zeta potential of particles was gradually decreased from-25 mV to-10.2 mV. As conclusion, the presence of PVAL could reduce the interfacial tension. However, to further stabilize the particle (e.g. reduce size and narrow size distribution) in the fabrication process, the steric stabilization provided by PVAL give more significant advantages.

Synthesis and Application of an Anionic Poly-Carboxylate Dispersant for Kaolin Slurry

A water-soluble graft copolymer, which was used to improve the dispersion properties of kaolin slurry with high solid content , was synthesized from sodium humate (HA), acrylic acid (AA), starch (St) and potassium persulfate (KPS) by aqueous solution polymerization. The influence of raw material ratio, dosage of initiator, temperature and reaction time to poly-dispersant properties, which was measured by kaolin slurry viscosity, was studied in detail. It was observed that poly-dispersant prepared in this study exhibited good dispersion properties for kaolin slurry. This is most probably due to high electrostatic repulsion force and steric stability between kaolin particles, which is fully covered by poly-dispersant with suitable molecular weight, molecules contain appropriate side chains and charge density. The optimum conditions are as follows: the mass ratio of St/(AA&HA) is 1:30, the mass ratio of HA/AA is 3:1, and the reaction temperature is 70°C, the dosage of KPS is 7%, reaction time is 2h. It was also observed that viscosity of kaolin slurry was strongly affected by concentrations of Poly(Starch-Acrylic acid-Sodium humate) (P(St-AA-HA)). The optimal content of the poly-dispersant is 0.5%. Fourier transform infrared (FTIR) proved that the product was a graft copolymer of St-AA-HA.

Dispersibility of Nano TiN Powder in Ethanol Liquid

Effect of pH value and dispersant of polyethylene imine (PEI) on dispersion of nano TiN in ethanol liquid was investigated by sedimentation volume and viscosity, surface electric characteristic of particles was measured by Zeta potential. Results showed that pH value and PEI concentration had an important effect on dispersion of nano TiN. Excellent dispersibility was obtained through adjusting PEI amount and pH value. It was found that PEI was an efficient dispersant for nano TiN to disperse in ethanol liquid. The dispersibility follows by electrostatic and space steric stability mechanism.