Antimicrobial properties of α-Ag2WO4 rod-like microcrystals synthesized by sonochemistry and sonochemistry followed by hydrothermal conventional method.

In this study we report the synthesis of silver tungstate microcrystals (α-Ag2WO4) by sonochemistry method (SC) at 65 °C and sonochemistry followed by conventional hydrothermal (SC + HC) for 1, 6 and 12 h, at 140 °C. The structural characterization by XRD confirms the alpha phase of the orthorhombic structure and the space group Pn2n, for all synthesized microcrystals. All the actives modes identified at the Raman spectroscopy were characteristic of alpha phase. The optical band gap by UV-Vis spectroscopy using the diffuse reflectance were 2.98, 3.0, 2.99 and 2.96 eV, for the microcrystals SC, SC + HC-1 h, SC + HC-6 h and SC + HC-12 h, respectively. FE-SEM images show the rod-like microcrystals, however, exhibiting the plane surface (1 0 1) only for the synthesized microcrystals with the assistance of the hydrothermal method (SC + HC-1 h, SC + HC- 6 h and SC + HC-12 h). The antimicrobial potential was confirmed for all α-Ag2WO4 microcrystals synthesized. However, the SC + HC-12 h microcrystals were more susceptible in the bacterial and fungal inhibition, with MIC values for microorganisms C. albicans, T. rubrum, MRSA e EHEC, 0.2-0.5, 4-9, 250 and 31.25 µg mL-1, respectively.

Nanocapsules of Sterculia striata acetylated polysaccharide as a potential monomeric amphotericin B delivery matrix.

Stable oil nanocapsules based on acetylated Sterculia striata polysaccharide (ASSP) were produced without the use of a surfactant, and derivatives of ASSP with four different degrees of substitution (DS) were synthesised. The data revealed that only derivatives with high DS were able to produce nanocapsules (NC), which exhibited monomodal size distribution profiles with a Z-average particle size, ζ-potential, and polydispersity index (PDI) that were dependent on ASSP DS and concentration. Nanocapsules were loaded with amphotericin B (AMB) with encapsulation efficiencies (EE%) that were dependent on drug and ASSP concentrations and DS. A maximum EE% value of 99.2% was achieved, and the loaded AMB was found to be in a monomeric form, even with a concentration one hundredfold higher than that usually observed for commercial AMB aqueous solutions. Loaded nanocapsules show an in vitro controlled release of AMB. As the monomeric AMB state decreased drug toxicity, ASSP nanocapsules loaded with AMB (NC1.68) have potential for use as a drug delivery system. AMB loaded NC 1.68 keeps its activity against 5 strains of Candida albicans tested.