Photocatalytic Removal of Antibiotics from Wastewater Using the CeO2/ZnO Heterojunction.

CeO2/ZnO-based photocatalytic materials were synthesized by the sol-gel method in order to establish heterojunctions that increase the degradation efficiency of some types of antibiotics by preventing the recombination of electron-hole pairs. The synthesized materials were analysed by XRD, SEM, EDAX, FTIR, and UV-Vis. After several tests, the optimal concentration of the catalyst was determined to be 0.05 g‧L-1 and 0.025 g‧L-1 for chlortetracycline and 0.05 g‧L-1 for ceftriaxone. CeO2/ZnO assemblies showed much better degradation efficiency compared to ZnO or CeO2 tested individually. Sample S3 shows good photocatalytic properties for the elimination of ceftriaxone and tetracycline both from single solutions and from the binary solution. This work provides a different perspective to identify other powerful and inexpensive photocatalysts for wastewater treatment.

Design, Preparation and Evaluation of HPMC-Based PAA or SA Freeze-Dried Scaffolds for Vaginal Delivery of Fluconazole.

PURPOSE: Aim of this work was preparation of bioadhesive gel formulations based on Hydroxypropyl methylcellulose (HPMC), Poly(acrylic acid) (PAA) or Sodium alginate (SA) loaded with anise/fluconazole ß-cyclodextrin inclusion complexes in 1:2 and 1:3 ratios intended for vaginal applications. METHODS: Freeze-drying method was effectively utilized and superporous morphology was obtained. The superporous morphology of the lyophilized gels, dynamic water vapor sorption measurements, drug release kinetics studies and their antimicrobial activities are presented. RESULTS: HPMC content influences especially the sorption/desorption behaviour of HPMC-based PAA gels and the morphology of the gel formulations with fluconazole/ß-cyclodextrin inclusion complexes, due to the interactions among the gel networks absorbing water molecules. It was found that fluconazole release kinetics correspond to quasi-Fickian, Fickian diffusion and non-Fickian mechanisms for the studied hydrogels. The tested vaginal formulations with ß-cyclodextrin inclusion complexes exhibited selectivity toward S. aureus ATCC 25923 and all tested Candida strains in comparison with the gel formulation without ß-cyclodextrin. CONCLUSIONS: The fluconazole/ß cyclodextrin inclusion complexes ensure a controlled release of fluconazole over a few days, the highest amount of drug release (92%) being observed after 43 h. These bioadhesive gel formulations could be very promising topical alternative for treatment of vaginal fungal infections.

Formulation and evaluation of anise-based bioadhesive vaginal gels.

Various formulations of anise-based bioadhesive gels are prepared. Freeze-drying method was successfully employed and superporous scaffolds were obtained. The resulting porous microarchitectures are strongly influenced by the composition of hydrogel formulations and temperature of freezing. Anise-based hydrogels frozen in liquid nitrogen and lyophilized generate regular assembly of polyhedral pores. For Carbopol 934-based hydrogels it was determined G'>G'' for whole tested strain amplitude range indicating solid-like behaviour due to their dense network and entanglement and interaction through hydrogen bonds and van-der Waals forces. For sodium alginate-based hydrogels it was determined G''>G' for whole tested strain amplitude range accompanied by the extended linear viscoelastic region indicating liquid-like behaviour due to the formation of a stable "pseudo-gel" structure. Biocompatibility features of tested hydrogels were evaluated by contact angle measurements and determination of surface tension parameters. It was found that all anise-based hydrogel formulations manifest modest activity against S. aureus and S. lutea and no activity against tested Gram negative bacteria. Carbopol 934-based hydrogels containing anise exhibit antifungal activity against C. albicans, C. glabrata and C. Parapsilosis.