Reduction of chlorinated hydrocarbons using nano zero-valent iron supported with an electric field. Characterization of electrochemical processes and thermodynamic stability.

Electric field assisted remediation using nano iron has shown outstanding results as well as economic benefits during pilot applications (Cerníková et al., 2020). This method is based on donating electrons to the zero-valent iron that possess an inherently strong reductive capacity. The reduction of chlorinated hydrocarbons may be characterized by a decrease in contaminants or better still by the evolution of ethene and ethane originating from the reduction of chlorinated ethenes. The evolution of ethene and ethane was observed predominantly in the vicinity of the anode despite reduction processes being expected near the cathode - the electron donor. The reduction near the anode occurred due to dissolved Fe2+ ions, whose presence was suggested by a Pourbaix diagram that combines Eh/pH values to characterize electrochemical stabilities between different species. No products of dechlorination were observed in the area of the cathode due to presence of oxidized Fe in the form of Fe3+ or Fe(OH)4-. The experimental work described in this research provides a deeper view of the processes of electrochemical reductive dechlorination using zero-valent iron and DC. It also showed an increase in the efficiency compared to the method using zero-valent iron only.

Effect of the configuration of poly(lactic acid) and content of poly(oxyethylene) blocks to the structure and functional properties of poly(lactic acid)-block-poly(oxirane)-based nanofibrous electrospun polyester-ether-urethanes used as potential drug-delivery system.

Poly(lactic acid)-block-poly(oxirane)s (PLA-b-POE) of various compositions were prepared using a one-pot approach and then extended in a reaction with l-lysine diethyl ester diisocyanate, thereby forming polyester-ether-urethanes (PEU) with prolonged chains and units with increased degradability. The PEUs are processed by electrospinning to prepare degradable nanofibrous sheet materials with and without encapsulating the antibiotic Vancomycin (VAC). PLA block isomerism and POE blocks oligomeric content (1000 g/mol) affect the thermal properties, processability, nanofibrous sheet morphology, abiotic degradation, cytocompatibility, and encapsulated antibiotic release rate of prepared PEUs. Therefore, our findings provide an effective approach to tuning the functional properties of these advanced biocompatible materials. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2378-2387, 2019.

Enhancement of 5-aminolevulinic acid phototoxicity by encapsulation in polysaccharides based nanocomplexes for photodynamic therapy application.

Polysaccharides based nanocomplexes have been developed for encapsulation, controlled delivery and to enhance the phototoxicity of the photosensitizer 5-aminolevulinic acid for application in photodynamic therapy. The nanocomplexes were prepared by coacervation in a solvent free environment using chitosan as polycation while alginic and polygalacturonic acid as polyanions. The complexes showed average dimension in the range 90-120nm, good stability in simulated physiological media and high drug encapsulation efficiency, up to 800µg per mg of carrier. Release studies demonstrate the possibility to tune the overall release rate and the intensity of the initial burst by changing the external pH. Cytotoxicity and photocytotoxicity tests confirmed the not toxicity of the used polysaccharides. Cell viability results confirmed the improvement of 5-aminolevulinic acid phototoxicity when loaded into the carrier compared to the free form. No effect of the irradiation on the nanocomplexes structure and on the release kinetics of the drug was observed. The results demonstrate that the prepared formulations have suitable properties for future application in photodynamic therapy and to ameliorate the therapeutic efficacy and overcome the side-effects related to the use of the photosensitizer 5-aminolevulinic acid.

Polysaccharide-based nanocomplexes for co-encapsulation and controlled release of 5-Fluorouracil and Temozolomide.

Polysaccharide-based nanocomplexes, intended for simultaneous encapsulation and controlled release of 5-Fluorouracil (5-FU) and Temozolomide (TMZ) were developed via the complexation method using chitosan, alginic and polygalacturonic acid. Investigation focused on the influence of polysaccharides on the properties of the system and amelioration of the stability of the drugs, in particular TMZ. The dimensions of particles and their ζ-potential were found to range between 100 and 200nm and -25 to +40mV, respectively. Encapsulation efficiency varied from 16% to over 70%, depending on the given system. The influence of pH on the release and co-release of TMZ and 5-FU was evaluated under different pH conditions. The stability of the loaded drug, in particular TMZ, after release was evaluated and confirmed by LC-MS analysis. Results suggested that the amount of loaded drug(s) and the release rate is connected with the weight ratio of polysaccharides and the pH of the media. One-way ANOVA analysis on the obtained data revealed no interference between the drugs during the encapsulation and release process, and in particular no hydrolysis of TMZ occurred suggesting that CS-ALG and CS-PGA would represent interesting carriers for multi-drug controlled release and drugs protection.