Application of nanocarriers for drug delivery brings numerous advantages, allowing both minimization of side effects common in systemic drug delivery and improvement in targeting, which has made it the focal point of nanoscience for a number of years. While most of the studies are focused on encapsulation of hydrophobic drugs, delivery of hydrophilic compounds is typically performed via covalent attachment, which often requires chemical modification of the drug and limits the release kinetics. In this paper, we report synthesis of biphilic copolymers of various compositions capable of self-assembly in water with the formation of nanoparticles and suitable for ionic binding of the common anticancer drug doxorubicin. The copolymers are synthesized by radical copolymerization of N-vinyl-2-pyrrolidone and acrylic acid using n-octadecyl-mercaptan as a chain transfer agent. With an increase of the carboxyl group’s share in the chain, the role of the electrostatic stabilization factor of the nanoparticles increased as well as the ability of doxorubicin as an ion binder. A mathematical description of the kinetics of doxorubicin binding and release is given and thermodynamic functions for the equilibrium ionic binding of doxorubicin are calculated.
The effective mineralization of nitrofurazone (10–100 mg L−1) was performed in aqueous solutions in the presence of chloride ions by electrochemical treatment. The destruction of the organic pollutant molecules was due to their interaction with active oxygen- and chlorine-containing species forming at the inert anode (Pt/Ti or BDD) during electrolysis. Measurements of nitrofurazone concentration, chemical oxygen demand (COD) and total organic carbon (TOC) were used to estimate the removal efficiency of the pollutant. Both the pollutant oxidation rate and the degree of its mineralization were higher for the BDD anode due to the higher anode potentials on it in the course of electrolysis, which provides a high rate of active oxidizer species generation. As a result, practically full nitrofurazone molecule destruction (>99%) was achieved in 30 min at an anodic current density of 0.1 A cm−2, a volume current density of 1.33 A L−1 and pH 2 using BDD anodes. On the other hand, the nitrafurazone degradation efficiency was about 95% for Pt/Ti anodes under the same conditions. Additionally, byproducts of nitrofurazone electrooxidation were investigated by means of liquid chromato-mass-spectrometry (LC/MS). It was found that the initial decolorization of nitrofurazone solution, which occurs during the first 5 min of electrolysis, is due to the formation of a dichloro derivative of nitrofurazone, which causes the destruction of the π−conjugated bond system. Further electrolysis resulted in the almost complete destruction of the dichloro derivative within 30 min of electrochemical treatment.
Anthraquinone-2,7-disulfonic acid (2,7-AQDS) is a promising organic compound, which is considered as a negolyte for redox flow batteries as well as for other applications. In this work we carried out a well-known reaction of anthraquinone sulfonation to synthesize 2,7-AQDS in mixture with other sulfo-derivatives, namely 2,6-AQDS and 2-AQS. Redox behavior of this mixture was evaluated with cyclic voltammetry and was almost identical to 2,7-AQDS. Mixture was then assessed as a potential negolyte of anthraquinone-bromine redox flow battery. After adjusting membrane-electrode assembly composition (membrane material and flow field)), the cell demonstrated peak power density of 335 mW cm−2 (at SOC 90%) and capacity utilization, capacity retention and energy efficiency of 87.9, 99.6 and 64.2%, respectively. These values are almost identical or even higher than similar values for flow battery with 2,7-AQDS as a negolyte, while the price of mixture is significantly lower. Therefore, this work unveils the promising possibility of using a mixture of crude sulfonated anthraquinone derivatives mixture as an inexpensive negolyte of RFB.