Dual encapsulation of hydrophobic and hydrophilic drugs in PLGA nanoparticles by a single-step method: Drug delivery and cytotoxicity assays

Dual drug encapsulation in biodegradable nanoparticles is always challenging and often requires strenuous optimization of the synthesis-encapsulation processes. This becomes even more difficult when the simultaneous encapsulation of molecules of different polarity is sought. Here we present a modified emulsification-evaporation process to produce polymeric nanoparticles (NPs) made of the biocompatible and biodegradable polymer poly(lactic-co-glycolic acid) (PLGA) and co-encapsulating simultaneously two different drugs, the hydrophobic dexamethasone (DX) and the hydrophilic diclofenac sodium (DS). Three independent processing parameters were systematically modified to promote the incorporation of the different-polarity drugs into PLGA and to control the particle size under 150 nm. The careful selection of the appropriate solvents (ethyl acetate and methanol) was a key requirement for the successful encapsulation of DX and DS. DS and DX release kinetics as well as cytotoxicity assays underlined the therapeutic potential of the dual encapsulation strategy. © 2016 The Royal Society of Chemistry

Development of an electrochemical immunoassay for detection of gatifloxacin in swine urine*

To detect gatifloxacin (GAT) residue in swine urine, an electrochemical immunoassay was established. An indirect competitive immunoassay was developed, in which the coating antigen is immobilized in an enzyme-linked immunosorbent assay (ELISA) plate and GAT residue from the sample competes with the limited binding sites in added anti-GAT antibody. Horseradish peroxidase (HRP) conjugated to goat anti-rabbit IgG was used as the enzymatic label. A carbon fiber working electrode was constructed and current signals were detected by using hydrogen peroxide as a substrate and hydroquinone as an electrochemical mediator. The electrochemical immunoassay was evaluated by analysis of GAT in buffer or swine urine and an average value of half inhibition concentration (IC50) of 8.9 ng/ml was obtained. Excellent specificity of the antibody was achieved with little cross-reaction with lomefloxacin (3.0%), ciprofloxacin (3.0%), and ofloxacin (1.9%) among commonly used (fluoro)quinolones. In conclusion, the immunoassay system developed in this research can be used as a rapid, powerful and on-site analytical tool to detect GAT residue in foods and food products