RESUMO
Cyclocreatine and its water-soluble derivative, cyclocreatine phosphate (CCrP), are potent cardioprotective drugs. Based on recent animal studies, CCrP, FDA-awarded Orphan Drug Designation, has a promising role in increasing the success rate of patients undergoing heart transplantation surgery by preserving donor hearts during transportation and improving the recovery of transplanted hearts in recipient patients. In addition, CCrP is under investigation as a promising treatment for creatine transporter deficiency, an X-linked inborn error resulting in a poor quality of life for both the patients and the caregiver. A newly designed molecularly imprinted polymer (MIP) material was fabricated by the anodic electropolymerization of o-phenylenediamine on screen-printed carbon electrodes and was successfully applied as an impedimetric sensor for CCrP determination to dramatically reduce the analysis time during both the clinical trial phases and drug development process. To enhance the overall performance of the proposed sensor, studies were performed to optimize the electropolymerization conditions, incubation time, and pH of the background electrolyte. Scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry were used to characterize the behavior of the developed ultrathin MIP membrane. The CCrP-imprinted polymer has a high recognition affinity for the template molecule because of the formation of 3D complementary cavities within the polymer. The developed MIP impedimetric sensor had good linearity, repeatability, reproducibility, and stability within the linear concentration range of 1 × 10-9 to 1 × 10-7 mol/L, with a low limit of detection down to 2.47 × 10-10 mol/L. To verify the applicability of the proposed sensor, it was used to quantify CCrP in spiked plasma samples.
RESUMO
Gemifloxacin (GEM) is a broad-spectrum quinolone antibiotic. The presence of GEM residuals in industrial and hospital wastewater has been associated with genotoxicity and antibiotic resistance. In this contribution, the photodegradation of GEM using titanium dioxide nanoparticles (TiO2NPs)/H2O2 as a catalyst was optimized to eliminate residual drug and its photodegradates with antibacterial activity. A half-factorial design was implemented, investigating the effects of pH, initial concentration, H2O2 concentration, TiO2NP loading, and irradiation time. Owing to the time-dependent, multi-transformation of GEM into a wide range of structurally related photodegradation products, the monitoring of GEM throughout the experiments was achieved using both HPLC and potentiometric ion-selective electrodes (ISE). The sensor enabled in-line tracking of residual GEM in the presence of its photodegradates in real time. Results indicated that the pH, irradiation time, and GEM initial concentration were the most significant factors. At the optimum set of experimental conditions, the reaction followed first-order reaction kinetics with a mean percentage degradation of ~ 95% in less than 30 min of irradiation time and almost complete loss of antibacterial activity against Escherichia coli. The promising results demonstrated the efficiency of UV/TiO2NP/H2O2 as a photocatalyst for the breakdown of the pharmacophore of fluoroquinolones from water samples. The high selectivity, minimal solvent consumption, and lack of harmful waste generation confirmed the superiority of in-line monitoring using ISE. Optimization and in-line monitoring protocol should be applicable also at the pharmaceutical industry scale to eliminate the risk of antibiotic resistance.