Facile fabrication of a portable PANI-NFs/c-MWCNT nano-composite electrochemical sensor for gefitinib: application to human plasma

A novel potentiometric solid contact (SC) sensor was developed to determine the anticancer drug gefitinib by employing a polyaniline nanofibers/carboxylated multi-walled carbon nanotube (PANI-NFs/c-MWCNT) nano-composite as an ion to electron transducer. The FDA approved gefitinib as the first line treatment of non-small cell lung cancer (NSCLC) that represents 90% of lung carcinomas. The PANI-NFs/C-MWCNT nano-composite was synthesized and characterized using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Twenty-three polyvinyl chloride (PVC) based sensors were fabricated through a systematic approach using different plasticizers and cationic exchangers to investigate their effects on the performance of the developed sensors. The incorporation of calix[8]arene (CX-8) notably enhanced the sensitivity of the developed sensor, confirmed by the docking study. The optimized sensor attained a fast and stable Nernstian slope of 29.14 mV per decade over the concentration range from 1.0 × 10^-2 to 1.5 × 10^-6 M with a LOD of 1.0 × 10^-6 M. The proposed method represents the first potentiometric sensor for GEF assay according to the authors' knowledge. It was validated as per the IUPAC guidelines and efficiently applied to determine GEF in its tablets and human plasma. This encourages quality control, bioavailability, and clinical centers to utilize the portable GEF sensor in its routine analysis.

Calixarene based portable sensor for the direct assay of indiscriminate ephedrine content of weight loss herbal preparations

A novel potentiometric sensor was developed and optimized for the quantitative analysis of ephedrine in non-prescribed herbal supplements used as adjunctive therapy for weight loss. An initial optimization study aimed to reach the optimum membrane composition, sensor assembly, and experimental conditions. The study evaluated the effect of several factors on the sensor performance including different ion-exchangers, plasticizers, ionophores, membrane thicknesses, soaking solution concentrations, soaking time intervals, and pH. The optimized polyvinyl chloride membrane included tungstophosphoric acid hydrate as a cation exchanger, tricresyl phosphate as a plasticizer, and calix[8]arene as an ionophore to enhance the sensitivity and selectivity of the developed sensor. The polyvinyl chloride membrane was drop-casted over a polyaniline modified glassy carbon electrode surface to form a solid-state sensor. The proposed membrane succeeded to quantify ephedrine over a linear range of 6 × 10-6 to 1 × 10-2 M with a LOD of 3.60 × 10-6 M, acceptable selectivity, and fast response time. The IUPAC characterization of sensor response and International Conference on Harmonization validation parameters were calculated. The method successfully determined ephedrine concentration in spiked herbal mixtures and determined labeled and undeclared ephedrine content of weight loss herbal preparations.