ABSTRACT
A highly sensitive, selective, stable, and cost-effective SnO2-based electrochemical sensor is reported for the detection of chloroquine phosphate (CQP). Hydrothermal synthesis is used to synthesize SnO2 nanoparticles, which are mixed with graphite and form a highly electrochemically active composite. The SnO2 nanoparticles and SnO2/graphite composite are fully characterized physico- and electrochemically. Using the optimal SnO2/graphite composite, an excellent analytical performance is demonstrated with an electrode sensitivity of 35.7 µA/µM.cm2, a linear range of 0.1-23.3 µM, and limits of detection and quantification of 0.01 µM and 0.04 µM, respectively. High CQP selectivity with minimal interference at 100 × concentration of interferents is shown. The sensor is also highly repeatable and reproducible with RSD of 2.46% and 1.86%, respectively, and can retain >85% of its activity upon storage. The validity of the new sensor for real sample analysis is shown by applying it to CQP tablets using the standard addition method, obtaining an excellent percentage recovery of ∼102%. The low cost, facile processing, and superior performance of the SnO2/graphite electrode make it an up-and-coming candidate for the commercial electrochemical detection of CQP and other small molecules.
ABSTRACT
A SARS-CoV-2 biosensor based on the biorecognition of the spike protein to the angiotensin-converting enzyme 2 (ACE-2) transmembrane receptor was developed using entire cell membranes as the biorecognition layer. In this new SARS-CoV-2 detection platform, cellular membranes from VeroCCL81 (mVero) and Calu-3 (mCalu) cells (which overexpress the ACE-2 transmembrane receptors) were extracted and immobilized as vesicles on an indium tin oxide electrode (ITO). Electrochemical impedance spectroscopy was used to optimize the performance of the developed devices for SARS-CoV-2 detection. This novel biosensor comprises a low-cost system (less than one US$ dollar) that uses the unique properties of cell membranes combined with the catalytic properties of electrochemical platforms to allow spike proteins recognition. A linear response from 10 to 100 ng/mL was obtained from the optimized biosensors, a limit of detection of 10.0 pg/mL and 7.25 pg/mL and limit of quantification of 30.4 pg/mL and 21.9 pg/mL were achieved with satisfactory accuracy for ITO-APTES-mVero and ITO-APTES-mCalu, respectively. Selectivity studies revealed that this platform was able to differentiate the target spike proteins from NS1 proteins from dengue and Zika viruses. In addition, sensors comprising cell membranes devoid of the ACE-2 transmembrane receptor exhibited no biorecognition signal. The developed devices are suitable for SARS-CoV-2 detection based on spike protein recognition, and capable of providing a low-cost, accurate, and accessible tool for use in a pandemic and post-pandemic scenario. [Display omitted] • Investigation on the interactions between natural cell membranes and Spike virus. • Influence of the ACE-2 receptors at the electrode surface to detect SARS-CoV-2. • Differentiation between SARS-CoV-2 from Dengue and Zika Virus using membrane cells elements. [ FROM AUTHOR]
ABSTRACT
A multi-faceted energy intensive technology that can be used for water disinfection and synthesis of electrolysed water (EW) is the need of the hour to achieve a sustainable post COVID 19 water management strategy. Direct sunlight driven processes are legislatively green technologies and hold the key in environmental sustenance. The development of a laboratory proto type reactor powered by a photovoltaic module for the treatment open source river water is described in this paper. This paper reports on the efficacy of the developed proto type technology for multipurpose application namely: (1) the production of Electrolysed water (EW) in a cost efficient manner using direct sunlight and (2) the removal of organic impurity from water using direct sunlight without the use of any photo catalyst or membrane. The prototype reactor utilizes chemical spray pyrolysis deposited highly photo-conducting indium sulphide thin films grown on fluorine doped tin oxide (F:SnO2) substrate (coated using chemical spray pyrolysis technique in-house) as the photo electrode. Dissolved organic matter arising in river water has distinctive fluorescence properties, and this research has utilized it to identify dissolved organic substances in both random samples and treated water. The work proves that photovoltaic module powered electrolytic reactors consisting of In2S3 electrodes can be used for treatment of river water. A diaphragm free, energy intensive route for the production of electrolysed water with the use of non-hazardous NaCl as the electrolyte has been demonstrated here. We conclude that In2S3 electrodes can be used for non-photo catalytic reduction of humic-derived impurities in river water. These results are also encouraging on the prospects of treating Nitrates present in the river water. The likes of techniques as described in this report that do not use photo catalyst or membranes may pave way for real time photovoltaic module powered floating reactors that can decontaminate water bodies on a large scale. The technique used by us demonstrates that a chlorine free route can be optimized for the synthesis of EW eliminating the production of large amounts of wastewater with high levels of biological oxygen demand (BOD).