K. Yugender Goud

Label free aptasensor for ochratoxin A detection using polythiophene-3-carboxylic acid

This work demonstrates the development of electrochemical aptasensor using ochratoxin A (OTA) aptamers. Different aptamer coupling strategies were tested using polythiophene-carboxylic acid (PT3C) and polypyrrole-3-carboxylic acid (PP3C). The best sensitivity was recorded by polythiophene-3-carboxylic acid (PT3C) on screen-printed carbon electrode (SPCE) to attain the direct detection of OTA. The quantification of OTA was achieved by using electrochemical impedance spectroscopy. A good dynamic range 0.125-2.5 ng ml-1 was obtained for OTA with limit of detection (LOD) 0.125 ng ml-1 and Limit of quantification (LOQ) 0.3 ng ml-1 respectively. The good reproducibility was recorded with RSD% of 3.68. The obtained straight line equation was y = 0.4061 × + 1.03, r = 0.99. For real sample applications, the developed aptasensors were demonstrated in coffee samples. The aptasensor displayed good recovery values in the range 88-89%, thus exhibited the effectiveness of proposed aptasensor for such complex matrices.

Progress on nanostructured electrochemical sensors and their recognition elements for detection of mycotoxins: A review

Nanomaterial-embedded sensors have been developed and applied to monitor various targets. Mycotoxins are fungal secondary metabolites that can exert carcinogenic, mutagenic, teratogenic, immunotoxic, and estrogenic effects on humans and animals. Consequently, the need for the proper regulation on foodstuff and feed materials has been recognized from times long past. This review provides an overview of recent developments in electrochemical sensors and biosensors employed for the detection of mycotoxins. Basic aspects of the toxicity of mycotoxins and the implications of their detection are comprehensively discussed. Furthermore, the development of different molecular recognition elements and nanomaterials required for the detection of mycotoxins (such as portable biosensing systems for point-of-care analysis) is described. The current capabilities, limitations, and future challenges in mycotoxin detection and analysis are also addressed.

Carbon nanotube ensembled hybrid nanocomposite electrode for direct electrochemical detection of epinephrine in pharmaceutical tablets and urine.

An efficient electrochemical sensor for selective detection of the neurotransmitter, epinephrine (Epn), has been fabricated with the aid of a functionalized multiwall carbon nanotube-chitosan biopolymer nanocomposite (Chit-fCNT) electrode. Multiwall carbon nanotubes (CNT) were successfully functionalized with the aid of nitric acid and confirmed by the Raman spectral data. Functionalized carbon nanotubes (fCNT) were dispersed in chitosan solution and the resulting bio-nanocomposite was used for the fabrication of sensor surface by drop and cast method. Electrochemical characteristics of the fabricated sensor were understood using cyclic, differential pulse voltammetry (CV, DPV) and electrochemical impedance analysis for the detection of Epn in phosphate buffer (pH7.4). CV and impedance analysis revealed that the Chit-fCNT modified electrode enhances the electrodic reaction of Epn and facilitated the electron transfer more readily compared to that of bare electrode. Applying DPV for the detection of Epn, achieved 30nM as the lowest detection limit in the determination range of 0.05-10μM and the analytical time as low as 10s. Selective determination of Epn against the coexistence of a number of biological electroactive interferents and reproducible results for the determination of Epn were demonstrated. The present biosensor has been found efficient for successful direct determination of Epn from pharmaceutical adrenaline formulations and urine samples.

Development of highly selective electrochemical impedance sensor for detection of sub-micromolar concentrations of 5-Chloro-2,4-dinitrotoluene

AbstractA highly selective and sensitive impedimetric sensor based on molecular imprinted polymer (MIP) has been developed for the detection of 5-chloro-2,4-dinitrotoluene (5CDNT). Computational simulations were carried out for the best combinations of MIP precursors by using Hyperchem software. MIP of 5CDNT is synthesized using the optimized combinations of polymer precursors such as the functional monomer and cross-linker. Synthesized MIP and non-imprinted polymer (NIP) were characterized by Fourier transform infrared spectroscopy (FT-IR) and BET adsorption isotherm analysis. The surface area and pore volume of MIP are quite high compared to that of NIP, while the average pore diameter of MIP is lower than that of NIP. However, the synthesized MIP with high surface area and quite good pore diameter for free flow of analytes is suitable for efficient binding with the analyte 5CDNT. Binding assay studies of MIP by using UV-Visible spectroscopy showed that the molecular imprinting factor is nearly thrice to that of NIP. Carbon paste electrodes incorporated with MIP were employed as a sensor for 5CDNT by applying electrochemical impedance spectroscopy (EIS) as transduction principle. The charge transfer resistance obtained by impedimetric analysis is proportional to the concentration of 5CDNT over a wide concentration range: 10 nM to 100 μM. A linear determination range of 1.0 to 100 μM was obtained, and the low-detection-limit was found to be 0.1 μM. The MIP carbon paste electrode has shown very good selectivity towards specific recognition of 5CDNT despite the coexistence of possible interferents like 2,4-dinitrotoluene and 1,3-dinitrobenzene. The present MIP based sensor system could be used successfully for direct determination of 5CDNT. Graphical AbstractA highly sensitive and selective impedimetric sensor for 5-Chloro-2,4-dinitrotoluene (5CDNT) has been fabricated using the molecular imprinting technology. A Computational screening was carried out for the best combinations of MIP precursors.