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Pesticide residues are posing an increasing threat to ecosystems and human health due to the over-application of synthetic pesticides in pest control to meet the global demand for agricultural food products. In this regard, electrochemical sensor and biosensor platforms have emerged as powerful analytical methods to detect pesticides due to several advantages, including synergistic aspects, systematic fabrication procedure, ease of detection, appreciable sensitivity, and selectivity. Furthermore, portable electrochemical devices have been fabricated recently for point-of-care and on-site detection of pesticides residues. This comprehensive review focuses on recent advances in portable electrochemical (bio)sensing methods for the on-site detection of pesticide residues in fruits and vegetables. Moreover, detailed information has been provided on the principal mechanism and electrochemical (bio)sensing behavior of the specified strategies. Discussed the significant developments in electrochemical strategies and the integration of smartphone technology with electrochemical sensing platforms for real-time monitoring. It is anticipated that the current review will be an added advantage and valuable tool for scientific and technological readers to understand the fabrication of portable electrochemical devices, the role of electrochemical (bio)sensing strategies for rapid on-site detection of pesticides, and to promote further developments in agricultural science, electrochemical science, and food science and technology.

Continuing efforts to develop stimuli-responsive polymers (SRPs) as novel smart materials/biomaterials are anticipated to upgrade the quality life of humans. The details of the molecular, physico chemical and biophysical interactions between SRPs and proteins are not fully understood. Indeed, protein - polymer interactions play a major role in a wide range of biomedical/biomaterial applications. In this regard, we have demonstrated the influence of proteins (β-lactoglobulin (BLG) and stem bromelain (BM) as biological stimuli) on the phase transition behavior of biomedical thermoresponsive poly(N-isopropylacrylamide) (PNIPAM). In order to predict these, we have used a set of biophysical techniques to unveil the influence of biological stimuli on the phase transition behavior of PNIPAM. Absorption spectroscopy, steady-state fluorescence spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) were operated at room temperature to examine the changes in absorbance, fluorescence intensity, molecular interactions and surface morphologies, respectively. Furthermore, temperature dependent fluorescence spectroscopy and dynamic light scattering (DLS) studies were also performed to analyze conformational changes, agglomeration behavior, particle size, coil to globule transition and phase behavior. The significant variations obtained in the phase transition temperature values, conformational changes and agglomeration behavior clearly reflects the different molecular interplay induced in presence of biological stimuli. The results demonstrated that the added proteins act as biological stimuli via preferential interactions between the amide group of the polymer and water molecules. The present study can be useful for the design and development of the next generation smart responsive materials/biomaterials.

Hypothesis Thorough knowledge of the biomolecular interactions between thermoresponsive polymers (TRPs) and proteins are necessary to fabricate potential materials for various bio-related science and technology applications. Although over the past four decades have evidenced that tremendous growth in the utilization of TRPs in the addition of various stimuli systems, a underlying molecular origins of the role of biological stimuli on TRPs phase transition is still missing. Experiments We demonstrated the comparative effect of heme proteins (biological stimuli) such as cytochrome c (Cyt c) and myoglobin (Mb) on the phase behaviour of poly(N-isopropylacrylamide) (PNIPAM) aqueous solution. The sophisticated multiple techniques have confirmed that the structural integrity of the proteins is found to play a vital role in altering the phase transition temperature of PNIPAM to different extents with increasing the concentration of proteins. Findings With the addition of Cyt c, the lower critical solution temperature (LCST) of PNIPAM (33.0 °C) increased towards higher temperature (35.7 °C) in contrast to this with the addition of Mb the LCST of PNIPAM decreased towards lower temperature (30.7 °C). This discrepancy is due to the difference in contrast structural arrangements of both proteins on the LCST of PNIPAM. On the basis of these results, the variation in the structures of both heme proteins, hydration and dehydration between the heme proteins are compared. These results demonstrated that depending on the type of smart polymers used for bio-related applications, it is necessary to take into account the effect of biological stimuli while designing polymers. We hope that the present study can stimulate more novel concepts and dramatic changes in smart polymer and protein interactions.