Some of the SARS-CoV-2 variants are said to be more infectious than the previous others and are causing panic around the globe. Cases related to Delta plus (δ+) and omicron (ο) variants are on the rise worldwide. This sudden surge warrants an investigation into the reasons for its binding with ACE-2. The present study attempts to find out the structural basis of binding interactions of SARS-CoV-2 mutants based on computational modeling and comparative analysis. In silico strategies including protein-protein docking, mutation analysis, molecular dynamics, and binding energy calculations were used to study the binding of the 'receptor binding domain' (RBD) of the seven ‘variants of concern’ which include Alpha (α), Beta (β), Gamma (γ), Kappa (κ), Delta (δ), Delta plus (δ+) and omicron (ο) with ACE-2 (human angiotensin-converting enzyme-2) and with antibodies. Among all the variants dealt with in this study, Delta plus and omicron were found to be binding more strongly to ACE-2 than others due to inherent mutations and the consequent change in the hydrophilic and hydrophobic environment of the binding site. Furthermore, molecular dynamic (MD) simulations and subsequent MM/PBSA calculations provided useful structural insights into key residues participating in the interaction. Infectivity of a virus could be dependent on the interplay of evading antibodies and simultaneously attaching strongly with the host receptor. A cross-correlation between mutant spike proteins' binding with ACE-2 and antibodies provides a holistic assessment of the binding nature of these mutants vis-à-vis native virus and offers opportunities for designing potential therapeutics against these new mutants. Graphical Abstract Communicated by Ramaswamy H. Sarma

Pesticides are commonly used in agriculture to control pests and improve crop yields, but they pose significant risks to human health and the environment due to potential residues in biological matrices. This study presents an innovative ultrasonicator-aided cartridge-based extraction method specifically designed for detecting pesticides in simulated biological samples, utilizing ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). To address the need for reliable analytical techniques in forensic science, we developed a robust method for determining Tetramethrin (TMT) and Dimethoate (DMT) in simulated gastric fluid and urine samples using UPLC-MS/MS. While various methods have been employed to analyze biological materials with different solvents, salt combinations, and solid-phase extraction (SPE) sorbents, there is limited research focused on optimizing conditions for detecting TMT and DMT using ultra sonicator aided cartridge based extraction method by following design of experiments. Moreover, no previous studies have reported on their detection in simulated urine and gastric fluid. Our approach involved ultrasound-facilitated HLB cartridge-based solid-phase extraction (SPE) to effectively extract the pesticides across a concentration range of 2.5 to 160 ng/mL and showed high sensitivity, precision, and accuracy, meeting the validation criteria established by the Scientific Working Group of Toxicology (SWGTOX). Its practicality and efficiency make it a valuable tool for analyzing pyrethroid and organophosphorus pesticides in forensic matrices, due to its efficient, rapid and straightforward sample preparation process.