Interaction between a local anesthetic drug, articaine (ART) and human serum albumin (HSA) was investigated in the absence and presence of paracetamol (PAR) and caffeine (CAF) using spectroscopic, voltammetric, and computational techniques for the first time. The results demonstrated that increasing concentrations of ART in HSA solution led to a decrease in HSA fluorescence signal, indicating the ART-HSA complex formation via the static quenching mechanism. The binding strength of the complex was moderate (binding constant, Ka = 5.87 × 103 M-1 in fluorescence and 6.31 × 103 M-1 in voltammetric at 298 K). Thermodynamic analysis (ΔS = +28.32 J mol-1 K-1; ΔH = -30.17 kJ/mol) of the binding reaction suggested involvement of hydrophobic interactions, van der Waal's forces and hydrogen bonding in stabilizing the ART-HSA complex. Significant microenvironmental alterations near the Trp and Tyr residues of HSA consequent to the ART-HSA complex formation. ART predominantly binds to Sudlow's site I of HSA with more negative binding energy and stronger hydrophobic interactions compared to Site II. The stability of the ART-HSA complex at Site I over a 100 ns timeframe, supported by stable hydrogen bonding and compact HSA structure throughout the molecular dynamics simulations. The effect of PAR and CAF on the binding strength between ART and HSA was also examined, and presence of PAR and CAF in the reaction mixture produced significant reduction in the binding affinity of ART to HSA. These findings underscore the competitive binding between ART, PAR, and CAF, which impacts their pharmacokinetics and efficacy. This study provides valuable insights into the complex interactions between anesthetic drugs and common pharmaceuticals, potentially guiding clinical practices and drug development.
Applying visible-wavelength interrogation Kretschmann SPR spectroscopy technique using a polymeric ZnO-Quantum Dot PVA (pZnOQD) layer for chloride ion detection represents a significant advancement in photonic technology. This method streamlines the detection process while maintaining high sensitivity. Molecular analysis reveals subtle shifts in specific peaks of the ZnOQD spectrum after the interaction, suggesting chloride ion interaction with the active layer. Subsequent SPR analysis confirms these findings, showing wavelength shifts in SPR peaks between 630 - 660 nm across different chloride ion concentrations. This technique demonstrates exceptional sensitivity, detecting chloride ion concentrations from 1.0 to 20.0 ppm, with two distinct sensitivity ranges (1.0 - 4.0 ppm and 4.0 - 20.0 ppm) and corresponding values of 1.7221 (R2 = 0.998) and 0.627 nm/ppm (R2 = 0.992), respectively. These results are comparable, with a low detection limit of 0.3 ppm. Experimental data fitting well with the Sips model yields an R2 value of 0.995 and a binding affinity of 3.876 × 102M-1, providing valuable insights for sensor development. This integrated analysis provides a comprehensive understanding of chloride ion interactions with the pZnOQD sensing layer, paving the way for advanced optical spectroscopy using quantum dots.