Optical and Structural Characterization of ZnO Nanoparticles for Binding Analysis with Semen Sample by Isothermal Titration Calorimetry

The present study investigated the optical and structural nature of zinc oxide nanoparticles (ZnO NPs) to look into the binding mechanism with sperm cell for exploring a domain of biosensing tools. The band gap and Urbach energy of the chemically fabricated ZnO NPs were calculated from UV-Vis spectroscopy and found to be 3.67 eV and 0.6792 eV, respectively. The excitonic strong band at room temperature of the NPs around similar to 366.5 nm showed Gaussian nature. The structural analysis from X-ray study demonstrated that the structure of the ZnO NPs is hexagonal with lattice parameters:a = 3.2483 angstrom, c = 5.2112 angstrom, average strain similar to 0.001985 and Atomic fraction similar to 75.4437%. The texture coefficients corresponding to the different X-ray diffraction peaks (hkl) and Gaussian fittings of the planes were accounted. The average size of the ZnO NPs is found to be similar to 24.45 nm and similar to 23 nm from the Scherrer formula calculation and HRTEM visual investigation respectively. The thermodynamics and binding energies as well as binding mechanism of the fabricated ZnO NPs with semen sample bioconjugate were studied by isothermal titration calorimetry (ITC) experiment. The resultant calorimetric data were fitted to a single set of identical site model showing the value of enthalpy change (Delta H) approximate to -21.63 +/- 0.39 kcal mol(-1), the stoichiometry (n) approximate to 0.040 +/- 0.0052, the binding affinity (K-b) approximate to (8.02 +/- 0.16) x 10(3) M-1, and entropy contribution (T Delta S) approximate to - 16.27 kcal/mol. The observed binding was found to be highly exothermic with the negative value of enthalpy and entropy.