Dey A.,Jadavpur University |
Layek A.,Bejoy Narayan Mahavidyalaya Itachuna |
Roychowdhury A.,UGC-DAE Consortium for Scientific Research |
Das M.,Jadavpur University |
And 4 more authors.
RSC Advances | Year: 2015
In this report the synthesis of novel zinc oxide (ZnO) with a lower defect density and its effect on the Al/ZnO Schottky junction has been demonstrated. The defect density was estimated by positron annihilation lifetime measurement which ensures the material's superiority (i.e. free from point defects or any type of vacancies) over the earlier reported results. The thin film device of synthesized ZnO was fabricated on an ITO coated glass substrate. As the front contact was made by aluminium, the characteristic I-V produced rectifying Schottky behavior. The underlying charge transport mechanism through a metal-semiconductor (i.e. Al/ZnO) junction was analyzed on the basis of thermoionic emission theory to find out the quality of the fabricated device. In this regard we have studied the charge transport mechanism by measuring the density of states (DOS) at the Fermi level, mobility-lifetime product and diffusion length. © The Royal Society of Chemistry 2015.
Spectroscopic exploration of drug-protein interaction: A study highlighting the dependence of the magnetic field effect on inter-radical separation distance formed during photoinduced electron transfer
Chakraborty B.,Bejoy Narayan Mahavidyalaya Itachuna |
Mitra P.,Saha Institute of Nuclear Physics |
Basu S.,Saha Institute of Nuclear Physics
RSC Advances | Year: 2015
In this article, we study the binding interaction of acridone (AD) with human serum albumin (HSA) using conventional spectroscopic techniques and then decipher the latent occurrence of photoinduced electron transfer (PET) using the laser flash photolysis (LFP) technique in conjunction with a weak magnetic field (MF). The experimental observations are further substantiated by docking results. An absorption study reveals the formation of a ground state complex between AD and HSA while a circular dichroism study implies that AD brings about a substantial change in the secondary and tertiary structures of the protein. A fluorescence study mainly helps in evaluation of the binding and thermodynamic parameters. This is one of the rare reports which utilize time-resolved emission spectra and time-resolved area normalized emission spectra to study drug-protein interactions. The detection of the occurrence of PET would be ignored if only the observations of conventional spectroscopic techniques had been considered. LFP detects the occurrence of PET from the tryptophan residue of HSA to AD and MF effect authenticates the triplet origin of the radical ions involved. Furthermore, the actual reaction pathway is elucidated with the help of the MF effect. Although the MF effect is generally observed in a restricted medium, in the present case the complex structure of the protein offers pseudo-confinement to the radical pairs or radical ion pairs resulting in observation of a substantial MF effect. The significance of maintaining the condition of "pseudo-confinement" or the optimum distance between radical ions originating from the acceptor and donor moieties in the observation of the MF effect has been specifically highlighted in this work by integrating the findings of the present study with our previous reports. © The Royal Society of Chemistry.