Virendra V. Singh

Effect of ambient hydrogen sulphide on the optical properties of evaporated cadmium sulphide films

Abstract The optical constants (n,k) of evaporated cadmium sulphide (CdS) thin films deposited in an ambient atmosphere of hydrogen sulphide (H2S) were determined over the wavelength range 350–800 nm from the measurement of reflection and transmission spectra. Low ambient atmosphere of H2S was obtained by thermal decomposition of thiourea inside the vacuum chamber. Cadmium sulphide thin films deposited with H2S ambient are more uniform, more adherent, pin hole free and have better crystallinity in comparison with the films without H2S atmosphere as inferred by the sharpness of the absorption spectra. Such films are inherently better suited for device fabrication.

DNA-probe-target interaction based detection of Brucella melitensis by using surface plasmon resonance

Surface plasmon resonance (SPR) immunosensor using 4-mercaptobenzoic acid (4-MBA) modified gold (4-MBA/Au) SPR chip was developed first time for the detection of Brucella melitensis (B. melitensis) based on the screening of its complementary DNA target by using two different newly designed DNA probes of IS711 gene. Herein, interaction between DNA probes and target molecule are also investigated and result revealed that the interaction is spontaneous. The kinetics and thermodynamic results derived from the experimental data showed that the interaction between complementary DNA targets and probe 1 is more effective than that of probe 2. Equilibrium dissociation constant (KD) and maximum binding capacity of analyte (Bmax) values for the interaction of complementary DNA target with the immobilized DNA probes were calculated by using kinetic evaluation software, and found to be 15.3 pM (KD) and 81.02m° (Bmax) with probe 1 and 54.9pM and 55.29m° (Bmax), respectively. Moreover, real serum samples analysis were also carried out using immobilized probe 1 and probe 2 with SPR which showed the applicability of this methodology and provides an alternative way for the detection of B. melitensis in less than 10min. This remarkable sensing response of present methodology offer a real time and label free detection of biological warfare agent and provide an opportunity to make miniaturized sensor, indicating considerable promise for diverse environmental, bio-defence, clinical diagnostics, food safety, water and security applications.