Rapid and Quantitative Determination of Biological Warfare Agent Brucella Abortus CSP-31 Using Surface Plasmon Resonance

A rapid and simple method for the real time monitoring of Brucella abortus CSP-31 (B. abortus CSP-31) by using Surface Plasmon resonance (SPR) is first time reported. SPR and electrochemical impedance spectroscopy (EIS) were used to characterize the B. abortus CSP-31 interaction on carboxymethyldextran modified gold disc with antibody. The EIS data revealed a decrease in impedance after interaction of antigen with antibody due to the effective binding. The present SPR biosensor is able to detect 0.05 pM concentration of B. abortus CSP-31 in phosphate buffered saline in less than 10 minute with linearity from 2.0 to 16.0 pM. The equilibrium constant (KD) and maximum binding capacity of analyte (Bmax) values for B. abortus CSP-31 were calculated to be 7.6 pM and 235.94 m, respectively. This KD value classifies the antibody as a high affinity one towards the antigen. Moreover, thermodynamic parameter change in Gibb’s free energy was calculated and found to be -63.34 kJ/mol. Interference study was also performed with B. abortus cell envelope (CE) antigen and a negative angle change was observed with exemplifying specificity for the antigen-antibody interaction of B. abortus CSP-31.