Rimki Bhattacharjya*, Priyakshi Bordoloi, Diganta Kumar Das
Lawsone (2-hydroxy-1,4-naphthoquinone) is the main active chemical constituent of Henna (Lawsoniainermis). Lawsone encapsulated in cationic surfactant cetyltrimethyl ammonium bromide modified pre-cleaned platinum electrode, coated with AgNO3, showed a decrease in cathodic and anodic currents in cyclic voltammetry and the peak current in square wave voltammetry. Electrochemical Impedance Spectroscopy of the modified electrode showed a linear increase in charge transfer resistance with cholesterol. The fluorescence intensity of Lawsone in ethanol-water was found to quench in presence of AgNO3 which then gradually increased on addition of cholesterol. The electrochemical behaviour of the modified electrode and the fluorescence behaviour of Lawsone in presence of AgNO3 towards cholesterol was found to be similar in artificial cerebrospinal fluid, confirming that NaCl, NaHCO3, KCl, CaCl2, glucose and uric acid do not interfere with the detection of cholesterol. The limit of detection of cholesterol in 0.1 M KCl is 4.0 × 10-7 M and 7.76 × 10-8 M in synthetic cerebrospinal fluid.