Metallic starch capped gold nanoparticles have been synthesized by the reduction of chloroaurate anions [AuCl4]- solution with hydrazine in the aqueous starch and ethylene glycol solution at room temperature and at atmospheric pressure. The characterization of synthesized gold nanoparticles by UV–Vis spectroscopy, Scanning electron microscopy (SEM), X-ray diffraction (XRD) indicate that average size of pure gold NPs is 5-10 nm, they are spherical in shape and are pure metallic gold. Starch capped gold nanoparticles along with tyrosinase enzyme are effectively entrapped within sol-gel matrix for application in catechol biosensor. Enzymatic reaction between tyrosinase and catechol results in the formation of a colored compound which shows characteristic absorbance at 410 nm. [email protected] based catechol biosensor showed fast response with linearity for catechol sensing from 1 to 5 mM. Effect of buffer pH and its concentration was also studied and results showed drastic changes in absorption intensity with pH and concentration variation. Along with catechol biosensor, starch capped gold NPs find their application in glucose, urease and peroxide biosensor, owing to their stability.