Fig. 5. Competition ELISA determined binding properties of morphine recognizing soluble and purified scFv fragment synthesized from selected clone isolated from Tomlinson I library. Nitrocellulose membrane was coated with morphine-BSA as test line (2 mg mL⁻¹) in 3% methanol. The morphine/scFv/AuNPs immunoprobe (1 : 200) was absorbed on to glass fiber lining, followed by addition of spiked morphine (B) in urine sample well. Cross reactivity studies were performed in heroin (C), MAM (A), codeine (D), where scFv did not showed any binding with heroin and codeine. The data represents mean ± standard deviation from duplicate measurements.