LAUSR

Abstract We report the study of methamphetamine (MA) sensing in urine samples using fiber optic particle plasmon resonance (FOPPR) biosensor. This approach is intended for on-site analysis of low-molecular-weight compounds. High sensitivity detection of MA at ultra-low concentration is realized by using a competitive inhibition immunoreaction scheme based on the competition of free MA in solution for anti-MA molecules that bind to the bovine serum albumin (BSA)–MA conjugate on the gold nanoparticle surface. With the BSA–MA functionalized sensor fiber, in the presence of a fixed concentration of anti-MA and various concentrations of MA in sample, the change of transmitted light intensity through the sensor fiber relative to that in a buffer solution decreases when the MA concentration increases because of the inhibition effect of MA. Based on this sensing method, the MA-functionalized FOPPR biosensor is capable for determining the concentration of MA with high sensitivity and wide linear dynamic range of 1–1000 ng/mL. The limit of detection for MA is 0.16 ng/mL. In addition, the MA functionalized FOPPR biosensor can detect MA in diluted human urine samples without nonspecific adsorption interference.