title: Fabrication of a protease sensor for caspase-3 activity detection based on surface plasmon resonance.
abstract: Diagnosis of apoptosis is essential to the early detection of therapy efficiency and the evaluation of disease progression. Caspase-3 is supposed to be closely related to cellular apoptosis. We describe here a label-free surface plasmon resonance (SPR) detection of apoptosis based on caspase-3 activity assay through enzyme digestion. An artificial peptide sequence was designed as a substrate of caspase-3 and immobilized on a gold disk through covalent binding. The 4Lys part at the end of the pentadecyl-peptide was designed to form a unique peptide array through electrostatic repulsion. The immobilization of the peptide on the gold surface was carefully characterized by SPR and atomic force microscopy. The catalytic conditions of caspase-3 were optimized with electrochemical impedance spectroscopy. The detection limit of caspase-3 was found at a concentration of 1 pg mL(-1). The activity of caspase-3 in apoptotic cells could also be measured sensitively by the one-step and intuitional SPR response decrease. The fabricated simple and convenient caspase-3 sensor is proposed for application in clinical analysis.
authors.affiliation: Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444, P R China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Chen
authors.forename: Qiaohan
authors.initials: Q
authors.lastname: Mei
authors.forename: Yafei
authors.initials: Y
authors.lastname: Hou
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhu
authors.forename: Kwangnak
authors.initials: K
authors.lastname: Koh
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Li
authors.forename: Genxi
authors.initials: G
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D053148:Caspase 3 / Q000032:analysis* / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D061986:MCF-7 Cells; D008969:Molecular Sequence Data; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D053148:Caspase 3