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 À1 . 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.

Fe3O4@Au nanoparticles as a means of signal enhancement in surface plasmon resonance spectroscopy for thrombin detection

“…The ratios of reactive volumes between Fe 3 O 4 and HAuCl 4 solution were 1:2. Stirring continued for 10 min after the color change ceased [25]. The solution was cooled to room temperature with a continuous stirring for another 45 min.…”

Sensitive cell apoptosis assay based on caspase-3 activity detection with graphene oxide-assisted electrochemical signal amplification

“…Additionally, these photometric approaches are confronted with insufficient sensitivity due to the technical limitation of themselves. Our group have reported a novel caspase-3 sensor with excellent sensitivity by using surface plasmon resonance (SPR) technique (Chen et al, 2013). However, it still has problems in terms of the cost of equipment and specially trained operator.…”

Electrochemical impedance spectroscopy for monitoring caspase-3 activity

“…Upon cleavage of the ferrocene-conjugated DEVD peptide, a decrease in ferrocene oxidation signal denoted caspase-3 activity in assay samples. Recently, Chen et al [24] reported the development of a caspase-3 sensor using surface plasmon resonance in connection with EIS. In their study, a pentadecylpeptide containing the caspase-3 specific peptide motif, DEVD, was covalently immobilized on Au surface using a cysteine placed at the C-terminus of the peptide sequence.…”

“…It was concluded that a 15-min incubation period with caspase-3 was sufficient for their procedure. However, the effect of non-specific adsorption or sensitivity issues in complex matrices such as cell lysates were not discussed [24].…”