One-step assay for optical prostate specific antigen detection using magnetically engineered responsive thin film.

We report a novel and very simple method for the detection of proteolytically-active prostate specific antigen (PSA) at a very low concentration using a self-assembled monolayer (SAM) of magnetic beads conjugated with peptide. The application of surface plasmon resonance (SPR) allows real-time optical characterization of the constructed recognition monolayer. This set-up is also capable of rapid monitoring of PSA samples through an instantaneous detection of medium refractive index shift induced by the enzymatic cleavage of the peptide and the dissociation of free magnetic beads.

Ultra-rapid colorimetric assay for protease detection using magnetic nanoparticle-based biosensors.

Sensitive protease detection methods often require time-consuming techniques and expensive instrumentation. To overcome this limitation, a novel, simple, sensitive and selective colorimetric detection approach was developed. This biosensing configuration was validated by the use of prostate specific antigen (PSA) protease as a model target.

Wash-less and highly sensitive assay for prostate specific antigen detection.

A novel, simple and facile biosensor for prostate specific antigen (PSA) detection was constructed. In this method, proteolytically active PSA is capable of cleaving PSA substrate-magnetic carrier complexes. Electrochemical analysis of the sensor layer showed a significant decrease in impedance signal after proteolysis has occurred, whereas a positive change in impedance was observed using a negative control substrate, indicating the specificity of our detection mechanism.

A novel and rapid assay for HIV-1 protease detection using magnetic bead mediation.

A simple sensing assay was established for label-free detection of HIV-1 protease. HIV-1 protease peptide substrate conjugated to magnetic beads via its N-terminus is directly fixed onto the sensor gold surface through the sulphur atom of cysteine. Surface plasmon resonance (SPR) was used to study the peptide substrate cleavage efficiency of the protease with magnetic beads of different sizes (1 μm and 30 nm).

Labeled magnetic nanoparticles assembly on polypyrrole film for biosensor applications.

In recent years, conducting polymers combined with metallic nanoparticles have been paid more attention due to their potential applications in microelectronics, microsystems, optical sensors and photoelectronic chemistry. The work presented in this paper describes the preparation and characterization of a nanocomposite composed by a thin polypyrrole (PPy) film covered with an assembly of magnetic nanoparticles (NPs). The magnetic particles were immobilized on PPy films under appropriate magnetic field in order to control their organization on the PPy film and finally to improve the sensitivity of the system in potential sensing applications.