Aptamer–nanoparticle-based chemiluminescence for p53 protein.

A simple colorimetric biosensing technique based on the interaction of gold nanoparticles (AuNPs) with
the aptamer was developed for detection of p53, a tumor suppressor protein, in the current study. Aggregation
of AuNPs was induced by desorption of the p53 binding RNA aptamer from the surface of AuNPs as
a result of the aptamer target interaction leading to the color change of AuNPs from red to purple. The
detection limit of p53 protein by the colorimetric approach was 0.1 ng/ml after successful optimization
of the amount of aptamer, AuNPs, salts, and incubation time. Furthermore, the catalytic activity of the
aggregated AuNPs was greatly enhanced by chemiluminescence (CL) reaction, where the detection limit
was enhanced to 10 pg/ml with a regression coefficient of R2 = 0.9907. Here the sensitivity was increased
by 10-fold compared with the AuNP-based colorimetric method. Hence, the sensitivity of detection was
increased by employing CL, by using the catalytic activity of aggregated AuNPs, on the luminol–hydrogen
peroxide reaction. Thus, the combination of colorimetric and CL-based aptasensor can be of great advantage
in increasing the sensitivity of detection for any target analyte.