A cost-effective and rapid aptasensor with chemiluminescence detection for the early diagnosis of prostate cancer

Abstract

A rapid aptasensor capable of early diagnosing prostate cancer was developed using a dual aptamer, which is composed of a prostate specific antigen (PSA) aptamer and hemin aptamer connected by a linker composed of 5 adenines. The dual aptamers immobilized on the surface of paramagnetic beads were able to competitively bind with PSA or hemin in human serum for 20 min at room temperature. After the incubation, the dual aptamers were separated from human serum using a magnetic separator. After the procedure, the mixture of Amplex Red and H2O2 in Tris–HCl (pH 8) was added in a microcentrifuge tube containing the dual aptamers. Resorufin was formed from the reaction of Amplex Red and H2O2 in the presence of horseradish peroxidase (HRP) mimicking DNAzyme formed from the reaction of hemin and the dual aptamer. The concentration of resorufin formed from the reaction was proportional to the concentration of HRP mimicking DNAzyme. Resorufin emitted bright red light with the addition of 1,1′-oxalyldiimidazole (ODI) chemiluminescence reagents such as ODI and H2O2. The brightness of the emission light was proportionally reduced with the increase of PSA in human serum due to the reduction of DNAzyme concentration with the binding of PSA and PSA aptamer linked to hemin aptamer. Using the calibration curve of the new aptasensor, trace levels of PSA in human serum was rapidly quantified for the early diagnosis of prostate cancer. The limit of detection (LOD = 3 s/slope) of the aptasensor was as low as 0.1 ng/ml. The accuracy, precision, and recovery of the aptasensor were studied with statistically acceptable methods.