The most common prostate cancer (PCa) diagnostics which is based on detection of prostate-specific antigen (PSA) in blood has specificity limitations often resulting in both false-positive and false-negative results ; therefore, improvement in PCa diagnostics using more specific PCa biomarkers is of high importance. Studies have shown that the long noncoding RNA Prostate Cancer Antigen 3 (lncPCA3) over-expressed in the urine of prostate cancer patients is an ideal biomarker for non-invasive early diagnostics of PCa. Geno-sensors based on aptamer bio-receptors (Apta-sensors) offer cost- and time-effective, and precise diagnostic tools for detection PCa biomarker . In this study, we report on further development of RNA-based Apta-sensors exploiting two different detection strategies, i.e. electrochemical (CV and IS) and optical (spectroscopic ellipsometry) measurements. These sensors were made by immobilization of thiolated CG-3 RNA aptamers on the surface of gold. Aptamer labelled with redox group (ferrocene) was used in electrochemical measurements, while non-labelled aptamer was used in total internal reflection ellipsometry (TIRE) measurements. The results obtained by these two methods were compared, the sensitivity in FM level of concentration was achieved and the required selectivity is provided by high affinity of PCA3-to-aptamer binding with K_A in 10⁷ L/mol range. The conditions for the aptamer immobilisation procedure (aptamer concentration, incubation time) were optimised. The detection of PCA3 in urine was attempted. The proposed detection approaches allow the reliable detection of PCA3 at low concentrations, thus providing a background for future development of novel, highly sensitive and cost-effective diagnostic methodologies for prostate cancer detection.

References:

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