New Quantum-Dot-Based Fluorescent Immunosensor for Cancer Biomarker Detection

Abstract

Cancer antigen 15-3 (CA 15-3) is a biomarker for breast cancer used to monitor response to treatments and disease recurrence. The present work demonstrates the preparation and application of a fluorescent biosensor for ultrasensitive detection of the cancer antigen CA 15-3 protein tumor marker using mercaptopropionic-acid-functionalized cadmium telluride (CdTe@MPA) quantum dots (QDs) conjugated with CA 15-3 antibodies. First, the QDs were synthesized by the hydrothermal route, resulting in spherical nanoparticles up to 3.50 nm in diameter. Subsequently, the QD conjugates were characterized by Fourier transform infrared spectroscopy (FTIR), UV absorption, and fluorescence. The interaction between the conjugates and the protein was studied by fluorescence spectroscopy in buffer and in 10-fold diluted commercial human serum. Calibration in spiked serum samples gave a detection limit of 0.027 U/mL, 1000-fold lower than the clinical limit for CA 15-3 (25 U/mL to 30 U/mL), indicating that this is an ultrasensitive technique. In addition, a rapid response was obtained within 10 min. The biosensor was selective in the presence of the interfering serum proteins BSA, CEA, and CA-125, with a maximum interference of 2% for BSA. The percent recovery was close to 100% with maximum relative standard deviation (RSD%) values of 1.56. Overall, the developed CA 15-3 biosensor provides a simple and sensitive method for ultrasensitive monitoring of breast cancer, as well as the ability to detect other molecules of interest in human serum matrices.

Bio-conjugated carbon dots for the bimodal detection of prostate cancer biomarkers via sandwich fluorescence and electrochemical immunoassays

“…In the case of fluorescence assay, a detection signal is obtained via FRET, IFE, PET and DET mechanisms. 26 In most fluorescence-based sensing systems, a decrease in fluorescence intensity was observed during detection events. However, a detection probe that amplifies fluorescence intensity during immune-complex formation is desired, which authenticates the reliability of the sensing system.…”

Increasing the sensitivity and accuracy of detecting exosomes as biomarkers for cancer monitoring using optical nanobiosensors

“…Moreover, when applied to loaded human serum samples, the biosensor demonstrated high recovery ratios, indicating that it is a cost-effective and straightforward method for quantifying the analytes of interest (Fig. 6 ) [ 192 ].…”

“…(A) Synthesis of QD; (B) Activation of carboxylic groups derived from QD; (C) Formation of a covalent bond via the EDAC/NHS reaction between the carboxylic groups of the NPs and the amine groups of the antibodies; (D) Obstruction of unbound regions. (E) QD conjugate binding to the CA 15 − 3 protein [ 192 ] …”

Moving towards Personalized Medicine—The Broad Use of Aptamers for Targeted Theranostic

“…Biosensors that use aptamers as recognition elements are called aptasensors and generally rely on the conformational changes in the aptamers after binding to its target. They have been applied in point-of-care miniaturized devices to detect environmental contaminants, cancer biomarkers or drugs, as example [85,131,132]. Additionally, they can also be used as a theragnostic tool, allowing to detect and treat cancer [133].…”