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

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.This research was funded by Fundação para a Ciência e Tecnologia, I.P, grant number 2022.09032.PTDCinfo:eu-repo/semantics/publishedVersio

Label-free quantum dot conjugates for human protein IL-2 based on molecularly imprinted polymer

The authors acknowledge the financial support from European Research Council though the Starting Grant, ERC-StG-3P´s/2012, GA 311086, (to MGF Sales) and from the CANCER project (NORTE-01-0145- FEDER-000029).info:eu-repo/semantics/publishedVersio

Label-free quantum dot conjugates for human protein IL-2 based on molecularly imprinted polymers

Herein, the development of a fluorescent-based sensor by combining quantum dots (QDs) with molecularly-imprinted technology (MIP), intensively optimized to generate exceptional operating features is presented. This sensor is designed to target human interleukin-2 (IL-2) in synthetic human serum. IL-2 is a regulatory protein released as a triggered response from the immune system towards an inflammation. For this purpose, cadmium telluride (CdTe) QDs are prepared with 3-mercaptopropionic acid (MPA) and modified afterwards to produce an IL-2 imprinted polymer with methacrylic acid and N,N´-methylenebis(acrylamide), upon removal of the template under optimized conditions. During IL-2 rebinding, the fluorescence intensity of CdTeThe authors acknowledge the financial support of European Research Council though the Starting Grant, 3P’s Starting Grant/ERC (GA 311086) and the financial support of Portugal 2020, FEDER and NORTE2020 through the project Strip2Sense (NORTE-01-0145-FEDER024358). AMLP also aknowledges Fundação para a Ciência e Tecnologia, I.P., for the grant reference SFRH/BPD/116067/2016.info:eu-repo/semantics/publishedVersio