All-in-one magnetic beads: Searching, capturing and simultaneous detection of dual tumor related proteins in real samples

Simultaneous assay of multiple tumor marker proteins is of great importance for accurate diagnosis of cancer because most of cancers are usually related to various tumor-related proteins. In this work, we prepared yellowcolored carbon dots (y-CDs) and blue-colored carbon dots (b-CDs) for simultaneous detection of carcinoembryonic antigen (CEA) and cancer antigen125 (CA125) based on the antifouling magnetic beads (MBs) in real samples. Two sandwich structures were constructed by MBs modified with aptamer 1(Apt1) of proteins and aptamer 2(Apt2) tagged with CDs in the presence of target proteins. After CDs were cut off and separated, the fluorescence intensities at 430 nm (b-CDs) and 550 nm (y-CDs), relating to quantities of two proteins, were measured at a single excitation wavelength, obtaining the detection limits of 0.11 ng mL-1 (CEA) and 0.57 U mL-1 (CA125) respectively. Due to the target specific searching, recognition, capturing with aptamers, magnetic separation and antifouling property of peptides, the simultaneous differentiating and assaying CEA and CA125 in human serum can be easily operated, and results reveal a good correlation with data from the electrochemiluminescent (ECL) immunoassay in hospitals, demonstrating the promising candidate for clinical diagnosis of ovarian cancer.

Automated summary

Simultaneous assay of multiple tumor marker proteins is important for accurate cancer diagnosis. In this study, yellow and blue carbon dots were prepared, and magnetic beads modified with aptamers were used for the simultaneous detection of CEA and CA125 in real samples. The fluorescence intensities of the carbon dots at specific wavelengths were measured to obtain the detection limits of the two proteins. This method showed good specificity, ease of operation, and correlation with existing electrochemiluminescent immunoassay results, making it a promising candidate for clinical diagnosis of ovarian cancer.