Colorimetric Single-nanoparticle collision electrochemistry for rapid discrimination and accurate quantification of MCF-7 cells

Abstract

Single-nanoparticle collision electrochemistry (SNCE) has become popular in biosensing due to its simplicity, rapid response, and ultra-sensitive properties. However, the widespread application of clinical samples for MCF-7 cell detection is hindered by low abundance of target content and numerous interfering substances within complicated matrices. In this work, a promising colorimetric SNCE biosensor was proposed for MCF-7 cell detection by combining gold ultramicroelectrodes modified with sulfide layer (S-Au UMEs), liposome encapsulation-release strategy and immunomagnetic separation. Immunomagnetic beads (IMBs) successfully captured and separated rare MCF-7 cells with an efficiency of 88.9 % in whole blood within 15 min. After IMBs-cell-lip complexes were formed, the extent of the cancer disease can be rapidly discriminated visually using the peroxidase activity of CuO NPs. The supernatant Ag NPs released from liposomes were gathered and collided with S-Au UME, enabling the accurate quantification of MCF-7 cells based on the relationship between cell concentration and the collision frequency (the number of transient currents occurring of unit time) of Ag NPs. The colorimetric SNCE biosensor detected MCF-7 cells at a low concentration of 5 cells/mL (from 5 cells/mL to 105 cells/mL) and was employed for analyzing peripheral blood samples from cancer patients. Two analysis forms provided more accurate detection outcomes to satisfy different testing requirements.