Efficient detection of single circulating tumor cell in blood using Raman mapping based on Aptamer-SERS bio-probe coupled with micropore membrane filtration

Rapid and accurate detection of rare circulating tumor cells (CTCs) in human blood still remains a challenge. We present a surface enhanced Raman spectroscopy (SERS) method based on aptamer-SERS bio-probe recognition coupled with micropore membrane filtration capture for the detection of CTCs at single cell level. The parylene micropore membrane with optimized micropore size installed on a filtration holder could capture bio-probe labeled CTCs by gravity in less than 10 s, and only with very less white blood cells (WBCs) residual. In order to facilitate the synthesis of the aptamer-SERS bio-probe, ethyl acetate dehydration method was established. The bio-probe can be rapidly synthesized within 2 h by binding SH-aptamer to 4- mercaptobenzoic acid (4-MBA) modified AuNPs with the help of ethyl acetate. The SERS bio-probe with selected specific aptamer could distinguish single human non-small cell lung cancer A549 cells from residual WBCs on membrane efficiently and reliably based on their Raman signal intensity difference at 1075 cm−1. Through the filter membrane coupled with aptamer-SERS bio-probe system, even 20 A549 cells in blood solution simulating CTCs sample can be detected, which the recovery rate and recognition rate are more than 90%. This method is rapid, reliable and cost-effective, which indicates a good prospect in clinical application for CTCs detection. An aptamer-SERS bio-probe was fabricated by binding specific aptamer of A549 tumor cell to Raman reporter 4-MBA modified AuNPs. CTCs sample labeled by the bio-probes can be captured on micropore parylene membrane with optimized micropore size by quick filtration. Single CTC on filter membrane was identified by SERS mapping method. [Display omitted] •Parylene membrane with suitable pore size capture CTCs rapidly and remove most WBCs.•Bioprobe synthesis with ethyl acetate dehydration in 2 h and keep Raman signal.•Selected aptamer ensure specificity for A549 cells compared to other cell and WBCs.•Low cost, time-saving, high capture efficiency and detection specificity for CTCs.