Antifouling Gold-Inlaid BSA Coating for the Highly Efficient Capture of Circulating Tumor Cells

Large amounts of coexisting contamination in complex biofluid samples impede the quantified veracity of biomarkers, which is the key problem for disease confirmation. Herein, amyloid-like transformed bovine serum albumin inlaid with gold nanoparticles was used as a coating (BGC) on a substrate composed of silicon nanowires (SW; BGC-SW) under ambient conditions. After modification with the recognition group, BGC-SW could serve as an outstanding platform for the selective separation and sensitive detection of biomarkers in complicated biosamples. First, the BGC on SW with a large surface area exhibits excellent adhesion resistance. The attached amounts of contaminations in biofluids were decreased by over 78% compared with native bovine serum albumin (BSA) as the blocking agent. This is because the phase-transformed BSA coating provides stronger interactions with the SW than bare BSA, which results in a tighter attachment and more uniform coverage of the BGC. Furthermore, the gold matrix laid inside the antiadhesive coating ensures simple cross-linking with the recognition groups to selectively capture various biomarkers in complex biofluids and create a gentle release method. Circulating tumor cells (CTCs) were chosen as template biomarkers to verify the application of A-BGC-SW (BGC-SW modified with sgc8-aptamer) in various separation processes of untreated biofluids. The results showed that approximately six cells could be captured from a 1 mL fresh blood sample containing only 10 CTCs. The easy fabrication and excellent antiadhesion property endow A-BGC-SW with great potential in the field of biological separation.