MBene Nanosheets with DNA Adsorbability for Circulating Tumor DNA Assay via Fluorescence Biosensing and Paper‐Based Microfluidic POCT

The detection of circulating tumor DNA (ctDNA) in blood is significant for non‐invasive cancer diagnosis and treatment monitoring. Herein, MBene nanosheets is synthesized and compared with MXene via Density Functional Theory (DFT) calculations and fluorescence kinetic evaluations, for first time, revealing MBene's exceptional DNA adsorbability and discrimination to single‐stranded DNA (ssDNA) and double‐stranded DNA (dsDNA). Then, a sensitive fluorescence biosensor for ctDNA detection is developed, demonstrating impressive performance. To facilitate point‐of‐care testing (POCT) ctDNA, a paper‐based microfluidic chip incorporated a delay area and a mixing channel is designed. The constricted‐expanded structure channel optimization is guided by numerical simulations and experiments. A WeChat mini program named “ctDNA Detection” is designed for readout assay. Furthermore, cell and mice serum samples are analyzed, with Magnetic Bead@Graphene Oxide (MB@GO) and clutch probes for magnetic pre‐enrichment. The results accuracy is confirmed by its consistency with standard qPCR results (AUC = 1). The successful detection of ctDNA in post‐surgery mouse models underscored the biosensor's potential for cancer treatment monitoring. Thus, this research not only advanced the understanding of the MBene‐DNA interaction in biosensing, but also can pave the way for novel applications in bioimaging and nanopore‐based nucleic acid sequencing, leveraging the digital transformation of DNA base‐MBene adsorption differences.