Modular DNA barcoding of nanobodies enables multiplexed in situ protein imaging and high-throughput biomolecule detection

Current immunodetection methods using antibody-DNA conjugates enable multiplexed target detection through orthogonal DNA barcodes, but existing conjugation approaches are labor-intensive and often compromise antibody function. Here, we present a modular, site-specific, and cost-efficient DNA tagging strategy - multiplexed and modular barcoding of antibodies (MaMBA). Utilizing nanobodies as modular adaptors, MaMBA enables direct site-specific labeling of off-the-shelf IgG antibodies with a one-component design. We first applied MaMBA to develop the MaMBA-assisted immunosignal hybridization chain reaction (<i>mis</i>HCR) method for highly multiplexed in situ protein imaging via orthogonal HCR. Its cleavable variant, <i>mis</i>HCRⁿ, achieves simultaneous visualization of 12 different targets within the same mouse brain sections through iterative probe use. We further extended the cleavable MaMBA to develop the barcode-linked immunosorbent assay (BLISA) for multiplexed and high-throughput biomolecule detections. By combining BLISA with next-generation sequencing, we successfully measured SARS-CoV-2 IgG and hepatitis B virus (HBV)-associated antigens in a large number of human serum samples. Additionally, we demonstrated a small-scale drug screen by using BLISA to simultaneously detect eight protein targets. In conclusion, MaMBA offers a highly modular and easily adaptable approach for antibody DNA barcoding, which can be broadly applied in basic research and clinical diagnostics.