Bifunctional Diblock DNA-Mediated Synthesis of Nanoflower-Shaped Photothermal Nanozymes for a Highly Sensitive Colorimetric Assay of Cancer Cells

The activity of a nanozyme is closely related to its surface area-to-volume ratio and the surrounding temperature. To acquire highly active nanozymes, one-pot metallization-like synthesis of novel nanoflower-shaped photothermal nanostructures was conducted using polyadenine-containing diblock DNA as the scaffold. The nanoflower-shaped structures with a high surface area-to-volume ratio and photothermal performance exhibited excellent peroxidase-mimicking activity, and the biorecognition capability was retained by the capping agent of diblock DNA. The functionalized nanostructures were used for a proof-of-concept colorimetric assay of cancer cells in vitro. Upon incorporation of 808 nm laser irradiation, high sensitivity and selectivity for the cancer cell assay were achieved with the lowest detection level of 10 cells/mL. Relative to spherical gold nanostructures, the nanoflower-shaped photothermal nanozyme exhibited higher assay sensitivity, paving the way for the construction of nanozyme-based colorimetric sensors for point-of-care testing.