Sensitive, Quantitative Naked‐Eye Biodetection with Polyhedral Cu Nanoshells

One of the most heavily used methods in chemical and biological labeling, detection, and imaging is based on silver shell‐based enhancement on Au nanoparticles (AuNPs) that is useful for amplifying Rayleigh scattering, colorimetric signal, surface‐enhanced Raman scattering, and electrical signal, but poor structural controllability and nonspecific growth of silver shells have limited its applications, especially with respect to signal reproducibility and quantification. Here, a highly specific, well‐defined Cu nanopolyhedral shell overgrowth chemistry is developed with the aid of polyethyleneimine (PEI) on AuNPs, and the use of this PEI‐mediated Cu polyhedral nanoshell (CuP) chemistry is shown as a means of light‐scattering signal enhancement for the development of naked‐eye‐based highly sensitive and quantitative detections of DNA and viruses. Remarkably, these CuPs are exclusively form…