Self-assembled 1D nanostructures for direct nanoscale detection and biosensing

Directly accurate detection of nanoscale objects remains a great challenge to many fields, including self-assembly, nanoparticle engineering, nanomaterial characterization, and biological diagnosis. Here, we report a general method for visualizable detection and measurement of many nanoscale objects by using one-dimensional (1D) nanostructures, including nanoparticles, defects, and pathogens. The large-scale 1D nanostructures are robustly prepared through the template-assisted self-assembly of colloidal nanoparticles, which exhibit wide spectral tunability in the visible region. In addition to the scalability, they can significantly amplify the weak optical signals from nanoscale objects, pushing the detection sensitivity down to the single-particle level. Then, we achieve the rapid and ultrasensitive testing of different clinical virus samples by using a simple optical microscope or a portable cell phone. This work demonstrates a label-free, simple, and high-efficiency optical detection platform at the nanoscale, which has a broad range of applications from material synthesis to in vitro diagnosis.