Innovative Progress of LSPR-Based Dark-Field Scattering Spectral Imaging in the Biomedical Assay at the Single-Particle Level

The growing demand for detection and sensing in the biomedical field is placing higher demands on technology. In clinical testing, it is expected to be able to realize both rapid large-field imaging and analysis of single particles (or single molecules or single cells), and it is expected to be able to grasp both the unique individuality of single particles in time and space during the complex reaction process, as well as the regular correlation between single particles in the same population distribution. Supported and promoted by the theory of localized surface plasmon resonance (LSPR), dark-field microscopy, as a single-particle optical imaging technique with a very high signal-to-noise ratio, provides a powerful new means to address the above clinical detection needs. This review will focus on the innovative applications of dark-field microscopy in biomedical-related assays in the past five years, introducing the basic principles and listing the impressing works. We also summarize how dark-field microscopy has been combined with other techniques, including surface-enhanced Raman scattering, fluorescence, colorimetry, electrochemistry, etc., to witness the joint progress and promotion of detection methods in the future. It also provides an outlook on the current challenges and future trends in this field.