We present recent development and applications of a surface‐enhanced Raman scattering (SERS) technology for use in medical diagnostics and biological imaging. For medical diagnostics, we use Raman‐active dye‐labeled DNA gene probes and nanostructured metallic substrates as SERS‐active platforms. The surface‐enhanced Raman gene probes can be used to detect DNA biotargets (e.g. gene sequences, bacteria and viral DNA) via hybridization to DNA sequences complementary to these probes. The SERS gene probes eliminate the need for radioactive labels and have great potential to provide both sensitivity, selectivity and label multiplexing for DNA sequencing and clinical assays. We also describe a hyperspectral surface‐enhanced Raman imaging (HSERI) system that combines imaging capabilities with SERS detection to identify cellular components with high spatial and temporal resolution. The HSERI system's application to biological imaging is demonstrated using Raman dye‐labeled silver nanoparticles in cellular systems. Copyright © 2005 John Wiley & Sons, Ltd.

Transition metal carbides (MXenes) are an emerging family of highly conductive two-dimensional materials with additional functional properties introduced by surface terminations. Further modification of the surface terminations makes MXenes even more appealing for practical applications. Herein, we report a facile and environmentally benign synthesis of reduced Ti₃C₂T_x MXene (r-Ti₃C₂T_x) via a simple treatment with L-ascorbic acid at room temperature. r-Ti₃C₂T_x shows a six-fold increase in electrical conductivity, from 471 ± 49 for regular Ti₃C₂T_x to 2819 ± 306 S m⁻¹ for the reduced version. Additionally, we show an enhanced oxidation stability of r-Ti₃C₂T_x as compared to regular Ti₃C₂T_x. An examination of the surface-enhanced Raman scattering (SERS) activity reveals that the SERS enhancement factor of r-Ti₃C₂T_x is an order of magnitude higher than that of regular Ti₃C₂T_x. The improved SERS activity of r-Ti₃C₂T_x is attributed to the charge transfer interaction between the MXene surface and probe molecules, re-enforced by an increased electronic density of states (DOS) at the Fermi level of r-Ti₃C₂T_x. The findings of this study suggest that reduced MXene could be a superior choice over regular MXene, especially for the applications that employ high electronic conductivity, such as electrode materials for batteries and supercapacitors, photodetectors, and SERS-based sensors.