A Au particle-on-wire system that can be used as a specific, sensitive, and multiplex DNA sensor is developed. A pattern formed by multiple Au nanowire sensors provides positional address and identification for each sensor. By using this system, multiplex sensing of target DNAs was possible in a quantitative manner with a detection limit of 10 pM. Target DNAs from reference bacteria and clinical isolates were successfully identified by this sensor system, enabling diagnostics for infectious diseases.KEYWORDS DNA, multiplex, pathogen, pattern, surface-enhanced Raman scattering M ultiplex, sensitive, and specific DNA detection is of great demand for various biological and biomedical studies including gene profiling, drug screening, and clinical diagnostics because it has a potential to provide the most information from a small sample volume at low cost.1 In this regard, simple, reliable, and highthroughput methods that allow detection of multiple DNAs in one assay have been developed by taking various sensing approaches such as the measurement of fluorescence, [1][2][3] surface plasmon resonance (SPR), 4 electric signals, 5 and mass changes.6 Among these DNA sensing methods, fluorescence-based assay is currently the most preferred technique for multiplex DNA detection.7 Surface-enhanced Raman scattering (SERS) has also been considered as an attractive method for label-free multiplex DNA detection because of its single molecule level sensitivity, 8-10 molecular specificity, 11 and insensitivity to quenching. 7,12 These distinct advantages have led to the development of a number of ingenious SERS sensing platforms. [13][14][15][16] However, achieving optimum reproducibility of SERS signals and detecting various target molecules with a very small sample volume in one assay still remain as challenging tasks for practical multiplex SERS sensors. It has been shown that hot spots at nanoscale gaps between a nanowire (NW) and nanoparticles (NPs) can become highly SERS-active. [17][18][19][20][21][22] We have recently reported a new biomolecule detection method that provides reproducible SERS signals by using nanoscale gaps between Au NW and NPs. 23Here we present a multiplex DNA detection method employing multiple Au particle-on-wire systems as a SERS sensing platform. The system operates by the self-assembly of Au NPs onto Au NW in the presence of target DNAs, providing reproducible SERS signals in proportion to the concentrations of target DNAs. Multiple pathogen DNAs could be successfully detected by employing this method, demonstrating that this multiplex SERS sensor can be used a convenient system for clinical diagnostic and biomolecular interaction studies.Raman signal can be dramatically enhanced by placing the signal carrying molecules in the interstices between the assembled nanostructures. [24][25][26][27][28][29] To fabricate a SERS-active nanostructure that can be turned on by biomolecular binding, we adopted an Au particle-on-wire structure constructed by self-assembly of Au NPs onto Au NW through DN...

Fabricating well-defined and highly reproducible platforms for surface-enhanced Raman scattering (SERS) is very important in developing practical SERS sensors. We report a novel SERS platform composed of a single metallic nanowire (NW) on a metallic film. Optical excitation of this novel sandwich nanostructure provides a line of SERS hot spots (a SERS hot line) at the gap between the NW and the film. This single nanowire on a film (SNOF) architecture can be easily fabricated, and the position of hot spots can be conveniently located in situ by using an optical microscope during the SERS measurement. We show that high-quality SERS spectra from benzenethiol, brilliant cresyl blue, and single-stranded DNA can be obtained on a SNOF with reliable reproducibility, good time stability, and excellent sensitivity, and thus, SNOFs can potentially be employed as effective SERS sensors for label-free biomolecule detection. We also report detailed studies of polarization- and material-dependent SERS enhancement of the SNOF structure.

Wearable devices are becoming widespread in a wide range of applications, from healthcare to biomedical monitoring systems, which enable continuous measurement of critical biomarkers for medical diagnostics, physiological health monitoring and evaluation. Especially as the elderly population grows globally, various chronic and acute diseases become increasingly important, and the medical industry is changing dramatically due to the need for point-of-care (POC) diagnosis and real-time monitoring of long-term health conditions. Wearable devices have evolved gradually in the form of accessories, integrated clothing, body attachments and body inserts. Over the past few decades, the tremendous development of electronics, biocompatible materials and nanomaterials has resulted in the development of implantable devices that enable the diagnosis and prognosis through small sensors and biomedical devices, and greatly improve the quality and efficacy of medical services. This article summarizes the wearable devices that have been developed to date, and provides a review of their clinical applications. We will also discuss the technical barriers and challenges in the development of wearable devices, and discuss future prospects on wearable biosensors for prevention, personalized medicine and real-time health monitoring.