Innovation Center Denmark

In the ever-evolving landscape of biomedical diagnostics, the early diagnosis of a disease is important for not only a patient but also the public health of a country. In this regard, the detection of pathogens as well as the analysis of biomarkers from body fluids, for preventive healthcare at a very low concentration have been the subject of intense research lately. Despite the availability of numerous analytical tools, detecting trace concentrations of analyte with high specificity remains a formidable challenge. Driven by the advances in micro-nanofabrication tools, photonics, and nanotechnologies, a variety of optical techniques that utilize nanostructures or nanoparticles are now being employed for the detection of trace amounts of analytes. Amongst these techniques, the surface-enhanced Raman spectroscopy (SERS) that exploits the tailor-made fabrication of plasmonic nanostructures and the miniaturization of spectroscopic devices are now emerging as the most preferred choice for biomolecule detection. The potential of this technique has already been demonstrated even at a single molecule detection level with high specificity. Aside from offering the possibility of developing portable systems, the SERS technique also enables multiplexed analytical detection and is thus explored for the development of point-of-care (POC) diagnostic devices. However, several problems still need to be addressed in using SERS-based POC devices to obtain repeatable, reproducible, and stable SERS readouts so that they can be employed for routine clinical diagnosis. In this review, we focus on the challenges in translating SERS-based POC devices from lab-scale research to real-time precision biosensing applications. Herein, we provide an account of various SERS active substrate design and POC device development strategies for highly sensitive, reproducible, and stable SERS-based POC development for biological applications. The sincere review points out current problems in existing SERS-based analytical methods, important factors for field tests with real samples, and considerable challenges of this development. This review provides a broader understanding of the device development using the SERS detection technique, existing methods, their challenges, and various possibilities herein to explore in this direction.

Although various types of on-site immunoassay platforms have been developed, facile and reliable sample-to-answer immunoassay systems are still under development. In this study, we proposed a lateral-flow immunoassay system utilizing a polymer sheet with microcone array structures fabricated by thermal imprinting. By adding a surfactant to the running/washing buffer, we were able to dispense with complicated chemical modification protocols, which are usually necessary to enhance antibody adsorption. We investigated three types of polymeric materials and confirmed that polycarbonate is most suitable as an imprinted polymer substrate. Experiments using microcone arrays with different distances revealed that the increased surface area with nanometer-scale surface roughness was key to achieving stable immobilization of antibodies. To assess the applicability of this assay to clinical diagnosis, C-reactive protein in a pure buffer and in a serum sample was analyzed as a model, with a ∼0.1 μg mL-1 lower limit of detection. The presented approach would open a new path to the development of immunoassay-based on-site point-of-care testing by virtue of its simplicity of operation, high sensitivity, and versatility.