Gold surface plasmon crystal structure based-on polystyrene template for biosensor application

Polystyrene microspheres with ultra-rough surfaces engineered using RIE technique and applied using SERS

In this study, we successfully fabricated two ultra-rough surfaces based on polystyrene (PS) microspheres by employing the reactive ion etching (RIE) technique. Elemental analysis confirmed a stable AlF3 composition of the structures of these surfaces. We proposed the mechanism of the formation of these surfaces and performed SERS-related tests; the prepared substrates exhibited excellent SERS performance.

Label-Free Near-Infrared Plasmonic Sensing Technique for DNA Detection at Ultralow Concentrations

Biomolecular detection at a low concentration is usually the most important criterion for biological measurement and early stage disease diagnosis. In this paper, a highly sensitive nanoplasmonic biosensing approach is demonstrated by achieving near-infrared plasmonic excitation on a continuous gold-coated nanotriangular array. Near-infrared incident light at a small incident angle excites surface plasmon resonance with much higher spectral sensitivity compared with traditional configuration, due to its greater interactive volume and the stronger electric field intensity. By introducing sharp nanotriangular metallic tips, intense localization of plasmonic near-fields is realized to enhance the molecular perception ability on sensing surface. This approach with an enhanced sensitivity (42103.8 nm per RIU) and a high figure of merit (367.812) achieves a direct assay of ssDNA at nanomolar level, which is a further step in label-free ultrasensitive sensing technique. Considerable improvement is recorded in the detection limit of ssDNA as 1.2 × 10-18 m based on the coupling effect between nanotriangles and gold nanoparticles. This work combines high bulk- and surface-sensitivities, providing a simple way toward label-free ultralow-concentration biomolecular detection.