RESUMO
This paper reports a digital micro-mirror device (DMD)-enabled real-time multi-channel biosensing system based on angular interrogation surface plasmon resonance (SPR). In the experiments, angular scanning is achieved by a DMD that facilitates SPR measurements using a single-point photodetector. In the four-channel measurement setup, real-time monitoring of bovine serum albumin (BSA) and anti-BSA binding interactions is performed at various concentration levels. The experimental results have verified that the system has a resolution of 3.54 × 10-6 RIU (refractive index unit); and a detection limit of 9 ng/mL. The new DMD-based SPR interrogation system presents a new design route for practical solid-state SPR biosensing with a user-selectable range of interrogation, enhanced signal-to-noise ratio, and fast data throughput.
RESUMO
Incorporating the temporal carrier technique with common-path spectral interferometry, we have successfully demonstrated an advanced surface plasmon resonance (SPR) biosensing system which achieves refractive index resolution (RIR) up to 2 × 10(-8) refractive index unit (RIU) over a wide dynamic range of 3 × 10(-2) RIU. While this is accomplished by optimizing the SPR differential phase sensing conditions with just a layer of gold, we managed to address the spectral phase discontinuity with a novel spectral-temporal phase measurement scheme. As the new optical setup supersedes its Michelson counterpart in term of simplicity, we believe that it is a significant contribution for practical SPR sensing applications.
RESUMO
Two-dimensional surface plasmon resonance (2D-SPR) imaging, which provides a real-time, sensitive, and high-throughput analysis of surface events in a two dimensional manner, is a valuable tool for studying biomolecular interactions and biochemical reactions without using any tag labels. The sensing principle of 2D-SPR includes angular, wavelength, and phase interrogation. In this chapter, the 2D-SPR imaging technique is applied for sensing a target microRNA by its corresponding oligonucleotide probes, with sequence complementarity, immobilized on the gold SPR sensing surface. However, the low SPR signal due to intrinsic properties such as low molecular weight and quantity (pico-nanomolar) of the microRNA in clinical samples limits the direct detection of microRNA. Therefore, we developed a biosensing technique known as MARS (MicroRNA-RNase-SPR) assay, which utilizes RNase H to digest the microRNA probes enzymatically for fast signal amplification, i.e., in order to increase both the SPR signal and readout speed without the need for pre-amplification of target cDNA by polymerase chain reaction (PCR). Practically, we targeted microRNA hsa-miR-29a-3p, whose signature correlates to influenza infection, for rapid screening of influenza A (H1N1) patients from throat swab samples.