Lensfree optofluidic plasmonic sensor for real-time and label-free monitoring of molecular binding events over a wide field-of-view

Abstract

We demonstrate a high-throughput biosensing device that utilizes microfluidics based plasmonic microarrays incorporated with dual-color on-chip imaging toward real-time and label-free monitoring of biomolecular interactions over a wide field-of-view of >20 mm2. Weighing 40 grams with 8.8 cm in height, this biosensor utilizes an opto-electronic imager chip to record the diffraction patterns of plasmonic nanoapertures embedded within microfluidic channels, enabling real-time analyte exchange. This plasmonic chip is simultaneously illuminated by two different light-emitting-diodes that are spectrally located at the right and left sides of the plasmonic resonance mode, yielding two different diffraction patterns for each nanoaperture array. Refractive index changes of the medium surrounding the near-field of the nanostructures, e.g., due to molecular binding events, induce a frequency shift in the plasmonic modes of the nanoaperture array, causing a signal enhancement in one of the diffraction patterns while suppressing the other. Based on ratiometric analysis of these diffraction images acquired at the detector-array, we demonstrate the proof-of-concept of this biosensor by monitoring in real-time biomolecular interactions of protein A/G with immunoglobulin G (IgG) antibody. For high-throughput on-chip fabrication of these biosensors, we also introduce a deep ultra-violet lithography technique to simultaneously pattern thousands of plasmonic arrays in a cost-effective manner.

Biosensors and bioelectronics on smartphone for portable biochemical detection

“…Then, the selective detection of concentration-dependent binding of antibodies can be implemented in the same way. Especially, the smartphone-based SPR sensor system can also be used in transmission measurement for other nano-SPR devices, such as nanoholes, nanorods, and nanocones (Coskun et al, 2014).…”

Emerging applications of label-free optical biosensors

“…However, to date, only a few truly compact devices have been demonstrated in the literature. Among these, a portable and simple biosensing device was exploited in combination with an array of plasmonic nano-holes integrated in a microfluidic cell ( Figure 2E) [17]. Notably, a similar sensing substrate used in a different portable device enabled the detection and molecular profiling of exosomes [22].…”

Recent advances in nanoplasmonic biosensors: applications and lab-on-a-chip integration

“…However, it has a limited sensitivity (in the range of microgram per milliliter) and it lacks microfluidics. The authors incorporated a flow cell (single channel) for sample and fluid handling in an upgraded version of the device [39]. Regarding sensing performance, the authors also combined two different LED sources spectrally located in the extremes of the plasmonic resonance mode, yielding two different diffraction patterns for each nanohole array.…”