High-resolution biosensor based on localized surface plasmons

Abstract

We report on a new biosensor with localized surface plasmons (LSP) based on an array of gold nanorods and the total internal reflection imaging in polarization contrast. The sensitivity of the new biosensor is characterized and a model detection of DNA hybridization is carried out. The results are compared with a reference experiment using a conventional high-resolution surface plasmon resonance (SPR) biosensor. We show that the LSP-based biosensor delivers the same performance as the SPR system while involving significantly lower surface densities of interacting molecules. We demonstrate a limit of detection of 100 pM and a surface density resolution of only 35 fg×mm-2 that corresponds to less than one DNA molecule per nanoparticle on average.

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

“…However, the claimed enhanced sensitivity that nanoplasmonic sensor devices can reach has not been fully achieved yet, and there is in fact some controversy in the field regarding the real improvement that LSPR can provide compared to conventional SPR sensors [7][8][9]. Conventional SPR sensors have proven effectiveness in the monitoring and characterization of biomolecular interactions with a sensitivity that usually ranges between 10 -5 and 10 -7 refractive index units (RIU).…”

“…Whereas, in terms of bulk sensitivity, SPR clearly outperforms LSPR [11], a significantly better surface sensitivity can be theoretically obtained in LSPR [11]. In general terms, although some publications have dealt with this controversy [7,8,11], there is still a lack of convincing studies that confirm whether nanoplasmonics is competitive enough with SPR in terms of surface sensing performance. However, a few recent works demonstrate that sensitivity levels are in the same order of magnitude, although the sensitivity seems to improve and be higher at low analyte concentration in the case of LSPR, both in a competitive assay [12] and in direct approaches [13,14].…”

Evaluation of the pH-sensitive swelling of a hydrogel by means of a plasmonic sensor substrate

“…To this end we bring a pHsensitive hydrogel into contact with a nanostructured metal surface, which supports surface plasmon oscillations. The plasmon oscillation is sensitive to changes in the refractive index which occur during swelling-deswelling of the hydrogel, which, in turn, reflects in spectral changes in the transmittance spectrum of the metal nanostructure (Piliarik et al, 2012;Yang et al, 2015;Zalyubovskiy et al, 2012). The refractive index sensitivity is confined to the very surface of the nanostructure so that rather thin hydrogel layers can be used as pH-sensitive material, which will consequently lead to faster response times.…”

A multiplexed label free plasmonic nano-device for near infrared applications

“…The chips for prismbased SPR detection do not require nanofabrication processes (a thin metallic layer is deposited above the prism surface) and the use of a reflective geometry decouples optical signals from fluidic channels [6,16,17].…”