New trends in instrumental design for surface plasmon resonance-based biosensors

Abstract

Surface plasmon resonance (SPR)-based biosensing is one of the most advanced label free, real time detection technologies. Numerous research groups with divergent scientific backgrounds have investigated the application of SPR biosensors and studied the fundamental aspects of surface plasmon polaritons that led to new, related instrumentation. As a result, this field continues to be at the forefront of evolving sensing technology. This review emphasizes the new developments in the field of SPR-related instrumentation including optical platforms, chips design, nanoscale approach and new materials. The current tendencies in SPR-based biosensing are identified and the future direction of SPR biosensor technology is broadly discussed.

Fig. 1

Electric field (E_z) distribution in the direction normal to the metal-dielectric interface during surface plasmon resonance. The normalized E_z intensity as a function of the distance from the interface shows the field enhancement and the exponential decay at 650 nm excitation wavelength for three metals: silver (50 nm; n=0.0666+ i 4.045), gold (50 nm; n=0.180+ i 3.55) and copper (50 nm; n=0.22+ i 3.54). The dielectric medium is water (n=1.333).

Fig. 2

Coupling schemes of incident light to surface plasmons: (a) prism coupling, (b) grating coupling, and (c) waveguide coupling. ( K_ph: wave vector of the incident light, K_sp: wave vector of the surface plasmons, K_g: wave vector of the guided mode, Λ: periodicity of the grating, m: diffraction order).

Fig. 3

SPR image of the interaction of different antibodies with human IgG inside the microchannels (top) and cross-sectional line profile (bottom). From left to right: IgG-anti6, IgG-anti8, IgG-anti7 and IgG-anti9. The inset is the calibration curve for IgG anti9 (Figure reproduced with permission from Dong et al., 2008).

Fig. 4

Sub-wavelength Nanoholes array for SPR biosensing. The nanoholes are fabricated in a metal layer (Au, Ag or Al) deposited on a quartz or glass slide or perforated silicon nitride membrane to enable the flow through the nanoholes. The detection is performed in transmission mode (collinear optics) for SPR spectroscopy or microscopy. The values indicated for gold thickness d, the nanohole diameter Φ, the periodicity a, and the incident wavelength λ represent the most used parameters in the literature.

Fig. 5

Different materials used in SPR-based chips.

Fig. 6

Hyphenation approach of SPR technology. The thick unidirectional arrows show the serial use of different analytical instruments. The HPLC/μFFE-SPR-MS sequence represents one of the most relevant combinations. The thin bidirectional arrows represent the exploitation of surface plasmons resonance phenomenon by another analytical technique.