Active Control of SPR by Thermoresponsive Hydrogels for Biosensor Applications

Abstract

The use of thermoresponsive poly(N-isopropylacrylamide)-based hydrogel (pNIPAAm) for rapid tuning of surface plasmon resonance (SPR) is reported. This approach is implemented by using an SPR layer architecture with an embedded indium tin oxide microheater and pNIPAAm film on its top. It takes advantage of rapid thermally induced swelling and collapse of pNIPAAm that is accompanied by large refractive index changes and leads to high thermo-optical coefficient of dn/dT = 2 × 10–2 RIU/K. We show that this material is excellently suited for efficient control of refractive index-sensitive SPR and that it can serve simultaneously as a 3D binding matrix in biosensor applications (if modified with biomolecular recognition elements for a specific capture of target analyte). We demonstrate that this approach enables modulating of the output signal in surface plasmon-enhanced fluorescence spectroscopy biosensors and holds potential for simple time-multiplexing of sensing channels for parallelized readout of fluorescence assays.

Dynamic Response of Anchored Poly(N‐isopropylacrylamide‐co‐methacrylic acid‐co‐benzophenone methacrylate) Terpolymer Hydrogel Layers to Physicochemical Stimuli

“…Poly( N ‐isopropylacrylamide) (PNIPAAm)‐based layers grafted onto solid substrates have been promoted by their large potential in biosensor applications . The precise design of PNIPAAm‐based sensor systems requires detailed knowledge of their structural and dynamical properties . Dynamics are expected to be particularly relevant for the diffusion of solutes into the gel layers, and for the time response following change of condition.…”

“…[ 14 ] The precise design of PNIPAAm-based sensor systems requires detailed knowledge of their structural and dynamical properties. [ 15 ] Dynamics are expected to be particularly relevant for the diffusion of solutes into the gel layers, and for the time response following change of condition. The current literature primarily reports on structural studies of grafted PNIPAAm layers using a variety of experimental techniques like surface plasmon resonance (SPR), [ 16,17 ] neutron refl ectivity, [18][19][20] AFM, [ 21 ] and quartz crystal microbalance methods.…”

Actively Tunable Collective Localized Surface Plasmons by Responsive Hydrogel Membrane

“…We demonstrate that the temperature modulation or exchanging the solvent allows for reversible shifting of plasmonic resonances in the near infrared part of the spectrum by up to 150 nm, which exceeds the spectral width of the resonance as low as 13 nm and allows its complete switching “on” and “off.” The potential capabilities for biosensing with the tethered configuration employing a hydrogel that can be post‐modified with protein ligands are assessed for the refractometric localized surface plasmon resonance biosensors, where a figure of merit as high as 29 was observed. The plasmonic architectures with on‐demand tunable optical properties also hold potential to be employed as active plasmonic substrates in other biosensor modalities taking advantage of plasmonically amplified optical spectroscopy and in miniature machines . For instance, the tunable plasmonic wavelength may find its applications in multiplexed plasmon‐enhanced fluorescence sensing or for the fine‐tuning of surface‐enhanced Raman spectroscopy enhancement for specific vibration bands.…”

Lab on Fiber Technology for biological sensing applications

“…MGs essentially are multiresponsive microsized cross‐linked polymer particles . In the presence of external stimuli (for example a variation of PH or temperature of the solution in which they are immersed), but also in response to ligand/analyte interactions, functionalized MGs respond by changing their structure, in terms of density and dimensions . In this framework, a novel device has been recently proposed, characterized by a MGs layer baked by a plasmonic nanostructure integrated on the optical fiber facet (see Fig.…”