Plasmonic Nanosensors for Simultaneous Quantification of Multiple Protein–Protein Binding Affinities

Abstract

Most of current techniques used for the quantification of protein-protein interactions require the analysis of one pair of binding partners at a time. Herein we present a label-free, simple, fast, and cost-effective route to characterize binding affinities between multiple macromolecular partners simultaneously, using optical dark-field spectroscopy and individual protein-functionalized gold nanorods as sensing elements. Our NanoSPR method could easily become a simple and standard tool in biological, biochemical, and medical laboratories.

Organization into Higher Ordered Ring Structures Counteracts Membrane Binding of IM30, a Protein Associated with Inner Membranes in Chloroplasts and Cyanobacteria

“…Polarizability can change because of the formation of a dense layer around the particle or even because of binding of a single protein (17,23). We calculate the shift of the plasmon resonance wavelength induced by the binding of a single IM30 ring ⌬ ring to compare this shift with those shifts measured in experiments to estimate the presence or absence of ring binding events.…”

“…Additionally, we show that also low molecular weight IM30 species bind to membrane surfaces, using NanoSPR (17) and an IM30 mutant that does not form stable ring structures anymore. In fact, the membrane binding affinity of these lower ordered IM30 species is increased when compared with IM30 proteins organized in ring structures.…”

“…To follow up on this observation, we studied the IM30 WT adsorption to lipid bilayers using the NanoSPR technique we recently introduced (17). NanoSPR works similar to conventional SPR sensors with the important difference that the sensor elements, the gold nanoparticles, have dimensions approaching the molecular size of proteins.…”

Polarization and mutual coupling effects in aluminum nanoantenna arrays

“…Nanoantennas are nanoscale devices which couple freely propagating light to localised surface plasmons and vice-versa. Applications of the technology range from imaging to photonic circuits and sensors [5][6][7][8][9]. When an optical emitter such as a quantum dot or fluorophore is brought into close proximity to a nanoantenna, Purcell enhanced emission can occur [4,10,11].…”

Fourier Transform Surface Plasmon Resonance (FTSPR) with Gyromagnetic Plasmonic Nanorods

“…[1] Among these efforts,l ocalized surface plasmon resonance (LSPR), ac ollective excitation of conductive electrons in metallic nanoparticles when irradiated with light, has spurred great interest with regard to biological sensing applications due to its mechanistic simplicity,w hich relies on the refractive index change in the surrounding media. [2][3][4] However,colloidal dispersion systems consisting of plasmonic nanoparticles show insufficient plasmon shifting upon changes in the local refractive index;t hus,t remendous efforts have been made to increase the sensitivity by either constructing complex nanostructures to enhance the local electric field or by designing sensing platforms with systematic configurations. [5] On the other hand, owing to its biocompatibility and remote controllability,u sage of an external magnetic field offers simultaneous and reversible modulation, which holds great promise for av ariety of applications.…”