Improved localized surface plasmon resonance biosensing sensitivity based on chemically-synthesized gold nanoprisms as plasmonic transducers

Abstract

Supporting substrate attached gold nanostructures display localized surface plasmon resonance (LSPR) properties at the visible and near-infrared (NIR) wavelengths. The LSPR wavelength is very responsive to the refractive index of the surrounding medium, allowing simple label-free biosensing when biomolecules are irreversibly adsorbed onto nanostructures. Herein, we show that chemically synthesized gold nanoprisms with 22 nm average edge lengths are very efficient plasmonic transducers for label-free biosensing. The LSPR properties of gold nanoprisms on silanized glass substrate were investigated and readily influenced by bulk refractive index changes and local changes very close to the sensing surface due to the analyte adsorption. The nanoprisms had a 583 nm/RIU (1.62 eV/RIU) refractive index sensitivity and a 4.9 figure of merit (FOM). In addition, the nanoprism surface was modified with straight chain alkanethiols. The LSPR wavelength (l max ) of chemisorbed nanoprisms on glass was very sensitive to surface modification by straight chain alkanethiols and linearly red-shifted by 2.5 nm with every methylene unit of the alkanethiol chain. Importantly, the biotin functionalized nanoprisms displayed red-shifts in l max upon streptavidin (SA) binding. The lowest SA concentration was measured to be 50 pM, much lower than gold nanospheres, nanorods, bipyramids, and nanostars.

Glucose-functionalized Au nanoprisms for optoacoustic imaging and near-infrared photothermal therapy

“…The band at 530 nm is attributed to the byproducts of the Au nanoparticles. 44 From the SEM image and AFM measurement, it is found that the asprepared Au NPrs are flat NPs with three congruent edge lengths of 94 nm and thicknesses of 10 nm (Fig. 1b, c and e).…”

Integrated Collinear Refractive Index Sensor with Ge PIN Photodiodes

“…A comparison of our experimental results with experimental data from selected conventional, non-integrated plasmonic structures for refractive index sensing shows that the sensitivity in our setup is markedly higher than what can be observed for plasmonic Au nanoparticles 12 and, in particular, exceeds the sensitivities typically obtained in Al nanohole arrays 27 (see table 1). 28 700 647 Au nanocross 29 1400 500 Au nanopillar 30 1300 -1500 1000 Periodic array of Au mushrooms 31 1260 1010 Hybrid Au nanohole array 15 650 -700 670 Suspended NHA in Au film 32 795 717 Passivated Al NHA 27 700 -750 487 This work 1310 -1350 1180 When the device is incorporated into a microfluidic setup with a laser diode as the vertical illumination light source 33 , the operating wavelength λop is fixed. In this operating mode, a resonance peak shift induced by a change in nSup can be detected as a change in responsivity at λop.…”

Synergistic enhancement via plasmonic nanoplate-bacteria-nanorod supercrystals for highly efficient SERS sensing of food-borne bacteria

“…Triangular silver nanoplate is a powerful candidate within anisotropic plasmonic nanoparticles for constructing the chemical or biological sensors due to their thinness as compared to nanosphere, leading to a significant extension of the electromagnetic field farther from their surface. Furthermore, the three tips of the nanoplates with larger refractive index sensitivity dramatically contributes to their near-field electromagnetic enhancement localized the tips [33][34][35]. As shown in Fig.…”