Reversible pH-Driven Conformational Switching of Tethered Superoxide Dismutase with Gold Nanoparticle Enhanced Surface Plasmon Resonance Spectroscopy

Abstract

A new class of surface-immobilized protein nanomachines can be reversibly actuated by cycling the solution pH between 2.5 and 12.3, which induces a conformational change, thereby modulating the thickness of superoxide dismutase (SOD1) tethered to the Au thin film. By placing Au nanoparticles (AuNP) atop the immobilized SOD1 by means of a gold-thiol assembly, the nanoscale motion of SOD1 at the interface produces mechanical work to lift and then lower the AuNP from the Au substrate by a distance of ca. 3 nm and transduces this motion into an easily measurable reflectivity change in the surface plasmon resonance (SPR) spectrum. As-made supported conjugate consisting of SOD1 and AuNP is quite robust and stable, and its operation in response to pH variations, which mirrors the conformational changes of responsive SOD1 at the interface, is found to be highly reversible and reproducible. This is the first demonstration of the development of novel solid-state sensors and/or switching devices based on substrate-bound protein conformational changes and AuNP enhanced SPR spectroscopy.

Individual Ag Nanowire Dimer for Surface-Enhanced Raman Scattering

“…2c reveals that |E| 2 at the tip apex does exhibit a larger value with θ=0°than that with θ=90°as lightning rod effect predicts. (2) The global maximum of localized |E| 2 is simulated to be about 5, 66, and 8 for the AgNW-a body, the dimer, and AgNW-a tip, respectively, whose quantitative order follows well with that of their experimental SERS intensities. It also theoretically confirms the most efficient SERS behavior of the dimeric part among the three different parts.…”

“…Surface-enhanced Raman scattering (SERS) provides a powerful technique to detect and identify chemical/ biological molecules with ultrahigh sensitivity, even down to single molecule level [1][2][3][4][5][6]. It is noted that noble metal nanostructures, commonly Ag and Au, have been widely used as effective SERS substrates owing to their unique optical properties.…”

The biocompatability of mesoporous inorganic–organic hybrid resin films with ionic and hydrophilic characteristics

“…Protein adsorptions to the resin thin films were measured at room temperature using an SPR spectrometer (K-MAC, Daejeon, Korea) with a monochromatic laser light source at a wavelength of 780 nm according to a method described elsewhere [33,34]. In the measurements, resin films, which were coated with 15-20 nm thickness on glass prisms deposited with 50 nm thick gold layer, were used.…”

Au NPs-enhanced surface plasmon resonance for sensitive detection of mercury(II) ions

“…Surface plasmon resonance (SPR) is one of the most exciting surface-sensitive techniques for detecting analytes adsorbed on a metal surface (Homola et al, 1999;Kang et al, 2006;Li et al, 2007;Riskin et al, 2006;Su and Zhang, 2004). In the last decades, great progress has been achieved in the development of SPR for the macro-biomolecular interaction analyses (BIA), such as protein-protein binding (Berger et al, 1998;Heyse et al, 1998), DNA hybridization (He et al, 2000;Jordan et al, 1997;Peterlinz et al, 1997;Thiel et al, 1997), and antigen-antibody association processes (Kaganer et al, 1999;Tanga et al, 2007).…”