Surface-enhanced infrared absorption spectroscopy and electrochemistry reveal the impact of nanoparticles on the function of protein immobilized on mimic biointerface

Abstract

Surface-enhanced infrared absorption spectroscopy and electrochemistry reveal the impact of nanoparticles on the function of protein immobilized on mimic biointerface, Electrochimica Acta http://dx. AbstractStudy of the interactions between engineered nanoparticles and biomolecules plays an important role in understanding nano-bio effect. However, most of studies focus on the interaction of protein with nanoparticle in bulk phase, the impact of nanoparticle on the function of protein immobilized on the biological interface has been ignored for a long time. In this paper, we study the effect of SiO2 NPs on electron transfer function of cytochrome c (cyt c) adsorbed onto the 11-mercaptoundecanoic acid (MUA) self-assembled monolayer (SAM) by surface-enhanced infrared absorption spectroscopy (SEIRAS) combined with electrochemistry. Our results disclose that instead of inhibiting the electron transfer, exposure of SiO2 NPs enhances the redox reversibility, electron transfer rate, and catalytic performance of adsorbed cyt c, but induces a slight negative shift in the formal potential of the adsorbed cyt c. Interaction of SiO2 NPs slightly induces the structural changes of the β-sheet in the oxidized form and the change of microenvironment surrounding them, which could further change the microenvironment and the orientation of heme, facilitating the hydration of cyt c at the oxidized state. It could be the enhanced hydration of cyt c (Fe 3+ ) and a smaller change in the total hydration from reduced to oxidized state that results in the slight negative shift in the formal potential and promotes the electron transfer capability. Besides, cyt c's slight conformational change and the disturbance to the microenvironment of heme resulting from the adsorption of SiO2 NPs could also be one of the reason that leads to the enhanced catalytic capability towards the reduction of H2O2.

In Situ Characterization of Protein Adsorption onto Nanoparticles by Fluorescence Correlation Spectroscopy

“…It measures the heat involved in NP–protein binding reactions rather than a size change. , Importantly, ITC provides not only the binding affinity but also enthalpy changes and binding stoichiometry between NPs and proteins in solution, which can be most helpful for further elucidation of corona formation. Other techniques such as surface plasmon resonance (SPR), fluorescence spectroscopy, , circular dichroism, nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), , and Raman spectroscopy , have also been utilized for quantitative studies of protein interactions with NPs in biological fluids. As each individual method has its own advantages and disadvantages, the choice of the characterization method depends on the specific NP–protein system and the scientific questions. , Usually, a combination of different approaches is necessary to comprehensively analyze NP–protein interactions and to understand the biological responses to the adsorption layer.…”

Disc Antenna Enhanced Infrared Spectroscopy: From Self-Assembled Monolayers to Membrane Proteins

“…Most relevant to biomembrane research is the ability to detect monolayers of adsorbed molecules. Herein, conformational changes of membrane proteins in surface-tethered systems have been resolved, − the folding reaction of membrane proteins has been traced , and protein–protein interactions have been monitored by SEIRAS. , …”

Exploring the pH Sensitivity of Ion-Pair Interactions on a Self-Assembled Monolayer by Scanning Electrochemical Microscopy

“…Many fundamental and central biological processes involve weak interactions (e.g., electrostatic interactions, hydrogen bonds, and hydrophobic interactions) between biomacromolecules and other bioactive species, and a well-known example is the specific recognition and association between proteins and ligands. − Therefore, an in-depth comprehension of the chemical essence of binding events occurring on biological surfaces at the molecular level is of particular interest, with the intent to understand the underlying workings of weak interactions and further manipulate complicated biological processes. Great effort has been exerted to investigate the mechanisms of weak interactions between biomacromolecules and organic or inorganic species through experimental and theoretical means. − The electrostatic interactions are typically found to dominate the overall binding process since most biomolecules are electrically charged in a physiological environment. − Meanwhile, molecule structures, especially charged groups, are demonstrated as the primary determinant of the strength of electrostatic interactions, allowing for binding processes to be affected by rational structural selection and charge regulation. , In contrast to simple electrostatic interactions (electrostatic attraction and repulsion), ion-pair interactions formed by a specific pair of oppositely charged ions place more emphasis on electrostatic attraction and show directional characteristics, especially when structural organic ions are involved, playing an essential role in the maintenance of biomolecular functions and participation in biological processes. − Notably, ion-pair interactions exhibit a significant dependence on the charged states of biomolecules, which implies the feasibility of artificially tuning ion-pair interactions by appropriately changing relevant system parameters (e.g., pH and salt concentration). , Thus, further studies of the intrinsic properties and chemical essence of ion-pair interactions on the biomolecular surface are essential and meaningful. However, in practice, the ion-pair interactions during surface binding are destined to be intricate due to the structural and molecular complexity of biomolecules.…”