Excellent Protein Immobilization and Stability on Heterogeneous C–TiO₂ Hybrid Nanostructures: A Single Protein AFM Study

Abstract

Enhancing molecular interaction is critical for improving the immobilization and stability of proteins on TiO 2 surfaces. In this work, mesoporous TiO 2 materials with varied pore geometries were decorated with phenyl phosphoric acid (PPA), followed by a thermal treatment to obtain chemically heterogeneous C−TiO 2 samples without changing the geometry and crystalline structure, which can keep the advantages of both carbon and TiO 2 . The molecular interaction force between the protein and the surfaces was measured using atomic force microscopy by decomposing from the total adhesion forces, showing that the surface chemistry determines the interaction strength and depends on the amount of partial carbon coverage on the TiO 2 surface (∼40−80%). Samples with 58.3% carbon coverage provide the strongest molecular interaction force, consistent with the observation from the detected friction force. Surface-enhanced Raman scattering and electrochemical biosensor measurements for these C−TiO 2 materials were further conducted to illustrate their practical implications, implying their promising applications such as in protein detection and biosensing.

Hydrated Ionic Liquids Boost the Trace Detection Capacity of Proteins on TiO2 Support

“…Regulating active substrates is often used to enhance the sensitivity (i.e., intensity) and selectivity for trace detection, especially for the semiconductor-based SERS techniques , with a low SERS intensity. Methods such as metal doping, use of composites, , as well as structure optimization and modification , have been used to increase the SERS intensity. Intrinsically, the SERS intensity is strongly related to the interactions among the adsorbed molecules and their electron-transfer ability, implying that regulating them is essential to improve the enhancement and to lower the limit of detection.…”

In silico study of substrate chemistry effect on the tethering of engineered antibodies for SARS-CoV-2 detection: Amorphous silica vs gold

“…The effect of surface chemistry on the stability and activity of immobilized proteins is critical in many fields, including biosensing, drug delivery and biofuel cells [1] , [2] , [3] , [4] , [5] , [6] , [7] , [8] . Because of this influence, the immobilization of proteins has been investigated using a variety of support materials, as for example gold [9] , [10] , silica [11] , [12] , carbon nanotubes [13] , [14] , graphene [15] , [16] , and self-assembled monolayers [17] , [18] .…”

“…Thus, determination of the strength of the interactions on the macroscale using adsorption capacity measures and electrical signals is not adequate. Instead, microscale measures using, for example, atomic force microscopy (AFM)-based methods enable quantification of the force between single protein molecules and the substrate surface [2] , [19] , [20] , [21] , [22] , [23] , even though identification of the key microscopic features affecting the stability of the immobilized protein is not possible.…”

Molecular Mechanistic Insights into the Ionic-Strength-Controlled Interfacial Behavior of Proteins on a TiO2Surface

“…), finding that these molecular forces depend both on the properties of the protein and the solid surface and the pH conditions but not the surface roughness. Importantly, these determined molecular forces can be further used as a guideline to design the macroscopic experiments, including protein separation measured by high-performance liquid chromatography, surface-enhanced Raman scattering (SERS)-based protein biodetection, and electron transfer ability of the enzyme tested using an electrochemical biosensor . We found that the magnitude of the ionic strength, induced by the buffer ions, significantly alters the interfacial process performance, while how the ionic strength affects the molecular interaction at the microscale and then influences the performance at the macroscale has not yet been clarified.…”