Molecular Interactions of Protein with TiO<sub>2</sub> by the AFM-Measured Adhesion Force

Dong, Yihui; An, Rong; Zhao, Shuangliang; Cao, Weixiao; Huang, Liangliang; Zhuang, Wei; Lü, Linghong; Lü, Xiaohua

doi:10.1021/acs.langmuir.7b02024

Cited by 28 publications

(49 citation statements)

References 54 publications

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“…The protein molecules of Cyt c were immobilized on the AFM tips coated with gold (NPG-10, Si 3 N 4 , tip radius: 20 nm) by a chemical attachment with almost the same procedure used for other proteins. 39 There is a little difference during the last step, where the tips were immersed into 5 mg·mL –1 Cyt c solution (two tips: one was for the measured-system without ILs, and the other was for the measured-system with the ILs immobilized on TiO 2 substrate) and with 0.01 g ILs adding into 5 mg·mL –1 Cyt c solution (one tip for the measured-system with ILs in PBS), respectively. The tips were washed with the PBS solutions and then dried with N 2 .…”

Section: Experimental Sectionmentioning

confidence: 99%

“…42 For a molecular-level understanding of the mechanism, quantifying the molecular force of Cyt c on the TiO 2 nanotube array in three different systems should be addressed first, where the values are obtained based on the combination of the adhesion force per unit contact area and the protein adsorption capacity per unit area, according to our previous work. 39 As we discussed above, on the small film-like TiO 2 nanotube array substrate, it is difficult to obtain the capacity of protein adsorption due to the trace amount. In this work, the mesoporous TiO 2 microparticles with different surface areas were used to provide the molecular force, and the provided molecular force is independent of the geometric structure of the materials as revealed in our previous work.…”

Section: Determination Of the Enhancement Factor (Ef)mentioning

confidence: 99%

“…It implies that the measurements at the microscale are critically needed. In our previous work, based on the atomic force microscopy (AFM), a method was proposed to determine the molecular force between the protein molecules and different TiO 2 surfaces. , However, applying this method to capture the interactions and to understand the SERS mechanism at the molecular level has not yet been carried out. Meanwhile, the enhancement factor (EF) is an essential parameter and key index in the field of SERS.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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Trace detection based on surface-enhanced Raman scattering (SERS) has attracted considerable attention, and exploiting efficient strategies to stretch the limit of detection and understanding the mechanisms on molecular level are of utmost importance. In this work, we use ionic liquids (ILs) as trace additives in a protein-TiO 2 system, allowing us to obtain an exceptionally low limit of detection down to 10 –9 M. The enhancement factors (EFs) were determined to 2.30 × 10 4 , 6.17 × 10 4 , and 1.19 × 10 5 , for the three systems: one without ILs, one with ILs in solutions, and one with ILs immobilized on the TiO 2 substrate, respectively, corresponding to the molecular forces of 1.65, 1.32, and 1.16 nN quantified by the atomic force microscopy. The dissociation and following hydration of ILs, occurring in the SERS system, weakened the molecular forces but instead improved the electron transfer ability of ILs, which is the major contribution for the observed excellent detection. The weaker diffusion of the hydrated IL ions immobilized on the TiO 2 substrate did provide a considerably greater EF value, compared to the ILs in the solution. This work clearly demonstrates the importance of the hydration of ions, causing an improved electron transfer ability of ILs and leading to an exceptional SERS performance in the field of trace detection. Our results should stimulate further development to use ILs in SERS and related applications in bioanalysis, medical diagnosis, and environmental science.

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Section: Experimental Sectionmentioning

confidence: 99%

Section: Determination Of the Enhancement Factor (Ef)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…Dong et al investigated the adhesion between a protein and a TiO 2 substrate by using a lysozyme-modified tip [ 43 ]. The adhesion was measured by the force jump upon retraction, i.e., identified as the pull-off force necessary for separation of the tip from the surface.…”

Section: Afm Techniquesmentioning

confidence: 99%

Atomic Force Microscopy (AFM) on Biopolymers and Hydrogels for Biotechnological Applications—Possibilities and Limits

2022

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Atomic force microscopy (AFM) is one of the microscopic techniques with the highest lateral resolution. It can usually be applied in air or even in liquids, enabling the investigation of a broader range of samples than scanning electron microscopy (SEM), which is mostly performed in vacuum. Since it works by following the sample surface based on the force between the scanning tip and the sample, interactions have to be taken into account, making the AFM of irregular samples complicated, but on the other hand it allows measurements of more physical parameters than pure topography. This is especially important for biopolymers and hydrogels used in tissue engineering and other biotechnological applications, where elastic properties, surface charges and other parameters influence mammalian cell adhesion and growth as well as many other effects. This review gives an overview of AFM modes relevant for the investigations of biopolymers and hydrogels and shows several examples of recent applications, focusing on the polysaccharides chitosan, alginate, carrageenan and different hydrogels, but depicting also a broader spectrum of materials on which different AFM measurements are reported in the literature.

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“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Martí

Martín-Martínez

Torras

et al. 2022

Colloids and Surfaces B: Biointerfaces

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The influence of the properties of different solid substrates on the tethering of two antibodies, IgG1-CR3022 and IgG1-S309, which were specifically engineered for the detection of SARS-CoV-2, has been examined at the molecular level using conventional and accelerated Molecular Dynamics (cMD and aMD, respectively). Two surfaces with very different properties and widely used in immunosensors for diagnosis, amorphous silica and the most stable facet of the face-centered cubic gold structure, have been considered. The effects of such surfaces on the structure and orientation of the immobilized antibodies have been determined by quantifying the tilt and hinge angles that describe the orientation and shape of the antibody, respectively, and the dihedrals that measure the relative position of the antibody arms with respect to the surface. Results show that the interactions with amorphous silica, which are mainly electrostatic due to the charged nature of the surface, help to preserve the orientation and structure of the antibodies, especially of the IgG1-CR3022, indicating that the primary sequence of those antibodies also plays some role. Instead, short-range van der Waals interactions with the inert gold surface cause a higher degree tilting and fraying of the antibodies with respect to amorphous silica. The interactions between the antibodies and the surface also affect the correlation among the different angles and dihedrals, which increases with their strength. Overall, results explain why amorphous silica substrates are frequently used to immobilize antibodies in immunosensors.

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Molecular Interactions of Protein with TiO₂ by the AFM-Measured Adhesion Force

Cited by 28 publications

References 54 publications

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

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

Atomic Force Microscopy (AFM) on Biopolymers and Hydrogels for Biotechnological Applications—Possibilities and Limits

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

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Molecular Interactions of Protein with TiO2 by the AFM-Measured Adhesion Force

Cited by 28 publications

References 54 publications

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

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

Atomic Force Microscopy (AFM) on Biopolymers and Hydrogels for Biotechnological Applications—Possibilities and Limits

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

Contact Info

Product

Resources

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Molecular Interactions of Protein with TiO₂ by the AFM-Measured Adhesion Force

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

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