Molecular Mechanisms of Interactions between Monolayered Transition Metal Dichalcogenides and Biological Molecules

Abstract

Single layered two-dimensional (2D) materials such as transition metal dichalcogenides (TMDs) show great potential in many microelectronic or nanoelectronic applications. For example, because of extremely high sensitivity, TMD-based biosensors have become promising candidates for next-generation label-free detection. However, very few studies have been conducted on understanding the fundamental interactions between TMDs and other molecules including biological molecules, making the rational design of TMD-based sensors (including biosensors) difficult. This study focuses on the investigations of the fundamental interactions between proteins and two widely researched single-layered TMDs, MoS2, and WS2 using a combined study with linear vibrational spectroscopy attenuated total reflectance FTIR and nonlinear vibrational spectroscopy sum frequency generation vibrational spectroscopy, supplemented by molecular dynamics simulations. It was concluded that a large surface hydrophobic region in a relatively flat location on the protein surface is required for the protein to adsorb onto a monolayered MoS2 or WS2 surface with preferred orientation. No disulfide bond formation between cysteine groups on the protein and MoS2 or WS2 was found. The conclusions are general and can be used as guiding principles to engineer proteins to attach to TMDs. The approach adopted here is also applicable to study interactions between other 2D materials and biomolecules.

Probing Molecular Behavior of Carbonyl Groups at Buried Nylon/Polyolefin Interfaces in Situ

“…Detailed information on the buried interfaces between the polymer thin films in the multilayer samples has seldom been investigated nondestructively at the molecular level due to the lack of appropriate analytical tools to probe this information. Sum frequency generation (SFG) vibrational spectroscopy is a second-order nonlinear optical technique and a powerful nondestructive, in situ tool to study the molecular structure of the buried interfacial structures, with sub-monolayer interface specificity. − SFG has been extensively applied to study many buried solid/solid interfaces involving a variety of polymers. − Recently, we have reported molecular orientation information, especially for methylene groups, at buried interfaces of nylon and functionalized polyolefin materials . In this study, we expand this to investigate the molecular structure of the nylon/MAH-grafted polyethylene buried interface, focusing on the polar CO groups of MAH-grafted polyethylene at buried CaF 2 and nylon interfaces in situ.…”

Acidic Environment Significantly Alters Aggregation Pathway of Human Islet Amyloid Polypeptide at Negative Lipid Membrane

“…Sum frequency generation vibrational spectroscopy (SFG-VS) is a powerful tool for real-time observations on biomolecules arranged at surfaces and interfaces. ,− In particular, femtosecond broad-band SFG-VS (BB-SFG-VS) can overcome above-mentioned difficulties and provide a unique chance to directly investigate interfacial amyloidosis process. ,, It has been demonstrated that the combined spectral features from peptide backbone vibrations of amide I, amide II, and amide III permits to effectively differentiate secondary structures of interfacial peptides and proteins. − Utilizing a highly sensitive femtosecond BB-SFG-VS system with simultaneous measurement of multiple polarization combinations, we have unraveled the conformational evolution mechanism of hIAPP assembled at negatively charged membrane surface and successfully distinguished different β-sheet intermediate conformers involved within this structural transformation process . Nevertheless, it should be noted that, when compared with in vitro experimental conditions, the realistic physiological milieu in vivo is much more complicated.…”

Nondestructive In Situ Detection of Chemical Reactions at the Buried Interface between Polyurethane and Isocyanate-Based Primer

“…Sum frequency generation (SFG) vibrational spectroscopy, in contrast, has been shown to be a powerful tool to observe molecular structures and interactions at buried interfaces in situ in real time. Extensive research has been successfully carried out through SFG to elucidate interfacial molecular behaviors. − SFG is a second-order nonlinear optical process involving two input beams and an output signal beam. ,,− As shown in Figure b, the sum frequency signals are generated from an interface by overlapping a frequency-fixed visible laser beam and a frequency tunable mid-IR laser beam at the interface. The signal intensity is resonantly enhanced when the frequency of the incident IR beam matches the frequency of a vibrational transition of the sample molecules at the interface. − The selection rule of the second-order nonlinear optical process indicates that SFG signals can only be generated from a medium with no inversion symmetry (under the electric dipole approximation), enabling SFG to nondestructively characterize buried interfaces with submonolayer interfacial specificity. ,− Therefore, SFG works as a suitable tool to study the molecular structure at buried interfaces in this study.…”