Local Nanostrain Engineering of Monolayer MoS2 Using Atomic Force Microscopy-Based Thermomechanical Nanoindentation.

Strain engineering in two-dimensional materials (2DMs) has important application potential for electronic and optoelectronic devices. However, achieving precise spatial control, adjustable sizing, and permanent strain with nanoscale resolution remains challenging. Herein, a thermomechanical nanoindentation method is introduced, inspired by skin edema caused by mosquito bites, which can induce localized nanostrain and bandgap modulation in monolayer molybdenum disulfide (MoS2) transferred onto a poly(methyl methacrylate) film utilizing a heated atomic force microscopy nanotip. Via adjustment of the machining parameters, the strains of MoS2 are manipulated, achieving an average strain of ≤2.6% on the ring-shaped expansion structure. The local bandgap of MoS2 is spatially modulated using three types of nanostructures. Among them, the nanopit has the largest range of bandgap regulation, with a substantial change of 56 meV. These findings demonstrate the capability of the proposed method to create controllable and reproducible nanostrains in 2DMs.

Scratch on Polymer Materials Using AFM Tip-Based Approach: A Review.

As a brand new nanomachining method, the tip-based nanomachining/nanoscratching (TBN) method has exhibited a powerful ability at machining on polymer materials and various structures have been achieved using this approach, ranging from the nanodot, nanogroove/channel, bundle to 2D/3D (three-dimensional) nanostructures. The TBN method is widely used due to its high precision, ease of use and low environmental requirements. First, the theoretical models of machining on polymer materials with a given tip using the TBN method are presented. Second, advances of nanostructures achieved by this method are given, including nanodots/nanodot arrays, a nanogroove/channel, 2D/3D nanostructures and bundles. In particular, a useful approach called the ultrasonic vibration-assisted method introduced to integrate with TBN method to reduce the wear of the tip is also reviewed, respectively. Third, the typical applications of the TBN method and the nanostructures achieved by it are summarized in detail. Finally, the existing shortcomings and future prospects of the TBN method are given. It is confirmed that this review will be helpful in learning about this method and push the technology toward industrialization.

Nanofluidic devices prepared by an atomic force microscopy-based single-scratch approach.

Nanofluidic chips with different numbers of nanochannels were fabricated based on a commercial AFM system using a single-scratch approach. The electrical characterization and enzymatic reactions at the nanoscale were demonstrated using the obtained chips. The effects of the number of nanochannels and the solution concentration on the measured electric current were investigated. The influence of the hydrodynamic convection generated from the induced inflow at the end of the nanochannel on the ion transport through the nanochannel was also studied. Moreover, the enzymatic reactions for trypsin towards poly-l-lysine (PLL) or thrombin were conducted with a nanofluidic chip to investigate the reaction specificity between trypsin and PLL. Results show that the electric current change during the experimental process could be used as a label-free indicator to detect the enzymatic activity.

Protective effect of a sesamin derivative, 3-bis (3-methoxybenzyl) butane-1, 4-diol on Aß-stressed PC12 cells.

Amyloid beta-protein (Aß) is involved in the pathogenesis of Alzheimer's disease (AD). Aß induces free radical production in neuronal cells, leading to oxidative stress and up-regulation of c-Jun N-terminal kinases (JNK), extracellular-signal-regulated kinases (ERK), p38 mitogen-activated protein kinase (MAPK) pathways and pro-apoptotic Bax expression. Sesamin has been shown to have protection to several models of neurodegenerative diseases by its antioxidant and anti-inflammatory properties. In the present study, we examined the neuroprotective effect of a sesamin derivative, 3-bis (3-methoxybenzyl) butane-1,4-diol (BBD) on Aß1-42 induced cytotoxicity of PC12 cells. Aß1-42 induced lipid peroxidation, calcium, reactive oxygen species from the PC12 cells. The effect of BBD on these harmful factors and the related signaling pathways were examined by biochemical and western blot assays. The result showed that BBD protected PC12 cells from Aß1-42 induced cytotoxicity with the increased cell viability and acetylcholine release, and the decreased lactate dehydrogenase, malondialdehyde and calcium release. BBD significantly reduced Aß-induced JNK, ERK, p38 MAPK pathways and Bax expression in PC12 cells. Therefore the neuroprotective effect of BBD on Aß-induced cytotoxicity was involved with antioxidant and anti-inflammatory effects. The result would help the development of new CNS drug for protection of AD.