A simple thermal annealing method for layer thinning and etching of mechanically exfoliated MoS2 nanosheets in air is reported. Using this method, single-layer (1L) MoS2 nanosheets are achieved after the thinning of MoS2 nanosheets from double-layer (2L) to quadri-layer (4L) at 330 °C. The as-prepared 1L MoS2 nanosheet shows comparable optical and electrical properties with the mechanically exfoliated, pristine one. In addition, for the first time, the MoS2 mesh with high-density of triangular pits is also fabricated at 330 °C, which might arise from the anisotropic etching of the active MoS2 edge sites. As a result of thermal annealing in air, the thinning of MoS2 nanosheet is possible due to its oxidation to form MoO3 . Importantly, the MoO3 fragments on the top of thinned MoS2 layer induces the hole injection, resulting in the p-type channel in fabricated field-effect transistors.

A simple approach is developed to identify the layer number of 2D MoS₂ sheets. By using an optical imaging method combined with image analysis software, a high-contrast image of the MoS₂ sheets can be extracted from the red (R) channel of the color optical microscopy image. The value of the intensity difference in the grayscale image of the R channel between MoS₂ sheets (1-3 layers) and the SiO₂ substrate can be used to identify the layer number of the sheet.

We presented a simple approach for in-situ synthesis of poly(dimethylsiloxane) (PDMS)-gold nanoparticles composite film based on the special characteristics of PDMS itself. It is an environmentally safe synthesis method without the requirement of additional reducing/stabilizing agents. The region where the resulting gold nanoparticles distribute (in the matrix or on the surface of the polymer) and the size of the nanoparticles, as well as the colour of the free-standing films, can be simply controlled by adjusting the ratio of curing agent and the PDMS monomer. The chemical and optical properties of these composite films were studied. Using such a method, gold nanoparticle micropatterns on PDMS surfaces can be performed. And based on the gold nanoparticles micropattern, further modification with antibodies, antigens, enzymes and other biomolecules can be achieved. To verify this ability, an immobilized glucose oxidase (GOx) reactor in microchannels was built and its performance was studied. The experiments have shown that the resulting composite film may have a lot of potential merits in protein immobilization, immunoassays and other biochemical analysis on PDMS microchips.

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The morphology of nanoparticles influences their cellular uptake process, while rough surface-enhanced affinity renders rough nanoparticles desirable in related biomedical applications. In this work, rattle-structured rough nanocapsules (Au@HSN-PGEA, AHPs) composed of in-situ-formed gold nanorod (Au NR) cores and polycationic mesoporous silica shells were constructed for trimodal complementary cancer therapy. Taking advantage of surface roughness, near-infrared (NIR) responsiveness, and controlled release manner, AHPs were expected to realize the co-delivery of sorafenib (SF, a hydrophobic antiproliferative and antiangiogenic drug) and antioncogene p53 for malignant hepatocellular carcinoma treatment. The rough surface feature of AHP was investigated for cellular uptake and the subsequent gene transfection. The feasibility of photothermal Au NR cores for NIR-triggered SF release was also tested. Notably, synergistic effects based on photothemal therapy-enhanced chemotherapy were achieved. In addition, the good in vivo performance of the proposed multifunctional nanoparticles with rough surfaces was also demonstrated. The current work extends the biomedical applications of the intriguing rough nanoparticles and provides a facile strategy to construct flexible platforms for complementary gene/chemo/photothermal therapy.