Monolayer and/or atomically thin transition metal dichalcogenides cover a wide range of two-dimensional (2D) materials, whose fascinating semiconducting and optical properties have made them promising candidate materials for optoelectronic devices. Controllable growth of these materials is critical for their device applications. By using MoCl and HS as precursors, monolayer and ultrathin molybdenum disulfide (MoS) films with controlled lamellar structure have been directly built layer by layer on SiO substrates without being followed by high-temperature annealing. Furthermore, the thickness of MoS films can be precisely regulated by applying different atomic layer deposition (ALD) cycles. Once an ALD cycle is applied, one molecular layer of MoS material will be 'added' on the substrate or original existing MoS films. At the initial stage (one to three ALD cycles), the density of MoS materials increases with an increase in ALD cycles, while a large area of continuous MoS film on the substrate can be obtained when four or more ALD cycles are applied. In this way, excellent triangular crystals of MoS with controlled atomic size in thickness and a highly oriented hexagonal crystal structures can be obtained by applying definite ALD cycles.

As a kind of specially modified chemical vapor deposition (CVD), atomic layer deposition (ALD) has long been used to fabricate thin films. The self-limiting reaction of ALD endows the films with excellent uniformity and precise controllability. The thickness of the films obtained by ALD can be controlled in an atomic scale (0.1 nm) on a large-area substrate even with complex structures. Therefore, it has recently been employed to produce the two-dimensional (2D) materials like MoS 2 . In this mini-review, the research progress in ALD MoS 2 is firstly summarized. Then the influences of precursors, substrates, temperature, and post-annealing treatment on the quality of ALD-MoS 2 are presented. Moreover, the applications of the obtained MoS 2 as an electrochemical catalysator are also described. Besides the perspective on the research of ALD of MoS 2 , the remaining challenges and promising potentials are also pointed out.

Cell penetrating peptides (CPPs) are commonly utilized for intracellular delivery of functional materials to circumvent biomembrane barrier. However, further application of CPPs is hindered by lacking selectivity toward targeted cells. The spider venom peptide, lycosin-I, is a CPP with potent cytotoxicity to cancer cells, which might enable lycosin-I to deliver functional materials into cancer cells selectively. In this study, we demonstrated that the lycosin-I-conjugated spherical gold nanoparticles (LGNPs) not only exhibited efficient cellular internalization efficiency toward cancer cells but also displayed unprecedented selectivity over noncancerous cells. Although LGNPs were removed from the living circulatory system via reticuloendothelial system-dominant clearance modes without noticeable adverse effects to animals, they actually displayed active tumor-targeting effects and efficient accumulation in tumors in vivo. Furthermore, the potential application of this platform for cancer therapy was explored by lycosin-I-conjugated gold nanorods (LGNRs). LGNRs exhibited selective intracellular translocation towards cancer cells and efficient photothermal effect under near infrared (NIR, 808 nm) irradiation, which consequently killed cancer cells in vitro and in vivo effectively. Therefore, the established LGNPs and LGNRs possessed great potential in cancer-targeting delivery and photothermal therapy.

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