Hydroxyl-Assisted Phosphorene Stabilization with Robust Device Performances

Black phosphorus-based nanoplatforms for cancer therapy: chemistry, design, biological and therapeutic behaviors

Cancer, a significant threat to human lives, has been the target of research for several decades. Although conventional therapies have drawbacks, such as side effects, low efficacy, and weak targeting, they have been applied extensively due to a lack of effective alternatives. The emergence of nanotechnology in medicine has opened up new possibilities and offered promising solutions for cancer therapy. In recent years, 2D nanomaterials have attracted enormous attention in nanomedicine due to their large surface-to-volume ratio, photo-responsivity, excellent electrical conductivity, etc. Among them, black phosphorus (BP) is a 2D nanomaterial consisting of multiple layers weakly bonded together through van der Waals forces. Its distinct structure makes BP suitable for biomedical applications, such as drug/gene carriers, PTT/PDT, and imaging agents. BP has demonstrated remarkable potential since its introduction in cancer therapy in 2015, particularly due to its selective anticancer activity even without the aid of near-infrared (NIR) or anticancer drugs. The present review makes efforts to cover and discuss studies published on the anticancer activity of BP. Based on the type of cancer, the subcategories are organized to shed light on the potential of BP nanosheets and BP quantum dots (BPQDs) against breast, brain, skin, prostate, and bone cancers, and a section is devoted to other cancer types. Since extensive attention has been paid to breast cancer cells and in vivo models, various subsections, including mono-, dual, and triple therapeutic approaches are established for this cancer type. Furthermore, the review outlines various synthesis approaches employed to produce BP nanomaterials, providing insights into key synthesis parameters. This review provides an up-to-date platform for the potential reader to understand what has been done about BP cancer therapy based on each disease, and the conclusions and outlook cover the directions in which this approach is going to proceed in the future.

Recent Advances in Phosphorene: Structure, Synthesis, and Properties

Phosphorene is a 2D phosphorus atomic layer arranged in a honeycomb lattice like graphene but with a buckled structure. Since its exfoliation from black phosphorus in 2014, phosphorene has attracted tremendous research interest both in terms of synthesis and fundamental research, as well as in potential applications. Recently, significant attention in phosphorene is motivated not only by research on its fundamental physical properties as a novel 2D semiconductor material, such as tunable bandgap, strong in-plane anisotropy, and high carrier mobility, but also by the study of its wide range of potential applications, such as electronic, optoelectronic, and spintronic devices, energy conversion and storage devices. However, a lot of avenues remain to be explored including the fundamental properties of phosphorene and its device applications. This review recalls the current state of the art of phosphorene and its derivatives, touching upon topics on structure, synthesis, characterization, properties, stability, and applications. The current needs and future opportunities for phosphorene are also discussed.

On the interface between biomaterials and two-dimensional materials for biomedical applications

Two-dimensional (2D) materials have garnered significant attention due to their ultrathin 2D structures with a high degree of anisotropy and functionality. Reliable manipulation of interfaces between 2D materials and biomaterials is a new frontier for biomedical nanoscience and combining biomaterials with 2D materials offers a promising way to fabricate innovative 2D biomaterials composites with distinct functionality for biomedical applications. Here, we focus exclusively on a summary of the current work in the interface investigation of 2D biomaterials. Specifically, we highlight extraordinary features that make 2D materials so desirable, as well as the molecular level interactions between 2D materials and biomaterials that have been studied thus far. Furthermore, the approaches for investigating the interface characteristics of 2D biomaterials are presented and described in depth. To capture the emerging trend in mass manufacturing of 2D materials, we review the research progress on biomaterial-assisted exfoliation. Finally, we present a critical assessment of newly developed 2D biomaterials in biomedical applications.

Suppression of Sn2+ and Lewis acidity in SnS2/black phosphorus heterostructure for ppb-level room temperature NO2 gas sensor

The selective detection of harmful gases is of great significance to human health and air quality, triggering the need for special customizations of sensing material structure. In this study, we prepared a novel SnS2/black phosphorus (BP) two-dimensional (2D)-2D heterostructure via the in situ hydrothermal growth of SnS2 nanosheets on exfoliated BP lamellae for NO2 sensing applications. In the SnS2/BP composite, the holes with high oxidizability in p-type BP could oxidize Sn2+ into Sn4+, thus inhibiting the formation of Lewis acidic S vacancies. This Sn2+/Lewis acidity suppression of the composite was further confirmed by X-ray photoelectron spectroscopy and acidic double-layer capacitance analyses, and promoted the adsorption and detection of acidic NO2. Owing to its valence and Lewis acidity engineering, the SnS2/BP heterostructure sensor could detect trace levels of NO2 as low as 100 ppb (parts per billion) with high response, fast response/recovery, good stability, and selectivity at room temperature. The high absorption energy of NO2 (-0.74 eV), as indicated by the density functional theory calculations, suggests that NO2 was chemically adsorbed on the SnS2/BP surface, which was also evidenced by the in situ Raman spectroscopy results. This work opens up interesting opportunities for the rational design of highly efficient NO2 gas sensors through Lewis acidity modification and interface engineering.

Unzipping of black phosphorus to form zigzag-phosphorene nanobelts

Phosphorene, monolayer or few-layer black phosphorus, exhibits fascinating anisotropic properties and shows interesting semiconducting behavior. The synthesis of phosphorene nanosheets is still a hot topic, including the shaping of its two-dimensional structure into nanoribbons or nanobelts. Here we report electrochemical unzipping of single crystalline black phosphorus into zigzag-phosphorene nanobelts, as well as nanosheets and quantum dots, via an oxygen-driven mechanism. The experimental results agree well with our theoretical calculations. The calculation for the unzipping mechanism study suggests that interstitial oxygen-pairs are the critical intermediate species for generating zigzag-phosphorene nanobelts. Although phosphorene oxidation has been reported, lengthwise cutting is hitherto unreported. Our discovery of phosphorene cut upon oxidation represents a previously unknown mechanism for the formation of various dimensions of phosphorene nanostructures, especially zigzag-phosphorene nanobelts. It opens up a way for studying the quantum effects and electronic properties of zigzag-phosphorene nanobelts.

Here, the authors demonstrate the electrochemical unzipping of single crystalline black phosphorus into zigzag-phosphorene nanobelts, nanosheets, and quantum dots, via a top-down oxygen-driven mechanism.