Biomedical applications of 2D monoelemental materials formed by group VA and VIA: a concise review

Abstract

The development of two-dimensional (2D) monoelemental nanomaterials (Xenes) for biomedical applications has generated intensive interest over these years. In this paper, the biomedical applications using Xene-based 2D nanomaterials formed by group VA (e.g., BP, As, Sb, Bi) and VIA (e.g., Se, Te) are elaborated. These 2D Xene-based theranostic nanoplatforms confer some advantages over conventional nanoparticle-based systems, including better photothermal conversion, excellent electrical conductivity, and large surface area. Their versatile and remarkable features allow their implementation for bioimaging and theranostic purposes. This concise review is focused on the current developments in 2D Xenes formed by Group VA and VIA, covering the synthetic methods and various biomedical applications. Lastly, the challenges and future perspectives of 2D Xenes are provided to help us better exploit their excellent performance and use them in practice.

Keywords: 2D materials; Biomedical applications; Group VA and VIA; Monoelemental.

Fig. 1

Schematic illustration of the main topics covered in this review

Fig. 2

a, b Crystal structure of few-layer phosphorene. a Perspective side view of few-layer phosphorene. b Side and top views of few-layer phosphorene. Reprinted with permission [48], Copyright 2014 American Chemical Society. c–h Antimonene flakes on SiO2 substrates. c Top left, millimeter-size crystals of antimony. Middle right, adhesive tape with sub-millimeter crystals of antimony. Bottom left, polymer on glass slide with micrometer antimony flakes. d Optical microscopy image where up to three large flakes of antimony can be seen. e AFM topographic image showing two flakes of anti-monene located inside the marked region in d. f AFM topography of the ≈ 0.2 μm2 antimonene flake inside the blue square in e showing terraces of different heights. g High-resolution TEM image of a few-layer antimonene flake. The inset is a digital magnification of the area inside the blue rectangle. h AFM topography acquired on the bilayer terrace marked with a green arrow in f showing atomic periodicity. Reprinted with permission [50], Copyright 2016 Wiley

Fig. 3

a Basic characterization of exfoliated black phosphorous (CHP as solvent, scale bars 100 μm, 500 nm and 1 nm). Reprinted with permission [52], Copyright 2015 Macmillan Publishers. a Schematic of solvent exfoliation of BP in NMP solvents via tip ultrasonication and characterization of solvent-exfoliated BP nanosheets. Reprinted with permission [53], Copyright 2015 American Chemical Society. c Schematic illustration of the synthesis of BPQDs and experimental morphological (TEM and AFM) images of BPQDs. Reprinted with permission [54], Copyright 2018 Elsevier. d Schematic of the preparation of arsenenenanosheets in NMP and nanodots in toluene from grey arsenic. Reprinted with permission [55], Copyright 2018 Royal Society of Chemistry. e Experimental morphological (TEM and AFM) images of arsenenenanosheets and nanodots. Reprinted with permission [55], Copyright 2018 Royal Society of Chemistry. f Experimental morphological (TEM and AFM) images of antimonene, reprinted with permission [56], Copyright 2016 Wiley. G Fabrication of PEG-coated AMQD. Reprinted with permission, [26] Copyright 2017 Wiley. h Photos of bulk antimony, antimony powder, AMQDs solution during the preparation, process, TEM and AFM image of AMQDs. Reprinted with permission [26], Copyright 2017 Wiley. i Fabrication of BiQDs. Reprinted with permission [57], Copyright 2018 American Chemical Society j Experimental morphological (TEM and AFM) images of BiQDs. Reprinted with permission [57], copyright 2018 American Chemical Society. k Characterizations of the as-prepared 2D Se through liquid-phase exfoliation. Reprinted with permission [58], Copyright 2019 Elsevier. l Characterization of ultrathin 2D Tenanosheets. Reprinted with permission [59], Copyright 2018 Wiley

Fig. 4

a Schematic of the black phosphorus exfoliation procedure. Snapshot of the electrochemical setup with BP flake anode and Pt foil cathode separated in acidic solution (0.5 M H₂SO₄) by a fixed distance of 2 cm at b no potential applied, c after 20 min applying a voltage of + 3 V and d after 2 h process. A-D Reprinted with permission [65], Copyright 2017 Wiley. e Low-Potential Electrochemical Exfoliation. Scheme. Low-potential electrochemical exfoliation of native As toward (mono)few-layer arsenene: (blue dots) cations (NH4+); (red dots) anions (PF6−). Reprinted with permission [66], Copyright 2017 Royal Society of Chemistry. f General scheme for the electrochemical exfoliation of layered Sb crystals into 2D sheets. Reprinted with permission [67], Copyright 2020 Wiley

Fig. 5

a TEM image of the multilayer arsenene/InN/InAs. (Inset:diffraction pattern of multilayer arsenene). b Thetheoretical atomic model of multilayer arsenene/InN/InAs layer structure. Reprinted with permission [69], Copyright 2016 American Chemical Society. c TEM image of the multilayer antimonene/InN/InSb. d The theoretical atomic model of multilayer antimonene/InN/InSb layer structure.Reprinted with permission [70], Copyright 2016 Royal Society of Chemistry

Fig. 6

a Atomic model of blue phosphorus and experimental morphological (STM) images of phosphorus. Reprinted with permission [74], Copyright 2016 American Chemical Society. b Monolayer antimonene formed on PdTe2 substrate, experimental morphological (TEM and AFM) images of antimonene. Reprinted with permission [75], Copyright 2017 Wiley. c Morphological of the transferred Bi films. Reprinted with permission [78], Copyright 2016 American Chemical Society. d Left: Topographic image (size: 100 × 100 nm2, sample bias: 1 V) of an epitaxial Te film showing an atomically flat terraces separated by steps of height of ~ 4 Å. (The inset presents a line profile taken along the white line drawn in the image). Right: Atomic resolution STM image (size 8 × 8 nm2, bias: 0.6 V) showing rectangular lattices as highlighted by the black rectangle. Reprinted with permission [79], Copyright 2017 Royal Society of Chemistry

Figure7

a The morphology evolution of the bulk red phosphorus materials during the high-temperature solvothermal reaction. b Low-magnification of TEM images of the holey phosphorus-based nanosheets. Reprinted with permission [86], Copyright 2016 Wiley. c HRTEM image of phosphorus-based nanosheets, showing the amorphous regions with some polycrystalline structure. d AFM image. e Synthetic protocol of the black phosphorus. f TEM image of the BP nanosheets. g HRTEM image corresponding to F. Lattice Image of a BP flake shows d spacing of the (020) plane of orthorhombic BP. h AFM image. Reprinted with permission [87], Copyright 2018 PNAS. i TEM images of the tellurium nanoflakes. j Corresponding HR-TEM image. k AFM image of typical tellurium nanoflake (top) and the corresponding height profile (bottom), scale bar is 1 µm. Reprinted with permission [88], Copyright 2018 American Chemical Society

Fig. 8

Emerging Xene-based bioimaging. a NB@BP-based fluorescence imaging (FL) and BP quantum dots based fluorescence imaging (FL). Reprinted with permission [94], Copyright 2017 American Chemical Society. Reprinted with permission [96], Copyright 2016 Wiley. b Antimonene-based fluorescence imaging (FL) and photoacoustic imaging (PAI). Reprinted with permission [27], Copyright2018 Wiley. c) BP-based photoacoustic imaging (PAI). Reprinted with permission [97], Copyright 2016 Elsevier. d Bismuthene-based X-ray computed tomography (CT) imaging. Reprinted with permission [101], Copyright 2017 Wiley

Fig. 9

Emerging Xene-based therapeutic applications. a Antimonene-based photothermal therapy (PTT). Reprinted with permission [26], Copyright 2017 Wiley. b Bismuth-based photothermal therapy (PTT). Reprinted with permission [101], Copyright 2017 Wiley. c Tellurium Nanodots-based photothermal therapy (PTT) and Photodynamic therapy (PDT) Reprinted with permission [22], Copyright 2017 American Chemical Society. d, e Black phosphorous-based Photodynamic therapy (PDT). Reprinted with permission [107], Copyright 2015American Chemical Society. f, g Tellurene-based photodynamic therapy (PDT). Reprinted with permission [109], Copyright 2018 Royal Society of Chemistry

Fig. 10

a, b Phosphorene-based drug delivery systems. Reprinted with permission [28], Copyright 2017 Wiley. c, d Polydopamine-modified black phosphorous-based drug delivery systems Reprinted with permission [112], Copyright 2019 Wiley. e, f Antimonene-based drug delivery systems. Reprinted with permission [27], Copyright 2018 Wiley

Fig. 11

Emerging Xene-based antimicrobial application. a Phosphorene-based antimicrobial application. Reprinted with permission [115], Copyright 2018 Royal Society of Chemistry. b–f BP loaded copper (BP/Cu)-based antimicrobial application. Reprinted with Reprinted with permission [116]. Copyright 2020 Elsevier. g Schematic illustration of the preparation of CS/AM NSs hydrogel and its use in treating bacterial wound infection. h, i Pictures of antibacterial effect in vitro and photographic images and tissue sections of wounds treated by Staphylococcus aureus infection. Reprinted with permission [117], Copyright 2020 Wiley