Comparison of cytotoxicity of black phosphorus nanosheets in different types of fibroblasts

The effect of charge and albumin on cellular uptake of supramolecular polymer nanostructures

Intracellular delivery of functional biomolecules by using supramolecular polymer nanostructures has gained significant interest. Here, various charged supramolecular ureido-pyrimidinone (UPy)-aggregates were designed and formulated via a simple "mix-and-match" method. The cellular internalization of these UPy-aggregates in the presence or absence of serum proteins by phagocytic and non-phagocytic cells, i.e., THP-1 derived macrophages and immortalized human kidney cells (HK-2 cells), was systematically investigated. In the presence of serum proteins the UPy-aggregates were taken up by both types of cells irrespective of the charge properties of the UPy-aggregates, and the UPy-aggregates co-localized with mitochondria of the cells. In the absence of serum proteins only cationic UPy-aggregates could be effectively internalized by THP-1 derived macrophages, and the internalized UPy-aggregates either co-localized with mitochondria or displayed as vesicular structures. While the cationic UPy-aggregates were hardly internalized by HK-2 cells and could only bind to the membrane of HK-2 cells. With adding and increasing the amount of serum albumin in the cell culture medium, the cationic UPy-aggregates were gradually taken up by HK-2 cells without anchoring on the cell membranes. It is proposed that the serum albumin regulates the cellular internalization of UPy-aggregates. These results provide fundamental insights for the fabrication of supramolecular polymer nanostructures for intracellular delivery of therapeutics.

Evaluation of the effect of precursor ratios on the electrochemical performances of binder-free NiMn-phosphate electrodes for supercapattery

Binary metal phosphate electrodes have been widely studied for energy storage applications due to the synergistic effects of two different transition elements that able to provide better conductivity and stability. Herein, the battery-type binder-free nickel-manganese phosphate (NiMn-phosphate) electrodes were fabricated with different Ni:Mn precursor ratios via microwave-assisted hydrothermal technique for 5 min at 90 °C. Overall, NiMn3P electrode (Ni:Mn = 1:3) showed an outstanding electrochemical performance, displaying the highest specific (areal) capacity at 3 A/g of 1262.4 C/g (0.44 C/cm2), and the smallest charge transfer resistance of 108.8 Ω. The enhanced performance of NiMn3P electrode can be ascribed to the fully grown amorphous nature and small-sized flake and flower structures of NiMn3P electrode material on the nickel foam (NF) surface. This configuration offered a higher number of active sites and a larger exposed area, facilitating efficient electrochemical reactions with the electrolyte. Consequently, the NiMn3P//AC electrode combination was chosen to further investigate its performance in supercapattery. The NiMn3P//AC supercapattery exhibited remarkable energy density of 105.4 Wh/kg and excellent cyclic stability with 84.7% retention after 3000 cycles. These findings underscored the superior electrochemical performance of the battery-type binder-free NiMn3P electrode, and highlight its potential for enhancing the overall performance of supercapattery.

Sonochemically synthesized black phosphorus nanoparticles: a promising candidate for piezocatalytic antibacterial activity with enhanced dielectric properties

The drawbacks inherent to traditional antibacterial therapies, coupled with the escalating prevalence of multi-drug resistant (MDR) microorganisms, have prompted the imperative need for novel antibacterial strategies. Accordingly, the emerging field of piezocatalysis in semiconductors harnesses mechanical stress to drive chemical reactions by utilizing piezo-generated free charge carriers, presenting a promising technology. To the best of our knowledge, this study is the first to provide a comprehensive overview of the eradication of pathogenic S. aureus bacteria using few-layer black phosphorus (SCBP) piezo catalyst under mechanical stimuli, along with the exploration of temperature dependent dielectric properties. The synthesis of the piezo catalysts involved a one-step cost-effective sonochemical method, and its structural, morphological, elemental, optical, and overall polarization properties were thoroughly characterized and compared with the traditional method-derived product (TABP). The synthesis-introduced defects, reduced crystalline diameters, modified bandgap (1.76 eV), nanoparticle aggregation, photoluminescence quenching, along with interfacial polarization, synergistically contribute to SCBP's exceptional dielectric response (4.596 × 107 @40 Hz), which in turn enhanced the piezocatalytic activity. When subjected to soft ultrasound stimulation at 15 kHz, the piezo catalyst SCBP demonstrated significant ROS-mediated antibacterial activity, resulting in a ∼94.7% mortality rate within 40 minutes. The impact of this study extends to cost-effective energy storage devices and advances in antibacterial therapy, opening new dimensions in both fields.

Screening 2D Materials for Their Nanotoxicity toward Nucleic Acids and Proteins: An In Silico Outlook

Since the discovery of graphene, two-dimensional (2D) materials have been anticipated to demonstrate enormous potential in bionanomedicine. Unfortunately, the majority of 2D materials induce nanotoxicity via disruption of the structure of biomolecules. Consequently, there has been an urge to synthesize and identify biocompatible 2D materials. Before the cytotoxicity of 2D nanomaterials is experimentally tested, computational studies can rapidly screen them. Additionally, computational analyses can provide invaluable insights into molecular-level interactions. Recently, various "in silico" techniques have identified these interactions and helped to develop a comprehensive understanding of nanotoxicity of 2D materials. In this article, we discuss the key recent advances in the application of computational methods for the screening of 2D materials for their nanotoxicity toward two important categories of abundant biomolecules, namely, nucleic acids and proteins. We believe the present article would help to develop newer computational protocols for the identification of novel biocompatible materials, thereby paving the way for next-generation biomedical and therapeutic applications based on 2D materials.

Covalently Bonded Ni Sites in Black Phosphorene with Electron Redistribution for Efficient Metal-Lightweighted Water Electrolysis

The metal-lightweighted electrocatalysts for water splitting are highly desired for sustainable and economic hydrogen energy deployments, but challengeable. In this work, a low-content Ni-functionalized approach triggers the high capability of black phosphorene (BP) with hydrogen and oxygen evolution reaction (HER/OER) bifunctionality. Through a facile in situ electro-exfoliation route, the ionized Ni sites are covalently functionalized in BP nanosheets with electron redistribution and controllable metal contents. It is found that the as-fabricated Ni-BP electrocatalysts can drive the water splitting with much enhanced HER and OER activities. In 1.0 M KOH electrolyte, the optimized 1.5 wt% Ni-functionalized BP nanosheets have readily achieved low overpotentials of 136 mV for HER and 230 mV for OER at 10 mA cm-2. Moreover, the covalently bonding between Ni and P has also strengthened the catalytic stability of the Ni-functionalized BP electrocatalyst, stably delivering the overall water splitting for 50 h at 20 mA cm-2. Theoretical calculations have revealed that Ni-P covalent binding can regulate the electronic structure and optimize the reaction energy barrier to improve the catalytic activity effectively. This work confirms that Ni-functionalized BP is a suitable candidate for electrocatalytic overall water splitting, and provides effective strategies for constructing metal-lightweighted economic electrocatalysts.

Mechanistic transcriptome comprehension of Chlamydomonas reinhardtii subjected to black phosphorus

Two-dimensional materials have recently gained significant awareness. A representative of such materials, black phosphorous (BP), earned attention based on its comprehensive application potential. The presented study focuses on the mode of cellular response underlying the BP interaction with Chlamydomonas reinhardtii as an algal model organism. We observed noticeable ROS formation and changes in outer cellular topology after 72 h of incubation at 5 mg/L BP. Transcriptome profiling was employed to examine C. reinhardtii response after exposure to 25 mg/L BP for a deeper understanding of the associated processes. The RNA sequencing has revealed a comprehensive response with abundant transcript downregulation. The mode of action was attributed to cell wall disruption, ROS elevation, and chloroplast disturbance. Besides many other dysregulated genes, the cell response involved the downregulation of GH9 and gametolysin within a cell wall, pointing to a shift to discrete manipulation with resources. The response also included altered expression of the PRDA1 gene associated with redox governance in chloroplasts implying ROS disharmony. Altered expression of the Cre-miR906-3p, Cre-miR910, and Cre-miR914 pointed to those as potential markers in stress response studies.

Concentration-Dependent Layer Exfoliation of Black Phosphorus by Human Serum Albumin and Its Corresponding Biocompatibility Change

Layered black phosphorus (LBP) is drawing increasing attention because of its excellent potential in biomedical applications. Properties and bioeffects of LBP depend on its layer number (LN). However, the variation of LN during applications, especially in organisms, is largely unknown. Herein, LBP is found to be exfoliated by human serum albumin (HSA) after the formation of protein coronas. The sorption of HSA on LBP exhibits multiple intermediate equilibrium and size-dependent capacity and is distinguished from traditional multilayer sorption. The loss of LN for LBP increases with the increase of HSA concentrations, e.g., 2, 4, and 6 layers of LBP are exfoliated at 35, 135, and 550 mg/L HSA, respectively. The energy distribution shows that at low HSA concentrations, exfoliation is mainly driven by electrostatic and hydrogen bond interactions. With middle or high HSA concentrations, exfoliation is mainly driven by p-π or hydrophobic interactions, respectively. Layer exfoliation causes the continuous emergence of an unsaturated LBP surface available for adsorbing further HSA, breaking previous sorption saturations. The complete exfoliation of LBP weakens cytotoxicity and promotes internalization to the A-549 cell line compared with pristine or less exfoliated LBP. This finding unveils the exfoliation mechanism of proteins toward LBP and is of benefit to evaluating application performance and biosafety of LBP.

ZnO/black phosphorus/C3N4 composite: An effective photocatalyst for Cr (VI) reduction and degradation of rhodamine B

The utilization of photocatalysts offers a promising approach for the removal of Cr (VI) and rhodamine dyes. Through the generation of reactive species and subsequent degradation reactions, photocatalysis provides an efficient and environmentally friendly method for the remediation of wastewater. In this study, we have synthesized an n-p-n heterojunction of carbon nitride (C3N4), zinc oxide (ZnO), and black phosphorus (BP) through the sonication-stirring method. The photocatalytic ability of this composite was examined for the decomposition rhodamine B (RhB) and detoxification of hexavalent chromium ion (up to 97% during 80 min) under Xenon irradiation. The results of trapper experiments indicated that the active species were hydroxyl radical (˙OH), electron (e-), and superoxide anion radical (˙O2-). Based on the obtained potential of the lowest unoccupied molecular orbitals (LUMO) and the highest occupied molecular orbital (HOMO) for the mentioned semiconductors, through Mutt-Schottky results, the double Z-scheme mechanism was proposed for the studied process. The electrochemical impedance spectroscopy data exhibited good charge transfer for the evaluated composite versus the pure compounds. The impressive separation of holes and electrons along with the low recombination were confirmed by the responses of photocurrent and quenching the photoluminescence (pl) intensity for the composite, respectively. The current density of the composite recorded 66.6%, 87.3%, and 92% higher than those of BP, C3N4, and ZnO, indicating an excellent electron-hole separation for the ternary composite compared to the pure semiconductors. Diffuse reflectance spectra (DRS) data revealed 2.9, 3.17, 1.15, and 2.63 eV as the band gap values for C3N4, ZnO, BP, and composite. The rate constant of the new composite to remove RhB and reduce hexavalent chromium were about 4.79 and 2.64 times higher than that of C3N4, respectively.

A novel strategy to enhance photocatalytic killing of foodborne pathogenic bacteria by modification of non-metallic monomeric black phosphorus with Elaeagnus mollis polysaccharides

New antibacterial agents are needed to overcome the challenges of microbial food contamination. In this study, we investigated the potential of Elaeagnus mollis polysaccharide (EMP) to modify black phosphorus (BP) for use as a bactericide for foodborne pathogenic bacteria. The resulting compound (EMP-BP) displayed enhanced stability and activity compared with BP. EMP-BP exhibited an increased antibacterial activity (bactericidal efficiency of 99.999 % after 60 min of light exposure) compared to EMP and BP. Further studies revealed that photocatalytically generated reactive oxygen species (ROS) and active polysaccharides acted collectively on the cell membrane, leading to cell deformation and death. Furthermore, EMP-BP inhibited biofilm formation and reduced expression of virulence factors of Staphylococcus aureus, and material hemolysis and cytotoxicity tests prove that the material had good biocompatibility. In addition, bacteria treated with EMP-BP remained highly sensitive to antibiotics and did not develop significant resistance. In summary, we report an environmentally friendly method for controlling pathogenic foodborne bacteria that is efficient and apparently safe.

Black phosphorous-based human-machine communication interface

Assistive technology involving auditory feedback is generally utilized by those who are visually impaired or have speech and language difficulties. Therefore, here we concentrate on an auditory human-machine interface that uses audio as a platform for conveying information between visually or speech-disabled users and society. We develop a piezoresistive tactile sensor based on a black phosphorous and polyaniline (BP@PANI) composite by the facile chemical oxidative polymerization of aniline on cotton fabric. Taking advantage of BP's puckered honeycomb lattice structure and superior electrical properties as well as the vast wavy fabric surface, this BP@PANI-based tactile sensor exhibits excellent sensitivity, low-pressure sensitivity, reasonable response time, and good cycle stability. For a real-world application, a prototype device employs six BP@PANI tactile sensors that correspond to braille characters and can convert pressed text into audio on reading or typing to assist visually or speech-disabled persons. Overall, this research offers promising insight into the material candidates and strategies for the development of auditory feedback devices based on layered and 2D materials for human-machine interfaces.

Synthesis of high quality boehmite and γ-alumina for phosphorus removal from water works sludge by extraction and hydrothermal treatment

Alum sludge from water treatment was calcined and extracted to synthesize high quality boehmite and γ-alumina for phosphate removal. Synthesized boehmite and γ-alumina were able to remove phosphate quickly and effectively. Boehmite (hydrothermal treatment at 60 °C) showed maximum phosphate removal (adsorption) of 61 mg P/g followed by γ-alumina (50 mg P/g) and the boehmite hydrothermally treated at 120 °C (41 mg P/g). The degree of crystallinity gave more effect on phosphate adsorption of boehmite than that of γ-alumina. The lower the pH, the more phosphate adsorbed on the boehmite and γ-alumina (adsorb phosphate more than 4 times at pH 3 than at pH 11). Spectroscopic analysis (SEM-EDS and FTIR) indicates that phosphate are removed by ligand exchange, electrostatic attraction, and surface precipitation on the synthesized boehmite and γ-alumina.

Hemin-loaded black phosphorus-based nanosystem for enhanced photodynamic therapy and a synergistic photothermally/photodynamically activated inflammatory immune response

The biocompatible nanosystem integrating hemin into black phosphorus nanosheets was ingeniously constructed through the easy modified strategy. Taking advantage of the enhanced permeability and retention (EPR) effect, the designed nanosystem could accumulate into the tumor location, leading to attractive cytotoxicity through the enhanced photodynamic therapy (PDT) ascribing to the catalytic oxygen supply and GSH depletion of hemin. Simultaneously, combining PDT and photothermal therapy (PTT) showed an apparent promotion in anti-tumor effect. Moreover, inflammatory response and immune activation amplified anti-tumor effect, which could compensate limitations of exogenous therapy (i.e., limited tissue depth and intensity-dependent curation effect) and potentiate the efficiency of the endogenous immune-activating behavior. Especially, the designed nanosystem degraded followed by being metabolized in the blood circulation. By and large, this constructed nanosystem provides the new insight into designing biocompatible nanomaterials and paves the ideal way for anti-tumor therapy. STATEMENT OF SIGNIFICANCE: Biocompatible nanomaterials-based synergistic tumor therapy offers the potential application prospect. Taking advantage of degradable black phosphorus, the nanosystem integrating hemin into black phosphorus for the enhanced photodynamic therapy and synergistic photothermal-photodynamic activating inflammation-immune response was developed and the results demonstrate that tumor growth was inhibited followed by activating inflammatory factors and leading to satisfactory immune response.

Ternary MXene-loaded PLCL/collagen nanofibrous scaffolds that promote spontaneous osteogenic differentiation

Conventional bioinert bone grafts often have led to failure in osseointegration due to low bioactivity, thus much effort has been made up to date to find alternatives. Recently, MXene nanoparticles (NPs) have shown prominent results as a rising material by possessing an osteogenic potential to facilitate the bioactivity of bone grafts or scaffolds, which can be attributed to the unique repeating atomic structure of two carbon layers existing between three titanium layers. In this study, we produced MXene NPs-integrated the ternary nanofibrous matrices of poly(L-lactide-co-ε-caprolactone, PLCL) and collagen (Col) decorated with MXene NPs (i.e., PLCL/Col/MXene), as novel scaffolds for bone tissue engineering, via electrospinning to explore the potential benefits for the spontaneous osteogenic differentiation of MC3T3-E1 preosteoblasts. The cultured cells on the physicochemical properties of the nanofibrous PLCL/Col/MXene-based materials revealed favorable interactions with the supportive matrices, highly suitable for the growth and survival of preosteoblasts. Furthermore, the combinatorial ternary material system of the PLCL/Col/MXene nanofibers obviously promoted spontaneous osteodifferentiation with positive cellular responses by providing effective microenvironments for osteogenesis. Therefore, our results suggest that the unprecedented biofunctional advantages of the MXene-integrated PLCL/Col nanofibrous matrices can be expanded to a wide range of strategies for the development of effective scaffolds in bone tissue regeneration.

Fabricating a Novel Three-Dimensional Skin Model Using Silica Nonwoven Fabrics (SNF)

Silica nonwoven fabrics (SNF) prepared using electrospinning have high biocompatibility, thermal stability, and porosity that allows growing three-dimensional culture of cells. In this study, we used SNF to construct a three-dimensional artificial skin model consisting of epidermal and dermal layers with immortalized and primary human cell lines, creating a novel model that minimizes tissue shrinkage. As a result, SNF dermal/epidermal models have enhanced functions in the basement membrane, whereas Collagen dermal/epidermal models have advantages in keratinization and barrier functions. The SNF dermal/epidermal model with mechanical strength formed a basement membrane mimicking structure, suggesting the construction of a stable skin model. Next, we constructed three-dimensional skin models consisting of SNF and collagen. In the combination models, the expression of genes in the basement membrane was significantly increased compared with that in the Collagen dermal/epidermal model, and the gene for keratinization was increased compared with that in the SNF dermal/epidermal model. We believe that the combination model can be a biomimetic model that takes advantage of both SNF and collagen and can be applied to various basic research. Our new skin model is expected to be an alternative method for skin testing to improve the shrinkage of the collagen matrix gel.

Mechanism investigation for ultra-efficient photocatalytic water disinfection based on rational design of indirect Z-scheme heterojunction black phosphorus QDs/Cu2O nanoparticles

Photocatalysis has been regarded as a promising inactivation technology targeting to reduce drug-resistant bacteria contamination, but developing efficient photocatalysts with broad visible light harvesting capability is still a challenge. Here we report a MOFs-derived BPQDs/Cu₂O/N-doped hollow porous carbon (BP/CNC) with indirect Z-scheme heterojunctions (BPQDs/Cu₂O), which can inactivate 99.99999% Methicillin-resistant Staphylococcus aureus (MRSA) at a concentration of only 10 mg/L. Combining photoelectrochemical techniques and electrochemical measurements, the efficient inactivation process was attributed to the synergistic effect of enhanced light utilization and effective suppression of photogenerated carrier recombination. The mechanism of gradually damaged cell membrane for MRSA was studied by employing scanning electron microscopy (SEM), fluorescence staining and coagulase titer test to further decipher the changes in bacterial cells. We propose that reactive oxygen species (ROS) destroys the cell wall membrane and causes the leakage of cell contents, eventually leading to death. In addition, a series of in vitro and in vivo toxicity tests were conducted to evaluate the biocompatibility of the antibacterial system and its potential use in practice. This strategy of BPQDs/Cu₂O indirect heterojunction fabrication can spatially inhibit the recombination of photogenerated carriers, expands the light absorption range, providing a feasible method for disinfecting microbial contaminated water.

Conductive Biomaterials as Bioactive Wound Dressing for Wound Healing and Skin Tissue Engineering

Conductive biomaterials based on conductive polymers, carbon nanomaterials, or conductive inorganic nanomaterials demonstrate great potential in wound healing and skin tissue engineering, owing to the similar conductivity to human skin, good antioxidant and antibacterial activities, electrically controlled drug delivery, and photothermal effect. However, a review highlights the design and application of conductive biomaterials for wound healing and skin tissue engineering is lacking. In this review, the design and fabrication methods of conductive biomaterials with various structural forms including film, nanofiber, membrane, hydrogel, sponge, foam, and acellular dermal matrix for applications in wound healing and skin tissue engineering and the corresponding mechanism in promoting the healing process were summarized. The approaches that conductive biomaterials realize their great value in healing wounds via three main strategies (electrotherapy, wound dressing, and wound assessment) were reviewed. The application of conductive biomaterials as wound dressing when facing different wounds including acute wound and chronic wound (infected wound and diabetic wound) and for wound monitoring is discussed in detail. The challenges and perspectives in designing and developing multifunctional conductive biomaterials are proposed as well.

Converging 2D Nanomaterials and 3D Bioprinting Technology: State-of-the-Art, Challenges, and Potential Outlook in Biomedical Applications

The development of next-generation of bioinks aims to fabricate anatomical size 3D scaffold with high printability and biocompatibility. Along with the progress in 3D bioprinting, 2D nanomaterials (2D NMs) prove to be emerging frontiers in the development of advanced materials owing to their extraordinary properties. Harnessing the properties of 2D NMs in 3D bioprinting technologies can revolutionize the development of bioinks by endowing new functionalities to the current bioinks. First the main contributions of 2D NMS in 3D bioprinting technologies are categorized here into six main classes: 1) reinforcement effect, 2) delivery of bioactive molecules, 3) improved electrical conductivity, 4) enhanced tissue formation, 5) photothermal effect, 6) and stronger antibacterial properties. Next, the recent advances in the use of each certain 2D NMs (1) graphene, 2) nanosilicate, 3) black phosphorus, 4) MXene, 5) transition metal dichalcogenides, 6) hexagonal boron nitride, and 7) metal-organic frameworks) in 3D bioprinting technology are critically summarized and evaluated thoroughly. Third, the role of physicochemical properties of 2D NMSs on their cytotoxicity is uncovered, with several representative examples of each studied 2D NMs. Finally, current challenges, opportunities, and outlook for the development of nanocomposite bioinks are discussed thoroughly.

Spontaneously promoted osteogenic differentiation of MC3T3-E1 preosteoblasts on ultrathin layers of black phosphorus

Recently, black phosphorus (BP) has garnered great attention as one of newly emerging two-dimensional nanomaterials. Especially, the degraded platelets of BP in the physiological environment were shown to be nontoxic phosphate anions, which are a component of bone tissue and can be used for mineralization. Here, our study presents the potential of BP as biofunctional and biocompatible nanomaterials for the application to bone tissue engineering and regeneration. An ultrathin layer of BP nanodots (BPNDs) was created on a glass substrate by using a flow-enabled self-assembly process, which yielded a highly uniform deposition of BPNDs in a unique confined geometry. The BPND-coated substrates represented unprecedented favorable topographical microenvironments and supportive matrices suitable for the growth and survival of MC3T3-E1 preosteoblasts. The prepared substrates promoted the spontaneous osteodifferentiation of preosteoblasts, which had been confirmed by determining alkaline phosphatase activity and extracellular calcium deposition as early- and late-stage markers of osteogenic differentiation, respectively. Furthermore, the BPND-coated substrates upregulated the expression of some specific genes (i.e., RUNX2, OCN, OPN, and Vinculin) and proteins, which are closely related to osteogenesis. Conclusively, our BPND-coating strategy suggests that a biologically inert surface can be readily activated as a cell-favorable nanoplatform enabled with excellent biocompatibility and osteogenic ability.

Real-Time Biomonitoring Device Based on 2D Black Phosphorus and Polyaniline Nanocomposite Flexible Supercapacitors

Flexible energy storage devices are becoming significantly important to power wearable and portable devices that monitor physiological parameters for many biomedical applications. Many hybrid nanomaterials based on 2D materials are used in order to improve the performance of flexible energy storage devices. Here, a hybrid nanocomposite is synthesized through in situ polymerization of aniline in the presence of black phosphorus (BP) nanoflakes. This nanocomposite, polyaniline (PANI)@BP, is employed to fabricate flexible supercapacitor (FSC) electrodes. PANI@BP FSCs can provide a power source for biometric devices. The generated signal can be transmitted to a smartphone in real time via wireless communication. Such a compact and lightweight integrated device has been used to track a human heart beat while powered by PANI@BP FSC. These findings are providing a promising example of a flexible energy storage device that can be integrated with different real-time health monitoring devices.

Emerging two-dimensional monoelemental materials (Xenes): Fabrication, modification, and applications thereof in the field of bioimaging as nanocarriers

In recent years, more and more research enthusiasm has been devoted to the development of emerging two-dimensional (2D) monoelement materials (Xenes) and explored potential applications in various fields, especially biomedicine and bioimaging. The inspiring results attribute to their excellent physicochemical properties, including adjustable band gap, surface electronic layout characteristics, and so on, making it easier for surface modification in order to meet designated needs. As a popular interdisciplinary research frontier, a variety of methods for fabricating 2D Xenes have recently been adopted for pre-preparing future practical bioimaging applications, which implies that these materials will have broad clinical application prospects in the future. In this review, we will concentrate on the family of 2D Xenes and summarize their fabrication and modification methods firstly. Then, their applications in bioimaging as nanocarriers will be described according to the Periodic Table of Elements. In addition, current challenges and prospects for further clinical applications will be under discussion and use black phosphorus as a typical example. At last, general conclusion will be made that it is worth expecting that 2D Xenes will play a key role in the next generation of oncologic bioimaging in the future. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Recent Advances in the Application of Two-Dimensional Nanomaterials for Neural Tissue Engineering and Regeneration

The complexity of the nervous system structure and function, and its slow regeneration rate, makes it more difficult to treat compared to other tissues in the human body when an injury occurs. Moreover, the current therapeutic approaches including the use of autografts, allografts, and pharmacological agents have several drawbacks and can not fully restore nervous system injuries. Recently, nanotechnology and tissue engineering approaches have attracted many researchers to guide tissue regeneration in an effective manner. Owing to their remarkable physicochemical and biological properties, two-dimensional (2D) nanomaterials have been extensively studied in the tissue engineering and regenerative medicine field. The great conductivity of these materials makes them a promising candidate for the development of novel scaffolds for neural tissue engineering application. Moreover, the high loading capacity of 2D nanomaterials also has attracted many researchers to utilize them as a drug/gene delivery method to treat various devastating nervous system disorders. This review will first introduce the fundamental physicochemical properties of 2D nanomaterials used in biomedicine and the supporting biological properties of 2D nanomaterials for inducing neuroregeneration, including their biocompatibility on neural cells, the ability to promote the neural differentiation of stem cells, and their immunomodulatory properties which are beneficial for alleviating chronic inflammation at the site of the nervous system injury. It also discusses various types of 2D nanomaterials-based scaffolds for neural tissue engineering applications. Then, the latest progress on the use of 2D nanomaterials for nervous system disorder treatment is summarized. Finally, a discussion of the challenges and prospects of 2D nanomaterials-based applications in neural tissue engineering is provided.

Black Phosphorus Nanostructure Based Highly Sensitive and Selective Surface Plasmon Resonance Sensor for Biological and Chemical Sensing: A Review

Surface plasmon resonance (SPR) is an attention-grabbing sensor type, which offers the sensitive and selective detection of biomolecules and environmentally toxic substances. Notably, the SPR sensor gives excellent rewards including real-time, in-situ, and label-free measuring capability as compared to existing sensing technologies. As a result, these noteworthy merits of the SPR sensor make it straightforward to investigate the molecular events and chemical/gas molecule interaction. Unfortunately, there are different binding events including smaller molecular mass substances, which cannot be detected at the SPR sensor. Accordingly, this downside of the SPR sensor eventually led to the design and implementation of new approaches for sensitivity and selectivity improvement for sensing applications in different fields. Recently, the black phosphorus (BP) derived 2 D nanomaterial is stand out as a distinctive nanostructure in comparison to recently reported other 2 D nanomaterials. Substantial and functional characteristics of BP including simplicity of operation, optical properties, high carrier mobility, stronger immobilization of receptors and biomolecules, electronic bridging playing important role in the highly selective and sensitive assessment of analyte. The designed BP nanostructures are mostly serving to accelerate the plasmon material signals followed by improved molecular sensing that may due to 40-times faster-sensing responses of BP nanostructure than reported 2 D nanomaterials. Therefore, the present review article sheds light on the latest significant advances in biological and toxic gas detection through 2D BP nanostructures based SPR sensors. In the future, this review will facilitate detailed insights into the development of BP-based groundbreaking frameworks for highly sensitive and selective recognition of biomolecules and environmental pollutants.

Cytocompatibility of stabilized black phosphorus nanosheets tailored by directly conjugated polymeric micelles for human breast cancer therapy

The novel procedure of few-layer black phosphorus (FLBP) stabilization and functionalisation was here proposed. The cationic polymer PLL and non-ionic PEG have been involved into encapsulation of FLBP to allow sufficient time for further nanofabrication process and overcome environmental degradation. Two different spacer chemistry was designed to bind polymers to tumor-homing peptides. The efficiency of functionalisation was examined by RP-HPLC, microscopic (TEM and SEM) and spectroscopic (FT-IR and Raman) techniques as well supported by ab-initio modelling. The cell and dose dependent cytotoxicity of FLBP and its bioconjugates was evaluated against HB2, MCF-7 and MDA-MB-231 cell lines. Functionalisation allowed not only for improvement of environmental stability, but also enhances therapeutic effect by abolished the cytotoxicity of FLBP against HB2 cell line. Moreover, modification of FLBP with PLL caused increase of selectivity against highly aggressive breast cancer cell lines. Results indicate the future prospect application of black phosphorus nanosheets as nanocarrier, considering its unique features synergistically with conjugated polymeric micelles.

Progress in the therapeutic applications of polymer-decorated black phosphorus and black phosphorus analog nanomaterials in biomedicine

Wonderful black phosphorus (BP) and some BP analogs (BPAs) have been increasingly studied for their biomedical applications owing to their fascinating properties and biodegradability, but opportunities and challenges have always coexisted in their study. Poor stability upon exposure to the natural environment is the major obstacle hampering their in vivo applications. BP/polymer and BPAs/polymer nanocomposites can not only efficiently prevent their oxidation and aggregation but also exhibit "biological activity" due to synergistic effects. In this review, we briefly describe the synthesis methods and stability strategies of BP/polymer and BPAs/polymer. Then, advances pertaining to their exciting therapeutic applications in various fields are systematically introduced, such as cancer therapy (phototherapy, drug delivery, and synergistic immunotherapy), bone regeneration, and neurogenesis. Some challenges for future clinical trials and possible directions for further study are finally discussed.

In Vivo Enrichment and Elimination of Circulating Tumor Cells by Using a Black Phosphorus and Antibody Functionalized Intravenous Catheter

The circulating tumor cell (CTC) count is closely related to cancer recurrence and metastasis. The technology that can in vivo destroy CTCs may bring great benefits to patients, which is an urgent clinical demand. Here, a minimally invasive therapeutic intravenous catheter for in vivo enriching and photothermal killing of CTCs is developed. The surface of catheter is modified with anti-EpCAM antibody and the interior is filled with black phosphorus nanosheets (BPNSs). CTCs in the peripheral blood are captured by the catheter continually with the aid of circulation. The captured CTCs are used for downstream analyses or in vivo eliminated by the near-infrared (NIR) photothermal effect of BPNSs. A capture efficiency of 2.1% is obtained during the 5 min of treatment, and 100% of the captured CTCs are killed by following NIR light irradiation in both an in vitro closed-loop circulation system and an in vivo rabbit model. This cost-effective modality for lowering the CTCs burden can be a good supplement to traditional therapies, which holds great promise as an effective clinical intervention for cancer patients.