Polyvinylpyrrolidone-assisted solvent exfoliation of black phosphorus nanosheets and electrochemical sensing of p-nitrophenol

Efficient detection of p-nitrophenol via a polypyrrole flower-decorated nickel foam-based electrochemical sensor

p-Nitrophenol (p-NP) is known as a common contaminant found in wastewater, agricultural runoff, and industrial effluents which can degrade water quality and cause potential carcinogenic and toxic effects on the human body. Its detection is essential for public health, industrial safety, environmental protection, and regulatory compliance, underscoring its broad applicability. In this study, a novel electrochemical sensor based on polypyrrole (PPy) flowers assembled via nanotubes was developed for the sensitive determination of p-NP. The nickel (Ni) foam modified with PPy flowers functioned as the working electrode and showed selectivity toward p-NP in a phosphate buffer medium at pH 7.0. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were utilized for the sensitive determination of p-NP. Under the optimum conditions, the peak currents of DPV versus the concentrations of p-NP in the range of 0.01-20 nM showed a good linear relationship (R2 = 0.9943), and the limit of detection (LOD) was calculated to be 7.18 pM (signal-to-noise ratio of 3, S/N = 3). The fabricated electrochemical p-NP sensor exhibited high sensitivity, a low detection limit, and a low response time. The recoveries of p-NP in real samples of groundwater and tap water using the PPy Fls/Ni foam electrode were in the range of 91.0-108.4% with a relative standard deviation (RSD) in the range of 6.65%. Consequently, the PPy Fls/Ni foam electrode could be applied as a rapid, precise, and sensitive electrochemical sensor platform for aqueous p-NP quantification and determination.

Research Progress on the Preparation Methods for and Flame Retardant Mechanism of Black Phosphorus and Black Phosphorus Nanosheets

Black phosphorus and black phosphorus nanosheets are widely used in the flame retardant field because of their excellent properties, but the immature preparation methods have resulted in extremely high preparation cost, which greatly limits their development and application. In this paper, various preparation methods of black phosphorus and black phosphorus nanosheets are described in detail, the advantages and disadvantages of each method are analyzed in depth, the flame-retardant mechanism and application of black phosphorus and black phosphorus nanosheets in flame retardants are discussed, and the subsequent development direction of black phosphorus and black phosphorus nanosheets is proposed.

Black phosphorus, an advanced versatile nanoparticles of antitumor, antibacterial and bone regeneration for OS therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor. In the clinic, usual strategies for OS treatment include surgery, chemotherapy, and radiation. However, all of these therapies have complications that cannot be ignored. Therefore, the search for better OS treatments is urgent. Black phosphorus (BP), a rising star of 2D inorganic nanoparticles, has shown excellent results in OS therapy due to its outstanding photothermal, photodynamic, biodegradable and biocompatible properties. This review aims to present current advances in the use of BP nanoparticles in OS therapy, including the synthesis of BP nanoparticles, properties of BP nanoparticles, types of BP nanoparticles, and modification strategies for BP nanoparticles. In addition, we have discussed comprehensively the application of BP in OS therapy, including single, dual, and multimodal synergistic OS therapies, as well as studies about bone regeneration and antibacterial properties. Finally, we have summarized the conclusions, limitations and perspectives of BP nanoparticles for OS therapy.

Nitrogen-rich carbon nitride (C3N5) coupled with oxygen vacancy TiO2 arrays for efficient photocatalytic H2O2 production

Developing efficient and facilitated recycling photocatalysts for H2O2 formation is an ideal strategy for solar-to-chemical energy conversion. In this work, we synthesized ultrathin C3N5 nanosheets through the process of thermal polymerization and polyvinylpyrrolidone (PVP)-assisted solvent exfoliation. Subsequently, the obtained ultrathin C3N5 nanosheets were tightly attached to the surface of TiO2-x arrays, resulting in an enhanced photocatalytic H2O2 production rate. The density functional theory (DFT) calculations demonstrate that an internal electric field (IEF) is generated between the TiO2-x array and the ultrathin C3N5 due to the different work functions. The presence of IEF provides an additional driving force for carrier separation and transfer in the heterointerface. Benefitting from this unique strategy, the optimal heterojunction obtains the highest H2O2 formation rate (2.93 μmol/L/min), which is about 4.1 times than that of TiO2-x arrays. The rotating disk electrode (RDE) analysis manifests H2O2 formation through 2e--dominated oxygen reduction reaction (ORR). This research provides an innovative strategy for assembling a type-II heterojunction with a useful IEF for efficient photocatalytic H2O2 production.

Innovative Phosphorene Nanoplatform for Light Antimicrobial Therapy

Over the past few years, antibiotic resistance has reached global dimensions as a major threat to public health. Consequently, there is a pressing need to find effective alternative therapies and therapeutic agents to combat drug-resistant pathogens. Photodynamic therapy (PDT), largely employed as a clinical treatment for several malignant pathologies, has also gained importance as a promising antimicrobial approach. Antimicrobial PDT (aPDT) relies on the application of a photosensitizer able to produce singlet oxygen (1O2) or other cytotoxic reactive oxygen species (ROS) upon exposure to appropriate light, which leads to cell death after the induced photodamage. Among different types of 2D nanomaterials with antimicrobial properties, phosphorene, the exfoliated form of black phosphorus (bP), has the unique property intrinsic photoactivity exploitable for photothermal therapy (PTT) as well as for PDT against pathogenic bacteria.

Preparation and Application of Electrochemical Horseradish Peroxidase Sensor Based on a Black Phosphorene and Single-Walled Carbon Nanotubes Nanocomposite

To design a new electrochemical horseradish peroxidase (HRP) biosensor with excellent analytical performance, black phosphorene (BP) nanosheets and single-walled carbon nanotubes (SWCNTs) nanocomposites were used as the modifier, with a carbon ionic liquid electrode (CILE) as the substrate electrode. The SWCNTs-BP nanocomposite was synthesized by a simple in situ mixing procedure and modified on the CILE surface by the direct casting method. Then HRP was immobilized on the modified electrode with Nafion film. The electrocatalysis of this electrochemical HRP biosensor to various targets was further explored. Experimental results indicated that the direct electrochemistry of HRP was realized with a pair of symmetric and quasi-reversible redox peaks appeared, which was due to the presence of SWCNTs-BP on the surface of CILE, exhibiting synergistic effects with high electrical conductivity and good biocompatibility. Excellent electrocatalytic activity to trichloroacetic acid (TCA), sodium nitrite (NaNO₂), and hydrogen peroxide (H₂O₂) were realized, with a wide linear range and a low detection limit. Different real samples, such as a medical facial peel solution, the soak water of pickled vegetables, and a 3% H₂O₂ disinfectant, were further analyzed, with satisfactory results, further proving the potential practical applications for the electrochemical biosensor.

Highly selective detection of adenine and guanine by NH2-MIL-53(Fe)/CS/MXene nanocomposites with excellent electrochemical performance

Adenine (A) and guanine (G) are mainly found in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) and play a crucial role in genetic information transfer and protein synthesis. In this study, NH₂-MIL-53(Fe)/CS/MXene nanocomposites were prepared for detecting guanine and adenine. With high specific surface area, excellent water dispersion, and numerous active sites, MXene (transition metal carbides, nitrides, and carbonitrides) provides a good platform for loading primitive metal-organic frameworks (MOFs). At the same time, the problem of poor conductivity and dispersion of MOFs is solved. The electrochemical catalytic oxidation of adenine and guanine of NH₂-MIL-53 (Fe)/CS/MXene nanocomposites was carried out by differential pulse voltammetry (DPV). Operating voltage of DPV: 0.7-0.9 V (vs. Ag/AgCl) for G, 1.0-1.2 V (vs. Ag/AgCl) for A, 0.8 V (vs. Ag/AgCl), and 1.1 V (vs. Ag/AgCl) for G and A. The concentration ranges for detecting A and G were 3-118 μM and 2-120 μM with detection limits of 0.57 μM and 0.17 μM (S/N = 3), respectively. The nanocomposite was used for detecting G and A in herring sperm DNA, and the content of G and A was found to be about 9 and 11 μM; the RSD values were 3.4 and 1.3%, respectively.

Sensitive electrochemical detection of p-nitrophenol by pre-activated glassy carbon electrode integrated with silica nanochannel array film

Convenient, rapid and sensitive detection of p-nitrophenol (p-NP), one of the priority environmental pollutants, in environmental samples is of great significance. Electrochemical sensor with simple fabrication process, high sensitivity and selectivity, good antifouling, and regeneration performance is highly desirable. Herein, an electrochemical sensing platform is demonstrated based on the integration of vertically-ordered mesoporous silica-nanochannel film (VMSF) on electrochemical pre-activated glassy carbon electrode (p-GCE), which is able to realize ultrasensitive detection of p-NP in environmental samples. Electrochemical pre-activation of GCE is achieved through a simple and green electrochemical polarization process including anodic oxidation at high voltage and the following cathodic reduction at low voltage. The p-GCE possesses enhanced active area and introduced active sites, and enables stable binding of VMSF. VMSF is easily grown on p-GCE through the electrochemically assisted self-assembly (EASA) method within 10 s. Owing to the hydrogen bonding between silanol groups and p-NP, VMSF nanochannels display strong enrichment effect for the detection of p-NP. The developed VMSF/p-GCE sensor can achieve sensitive detection of p-NP ranging from 10 nM to 1 μM and from 1 to 30 μM with a limit of detection (LOD) of 9.4 nM. Considering the antifouling ability of VMSF, detection of p-NP in pond water is achieved.

NaYF4:Yb3+(58%),Tm3+@NaYF4@Au nanocomposite for 4-nitrophenol ultrasensitive quantitative detection and highly efficient catalytic reduction

NaYF4:Yb3+(58%),Tm3+@NaYF4@Au composite nanomaterials were designed and synthesized through condition optimization for the quantitative detection and catalytic reduction of 4-NP.

Black Phosphorus, an Emerging Versatile Nanoplatform for Cancer Immunotherapy

Black phosphorus (BP) is one of the emerging versatile nanomaterials with outstanding biocompatibility and biodegradability, exhibiting great potential as a promising inorganic nanomaterial in the biomedical field. BP nanomaterials possess excellent ability for valid bio-conjugation and molecular loading in anticancer therapy. Generally, BP nanomaterials can be classified into BP nanosheets (BPNSs) and BP quantum dots (BPQDs), both of which can be synthesized through various preparation routes. In addition, BP nanomaterials can be applied as photothermal agents (PTA) for the photothermal therapy (PTT) due to their high photothermal conversion efficiency and larger extinction coefficients. The generated local hyperpyrexia leads to thermal elimination of tumor. Besides, BP nanomaterials are capable of producing singlet oxygen, which enable its application as a photosensitizer for photodynamic therapy (PDT). Moreover, BP nanomaterials can be oxidized and degraded to nontoxic phosphonates and phosphate under physiological conditions, improving their safety as a nano drug carrier in cancer therapy. Recently, it has been reported that BP-based PTT is capable of activating immune responses and alleviating the immunosuppressive tumor microenvironment by detection of T lymphocytes and various immunocytokines, indicating that BP-based nanocomposites not only serve as effective PTAs to ablate large solid tumors but also function as an immunomodulation agent to eliminate discrete tumorlets. Therefore, BP-mediated immunotherapy would provide more possibilities for synergistic cancer treatment.