Tungsten Carbide Nanotubes Supported Platinum Nanoparticles as a Potential Sensing Platform for Oxalic Acid

Laponite®-From Dispersion to Gel-Structure, Properties, and Applications

Laponite® (LAP) is an intensively studied synthetic clay due to the versatility given by its layered structure, which makes it usable in various applications. This review describes the multifaceted properties and applications of LAP in aqueous dispersions and gel systems. The first sections of the review discuss the LAP structure and the interactions between clay discs in an aqueous medium under different conditions (such as ionic strength, pH, temperature, and the addition of polymers) in order to understand the function of clay in tailoring the properties of the designed material. Additionally, the review explores the aging phenomenon characteristic of LAP aqueous dispersions as well as the development of shake-gels by incorporating LAP. The second part shows the most recent studies on materials containing LAP with possible applicability in the drilling industry, cosmetics or care products industry, and biomedical fields. By elucidating the remarkable versatility and ease of integration of LAP into various matrices, this review underscores its significance as a key ingredient for the creation of next-generation materials with tailored functionalities.

Carbon dots derived from peptone as "off-on" fluorescent probes for the detection of oxalic acid

A simple and rapid microwave heating approach was reported for the preparation of water soluble carbon dots (CDs) using peptone as carbon source with the assistance of ethylenediamine. Several characterization techniques such as transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were employed to analyze CDs. The optical properties of synthesized CDs were examined by UV-vis and fluorescence spectroscopy. The CDs exhibit strong blue emission under 365 nm UV lamp and have the excitation and pH (2.0-12.0) dependent emission behavior. The fluorescence intensity of CDs can be selectively quenched by Co²⁺ via dynamic mechanism, while the addition of oxalic acid (OA) results in a remarkable recovery of the fluorescence intensity due to the strong coordination binding between oxalic acid and Co²⁺. Hence, the prepared CDs can conveniently serve as "off-on" fluorescent probes for highly sensitive determination of oxalic acid. The wide linear range is 0.5-70 mg/L with a low detection limit of 0.288 mg/L. Furthermore, the probes were successfully applied to detect oxalic acid in tomato and cherry tomato samples with the recovery of 96.4 %-106.4 % and the relative standard deviation lower than 0.25 %.

Tungsten-based Nanomaterials in the Biomedical Field: A Bibliometric Analysis of Research Progress and Prospects

Tungsten-based nanomaterials (TNMs) with diverse nanostructures and unique physicochemical properties have been widely applied in the biomedical field. Although various reviews have described the application of TNMs in specific biomedical fields, there are still no comprehensive studies that summarize and analyze research trends of the field as a whole. To identify and further promote the development of biomedical TNMs, a bibliometric analysis method is used to analyze all relevant literature on this topic. First, general bibliometric distributions of the dataset by year, country, institute, referenced source, and research hotspots are recognized. Next, a comprehensive review of the subjectively recognized research hotspots in various biomedical fields, including biological sensing, anticancer treatments, antibacterials, and toxicity evaluation, is provided. Finally, the prospects and challenges of TNMs are discussed to provide a new perspective for further promoting their development in biomedical research.

Wild jujube-based fluorescent carbon dots for highly sensitive determination of oxalic acid

Fluorescent carbon dots (CDs) were synthesized by a one-step hydrothermal treatment of wild jujube and dl-tryptophan. The structure and properties of the CDs were confirmed by transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet visible absorption spectroscopy, fluorescence spectroscopy and so on. The as-prepared CDs exhibit excellent excitation-independent but pH-dependent (4.0-12.0) fluorescent features and emit blue strong fluorescence under 365 nm light. Hg²⁺ can decrease the fluorescence intensity of the CDs through static quenching, while the addition of oxalic acid (OA) recovers it owing to the coordination binding between oxalic acid and Hg²⁺. Based on this, the as-prepared CDs were used as a new "off-on" fluorescent probe for highly sensitive determination of oxalic acid with a wide linear detection range of 0.1-20 mg L^-1 and a low detection limit of 0.057 mg L^-1. Moreover, the fluorescent probe was successfully applied to detect oxalic acid in tomato and cherry tomato samples with satisfactory results.

Electrochemical Enzyme-free Sensing of Oxalic Acid Using an Amine-mediated Synthesis of CuS Nanosphere

Copper sulfide nanospheres (CuS NS) were prepared by a solvothermal method with the support of p-phenylene diamine as a structure direct agent. The formation of CuS NS was evaluated using XRD, FE-SEM, HR-TEM, XPS, and electrochemical methods. The CuS NS modified electrode demonstrated excellent electro-catalytic behavior for the electro-oxidation of oxalic acid (OA). The modified electrode showed a good linear range (50 to 700 μM), high sensitivity (0.0353 μA μM^-1 cm^-2), a low detection limit (35.6 μM), long term stability and good anti-interference behavior.

Simple and ultrasensitive electrochemical sensor for oxalic acid detection in real samples by one step co-electrodeposition strategy

Oxalic acid (OA), naturally available in vegetables and foodstuffs derived from them, easily combines with calcium and iron to form insoluble oxalates. Their chelation will result in various renal diseases; thus, the accurate determination of OA is quite significant in the evaluation of food quality and healthcare settings. Here, we developed an electrochemically induced alcohol-free sol-gel method to obtain platinum nanoparticles (PtNPs) adhered with porous silica on glassy carbon electrode (PSiO₂-PtNPs/GCE) by a one-step process, which can be potentially used as an excellent catalyst towards electrochemical oxidation of OA for the first time. Without any redox mediator, PSiO₂-PtNPs/GCE exhibited a low oxidation overpotential and a significantly high current signal, achieving a wide linear range of concentration from 0 to 45 μM and a detection limit as low as to 25 nM for OA detection. Moreover, this present alcohol-free sol-gel approach towards OA determination was verified in real samples, which is promising for foodstuff analysis and clinical diagnosis. Graphical abstract.

Improving photoelectrochemical response of ZnO nanowire arrays by coating with p-type ZnO-resembling metal-organic framework

Coupling semiconducting metal-organic frameworks (MOFs) with metal oxide (MO) semiconductor nanowires is an efficient solution to tune the photoelectric properties of both the parties. In this report, we demonstrate a facile surfactant-free growth strategy for modification of zinc oxide (ZnO) single-crystal nanowire arrays (NWAs) with the MOF zinc glycolate (noted as Zn-GA) that contains an embedded continuous 3D Zn-O network. Due to the structural resemblance of the Zn-O network between Zn-GA and ZnO, the prepared ZnO@Zn-GA nanowires present a tight contact at the core-shell interface in a partially epitaxial manner, and the loading amount of Zn-GA can be well controlled in the synthetic process. The inherent p-type Zn-GA in combination with the widely available n-type ZnO assures the construction of tandem n-p heterojunctions at the core-shell interface, which is confirmed by Mott-Schottky analysis. By implementation of the ZnO@Zn-GA NWAs as photoanodes for photoelectrochemical oxidation of water and oxalic acid, improved photocurrent responses are obtained relative to the primary ZnO NWAs. The most significant photoresponse is observed in the ZnO nanowires shelled by a compact Zn-GA particulate thin film with the largest junction region. These results are elucidated by the enhanced spatial separation efficiency of photogenerated charge carriers, which is favored by the built-in electric field at the interface of the n-p heterojunctions.

Preparation of small-sized tungsten carbide nanorods for loading Pt with promoted electrocatalytic activity and stable anti-poisoning performance

The WO₃·H₂O rod with diameter and length of 20 and 100 nm was controlled by citric acid and DWCNTs. When the samples were heated in air and carbonized in nitrogen, WC nanorods with high specific surface area of 32.2 m² g⁻¹ were obtained.

Design and Electrochemical Study of Platinum-Based Nanomaterials for Sensitive Detection of Nitric Oxide in Biomedical Applications

The extensive physiological and regulatory roles of nitric oxide (NO) have spurred the development of NO sensors, which are of critical importance in neuroscience and various medical applications. The development of electrochemical NO sensors is of significant importance, and has garnered a tremendous amount of attention due to their high sensitivity and selectivity, rapid response, low cost, miniaturization, and the possibility of real-time monitoring. Nanostructured platinum (Pt)-based materials have attracted considerable interest regarding their use in the design of electrochemical sensors for the detection of NO, due to their unique properties and the potential for new and innovative applications. This review focuses primarily on advances and insights into the utilization of nanostructured Pt-based electrode materials, such as nanoporous Pt, Pt and PtAu nanoparticles, PtAu nanoparticle/reduced graphene oxide (rGO), and PtW nanoparticle/rGO-ionic liquid (IL) nanocomposites, for the detection of NO. The design, fabrication, characterization, and integration of electrochemical NO sensing performance, selectivity, and durability are addressed. The attractive electrochemical properties of Pt-based nanomaterials have great potential for increasing the competitiveness of these new sensors and open up new opportunities in the creation of novel NO-sensing technologies for biological and medical applications.

A one-pot gold seed-assisted synthesis of gold/platinum wire nanoassemblies and their enhanced electrocatalytic activity for the oxidation of oxalic acid

Three-dimensional (3D) noble metal nanoassemblies composed of one-dimensional (1D) nanowires have been attracting much interest due to the unique physical and chemical properties of 1D nanowires as well as the particular interconnected open-pore structure of 3D nanoassemblies. In this work, well-defined Au/Pt wire nanoassemblies were synthesized by using a facile NaBH4 reduction method in the presence of a branched form of polyethyleneimine (PEI). A study of the growth mechanism indicated the morphology of the final product to be highly related to the molecular structure of the polymeric amine. Also, the preferred Pt-on-Pt deposition contributed to the formation of the 1D Pt nanowires. The Au/Pt wire nanoassemblies were functionalized with PEI at the same time that these nanoassemblies were synthesized due to the strong N-Pt bond. The chemically functionalized Au/Pt wire nanoassemblies exhibited better electrocatalytic activity for the electro-oxidation of oxalic acid than did commercial Pt black.

Close-packed assemblies of discrete tiny silver nanoparticles on triangular gold nanoplates as a high performance SERS probe

An island like array of tiny Ag nanoparticles bounded on triangular Au nanoplates was synthesized as surface-enhanced Raman spectroscopy substrate.