Hydrothermal synthesis of Fe2O3/graphene nanocomposite for selective determination of ascorbic acid in the presence of uric acid

Rugby ball-shaped magnetic microcapsule for tumor hyperthermia

Magnetic hyperthermia (MH) induced by magnetic particles has been widely used to treat tumors. However, the limited heating conversion efficiency inspires the design and synthesis of versatile magnetic materials for enhancing the performance of MH. Herein, we developed rugby ball-shaped magnetic microcapsules as efficient MH agents. The size and shape of the microcapsules can be precisely controlled by adjusting the reaction time and temperature without surfactant assistance. Because of their high saturation magnetization and uniform size/morphology, the microcapsules showed excellent thermal conversion efficiency, with a specific absorption rate of 2391 W g-1. Additionally, we performed in vivo anti-tumor studies on mice and found that MH mediated by magnetic microcapsules effectively inhibited the advancement of hepatocellular carcinoma. The microcapsules' porous structure might allow them to efficiently load different therapeutic drugs and/or functional species. These beneficial properties make microcapsules ideal candidates for medical applications, particularly in disease therapy and tissue engineering.

A dual luminescent sensor coordination polymer for simultaneous determination of ascorbic acid and tryptophan

Simultaneous high sensitivity detection of biomolecules is important for research in medicine, living cells and environmental samples. In this work, a water stable coordination polymer, [Cd₂(bptc)(4,4'-bpy)(H₂O)₃]ˑH₂O 1 (H₄bptc = 2,3,3',4'-biphenyl tetracarboxylic acid, 4,4'-bpy = 4,4'-bipyridine), was designed and successfully synthesized as a luminescent sensor for simultaneous recognition of Ascorbic Acid (AA) and L-Tryptophan (L-Trp) based on luminescent -OFF and -ON, respectively. Importantly, the proposed sensing system showed an excellent performance with high K_SV values of 4.85 × 10⁴ M^-1, 9.60 × 10⁷ M^-1 and low limit of detection (LOD) of 0.28 nM, 63 nM, respectively. In addition, the probable mechanisms are also discussed. The luminescent quenching behavior by AA can be mainly attributed to the static resonance energy transfer between complex 1 and the analytes. Whereas the enhancing effect of L-Trp comes from the intrinsic strong luminescence for L-Trp itself and photo-competitive mechanism between CP 1 sensor and L-Trp, supposedly. In addition, the repeatability of both systems were also investigated.

Nanoscale dynamic chemical, biological sensor material designs for control monitoring and early detection of advanced diseases

Early detection and easy continuous monitoring of emerging or re-emerging infectious, contagious or other diseases are of particular interest for controlling healthcare advances and developing effective medical treatments to reduce the high global cost burden of diseases in the backdrop of lack of awareness regarding advancing diseases. Under an ever-increasing demand for biosensor design reliability for early stage recognition of infectious agents or contagious diseases and potential proteins, nanoscale manufacturing designs had developed effective nanodynamic sensing assays and compact wearable devices. Dynamic developments of biosensor technology are also vital to detect and monitor advanced diseases, such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), diabetes, cancers, liver diseases, cardiovascular diseases (CVDs), tuberculosis, and central nervous system (CNS) disorders. In particular, nanoscale biosensor designs have indispensable contribution to improvement of health concerns by early detection of disease, monitoring ecological and therapeutic agents, and maintaining high safety level in food and cosmetics. This review reports an overview of biosensor designs and their feasibility for early investigation, detection, and quantitative determination of many advanced diseases. Biosensor strategies are highlighted to demonstrate the influence of nanocompact and lightweight designs on accurate analyses and inexpensive sensing assays. To date, the effective and foremost developments in various nanodynamic designs associated with simple analytical facilities and procedures remain challenging. Given the wide evolution of biosensor market requirements and the growing demand in the creation of early stage and real-time monitoring assays, precise output signals, and easy-to-wear and self-regulating analyses of diseases, innovations in biosensor designs based on novel fabrication of nanostructured platforms with active surface functionalities would produce ​remarkable biosensor devices. This review offers evidence for researchers and inventors to focus on biosensor challenge and improve fabrication of nanobiosensors to revolutionize consumer and healthcare markets.

N-Doped Modified Graphene/Fe2O3 Nanocomposites as High-Performance Anode Material for Sodium Ion Storage

Sodium-ion storage devices have received widespread attention because of their abundant sodium resources, low cost and high energy density, which verges on lithium-ion storage devices. Electrochemical redox reactions of metal oxides offer a new approach to construct high-capacity anodes for sodium-ion storage devices. However, the poor rate performance, low Coulombic efficiency, and undesirable cycle stability of the redox conversion anodes remain a huge challenge for the practical application of sodium ion energy storage devices due to sluggish kinetics and irreversible structural change of most conversion anodes during cycling. Herein, a nitrogen-doping graphene/Fe₂O₃ (N-GF-300) composite material was successfully prepared as a sodium-ion storage anode for sodium ion batteries and sodium ion supercapacitors through a water bath and an annealing process, where Fe₂O₃ nanoparticles with a homogenous size of about 30 nm were uniformly anchored on the graphene nanosheets. The nitrogen-doping graphene structure enhanced the connection between Fe₂O₃ nanoparticles with graphene nanosheets to improve electrical conductivity and buffer the volume change of the material for high capacity and stable cycle performance. The N-GF-300 anode material delivered a high reversible discharge capacity of 638 mAh g⁻¹ at a current density of 0.1 A g⁻¹ and retained 428.3 mAh g⁻¹ at 0.5 A g⁻¹ after 100 cycles, indicating a strong cyclability of the SIBs. The asymmetrical N-GF-300//graphene SIC exhibited a high energy density and power density with 58 Wh kg⁻¹ at 1365 W kg⁻¹ in organic solution. The experimental results from this work clearly illustrate that the nitrogen-doping graphene/Fe₂O₃ composite material N-GF-300 is a potential feasibility for sodium-ion storage devices, which further reveals that the nitrogen doping approach is an effective technique for modifying carbon matrix composites for high reaction kinetics during cycles in sodium-ion storage devices and even other electrochemical storage devices.

Microwave-assisted Synthesis of N,S-co-carbon Dots as Switch-on Fluorescent Sensor for Rapid and Sensitive Detection of Ascorbic Acid in Processed Fruit Juice

To achieve a rapid, sensitive, and economical method for the detection of ascorbic acid (AA) in the presence of Fe³⁺, a nitrogen and sulfur co-doped carbon dots (N,S-co-CDs) based fluorescence sensing system was developed. In this work, N,S-co-CDs were successfully synthesized via a one-step microwave-assisted method within 2.5 min using ammonium citrate and L-cysteine as precursors. The fluorescence of N,S-co-CDs was quenched (off ) by Fe³⁺ through a static-quenching mechanism. Subsequently, the fluorescence was recovered (on) after introducing AA into the quenched system, which was attributed to the reduction effect of AA for Fe³⁺. Therefore, a switch-on sensor (N,S-co-CDs/Fe³⁺ system) was developed for AA detection. Under optimal conditions, the limit of detection (LOD) of 2.31 μmol/L for AA was obtained over a linear range from 0 to 150 μmol/L. Furthermore, the proposed sensing method was successfully applied to detect AA in processed fruit juice with satisfactory results. The most important is that the sensor derived from a microwave-assisted method has simple and eco-friendly synthesis processes, is rapid, and has high detection efficiency. Therefore, such a switch-on sensor may be a promising candidate sensor for AA detection in processed fruit samples.

The fabrication of an Ni6MnO8 nanoflake-modified acupuncture needle electrode for highly sensitive ascorbic acid detection

The current work describes the use of a steel acupuncture needle as an electrode substrate in order to construct an Ni6MnO8 nanoflake layer-modified microneedle sensor for highly sensitive ascorbic acid detection. For the purpose of constructing the functionalized acupuncture needle, first, a carbon film was layered on the needle surface as the seed layer. Subsequently, a straightforward hydrothermal reaction-calcination process was employed for the growth of Ni6MnO8 nanoflakes on the needle to function as a sensing interface. Electrochemical investigations illustrated the fact that the Ni6MnO8 nanoflake-altered acupuncture needle electrode manifested outstanding efficiency toward the amperometric identification of ascorbic acid. In addition, the electrode manifested elevated sensitivity of 3106 μA mM-1 cm-2, detection limit of 0.1 μM, and a broad linear range between 1.0 μM and 2.0 mM. As demonstrated by the results, the Ni6MnO8 nanoflake-modified acupuncture needle constitutes a potentially fresh platform to construct non-enzymatic ascorbic acid sensors.

A turn-on fluorescent probe for sensitive detection of ascorbic acid based on SiNP–MnO2nanocomposites

A nanoprobe prepared by coupling nanoparticles (SiNPs) with BSA templated-MnO₂nanosheets was constructed for ascorbic acid analysis.

Prussian blue nanocubes with an open framework structure coated with polyoxometalates as a highly sensitive platform for ascorbic acid detection in drinks/human urine

A novel PB NC@POM platform was constructed and demonstrated high electrochemical response to ascorbic acid due to the excellent synergistic effect.

Application of Hierarchical CuO Bowl-like Array Film to Amperometric Detection of l-Ascorbic Acid

A hierarchical CuO array film was fabricated by electrochemical deposition with the aid of a colloidal monolayer as a template, followed by oxidation at high temperature. The prepared CuO film with a granular structure was arranged with ordered, hexagonal close-packed, and bowl-like pores. Combined with a gold layer sputtered on a glass substrate, this CuO array film was used as an electrochemical electrode in the amperometric detection of l-ascorbic acid. The array film exhibited a high sensitivity of 3484 μA mM^-1 cm^-2, a wide linear range from 1 μM to 7 mM, and a detection limit of 0.2 μM. Excellent stability was also achieved. The results demonstrate that the hierarchical CuO bowl-like array film is a promising new platform for the construction of non-enzymatic ascorbic acid sensors.

Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

Iron oxide nanostructures (IONs) in combination with graphene or its derivatives-e.g., graphene oxide and reduced graphene oxide-hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (bio)chemical substances.

New Approach for Porous Chitosan-Graphene Matrix Preparation through Enhanced Amidation for Synergic Detection of Dopamine and Uric Acid

Amide-functionalized materials have emerged as promising nonprecious catalysts for electrochemical sensing and catalysis. The covalent immobilization of chitosan (CS) onto graphene sheet (GS) (denoted as CS-GS) has been done via higher degree of amidation reaction to develop an electrochemical sensing matrix for simultaneous determination of dopamine (DA) and uric acid (UA). The enhanced amidation between CS and GS has not been reported previously. However, electrochemical results have revealed that the CS-GS enhances the electrocatalytic performance in terms of the oxidation potential and peak current due to the higher degree of amide functionalization compared to that of CS/GS, which has a lower amidation. Differential pulse voltammetry-based studies have indicated that the CS-GS matrix works at a lower detection limit (0.14 and 0.17 μM) (S/N = 3) and over a longer linear range (1-700 and 1-800 μM), with a comparatively higher sensitivity (2.5 and 2.0 μA μM^-1 cm^-2), for DA and UA, respectively. In addition, the CS-GS matrix demonstrates good selectivity toward the detection of DA and UA in the presence of a 10-fold higher concentration of AA and glucose. The as-prepared three-dimensional porous CS-GS also endows selective determination toward DA and UA in various real samples.

Synthesis of an ordered nanoporous Fe2O3/Au film for application in ascorbic acid detection

Ordered nanoporous Fe₂O₃/Au film was synthesized and used as an effective non-enzymatic sensor for detection of ascorbic acid.

Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications

Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities.