Real Blood Serum Samples Research Articles

An integrated liposome-based microfluidic strategy for rapid colorimetric analysis: A case study of microRNA-21 detection

In this study, a novel integrated liposome-based microfluidic platform combined with a smartphone was designed for the rapid colorimetric detection of microRNA-21 (miRNA-21) in real samples. The flowing surface-functionalized liposomes were first captured by nucleic acid-functionalized Au nanoparticles in the microfluidic chip. In the presence of miRNA-21, the DNA strand modified on the surface of Au nanoparticles hybridized with the target to form double-stranded products and was cleaved by duplex-specific nuclease (DSN) enzyme, causing the liposomes to be re-released. Then, as the liposomes in the colorimetric module were lysed and the “cellular” contents were released, a step-by-step “glucose-glucose oxidase-3,3′,5,5′-tetramethylbenzidine (TMB)” colorimetric reaction process catalyzed by the G-quadruplex/hemin was triggered. The grayscale values were recorded and recognized by the smartphone camera for miRNA-21 analysis. The advantages of the present strategy included the portability of smartphone-based colorimetric assay, the encapsulation and transport of reactants by liposomes and the low solvent usage of microfluidic chip. Under optimal conditions, this assay exhibited a wide linear range from 1 pM to 1 nM (r2 = 0.9981), and the limit of detection of miRNA-21 was as low as 0.27 pM. Moreover, the high specificity of this strategy allowed its successful application to the rapid analysis of miRNA-21 in real blood serum samples of people with type 2 diabetes.

Copper oxide nanocolumns for high-sensitive non-enzymatic glucose sensing

This paper presents a facile method to fabricate nanostructured copper-oxide (Cu2O/CuO) electrodes with columnar morphology for non-enzymatic glucose sensing. The electrodes were fabricated using a two-step method; first by producing Cu nanostructures through glancing angle deposition (GLAD), followed by a thermal annealing process at various temperatures. The nanostructures were characterized by X-ray diffraction and scanning electron microscopy to evaluate their structural and morphological properties. The optical properties of the electrodes were also investigated by VIS/NIR spectroscopy. Electrochemical characterization revealed that Cu2O outperformed other copper-based nanostructures, with the best sensitivity of 1394 μAcm-2 mM-1 and the lowest limit of detection (LOD) of 0.052 μM. The superior sensor also exhibits two broad linear ranges of 0.01–2 mM and 2–5 mM at the optimized potential of 0.6 V. The Cu2O electrodes demonstrate the merits of reproducibility, selectivity, fast response time, and high accuracy in measuring glucose levels in real blood serum samples.

A highly selective sensor based on p-tetranitrocalix[4]arene-capped copper nanoparticles for colorimetric and bare-eye detection of cyclophosphamide.

In the current study, one of the outstanding facile and simple protocols is proposed for the synthesis of copper nanoparticles (CuNPs) using NaBH4 as a reducing agent and p-tetranitrocalix[4]arene (p-TNC4) as a capping agent. According to our knowledge, no such technique is available in the literature for colorimetric detection of cyclophosphamide (CPA) using CuNPs at the trace level. The well-organized synthesis was confirmed via advanced spectroscopic techniques. The crystallite size, shape, phase purity, and morphological characteristics were determined via XRD, AFM, FT-IR, and UV-visible spectroscopy. At the optimal conditions for CPA detection, the sensor reveals an excellent sensitivity, selectivity, as well as stability with LOD and LOQ 20nM and 60nM, respectively. However, the proposed sensor showed excellent potential and selectivity for the sensing of colorimetric detection of CPA that can be effectively applied to real blood serum samples. The proposed approach is better suited as compared to reported protocols in terms of handling, simplicity, economic, energy consumption, reproducibility, and excellent performance in a very short time.

Portable Electrochemical Platform With Carbon Fibre Microelectrodes Integrated on an OHP Sheet for Snake Venom Analysis.

Snake bite is a serious medical emergency often leading to untimely fatalities. Serotherapy is the only treatment method adapted for this, whose efficacy depends on identification of the Snake species and venom type. As a specific antivenom has to be implicated for saving the victim, in most of the cases, such identification is challenging, thus, leading to mortality due to delay in treatment or side effects of injecting polymeric non-specific antivenom. Therefore, a point-of-care, venom specific detection device could be an impactful diagnostic tool. Herein, a prototype of miniaturized electrochemical sensing platform is presented for detection of Crotaline, venom from various common pit viper snakes. A three electrode based micro-platform with carbon fibre microelectrode, modified with mesoporous carbon, embedded and laminated in commercial OHP sheet, has been developed. The dimensions of the miniaturized platform was 25 mm ×35 mm, size of electrode was 0.5 mm ×25 mm with an electrochemical testing zone of diameter 10 mm, electrode spacing as 3 mm. The microscopic characterization revealed immobilization of porous carbon on fine fibrous structure. The device gave highly stable and sensitive electro-catalytic oxidation of Crotaline at E'= at 0.81 V, and provided a linear range of 50- [Formula: see text], limit of detection as [Formula: see text] and limit of quantification as [Formula: see text]. The device exhibited negligible interference from physiological blood serum biochemicals, high stability and reproducibility. Further, real blood serum samples, analysis via standard addition approach, was performed which showcased appreciable recovery values confirming the practical applicability of the device.

Blood glucose sensing by back gated transistor strips sensitized by CuO hollow spheres and rGO

In this work, a highly sensitive flexible glucose sensor based on a field effect transistor (FET) has been fabricated. It is shown that the proposed flexible transistor can be used as new non-enzymatic blood glucose test strips. CuO hollow-spheres decorated with reduced graphene oxide have been synthesized using the hydrothermal method. The shells of the hollow micro-spheres are formed by nanostructures. The synthesized nanostructured hollow micro-spheres (rGO/CuO–NHS) are deposited on a flexible PET substrate between interdigitated electrodes as the channel of a back gate transistor. The channel concentration and the FET bias are optimized so that the sensor exhibits extremely low limit of detection and high sensitivity. The combination of selective porous CuO hollow spheres and the high surface to volume ratio of their nanostructured shells with the high mobility and high conductivity rGO led to faster and higher charge-transfer capability and superior electro-catalyst activity for glucose oxidation. The glucose-dependent electrical responses of the sensor is measured in both resistive and transistor action modes. The amplification of the current by the induced electric field of the gate in the proposed FET-based biosensor provides advantages such as higher sensitivity and lower limit of detection compared to the resistive sensor. The flexible glucose sensor has a sensitivity of 600 μA μM−1 and a limit of detection of 1 nM with high reproducibility, good stability, and highly selectivity. The high accuracy response of the biosensor towards the real blood serum samples showed that it can be used as a test strip for glucose detection in real blood samples.

Colloidal lithography as a novel approach for the development of Ni-nanocavity insulin sensor

In this study, a highly sensitive, fast, and selective enzyme-free electrochemical sensor based on the deposition of Ni cavities on conductive glass was proposed for insulin detection. Considering the growing prevalence of diabetes mellitus, an electrochemical sensor for the determination of insulin was proposed for the effective diagnosis of the disease. Colloidal lithography enabled deposition of nanostructured layer (substrate) with homogeneous distribution of Ni cavities on the electrode surface with a large active surface area. The morphology and structure of conductive indium tin oxide glass modified with Ni cavities (Ni-c-ITO) were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The diameter of the resulting cavities was approximately 500 nm, while their depth was calculated at 190 ± 4 nm and 188 ± 18 nm using AFM and SEM, respectively. The insulin assay performance was evaluated by cyclic voltammetry. Ni-c-ITO exhibited excellent analytical characteristics, including high sensitivity (1.032 µA µmol−1 dm3), a low detection limit (156 µmol dm−3), and a wide dynamic range (500 nmol dm−3 to 10 µmol dm−3). Finally, the determination of insulin in buffer with interferents and in real blood serum samples revealed high specificity and demonstrated the practical potential of the method.

Design and Development of a Non‐Enzymatic Electrochemical Biosensor for the Detection of Glutathione

AbstractGlutathione (GSH‐reduced form) is a tripeptide that plays a vital role as an antioxidant to remove xenobiotics in the human body and changes in GSH levels are a marker for the progression of various diseases. In this context, a highly sensitive non‐enzymatic electrochemical biosensor for the detection of GSH has been developed using reduced graphene oxide Manganese oxide (rGMnO) nanocomposite as the nano‐interface. Initially, graphene oxide was synthesized by Hummer's method and then thermally reduced in the presence of MnO2in a blast furnace to obtain rGMnO nanocomposite. The nanocomposite was characterized to validate its structure and morphological properties via Scanning electron microscopy (SEM), X‐ray diffraction (XRD), Raman, and X‐ray photoelectron spectroscopy (XPS). Cyclic voltammetry and amperometry studies showed that upon the addition of GSH, the Pt/rGMnO modified working electrode exhibited a linear response in the range of 1–100 μM at an input voltage of −0.62 V. The developed sensor was found to have a sensitivity of 0.3256 μA μM−1and LOD of 970 nM with a recovery of 92–104 % in real blood serum samples.

Facile and fast synthesis of three-dimensional Ce-MOF/Ti3C2TX MXene composite for high performance electrochemical sensing of L-Tryptophan

Rational design and constructed new electrode material as high performance electrochemical sensor with outstanding selectivity, reproducibility and stability is an urgent demand for trace detection. Herein, a novel Ce-MOF/Ti3C2TX MXene composite as electrochemical sensor for L-Tryptophan (L-Trp) was constructed by utilizing the three-dimensional straw-sheaf-like Ce-MOF and Ti3C2TX MXene nanosheets. The combination of Ce-MOF and Ti3C2TX MXene not only significantly improves the conductivity of metal-organic framework (MOF) but also effectively prevents the stacking of Ti3C2TX MXene nanosheets. The electrochemical properties of the proposed sensor were investigated by electrochemical techniques in detail. The L-Trp sensor exhibits a wide linear range (0.2 ​μM–139 ​μM) and a low limit of detection (0.19 ​μM, S/N ​= ​3). Moreover, the proposed sensor exhibits excellent selectivity, good reproducibility and long-term stability, as well as satisfactory practical ability in real blood serum samples.

Application of FTIR Spectroscopy for Quantitative Analysis of Blood Serum: A Preliminary Study.

The aim of this study was to analyze the possibility of simultaneous determination of the concentration of components from the characteristics of FTIR spectra using the example of a model blood serum. To prepare model solutions, a set of freeze-dried control sera based on bovine blood serum was used, certified for approximately 38 parameters. Based on the values of the absorbance and areas of absorption bands in the FTIR spectra of model solutions, a regression equation was constructed by solving a nonlinear problem using the generalized reduced gradient method. By using the absorbance of the absorption bands at 1717 and 3903 cm−1 and the areas of the absorption bands at 616, 3750, and 3903 cm−1, it is possible to simultaneously determine the concentrations of 38 components with an error of less than 0.1%. The results obtained confirm the potential clinical use of FTIR spectroscopy as a reagent-free express method for the analysis of blood serum. However, its practical implementation requires additional research, in particular, analysis of real blood serum samples and validation of the method.

Portable fiber-optic SPR platform for the detection of NS1-antigen for dengue diagnosis

Here, we present a portable, selective and cost-effective fiber-optic surface plasmon resonance (SPR) based platform for early detection of Dengue virus. NS1 protein was targeted as the biomarker of dengue. Antibody-antigen specific binding was exploited for NS1 antigen detection. The binding of antibody was assisted by a self-assembled monolayer of alkanethiols on the surface of silver-coated unclad fiber. A wavelength interrogation mode of SPR was utilized to detect NS1 antigen in the dynamic range of 0.2–2.0 μg/ml. The 40 nm thick silver coated optical fiber exhibited resonance wavelength around 500 nm and change in resonance wavelength was monitored for each attachment step on the fiber. The sensitivity at the lowest concentration of NS1 antigen was found to be 54.7 nm/(μg/ml). The limit of detection of the sensor was found to be 0.06 μg/ml, which lies in the physiological range of NS1 protein present in the infected blood, hence the present technique may provide a very early detection advantage. Real blood serum samples were also successfully tested on the set-up, confirming compatibility with the conventional methods. The presented field-deployable platform has wide applications in mass monitoring of dengue, such as during outbreaks and epidemics.

Covalent Immobilisation of a Nanoporous Platinum Film onto a Gold Screen-Printed Electrode for Highly Stable and Selective Non-Enzymatic Glucose Sensing

Progress in the development of commercially available non-enzymatic glucose sensors continues to be problematic due to issues regarding selectivity, reproducibility and stability. Overcoming these issues is a research challenge of significant importance. This study reports a novel fabrication process using a double-layer self-assembly of (3 mercaptopropyl)trimethoxysilane (MPTS) on a gold substrate and co-deposition of a platinum–copper alloy. The subsequent electrochemical dealloying of the less noble copper resulted in a nanoporous platinum structure on the uppermost exposed thiol groups. Amperometric responses at 0.4 V vs. Ag/AgCl found the modification to be highly selective towards glucose in the presence of known interferants. The sensor propagated a rapid response time <5 s and exhibited a wide linear range from 1 mM to 18 mM. Additionally, extremely robust stability was attributed to enhanced attachment due to the strong chemisorption between the gold substrate and the exposed thiol of MPTS. Incorporation of metallic nanomaterials using the self-assembly approach was demonstrated to provide a more reproducible and controlled molecular architecture for sensor fabrication. The successful application of the sensor in real blood serum samples displayed a strong correlation with clinically obtained glucose levels.

An electrochemical immunosensor using SARS-CoV-2 spike protein-nickel hydroxide nanoparticles bio-conjugate modified SPCE for ultrasensitive detection of SARS‐CoV‐2 antibodies

As a promising approach for serological tests, the present study aimed at designing a robust electrochemical biosensor for selective and quantitative analysis of SARS‐CoV‐2-specific viral antibodies. In our proposed strategy, recombinant SARS-CoV-2 spike protein antigen (spike protein) was used as a specific receptor to detect SARS‐CoV‐2-specific viral antibodies. In this sense, with a layer of nickel hydroxide nanoparticles (Ni(OH)2 NPs), the screen-printed carbon electrode (SPCE) surface was directly electrodeposited to ensure better loading of spike protein on the surface of SPCE. The differential pulse voltammetry (DPV) showed signals which were inversely proportional to the concentrations of the antibody (from 1 fg mL−1 L to 1 µg mL−1) via a specific and stable binding reaction. The assay was performed in 20 min with a low detection limit of 0.3 fg mL−1. This biodevice had high sensitivity and specificity as compared to non-specific antibodies. Moreover, it can be regarded as a highly sensitive immunological diagnostic method for SARS‐CoV‐2 antibody in which no labeling is required. The fabricated hand-held biodevice showed an average satisfactory recovery rate of ~99-103% for the determination of antibodies in real blood serum samples with the possibility of being widely used in individual serological qualitative monitoring. Also, the biodevice was tested using real patients and healthy people samples, where the results are already confirmed using the enzyme-linked immunosorbent assay (ELISA) procedure, and showed satisfactory results.

Nanostructured Molecular Imprinted Polymers for Chemosensing of Hormone Proteins

Immunoassays and high-performance liquid chromatography combined with mass spectrometry are common methods to selectively determine protein biomarkers in biological samples. The excellent accuracy of these determinations is at the expense of a high cost, including the cost of specific antibodies supply or instrumentation and experienced operation. Several biosensors were devised and fabricated for fast and selective quantification of the protein biomarkers. The most interesting protein biomarkers belong to the glycoprotein family. Unfortunately, it seems challenging to generate antibodies for this family because of low immunogenicity. Thus, an alternative research field is developing which claims to synthesize more stable artificial antibody-like receptors for the replacement of natural antibodies.Here, a semi-covalent procedure is proposed to elaborate surface imprinted polymers for selective recognition of gonadotropin hormones.1,2 Briefly, this strategy consists of a combination of three methods, namely, (i) lithography, (ii) surface imprinting, and (iii) semi-covalent imprinting. Hard template silica beads were used as a mold to prepare a highly organized opal structure. On top of this, template proteins were immobilized. Later, the protein was derivatized with functional monomers. These functionalized template molecules were electrochemically cross-linked with an excess of cross-linking monomer. Removal of the silica mold creates a nanostructure containing molecular cavities on the surface. Such nanostructures are advantageous for non-restrictive diffusion of bulky proteins toward the respective molecular cavities.We confirmed regular and hexagonal packing of silica beads, resulting in inverse opal surface imprinted molecular films, by Scanning Electron Microscope (SEM). The recognition of proteins by the nanostructured molecular imprinted polymer films was transduced with the help of capacitive impedimetry. The suitability of the synthetic receptor was further confirmed by measuring proteins in real blood serum samples.

Facile copper-based nanofibrous matrix for glucose sensing: Eenzymatic vs. non-enzymatic

The current study aims to provide a valid comparison between glucose detection efficiency with an enzymatic and a non-enzymatic sensing platform. A low-cost nano-matrix for glucose sensing was developed by drop-coating copper nanoparticles (Cu NPs) onto a polyacrylonitrile (PAN) electrospun nanofibrous assembly. The PAN NFs/Cu NPs matrix was optimized regarding electrospinning time and Cu NPs content and employed as a non-enzymatic sensor or further modified by cross-linking of glucose oxidase (GOD) for the development of an enzymatic sensor.The non-enzymatic glucose sensor was three times more sensitive (300 mAM−1cm−2) than the enzymatic one (81 mAM−1cm−2) with similar limit of detection values (5.9 and 5.6 µM, respectively). Incorporation of MWCNTs improved both the LOD (3.3 µM) and the operational stability of the non-enzymatic configuration (RSD 7.3%). The interference effect proved insignificant for the enzymatic sensor due to the innate catalytic selectivity whilst the non-enzymatic sensor acquired selectivity due to the nanofibrous PAN matrix and Nafion coating.The non-enzymatic PAN NFs/Cu NPs sensor was chosen for the detection of glucose in real blood serum samples whilst the PAN NFs/Cu NPs/GOD sensor was applied for glucose detection in fruit juices, both proving recovery results close to 100%.

In-situ engineered MXene-TiO2/ BiVO4 hybrid as an efficient photoelectrochemical platform for sensitive detection of soluble CD44 proteins

Interfacial charge-carrier recombination is a bottle-neck issue restricting photoelectrochemical biosensors advancement in the wearable clinical electronics. In this study, we propose a simple approach to construct a highly efficient photoactive heterojunction capable of functioning as an active substrate in PEC biosensing of CD44 proteins. Taking the advantage of high photocatalytic activity of BiVO4, and biocompatible yet conductive 2D-Ti3C2Tx nanosheets, a workable heterojunction was constructed between in-situ formed TiO2 from the partially oxidized Ti3C2Tx and lysine functionalized BiVO4 (TiO2/MX-BiVO4). The interfacial arrangement was ideal for promoting fast charge transfer from photo-excited BiVO4 and TiO2 to Ti3C2Tx, constructing an energy level-cascade that permits minimal charge-carrier recombination besides robust photocatalytic redox activity. The PEC biosensor relies on the ligand-protein interaction, where hyaluronic acid was directly immobilized over TiO2/MX-BiVO4 based on the interactions between carboxyl of lysine and amino moieties of hyaluronic acid. The PEC biosensor response depends on the inhibition in the measured photo-oxidation current of mediator species, i.e., ascorbic acid after the addition of CD44 proteins. The superior photo-activity, and robust heterojunction arrangement, produced a sensitive signal capable of recognizing CD44 in the wide concentration window of 2.2 × 10−4 ng mL−1 to 3.2 ng mL−1 with a low-detection limit of 1.4 × 10−2 pg mL−1. The strong interaction between lysine functionalized BiVO4 and hyaluronic acid enabled biosensor to exhibit robust antifouling characteristics towards similar proteins such as PSA and NSE. The quantification of CD44 protein from real-blood serum samples further confirmed the biosensor's reliability for clinical application.

High Sensitivity Sensor for C-Reactive Protein Detections

Among the various type of sensor strucrures, cyclic voltammetry (CV), chronoamperometry, impedance spectroscopy, and various methods based on ion sensitive field effect transistors (ISFET) in combination with modern low-dimensional systems are very popular. ISFET sensors show a high signal-to-noise ratio, high measurement speed, compactness and portability. This work is dedicated to development sensor to detect C-reactive protein (CRP) based on ISFET. CRP - inflammatory protein that dramatically increases during the inflammatoryduring inflammatory.For the first time, a multilayer structure for the C-reactive protein detection was proposed, using a sensor based on the CeO2 ISFET as a sudgate dielectric and n-type field-effect transistor as a platform. For this sensor, the limit of detection at 0.1 mg/L and the sensitivity at 290 mV/(mg/L) were established. For this analysis should be only 20 μl of the reagent and about 1 min of time was needed. The developed sensor showed good stability in work for 30 days. Another interesting feature of this sensor was observed. It can work not just with standard test kits, but also in real human blood serum. The response of the sensor on real blood serum samples was just 18% less than the results from the calibrations antigen CRP concentrations for the standard test kit at the enzyme-linked immunosorbent assay.To increase the sensitivity the additional buffer layer - melanin was used. Such layer increased the sensor sensitivity by almost 61%.To get good and stable results the experiment was carried out at the stable ambient conditions: temperature ~ 20°C and at the same level of illumination (put sensor in dark box).The performance of the biosensor is influenced not just by the antibody concentration and also by the incubation time of CRP. During incubation, the antigen antigen-antibody complex is formed. It takes some time to get this complex on the sensor working surface. With an increasing incubation time, the current response decreases and stabilizes after ~0.5 hourds. To obtain the optimal current response the incubations time of 30 min was found.In conclusion, such results of CRP sensor based on ISFET with CeO2 as gate dielectric are the basis for using this sensor in real clinical trials, particularly for screening trials. Figure 1

Fabrication of Polymeric Ferrocene Nanoparticles for Electrochemical Aptasensing of Protein with Target-Catalyzed Hairpin Assembly.

Herein we describe a novel isothermal and enzyme-free electrochemical aptasensor for protein detection via the employment of polymeric ferrocene nanoparticles (PFcNPs) and target-catalyzed hairpin assembly amplification. The synthesized PFcNPs not only load numerous Fc molecules for enhanced electrochemical output but also possess plenty of amino groups, which increase the water solubility and facilitate the conjugation with the aptamer toward the recognition of target protein. After the formation of an aptamer/protein complex, the conformation of the DNA probe changes, which further triggers hairpin assembly on top of DNA tetrahedral structures modified on the electrode interface. The process can be recycled, and multiple PFcNPs are localized on the electrode. Thus, an amplified electrochemical signal is able to be recorded, which is sufficient to achieve a demonstrated limit of detection as low as 67 fM. This developed aptasensor can also discriminate target protein from other interfering substances with a high selectivity. Furthermore, it has been successfully applied in diluted real blood serum samples. All of these features make the present methodology a promising candidate for ultratrace protein biosensors.

Pt-Decorated Boron Nitride Nanosheets as Artificial Nanozyme for Detection of Dopamine.

Over the past decade, nanosized metal oxides, metals, and bimetallic particles have been actively researched as enzyme mimetic nanomaterials. However, the common issues with individual nanoparticles (NPs) are stabilization, reproducibility, and blocking of active sites by surfactants. These problems promote further studies of composite materials, where NPs are spread on supports, such as graphene derivatives or dichalcogenide nanosheets. Another promising type of support for NPs is the few-layered hexagonal boron nitride (hBN). In this study, we develop surfactant-free nanocomposites containing Pt NPs dispersed on chemically modified hydrophilic hBN nanosheets (hBNNSs). Ascorbic acid was used as a reducing agent for the chemical reduction of the Pt salt in the presence of hBNNS aqueous colloid, resulting in Pt/hBNNS nanocomposites, which were thoroughly characterized with X-ray diffraction, transmission electron microscopy, dynamic light scattering,andX-ray photoelectron andinfraredspectroscopies. Similar to graphene oxide binding the metal NPs more efficiently than pure graphene, hydrophilic hBNNSs well stabilize Pt NPs, with particle size down to around 8 nm. We further demonstrate for the first time that Pt/hBNNS nanocomposites exhibit peroxidase-like catalytic activity, accelerating the oxidation of the classical colorless peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) to its corresponding blue-colored oxidized product in the presence of H2O2. Kinetic and mechanism studies involving terephthalic acid and isopropanol as a fluorescent probe and an •OH radical scavenger, respectively, proved that Pt/hBNNSs assist H2O2 decomposition to active oxygen species (•OH), which are responsible for TMB oxidation. The Pt/hBNNS nanocomposite-assisted oxidation of TMB provides an effective platform for the colorimetric detection of dopamine, an important biomolecule. The presence of increased amounts of dopamine gradually inhibits the catalytic activity of Pt/hBNNSs for the oxidation of TMB by H2O2, thus enabling selective sensing of dopamine down to 0.76 μM, even in the presence of common interfering molecules and on real blood serum samples. The present investigation on Pt/hBNNSs contributes to the knowledge of hBN-based nanocomposites and discovers their new usage as nanomaterials with good enzyme-mimicking activity and dopamine-sensing properties.

Rational design of a stable peroxidase mimic for colorimetric detection of H2O2 and glucose: A synergistic CeO2/Zeolite Y nanocomposite

Owing to the high costs and instability of natural enzymes, the development of enzyme mimics based on inorganic nanomaterials has attracted a wide concern in recent years. In this work, a stable nanocomposite composed of highly dispersed CeO2 nanoparticles decorated on zeolite Y as support (CeO2/Y) was synthesized by a facile wet impregnation method, and the CeO2/Y nanocomposite was firstly proposed as an efficient peroxidase-mimicking nanozyme for accurate detection of H2O2 and glucose. The best catalyst was the nanocomposite with CeO2 to zeolite Y mass ratio of 0.20 (denoted as 20CeO2/Y), showing a better affinity and higher catalytic constant to the substrate of H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB) than horseradish peroxidase (HRP) enzymes by the steady-state kinetic analysis. The enzyme-mimicking catalyst could be used over a wider range of pH and temperature for a long-time reuse in TMB oxidation. A facile colorimetric assay was set up for the accurate detection of H2O2 and glucose, with the detection limits of 0.323 μM and 35.4 μM, respectively. The CeO2/Y-based peroxidase mimic was used to precisely detect the glucose concentration in real blood serum samples, exhibiting a great potential to be constructed as a reliable biosensor for glucose detection in some complex systems. The superior peroxidase-mimicking performance of CeO2/Y nanocomposite is attributed to the synergistic effects of outstanding activity of highly dispersed CeO2 nanoparticles (5–10 nm) and adsorption properties of zeolite Y with large surface area (517 m2·g−1) and pore volume (0.329 cm3·g−1).

Rational Design of Yolk-Shell CuO/Silicalite-1@mSiO2 Composites for a High-Performance Nonenzymatic Glucose Biosensor.

In this study, an interface coassembly strategy is employed to rationally synthesize a yolk-shell CuO/silicalite-1@void@mSiO2 composite consisting of silicalite-1 supported CuO nanoparticles confined in the hollow space of mesoporous silica, and the obtained composite materials were used as a novel nonenzymatic biosensor for highly sensitive and selective detecting glucose with excellent anti-interference ability. The synthesis of CuO/silicalite-1@mSiO2 includes four steps: coating silicalite-1 particles with resorcinol-formaldehyde polymer (RF), immobilization of copper species, interface deposition of a mesoporous silica layer, and final calcination in air to decompose RF and form CuO nanoparticles. The unique hierarchical porous structure with mesopores and micropores is beneficial to selectively enrich glucose for fast oxidation into gluconic acid. Besides, the mesopores in the silica shell can effectively inhibit the large interfering substances or biomacromolecules diffusing into the void as well as the loss of CuO nanoparticles. The hollow chamber inside serves as a nanoreactor for glucose oxidation catalyzed by the active CuO nanoparticles, which are spatially accessible for glucose molecules. The nonenzymatic glucose biosensors based on CuO/silicalite-1@mSiO2 materials show excellent electrocatalytic sensing performance with a wide linear range (5-500 μM), high sensitivity (5.5 μA·mM-1·cm-2), low detection limit (0.17 μM), and high selectivity against interfering species. Furthermore, the unique sensors even display a good capability in the determination of glucose in real blood serum samples.