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Home potentiometric sensing devices can real-time monitor personal health status and are widely used in the prevention and management of related diseases. However, variations in the composition and the pH of the sample matrix tend to change the basic potential and response slope of some potentiometric sensors, thus affecting detection reliability. Therefore, this work uses the detection of urea in urine as a model to improve reliability of the potentiometric sensor in home detection. Au@urease nanoparticles were synthesized as the sensing material to improve the stability of the urease-based potentiometric sensor. Meanwhile, a multicalibrated urea potential (MCUP) sensing array was designed, which consists of a urea electrode group, a pH electrode group, and a reference channel. The urea electrode group and the pH electrode group contain respectively a sensing channel and a calibration channel. The basic potential of sensing channels can be calibrated through the corresponding calibration channels. Moreover, the pH electrode group can not only measure the pH values of the samples but also calibrate the response slope of the urea electrode group through the calibration coefficient, thus improving the reliability of home detection. Consequently, the potentiometric sensing array based on the enzyme reaction can be applied in body fluids with a wide pH range.

An all-solid-state ion-selective electrode (ASS-ISE) array that is portable and easily miniaturized can meet the needs of home sensing devices for long-term health monitoring. However, their stability and accuracy are affected by the multistep modification required for ASS-ISE manufacturing and the complex background signal of real samples. In this study, a four-channel ISE array with the integration of a calibration channel has been developed based on polystyrene-Au (PS-Au) ion-sensing nanocomposites (PS-Au ISE array) for the home detection of Na+ and K+. The nanocomposites combine target recognition function and ion-electron transduction function and could be modified on the channel surface by direct drop-casting, thus simplifying the preparation process and then improving the stability. Meanwhile, the integrated calibration channel could automatically deduct complex background signals in real sample analysis and thus improve the accuracy. As a result, the proposed self-calibrated PS-Au ISE array showed a near Nernstian behavior for Na+ and K+ in the range of 1 × 10-2 M-1 × 10-4 M, and the detection limits were 6.8 × 10-5 M and 5.5 × 10-5 M in artificial urine. The linear equations can be obtained according to the slopes and intercepts of Na+ and K+, and thus, the concentration of the target ions can be directly read out by combining this PS-Au ISE array with the smart electronic device. Furthermore, the detection results of Na+ and K+ in human urine agreed well with those obtained by ICP-AES, suggesting that this proposed self-calibrated PS-Au ISE array is very suitable for home smart sensing devices, facilitating the health monitoring.

Current strand displacement amplification (SDA)-based nucleic acid sensing methods generally rely on a ssDNA template that involves complementary bases to the endonuclease recognition sequence, which has the limitation of detecting only short nucleic acids. Herein, a new SDA method in which the defective T junction structure is first used to support SDA (dT-SDA) was proposed and applied in longer DNA detection. In dT-SDA, an auxiliary probe and a primer were designed to specifically identify the target gene, following the formation of a stable defective T junction structure through proximity hybridization, and the formation of defective T junctions could further trigger cascade SDA cycling to produce numerous ssDNA products. The quantity of these ssDNA products was detected through microchip electrophoresis (MCE) and could be transformed to the concentration of the target gene. Moreover, the applicability of this developed strategy in detecting long genomic DNA was verified by detecting bacterial 16S rDNA. This proposed dT-SDA strategy consumes less time and has satisfactory sensitivity, which has great potential for effective bacterial screening and infection diagnosis.

Breast cancer is a heterogeneous disease, and it lacks special tumor markers. Exosomes, new noninvasive biomarkers, with the proteins on the exosome surface show potential for the diagnosis and prognosis of a tumor. However, assessing the variations of exosomal proteins still faces significant challenges. Herein, a magneto-mediated electrochemical sensor based on host-guest recognition has been developed for simultaneous analysis of breast cancer exosomal proteins. Magnetic beads (MB) modified with CD63 aptamer was first employed to capture exosomes. Silica nanoparticles (SiO2 NPs) was modified with MUC1, HER2, EpCAM, and CEA aptamers for specific exosomal proteins identification, respectively, and functionalized with N-(2-((2-aminoethyl)disulfanyl)ethyl) ferrocene carboxamide (FcNHSSNH2) as the signal molecule. The sandwich structure (MB-exosomes-SiO2 NPs probe) was separated by a magnet, and N-(2-mercaptoethyl) ferrocene carboxamide (FcNHSH) was released to the supernatant by the addition of reductants (dithiothreitol, DTT) that break the disulfide bond of FcNHSSNH2. FcNHSH and the graphene oxide-cucurbit [7](GO-CB[7]) modified screen-printed carbon electrode (SPCE) was employed to monitor the oxidation current signals. In this way, four tumor markers on different breast cancer cells (MCF-7, SK-BR-3, MDA-MB-231, and BT474) derived exosomes were sensitively detected. Furthermore, the present assay enabled accurate analysis of exosomes from breast cancer patients, suggesting the potential of exosome analysis in clinic diagnosis.

An all-solid-state potentiometric aptasensor array based on a multichannel disposable screen-printed carbon electrode (SPCE) was demonstrated for the simultaneous detection of Hg2+, Cd2+, and As3+ by open circuit potential (OCP) technology. The potential of the channel with an internal calibration DNA sequence (IC-DNA) was employed as the internal calibration potential (ICP) to subtract the background signal generated by the detection system, providing a built-in correction methodology. As a result, the developed aptasensor array showed high sensitivity and accuracy for detecting Hg2+, Cd2+, and As3+ without mutual interference or interference from other ions. The linear response ranged from 2.5 pM to 2.5 μM, and the detection limits for Hg2+, Cd2+, and As3+ were 2.0, 0.62, and 0.17 pM, respectively. Furthermore, the potentiometric aptasensor array was successfully applied for the simultaneous detection of three ions in real samples. The results obtained from the developed approach agreed well with the re...

Herein we propose a multiple signal amplification strategy designed for ultrasensitive electrochemical detection of glycoproteins. This approach introduces a new type of boronate-affinity sandwich assay (BASA), which was fabricated by using gold nanoparticles combined with reduced graphene oxide (AuNPs-GO) to modify sensing surface for accelerating electron transfer, the composite of molecularly imprinted polymer (MIP) including 4-vinylphenylboronic acid (VPBA) for specific capturing glycoproteins, and SiO2 nanoparticles carried gold nanoparticles (SiO2@Au) labeled with 6-ferrocenylhexanethiol (FcHT) and 4-mercaptophenylboronic acid (MPBA) (SiO2@Au/FcHT/MPBA) as tracing tag for binding glycoprotein and generating electrochemical signal. As a sandwich-type sensing, the SiO2@Au/FcHT/MPBA was captured by glycoprotein on the surface of imprinting film for further electrochemical detection in 0.1 M PBS (pH 7.4). Using horseradish peroxidase (HRP) as a model glycoprotein, the proposed approach exhibited a wide ...

Data analysis for nanopore experiments remains a fundamental and technological challenge because of the large data volume, the presence of unavoidable noise, and the filtering effect. Here, we present an accurate and robust data process that recognizes the current blockades and enables evaluation of the dwell time and current amplitude through a novel second-order-differential-based calibration method and an integration method, respectively. We applied the developed data process to analyze both generated blockages and experimental data. Compared to the results obtained using the conventional method, those obtained using the new method provided a significant increase in the accuracy of nanopore measurements.

Carbon nanotubes have been proposed as support materials for numerous applications, including the development of DNA sensors. One of the challenges is the immobilization of DNA or other biological molecules on the sidewall of carbon nanotubes. This paper introduces a new fabrication of DNA-carbon nanotubes particles using the layer-by-layer (LBL) technique on single-walled carbon nanotubes (SWCNTs). Poly(diallyldimethylammonium) (PDDA), a positively charged polyelectrolyte, and DNA as a negatively charged counterpart macromolecule are alternatively deposited on the water-soluble oxidized SWCNTs. Pure DNA/PDDA/SWCNTs particles can be prepared and separated by simple unltracentrifugation. The characterization of DNA/PDDA/SWCNTs particles was carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible spectroscopy, Raman spectroscopy, and thermogravimetric analysis (TGA). An electrode modified by the DNA/PDDA/SWCNTs particles shows a dramatic change of the electrochemical signal in solutions of tris(2,2'-bipyridyl)ruthenium(II) ((Ru(bpy)(3)2+) as a reporting redox probe. A preliminary application of the DNA-modified carbon nanotubes in the development of DNA sensors used in the investigation of DNA damage by nitric oxide is presented.

Multicomponent structures were constructed by DNA-directed self-assembling of multiple carbon nanotubes and gold nanoparticles. The work presented here represents an important advance in constructing many multicomponent nanotube structures for multifunctional material and device applications.

A series of novel mesostructured lamellar molybdenum disulfides with the d spacings from 17 to 30 A can be prepared by the reaction of Mo(CO)6 with elemental sulfur using a molten n-alkylamine as the solvent as well as the template at 140 degrees C. Such intercalated phases can be transformed into mesoporous molybdenum disulfides by slow thermal treatments at 200 degrees C.

The reaction of methylviologen iodide with crystalline V2O5 in the molar ratio of 1 to 3.8 at 100 °C in water led to the formation of (MV)0.25V2O5 in quantitative yield. The structure of this organic−inorganic multilayered hybrid compound was determined by single-crystal X-ray crystallography. Strong van der Waals interactions were found between the electron-deficient aromatic organic molecules and the inorganic layers. In the solid state, the compound is a semiconductor due to small polaron hopping and shows novel reversible alkali-ion intercalation/deintercalation via electrochemistry.