Highly sensitive and selective solid-contact calcium sensor based on Schiff base of benzil with 3-aminosalycilic acid covalently attached to polyacrylic acid amide for health care

Creative synthesis of pH-dependent nanoporous pectic acid grafted with acrylamide and acrylic acid copolymer as an ultrasensitive and selective riboflavin electrochemical sensor in real samples

In current research, an innovative pectic acid was grafted with poly (acrylamide-co-acrylic acid) [PA-g-poly (AAm-co-AA)] nanoporous membrane using a free radical-mediated grafting copolymerization process. The optimized parameters for the grafting copolymerization reaction such as initiator concentration, monomer concentrations, polymerization reaction time, and temperature were studied. Additionally, the solid content, graft percentage, and conversion were calculated. The unique polymeric membrane was characterized using Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetry (TG), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) supported by energy dispersive X-ray spectroscopy (EDX). The formulated novel PA-g-poly (AAm-co-AA) had a nanoporous structure with a diameter of 113 nm. pH-dependent swelling and biodegradation measurements were also studied. The electrochemical characterizations of PA-g-poly (AAm-co-AA) were conducted through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Furthermore, the screen-printed electrode (SPE) was modified with pure PA and the new generation of its grafted polymeric nanoparticles to detect and quantify the concentration of riboflavin (RF) in real samples using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified electrode showed two linear concentration ranges from 0.01 - 2 nM and 2 - 90 nM with low detection limits (LODs) of 0.004 and 0.97 nM, respectively, demonstrating high sensitivity. Besides, the fabricated sensor exhibited more selectivity, simplicity, great reproducibility, repeatability, and good stability. Finally, the PA-g-poly (AAm-co-AA)-modified SPE based sensor was effectively used in real sample analysis of egg yolk, milk, and vitamin B2 drugs with good recovery rates.

Nanohexagonal iron barium titanate nanoparticles surface-modified NiFe2O4 composite screen-printed electrode for enzymatic glucose monitoring

A nanocomposite of iron barium titanate/NiFe2O4 (FBT/NF) was synthesized using sol-gel techniques to form organized hexagonal structures. The effects of NiFe2O4 nanostructures on FBT's phase purity, morphology, and dielectric properties were systematically explored and intensively discussed. TEM imaging confirmed the hexagonal structure, and electrical measurements revealed that para-electric NF influenced the conductivity and impedance of ferroelectric FBT, with a shift in Curie temperature to lower values. The FBT/NF nanocomposite was optimized for use in glucose amperometric biosensors, offering fast and direct electron transfer from glucose oxidase that was chemically immobilized on disposable sensor chips. Thus, the biosensor exhibited high sensitivity (757.14 μA mM-1 cm-2), a fast response time of 50 seconds, and a wide linear range of 0.0027-1.9 mM with a low detection limit of 0.5 μM. Accordingly, the biosensor was exploited for blood glucose detection, showing high precision compared to reference methods. These findings highlighted the potential of the FBT/NF nanocomposite for use in developing biosensor portable devices.

Antioxidant-rich brilliant polymeric nanocomposites for quick and efficient non-enzymatic hydrogen peroxide sensor

In our current research, a new type of functional nanocomposites known as poly(methyl methacrylate/N,N-dimethyl aminoethylmethacrylate/(E)-2-cyano-N-cyclohexyl-3 (dimethylamino) acrylamide) [poly(MMA/DMAEMA/CHAA)] has been developed. These nanocomposites were created using microemulsion polymerization in conjunction with synthesized titanium dioxide (TiO2), and vanadium pentoxide (V2O5) nanoparticles. To understand the physio-chemical characteristics of the poly(MMA/DMAEMA/CHAA) and the metal oxide nanoparticles (MOs) integrated within them, various analytical techniques were employed. These techniques included Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and electrical approaches such as cyclic voltammetry (CV) and electrical impedance spectra (EIS). Based on the TEM results, nanospheres with a well-defined structure were developed for both the pure polymer and its composite with sizes ranging from 45 to 75 nm. All the TiO2 and V2O5-based nanocomposites showed significantly enhanced electrical attributes, with capacitance values surpassing those of the poly(MMA/DMAEMA/CHAA) nanosphere assemblies by a considerable margin. As a result, both direct electron transfer and direct hydrogen peroxide identification were evaluated for the nanocomposites. The amperometry results demonstrated a lower detection limit of 0.0085 μM and a rapid linear sensitivity in the range of 1 to 800 μM. The greatly improved electrolytic qualities of these nanocomposites make them suitable for various applications in fields such as battery storage, sensors, and biosensors.

Non-enzymatic disposable electrochemical sensors based on CuO/Co3O4@MWCNTs nanocomposite modified screen-printed electrode for the direct determination of urea

A new electrochemical impedimetric sensor for direct detection of urea was designed and fabricated using nanostructured screen-printed electrodes (SPEs) modified with CuO/Co3O4 @MWCNTs. A facile and simple hydrothermal method was achieved for the chemical synthesis of the CuO/Co3O4 nanocomposite followed by the integration of MWCNTs to be the final platform of the urea sensor. A full physical and chemical characterization for the prepared nanomaterials were performed including Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), contact angle, scanning electron microscope (SEM) and transmission electron microscopy (TEM). Additionally, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to study the electrochemical properties the modified electrodes with the nanomaterials at different composition ratios of the CuO/Co3O4 or MWCNTs. The impedimetric measurements were optimized to reach a picomolar sensitivity and high selectivity for urea detection. From the calibration curve, the linear concentration range of 10-12-10-2 M was obtained with the regression coefficient (R2) of 0.9961 and lower detection limit of 0.223 pM (S/N = 5). The proposed sensor has been used for urea analysis in real samples. Thus, the newly developed non-enzymatic sensor represents a considerable advancement in the field for urea detection, owing to the simplicity, portability, and low cost-sensor fabrication.

Novel (E)−2-((1-(thiophen-2-yl)ethylidene)-amino) phenol Manganese(II) as an Ionophore Based on Thiocyanate-Selective Electrodes and Its Applications

Novel highly selective potentiometric sensor based on aquadichloro(E)−2-((1-(thiophen-2-yl)ethylidene)-amino)phenol manganese(II)trihydrate as an anion carrier. The thiocayanate electrode displayed a very high selectivity compared with others inorganic anions. Different sensors with plasticized PVC membranes have been investigated. The sensors construction containing different amounts of ionophore with and without additives. The pH over 3.5–6.5 range has been studied. Optimized membrane electrode included 66 mg PVC, 132 mg o-nitrophenyloctylether, 10 mol % tetrakis(trifluoromethyl)phenyl borate and 2% [Mn(C12H11NOS)(Cl2)(H2O)]· 3H2O. The optimized sensors exhibit Nernstian response for thiocyanate through a linear concentration ranging from (5 × 10−8 to 9.06 × 10−1 M) with a detection limit of 3 × 10−8 M and a slope of −57.7 mV decade−1, the measurement carried out in acetate buffer pH 4.7. The response time of electrode <10 s and the lifetime of the sensor more than 6 weeks. The proposed electrode was effectively utilized to estimation of thiocyanate in saliva sample, the results revealed a valid agreement with reference colorimetric method.

A miniaturized solid-contact potentiometric multisensor platform for determination of ionic profiles in human saliva

This paper describes a miniaturized multisensor platform (MP-ISES) consisting of electrodes: a reference one (RE) and ion-selective electrodes (ISEs) for monitoring Na+, K+, Ca2+, Mg2+, Cl−, and SCN− ions and pH in human saliva. Gold electrode surface was modified by deposition of two layers: electrosynthesized PEDOT:PSS forming an intermediate layer, and ion-selective membrane. The developed ISEs were characterized by a wide linear range and sensitivity consistent with the Nernst model. The entire MP-ISEs are characterized by satisfactory metrological parameters demonstrating their applicability in biomedical research, in particular in measurements concerning determination of ionic profiles of saliva. Saliva samples of 18 volunteers aged from 20 to 26 participating in a month experiment had been daily collected and investigated using the MP-ISEs assigned individually to each person. Personalized profiles of ions (ionograms) in saliva, such as Na+, K+, Ca2+, Mg2+, Cl−, SCN−, and H+, were obtained.

Nanosensors based on polymer vesicles and planar membranes: a short review

This review aims to summarize the advance in the field of nanosensors based on two particular materials: polymer vesicles (polymersomes) and polymer planar membranes. These two types of polymer-based structural arrangements have been shown to be efficient in the production of sensors as their features allow to adapt to different environment but also to increase the sensitivity and the selectivity of the sensing device. Polymersomes and planar polymer membranes offer a platform of choice for a wide range of chemical functionalization and characteristic structural organization which allows a convenient usage in numerous sensing applications. These materials appear as great candidates for such nanosensors considering the broad variety of polymers. They also enable the confection of robust nanosized architectures providing interesting properties for numerous applications in many domains ranging from pollution to drug monitoring. This report gives an overview of these different sensing strategies whether the nanosensors aim to detect chemicals, biological or physical signals.