Polymeric hydrogel integrated paper-based potentiometric ion-sensing device for the determination of sodium ions in human urine

A paper-based potentiometric sensor integrated with a polymeric hydrogel has been developed for sodium ion (Na+) determination in human urine. The construction of an all-solid-state ion selective electrode (s-ISE) and an all-solid-state reference electrode (s-RE) on a photo paper substrate was achieved using an inkjet printing method. For s-ISE fabrication, carbon nanotubes (CNTs) and gold nanoparticles (AuNPs) were printed on the substrate as a nanocomposite solid contact. A polymeric hydrogel containing lithium acetate (CH3COOLi) was then prepared and used as an intermediate layer to improve the adhesion between the ion selective membrane (ISM) and the AuNP/CNT solid contact, leading to enhanced detection sensitivity. The printed s-RE consisted of a pseudo silver/silver chloride electrode (p-Ag/AgCl) coated with a polymeric hydrogel containing KCl to improve the potential stability of the sensor. Under the optimal conditions, the hydrogel-integrated paper-based potentiometric sensor provided a response toward Na+ over a linear range of 10-7 M to 1 M with a near Nernstian slope of 56.42 ± 0.68 mV per decade. This sensor exhibited fast response, good sensitivity, and reasonable selectivity for Na+ measurement. Furthermore, the developed sensor was effectively applied for the detection of Na+ in urine samples with high accuracy. The presented work can be considered as a good addition to the growing field of potentiometric analytical platforms suitable for large-scale production using inkjet printing technology.

Application of a Solid‐State Potentiometric Sensor for Point‐of‐care Diagnostics of Flucloxacillin in Spiked Human Plasma; Whiteness Evaluation

Antibiotic resistance is a crisis that is escalating nowadays. Thus, therapeutic drug monitoring (TDM) is crucial to personalize the dose. Point‐of‐care (POC) devices are very effective in TDM where drug concentration can be easily and continuously monitored. This work describes for the first time the use of inexpensive, transportable, efficacious, and eco‐friendly POC solid‐state potentiometric sensor for the TDM of Flucloxacillin (FLU) in spiked plasma samples. This was achieved by using an innovative glassy carbon electrode modified with ion sensing membrane doped with carbon nanotubes. Optimization of the sensing membrane composition was performed using different plasticizers and by adding an ionophore. This was followed by doping the ion sensing membrane with carbon nanotubes which resulted in enhancing the sensor's sensitivity towards FLU. Over a concentration range from 1.0×10−5–1.0×10−2 M FLU, a linear response was obtained with a slope of 56.6 mV/decade. Our proposed sensor has been validated according to IUPAC recommendations with acceptable results.

It was effectively employed for a selective determination of FLU in the presence of a co‐formulated antibiotic (Amoxicillin), along with other excipients in the dosage form, and in spiked plasma samples, without any interference. The whiteness of the method was assessed, which proves the high greenness and superb functionality of our proposed method.

Recent advances in nanomaterial-based solid-contact ion-selective electrodes

Solid-contact ion-selective electrodes (SC-ISEs) are advanced potentiometric sensors with great capability to detect a wide range of ions for the monitoring of industrial processes and environmental pollutants, as well as the determination of electrolytes for clinical analysis. Over the past decades, the innovative design of ion-selective electrodes (ISEs), specifically SC-ISEs, to improve potential stability and miniaturization for in situ/real-time analysis, has attracted considerable interest. Recently, the utilisation of nanomaterials was particularly prominent in SC-ISEs due to their excellent physical and chemical properties. In this article, we review the recent applications of various types of nanostructured materials that are composed of carbon, metals and polymers for the development of SC-ISEs. The challenges and opportunities in this field, along with the prospects for future applications of nanomaterials in SC-ISEs are also discussed.

The New Ion-Selective Electrodes Developed for Ferric Cations Determination, Modified with Synthesized Al and Fe-Based Nanoparticles

The solid-state ion-selective electrodes presented here are based on the FePO₄:Ag₂S:polytetrafluoroethylene (PTFE) = 1:1:2 with an addition of (0.25-1)% microwave-synthesized hematite (α-Fe₂O₃), magnetite (Fe₃O₄), boehmite [γ-AlO(OH)], and alumina (Al₂O₃) nanoparticles (NPs) in order to establish ideal membrane composition for iron(III) cations determination. Synthesized NPs are characterized with Fourier-Transform Infrared (FTIR) spectroscopy, Powder X-Ray Diffraction (PXRD), and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). The iron oxides NPs, more specifically, magnetite and hematite, showed a more positive effect on the sensing properties than boehmite and alumina NPs. The hematite NPs had the most significant effect on the linear range for the determination of ferric cations. The membrane containing 0.25% hematite NPs showed a slope of -19.75 mV per decade in the linear range from 1.2∙10^-6 to 10^-2 mol L^-1, with a correlation factor of 0.9925. The recoveries for the determination of ferric cations in standard solutions were 99.4, 106.7, 93.6, and 101.1% for different concentrations.

Development of Chromium(III) Selective Potentiometric Sensors for Its Determination in Petroleum Water Samples Using Synthesized Nano Schiff Base Complex as an Ionophore

BACKGROUND

Many analytical techniques, such as X-ray fluorescence spectrometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), and even traditional spectroscopic and fluorimetric methods, are used for the measurement of Cr(III) ions. These methods are sophisticated and very expensive. So, the chipset and the low cost ion selective electrodes were used.

OBJECTIVE

The quantification of Cr(III) ions in various samples of petroleum water using ion selective electrodes was suggested. Nano chromium modified carbon paste sensor (MCPE) and nano chromium modified screen printed sensor (MSPE) based on Schiff base Cr(III) complex are developed.

METHOD

The developed nano Cr(III) Schiff base chelate was characterized utilizing elemental, spectroscopic, and thermal analysis techniques. The proposed nano Cr(III) has a good properties for antibacterial and antifungal activity. The modified carbon paste and screen-printed sensors were fabricated for determination of Cr(III) ion.

RESULT

The proposed MCPE (sensor I) and MSPE (sensor II) obeys Nernstian equation upon incorporating nono Cr(III) ionophore in the paste at 25 °C with a trivalent cationic slope of 18.8 ± 0.2 and 20.0 ± 0.4 mV/decade. They have showed fast response time around 8 and 5 s, and they may be utilized for at least 98 and 240 days without significant changes in MCPE and MSPE potential, respectively. The sensors I and II showed good selectivity for Cr(III) ion toward a wide variety of metal ions or anions as confirmed by potentiometric selectivity coefficients values. The detection and quantification limits were defined alongside the other process validation parameters. The results have been compared well to those obtained by atomic absorption spectrometry (AAS) and the data of F- and t-test indicated no significant difference between the proposed and AAS methods.

CONCLUSION

These sensors have been utilized to determine Cr(III) ions in genuine spiked different petroleum well water samples with satisfactory percentage recoveries, low standard and relative standard deviation values using direct potentiometric and standard addition methods. The proposed method of producing nano Cr(III) complex as a sensor material possesses the distinct advantages of being simple, easily reproducible, appropriate for operation, and highly selective and sensitive.

HIGHLIGHTS

Modified carbon paste and screen-printed electrodes were fabricated based on nano Cr(III) complex as ionophore. The electrodes follow Nernstian behavior and they optimized according to IUPAC recommendation. They showed a high selectivity for Cr(III) ion over many bi or trivalent metal ions and anions. The results obtained compared well with those obtained using atomic absorption spectrometry (AAS). They successfully applied for determination of Cr(III) in petroleum water samples.

New Construction of Functionalized CuO/Al2O3 Nanocomposite-Based Polymeric Sensor for Potentiometric Estimation of Naltrexone Hydrochloride in Commercial Formulations

Electrically conductive polymeric nanocomposites with nanoparticles are adaptable types of nanomaterials that are prospective for various applications. The extraordinary features of copper oxide (CuO) and aluminium oxide (Al₂O₃) nanostructures, encourages extensive studies to prospect these metal oxide nanocomposites as potential electroactive materials in sensing and biosensing applications. This study suggested a new CuO/Al₂O₃ nanocomposite-based polymeric coated wire membrane sensor for estimating naltrexone hydrochloride (NTX) in commercial formulations. Naltrexone hydrochloride and sodium tetraphenylborate (Na-TPB) were incorporated in the presence of polymeric polyvinyl chloride (PVC) and solvent mediator o-nitrophenyloctyl ether (o-NPOE) to form naltrexone tetraphenylborate (NTX-TPB) as an electroactive material. The modified sensor using NTX-TPB-CuO/Al₂O₃ nanocomposite displayed high selectivity and sensitivity for the discrimination and quantification of NTX with a linearity range 1.0 × 10^-9-1.0 × 10^-2 mol L^-1 and a regression equation E_mV = (58.25 ± 0.3) log [NTX] + 754.25. Contrarily, the unmodified coated wire sensor of NTX-TPB exhibited a Nernstian response at 1.0 × 10^-5-1.0 × 10^-2 mol L^-1 and a regression equation E_mV = (52.1 ± 0.2) log [NTX] + 406.6. The suggested modified potentiometric system was validated with respect to various criteria using the methodology recommended guidelines.

Reliable release testing for nanoparticles with the NanoDis System, an innovative sample and separate technique

One of the critical quality attributes of nanoparticle formulations is drug release. Their release properties should therefore be well characterized with predictive and discriminative methods. However, there is presently still no standard method for the release testing of extended release nanoformulations. Dialysis techniques are widely used in the literature but suffer from severe drawbacks. Burst release of formulations can be masked by slow permeation kinetics of the free drug through the dialysis membrane, saturation in the membrane, and absence of agitation in the membrane. In this study, the release profile of poly(lactic co-glycolic) (PLGA) nanocapsules loaded with all-trans retinoic acid was characterized using an innovative sample and separate set-up, the NanoDis System, and compared to the release profile measured with a dialysis technique. The NanoDis System showed clear superiority over the dialysis method and was able to accurately characterize the burst release from the capsules and furthermore discriminate between different all-trans retinoic acid nanoparticle formulations.

Highly Functionalized Modified Metal Oxides Polymeric Sensors for Potentiometric Determination of Letrozole in Commercial Oral Tablets and Biosamples

The advanced and high-functional activities of magnesium oxide and copper oxide nanoparticles encourage the extensive use of these metal oxides as remarkable electroactive materials in electrochemical and sensing detections. The current study described a comparative sensing activity and selectivity of modified coated wire membrane sensors enriched with magnesium oxide and copper oxide nanoparticles for quantifying the breast cancer medication letrozole (LTZ) in its pharmaceutical form and human plasma. The fabricated sensors were based on the incorporation of LTZ with phosphomolybdic acid (PMA) to form the electroactive complex letrozole-phosphomolybate (LTZ-PM) in the presence of o-nitrophenyloctyl ether (o-NPOE) as a solvent mediator. Under optimum conditions, the modified sensors LTZ-PM-MgONPs and LTZ-PM-CuONPs demonstrated linear relationships of 1.0 × 10-8-1.0 × 10-2 and 1.0 × 10-10-1.0 × 10-2 mol L-1, respectively. Least square equations were calculated as EmV = (56.4 ± 0.7) log [LTZ] + 569.6 and EmV = (58.7 ± 0.3) log [LTZ] + 692.6 for LTZ-PM-MgONPs and LTZ-PM-CuONPs, respectively. The conventional type LTZ-PM showed a potential response EmV = (53.3 ± 0.5) log [LTZ] + 451.4 over concentration range of 1.0 × 10-6-1.0 × 10-2 mol L-1. The suggested sensors were successfully used to determine LTZ in pharmaceutical formulations and biosamples. Method validation ensured the suitability of the suggested potentiometric sensors.

Potentiometric Carbon Quantum Dots-Based Screen-Printed Arrays for Nano-Tracing Gemifloxacin as a Model Fluoroquinolone Implicated in Antimicrobial Resistance

Antimicrobial resistance (AMR) is a neglected issue that poses a serious global threat to public health, causing long-term negative consequences at both humanitarian and economic levels. Herein, we report an unprecedented economic fabrication method of seven potentiometric screen-printed sensors for the ultra-trace determination of gemifloxacin (GEMI) as a model of the fluoroquinolones antibiotics deeply involved in the growing AMR problem. Sensors were constructed by depositing homemade carbon ink on a recycled X-ray sheet, patterned using stencils printed with an office printer in simple, cost-effective steps requiring no sophisticated equipment. Four sensors were modified using carbon quantum dots (CQDs) synthesized from dextrose through a single-step method. Sensors exhibited a linear response in the concentration ranges 10−5–10−2 M (sensors 1, 3 and 4), 10−6–10−3 M (sensor 2) and 10−6–10−2 M (sensors 5, 6 and 7). LOD allowed tracing of the target drug at a nano-molar level down to 210 nM. GEMI was successfully determined in pharmaceutical formulations and different water samples without any pretreatment steps with satisfactory recovery (96.93–105.28% with SD values < 3). All sensors revealed a long lifetime of up to several months and are considered promising tools for monitoring water quality and efficiency of water treatment measures.

Electrochemical impedimetric biosensors, featuring the use of Room Temperature Ionic Liquids (RTILs): Special focus on non-faradaic sensing

Over the last decade, significant advancements have been made in the field of biosensing technology. With the rising demand for personalized healthcare and health management tools, electrochemical sensors are proving to be reliable solutions; specifically, impedimetric sensors are gaining considerable attention primarily due to their ability to perform label-free sensing. The novel approach of using Room Temperature Ionic Liquids (RTILs) to improve the sensitivity and stability of these detection systems makes long-term continuous sensing feasible towards a wide range of sensing applications, predominantly biosensing. Through this review, we aim to provide an update on current scientific progress in using impedimetric biosensing combined with RTILs for the development of sensitive biosensing platforms. This review also summarizes the latest trends in the field of biosensing and provides an update on the current challenges that remain unsolved.

New Functionalized Polymeric Sensor Based NiO/MgO Nanocomposite for Potentiometric Determination of Doxorubicin Hydrochloride in Commercial Injections and Human Plasma

The ultra-functional potential of nickel oxide (NiO) and magnesium oxide (MgO) nanoparticles (NPs), provides for extensive attention in the use of these metal oxides as a remarkable and electroactive nanocomposite in potentiometric and sensing investigations. This work proposed a new strategy for quantifying doxorubicin hydrochloride (DOX) in pharmaceuticals and human plasma by preparing a NiO/MgO core-shell nanocomposite modified coated wire membrane sensor. Doxorubicin hydrochloride was incorporated with phosphomolybdic acid (PMA) to produce doxorubicin hydrochloride phosphomolybdate (DOX-PM) as an electroactive material in the presence of polymeric high molecular weight poly vinyl chloride (PVC) and solvent mediator o-nitrophenyloctyl ether (o-NPOE). The modified sensor exhibited ultra sensitivity and high selectivity for the detection and quantification of doxorubicin hydrochloride with a linear relationship in the range of 1.0 × 10-11-1.0 × 10-2 mol L-1. The equation of regression was estimated to be EmV = (57.86 ± 0.8) log [DOX] + 723.19. However, the conventional type DOX-PM showed a potential response over a concentration range of 1.0 × 10-6-1.0 × 10-2 mol L-1 and a regression equation of EmV = (52.92 ± 0.5) log [DOX] + 453.42. The suggested sensors were successfully used in the determination of doxorubicin hydrochloride in commercial injections and human plasma.

Highly sensitive potentiometric sensors for thorium ions detection using morpholine derivative self-assembled on silver nanoparticles

Potentiometric screen-printed electrodes were constructed for Th(iv) determination in water samples. The optimized electrodes exhibited fast response time, wide linear range, low detection limit and high selectivity towards Th(iv) ions.