Potentiometric planar platforms modified with a multiwalled carbon nanotube/polyaniline nanocomposite and based on imprinted polymers for erythromycin assessment.

A screen-printed potentiometric sensor for the erythromycin macrolide antibiotic (ERY) that is affordable, highly selective, and sensitive is made, described, and used for drug monitoring. Two circular carbon dots with a diameter of 4 mm make up the sensor. Multiwalled carbon nanotubes and polyaniline (f-MWCNTs/PANi) nanocomposites are used to change one carbon spot, which is then used as an ion-to-electron transfer material. Ag/AgCl is applied to the other spot, which is then used as a reference electrode. A solid-state polyvinyl butyral (PVB) is placed onto the second carbon spot to work as a reference electrode, and an ERY molecularly imprinted drug polymer (MIP) is coated onto the f-MWCNTs/PANi-containing strip to serve as a drug identification sensing material. Chronopotentiometry (CP) is used to analyze the integrated sensor's performance characteristics. It is confirmed that f-MWCNTs/PANi has an increased impact on the potential stability as well as the sensing membrane's interfacial double-layer capacitance. At a detection limit of 9.6 ± 0.4 × 10-7 M, the developed sensor exhibits a Nernstian slope of 54.0 ± 0.5 mV per decade (R2 = 0.9994) over the linear range of 4.6 × 10-6 to 1.0 × 10-3 M. When exposed to different related substances such azithromycin, clarithromycin, dirithromycin, paracetamol, and ascorbic acid, the sensor exhibits excellent selectivity. For the direct potentiometric determination of ERY in some pharmaceutical formulations and in samples of spiked human urine, the assay method has been validated and shown to be adequate. The obtained recovery ranges from 93.0 ± 0.5 to 104.3 ± 0.7 of the nominal or spiked concentration, with a mean relative standard deviation of ±0.6%. Due to the near closeness of the responsive membrane and the liquid junction, the use of all-solid-state electrodes coupled with a planar disposable platform enables applications with a minimum sample volume. The effectiveness of the suggested sensor in a complex urine matrix points to its use in hospitals for quick overdose patient detection as well as for quality control/quality assurance tests in the pharmaceutical sector.

New Potentiometric Screen-Printed Platforms Modified with Reduced Graphene Oxide and Based on Man-Made Imprinted Receptors for Caffeine Assessment.

Caffeine is a psychoactive drug that is administered as a class II psychotropic substance. It is also considered a component of analgesics and cold medicines. Excessive intake of caffeine may lead to severe health damage or drug addiction problems. The assessment of normal caffeine consumption from abusive use is not conclusive, and the cut-off value for biological samples has not been established. Herein, new cost-effective and robust all-solid-state platforms based on potentiometric transduction were fabricated and successfully utilized for caffeine assessment. The platforms were modified with reduced graphene oxide (rGO). Tailored caffeine-imprinted polymeric beads (MIPs) based on methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) were prepared, characterized, and used as recognition receptors in the presented potentiometric sensing devices. In 50 mM MES buffer, the sensors exhibited a slope response of 51.2 ± 0.9 mV/decade (n = 6, R2 = 0.997) over the linear range of 4.5 × 10−6−1.0 × 10−3 M with a detection limit of 3.0 × 10−6 M. They exhibited fast detection of caffeinium ions with less than 5 s response time (<5 s). The behavior of the presented sensors towards caffeinium ions over many common organic and inorganic cations was evaluated using the modified separate solution method (MSSM). Inter-day and intra-day precision for the presented analytical device was also evaluated. Successful applications of the presented caffeine sensors for caffeine determination in commercial tea and coffee and different pharmaceutical formulations were carried out. The data obtained were compared with those obtained by the standard liquid chromatographic approach. The presented analytical device can be considered an attractive tool for caffeine determination because of its affordability and vast availability, particularly when combined with potentiometric detection.

Low-cost potentiometric paper-based analytical device based on newly synthesized macrocyclic pyrido-pentapeptide derivatives as novel ionophores for point-of-care copper(ii) determination.

A simple, cost-effective, portable and disposable paper-based analytical device is designed and fabricated for copper(ii) determination. All solid-state ion-selective electrodes (ISEs) for copper and a Ag/AgCl reference electrode were constructed and optimized on the paper substrate. The copper electrodes were built using carbon nano-tube ink as a conductive substrate and an ion-to electron transducer. A suitable polymeric membrane is drop-cast on the surface of the conductive carbon ink window. The copper-sensing membrane is based on newly synthesized macrocyclic pyrido-pentapeptide derivatives as novel ionophores for copper detection. Under the optimized conditions, the presented all-solid-state paper-based Cu2+-ISEs showed a Nernstian response toward Cu2+ ions in 30 mM MES buffer, pH 7.0 over the linear range of 5.0 × 10-7-1.0 × 10-3 M with a limit of detection of 8.0 × 10-8 M. The copper-based sensors exhibited rapid detection of Cu2+ ions with a short response time (<10 s). The selectivity pattern of these new ionophores towards Cu2+ ions over many common mono-, di- and trivalent cations was evaluated using the modified separate solution method (MSSM). The presented paper-based analytical device exhibited good intra-day and inter day precision. The presented tool was successfully applied for trace Cu2+ detection in real samples of serum and whole blood collected from different children with autism spectrum disorder. The data obtained by the proposed potentiometric method were compared with those obtained by the inductively-coupled plasma (ICP) as a reference method. The presented copper paper-based analytical-device can be considered as an attractive tool for point-of-care copper determination because of its affordability, vast availability, and self-pumping ability, particularly when combined with potentiometric detection.

New anthranilic acid-incorporating N-benzenesulfonamidophthalimides as potent inhibitors of carbonic anhydrases I, II, IX, and XII: Synthesis, in vitro testing, and in silico assessment.

The carbonic anhydrase (CA) inhibitory activity of newly synthesized compounds 4-21 against the human CA (hCA) isoforms I, II, IX, and XII was measured and compared to that of standard sulfonamide inhibitors, acetazolamide (AAZ) and SLC-0111. Among this series; benzensulfonamides 6-11 gave the best potent hCA inhibitors with inhibition constants (KIs) ranging from 81.9 to 456.6 nM (AAZ and SLC-0111: KIs, 250.0 and 5080 nM, respectively). Compounds 6-11 proved to be effective hCA II inhibitors (KIs, 8.9-51.5 nM); they were almost equally potent to AAZ (KI, 12.0 nM) and had superior potency to SLC-0111 (KI, 960.0 nM). For hCA IX inhibition, compounds 6-11 proved to be potent inhibitors, with KI values of 3.9-36.0 nM, which were greater than or equal to that of AAZ and greater than that of SLC-0111 (KIs, 25.0 and 45.0 nM, respectively). For hCA XII inhibitory activity, compounds 6-11 displayed effective inhibition with KI values ranging from 4.6 to 86.3 nM and were therefore comparable to AAZ and SLC-0111 (KIs, 5.7 and 4.5 nM, respectively). Molecular docking studies of compounds 6, 7, 10, and 11 were conducted using the crystal structures of hCA isozymes I, II, IX, and XII to study their binding interactions for further lead optimization.