Norhayati Hashim

This study presents the fabrication of a ferrocenium tetrachloromagnesate (FTM) modified multi-walled carbon nanotubes (MWCNTs) electrode for the voltammetric determination of bismuth ions (Bi3+) in aquatic environments. The FTM was synthesized from the reaction of mag­nesium chloride with ferrocene. The incorporation of FTM, a redox-active species, was shown to markedly improve electron transfer kinetics and overall electrochemical conductivity. Structural and morphological characterizations via Fourier transform infrared spectroscopy, transmission electron microscopy, energy dispersive x-ray, field emission scanning electron microscopy and X-ray diffraction confirmed the successful embedding of FTM within the electrode matrix. Electrochemical assessments using cyclic voltammetry, electrochemical impe­dance spectro­scopy, and chronocoulometry revealed that a 10 wt.% FTM loading provided the most optimal charge transfer and interfacial behaviour. Differential pulse stripping voltammetry further demonstrated the high sensitivity of the developed electrode, achieving an ultralow detection limit of 0.543 nM with two broad linear ranges of 1.0 nM to 0.1 and 1.0 µM to 0.1 mM for Bi3+. The sensor also exhibited remarkable reproducibility (RSD 8.67 %) and stability (RSD 7.77 %). Furthermore, excellent selectivity toward Bi3+ was maintained in the presence of potentially interfering ions such as Mn2+, La3+, Ni2+, Li+, Zn2+, Fe2+, Cd2+, Cu2+, Er2+ and Pb2+. Real water-sample analyses yielded recoveries of 89 to 104 %, confirming the practical feasibility of the electrode for environmental monitoring.

The study introduces a novel electrochemical sensor for paracetamol (PCM) determination based on a nanocomposite composed of zinc layered hydroxide (ZLH) intercalated with sodium dodecyl sulphate and thiacloprid (SDS-THI), integrated with multiwalled carbon nano­tubes (MWCNTs). The sensor aims to address limitations of conventional analytical techniques and improve sensitivity, detection limits, and portability. Electrochemical techniques, including electrochemical impedance spectroscopy, square wave voltammetry and cyclic voltammetry, were employed to characterize the sensor performance. The ZLH-SDS-THI/MWCNTs sensor showed superior electrocatalytic activity, with a wide linear range (0.7 to 30 mM) and a low detection limit (LOD = 0.33 mM), outperforming several previously reported sensors. The enhanced performance is attributed to the synergistic properties of the composite materials, which offer improved electron transfer, a high surface area, and effective analyte interaction. Importantly, the sensor demonstrated excellent selectivity, as interference studies revealed that common biological and ionic species such as ascorbic acid, glucose, fructose, lysine, chloride, magnesium, and sulphate ions, even when present at 10-, 20-, and 50-fold excess concentrations relative to PCM, caused less than 10 % signal variation. This confirms the sensor’s robustness and reliability in complex sample matrices. Overall, this work highlights the potential of incorporating unconventional organic dopants, such as thiacloprid, into layered nanostructures to enhance the performance of electrochemical sensors, offering a promising platform for the selective and sensitive determination of pharmaceutical compounds in environmental and clinical applications.

This study' purposes are to synthesize molecularly imprinted polymer (MIP) with hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate (TEGDMA) using p-xylene under ultraviolet curing at 405 nm for the recognition of hydroquinone (HQ) in aqueous medium. The template was extracted from the polymer with a mixture of methanol and acetic acid (9:1) by volume (v/v). The Fourier transform infrared (FTIR) spectrum of MIP (after wash) showed the absence of peak at the range of 840–860 cm−1, which represented the stretching outside the aromatic plane C–H at the para position (p-xylene). Field emission scanning electron microscope (FESEM) micrograph showed that the MIP had cavities compared to non-imprinted polymer (NIP). The MIP (MIP-Pxy) with ratio (monomer:crosslinker) 0.25 and 1.00% template gave the highest uptake of hydroquinone (HQ) in aqueous solution, which implied more specific recognition (highest KD value). The rebinding of HQ onto MIP-Pxy was best described by both isotherm (Langmuir and Freundlich) and kinetic model (pseudo-first and -second). The MIP was successfully synthesized using p-xylene, able to recognize HQ and was very selective to p-CP. Implication of the study, the synthesized MIP can be used for recognition and sensing materials for HQ and any similar molecules.

The fabrication of a zinc hydroxide nitrate-sodium dodecylsulfate bispyribac modified with multi-walled carbon nanotube (ZHN-SDS-BP/MWCNT) paste electrode for uric acid and bisphenol A detection was presented in this study. Electrochemical impedance spectroscopy, chronocoulometry, square-wave voltammetry, and cyclic voltammetry were all used to examine the electrocatalytic activities of modified paste electrodes. The modified electrode’s sensitivity and selectivity have been considered in terms of the composition of the modifier in percentages, the types of supporting electrolytes used, the pH of the electrolyte, and square-wave voltammetry parameters like frequency, pulse size, and step increment. Square-wave voltammetry is performed by applying a small amplitude square-wave voltage to a scanning potential from −0.3 V to +1.0 V, demonstrating a quick response time and high sensitivity. The ZHN-SDS-BP/MWCNT sensor demonstrated a linear range for uric acid and bisphenol A from 5.0 µM to 0.7 mM, with a limit of detection of 0.4 µM and 0.8 µM, respectively, with good reproducibility, repeatability, and stability as well. The modified paste electrode was successfully used in the determination of uric acid and bisphenol A in samples of human urine and lake water.

Zinc Layered hydroxide (ZLH) is a layered material easily synthesized with a structure identical to brucite-like material. Due to the exchangeable anions in the interlayer compensating for the positive charge of a brucite-type layer, ZLH provides a wide application in many fields. This review focuses on the properties and method of synthesis of ZLH by giving an overview of intercalated guest anion in the interlayer of ZLH. The further discussion involved the application of intercalated guest anion in zinc layered hydroxide layer and its properties as a sensitizer, controlled release biomedical, and agriculture to provide the scientific community for research and development by giving current findings. This brief review also presents the success of anion intercalation for controlled release along with the kinetic model involved, which increases the bioavailability and effectiveness of the nanocomposite on its target. It shows the development of research on ZLH nanocomposites toward the sustainability of human life and the environment. This study implies that it is a source of knowledge for researchers about zinc-layered hydroxide materials involving synthesis methods and their application to produce more beneficial nanomaterials.

An electrochemical chemical sensor for determination of uric acid (UA) with highly sensitive and widely working range was fabricated using zinc layered hydroxide-sodium dodecyl sulphate-propoxur (ZLH-SDS-PRO) nanocomposites modified with multiwall carbon nanotubes (MWCNT). Introduction of the ZLH-SDS-PRO as a conducting matrix has enhanced the conductivity of MWCNT. The ZLH-SDS-PRO/MWCNT morphology was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), meanwhile the electrochemical behaviour of UA and K3[Fe(CN)6] at ZLH-SDS-PRO/MWCNT paste electrode was studied by square wave voltammetry (SWV) and cyclic voltammetry (CV), respectively. Under the optimized experimental conditions, the electrode established linear plot for UA from 7.0 µmol/L to 0.7 mmol/L (R2 = 0.9920) and the LOD was calculated to be 4.28 µmol/L (S/N = 3). The fabricated electrochemical electrode was successfully applied to urine samples and exhibit excellent stability and reproducibility, which made it worthwhile to be explored for analytical applications.

Global food demand has increased in tandem with the world’s growing population, prompting calls for a new sustainable agricultural method. The scarcity of fertile soil and the world’s agricultural land have also become major concerns. Soilless and microgreen farming combined with nanotechnology may provide a revolutionary solution as well as a more sustainable and productive alternative to conventional farming. In this review, we look at the potential of nanotechnology in soilless and microgreen farming. The available but limited nanotechnology approaches in soilless farming include: (1) Nutrients nanoparticles to minimize nutrient losses and improve nutrient uptake and bioavailability in crops; (2) nano-sensing to provide real-time detection of p H, temperature, as well as quantifying the amount of the nutrient, allowing desired conditions control; and (3) incorporation of nanoparticles to improve the quality of substrate culture as crop cultivation growing medium. Meanwhile, potential nanotechnology applications in soilless and microgreen farming include: (1) Plant trait improvement against environmental disease and stress through nanomaterial application; (2) plant nanobionics to alter or improve the function of the plant tissue or organelle; and (3) extending the shelf life of microgreens by impregnating nanoparticles on the packaging or other preservation method.