Surface functionalization of natural hydroxyapatite by polymerization of β-cyclodextrin: application as electrode material for the electrochemical detection of Pb(II)

Ready-to-use Nafion-Bi2O3 modified graphite paper/gel electrode for the detection of lead in vegetables and fruits and its anti-interference performance

Electrochemical detection has been used to measure heavy metals in food, but matrix interferences remain limited the rapid treatment-detection. This study developed a Nafion-Bi2O3 coating modified graphite paper/sodium alginate gel electrode to amplify the electrical signal of Pb(II) and improve the anti-interference towards organic acids and metal ions. Although negatively charged organic acids were excluded by Nafion, interferences of exchangeable ions were amplified. In the mix drip coating, Bi2O3 was chemical combined and electrostatic interacted with OH, SO3- and C-S in Nafion. This modification reduced diffusion resistance, enhanced surface hydrophobicity and provided additional reactive oxygen binding sites. The peak current of Pb(II) increased 56.62 % and the detection limit was lowered to 0.015 μg/L. The recoveries of Pb in matrices were 78.33 %-106.45 %. The easy field modified graphite paper electrode represents an innovation, and this study will propel the rapid detection of heavy metals based on acid-extraction.

Surface engineered gold nanodendrites decorated flexible carbon fiber-based electrochemical sensor platform for sensitive detection of L-Cysteine in serum and urine samples

In this work, highly dispersed gold nanodendrites (Au NDs) decorated flexible carbon fiber electrode (Au NDs@FCF electrode) were fabricated by facile, green, and one-step electrochemical deposition protocol and utilized for the direct electrochemical determination of L-Cysteine (L-Cys). The prepared Au NDs@FCF electrodes were characterized by SEM, HR-TEM, XRD, XPS, CV, and EIS towards the dimensions, surface morphological traits, crystalline nature, chemical composition, and electrochemical catalytic oxidation towards L-Cys and electrochemical active surface area (ECASA) of the Au NDs. The developed Au NDs@FCF electrode demonstrates an enzyme mimics electrocatalytic efficiency towards the oxidation of L-Cys at the operating potential of 0.82 V (vs Ag/AgCl) with a lower experimental detection limit of 0.16 nM, higher sensitivity of ∼50.2 μA μM-1 cm-2, and a wide concentration ranges from 100 to 3000 nM with a correlation coefficient of R2 = 0.996. In addition, the developed Au NDs@FCF electrode has exhibited excellent selectivity with various anti-interferences such as glucose, dopamine, uric acid, Na+, Mg2+, Ca2+, high reproducibility, and repeatability with RSD of 2.3 %. The Au NDs@FCF electrode demonstrates outstanding electrocatalytic oxidation and a rapid sensing response time of ∼3 s. The current Au NDs@FCF electrode achieving the successful detection of L-Cys in practical human serum and urine samples highlights its potential application in biomedical diagnostics. This advancement indicates that the sensor can effectively operate in real-world conditions, offering a valuable tool for medical professionals to monitor L-Cys levels in patients accurately.

Evolution and recent development of cellulose-modified, nucleic acid-based and green nanosensors for trace heavy metal ion analyses in complex media: A review

With increased manufacturing activities and energy sector development, monitoring of heavy metal ion (HMI) pollution is becoming increasingly pressing. The discharge of metals from industrial effluents into the waterways could cause major economic and environmental disruption. In situ and on-site detection methods of trace HMIs can be effective countermeasures before the toxicity spreads out to larger areas, affecting the ecosystem. Conventional methods are often lacking in portability and costly. In contrast, electrochemical sensing, especially with nanoplatforms, is promising for trace detection of HMIs in complex media because of the ease of fabrication and adaptability of incorporating green technology. Appropriate electrode selection with suitable modifiers is crucial in complex medium analyses to overcome electrode fouling. In this review, the evolution from metal-based and carbon-based electrodes to advancements in electrode modification involving agro/biocomposite nanomaterials (NMs) such as cellulose, chitosan, and hydroxyapatite is discussed. The fabrication of nucleic acid-based aptasensors for analyzing HMIs and the adoption of smart systems based on microfluidics with high selectivity, operational stability, and sensitivity are highlighted. The challenges and future prospects for trace HMI determination based on electrochemical sensors in real complex media, including blood and industrial effluent or wastewater, are critically examined.

Citric acid cross-linked β-cyclodextrins: A review of preparation and environmental/biomedical application

The β-cyclodextrins (β-CD) are biocompatible macrocyclic candidates for the preparation of various composites with enhanced functions. While nontoxic and biodegradable citric acid (CA) is the favorite crosslinking agent for fabricating hierarchical advanced structures. The carboxyl and hydroxyl groups on CA can serve as "structural bridges" and enhance the solubility of β-CD. Leading to the construction of CA cross-linked β-CD with marvelous complicated structures and targeted functions. Here, we directly categorized the grafted composite materials into two main types such as organic and inorganic materials. Particularly, some representative composite materials are listed and analyzed in detail according to their preparation, advantages of unique characteristics, as well as the possible applications in environmental and biomedical fields such as adsorption of pollutants, sensors, and biomedical applications.

Biomass-Derived Carbon-Based Electrodes for Electrochemical Sensing: A Review

The diverse composition of biomass waste, with its varied chemical compounds of origin, holds substantial potential in developing low-cost carbon-based materials for electrochemical sensing applications across a wide range of compounds, including pharmaceuticals, dyes, and heavy metals. This review highlights the latest developments and explores the potential of these sustainable electrodes in electrochemical sensing. Using biomass sources, these electrodes offer a renewable and cost-effective route to fabricate carbon-based sensors. The carbonization process yields highly porous materials with large surface areas, providing a wide variety of functional groups and abundant active sites for analyte adsorption, thereby enhancing sensor sensitivity. The review classifies, summarizes, and analyses different treatments and synthesis of biomass-derived carbon materials from different sources, such as herbaceous, wood, animal and human wastes, and aquatic and industrial waste, used for the construction of electrochemical sensors over the last five years. Moreover, this review highlights various aspects including the source, synthesis parameters, strategies for improving their sensing activity, morphology, structure, and functional group contributions. Overall, this comprehensive review sheds light on the immense potential of biomass-derived carbon-based electrodes, encouraging further research to optimize their properties and advance their integration into practical electrochemical sensing devices.

Hydroxyapatite/L-Lysine Composite Coating as Glassy Carbon Electrode Modifier for the Analysis and Detection of Nile Blue A

An amperometric sensor was developed by depositing a film coating of hydroxyapatite (HA)/L-lysine (Lys) composite material on a glassy carbon electrode (GCE). It was applied for the detection of Nile blue A (NBA). Hydroxyapatite was obtained from snail shells and its structural properties before and after its combination with Lys were characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analyses. The coupling of Lys to HA was attributed to favorable interaction between negatively charged -COO^- groups of Lys and divalent ions Ca²⁺ of HA. Electrochemical investigations pointed out the improvement in sensitivity of the GCE/Lys/HA sensor towards the detection of NBA in solution. The dependence of the peak current and potential on the pH, scan rate, and NBA concentration was also investigated. Under optimal conditions, the GCE/Lys/HA sensor showed a good reproducibility, selectivity, and a NBA low detection limit of 5.07 × 10^-8 mol L^-1. The developed HA/Lys-modified electrode was successfully applied for the detection of NBA in various water samples.