Simultaneous determination of environmental contaminants using a graphite oxide – Polyurethane composite electrode modified with cyclodextrin

Cyclodextrin-based architectures for electrochemical sensing: from molecular recognition to functional hybrids

This review surveys recent advances in the integration of cyclodextrins (CDs) with diverse materials for electrochemical detection of a wide range of analytes in environmental, pharmaceutical, and clinical contexts. CDs, featuring a hydrophobic cavity and a hydrophilic exterior, enable selective host-guest binding of small organic and inorganic molecules. By anchoring CDs onto electrode surfaces via strategies such as self-assembled monolayers, layer-by-layer deposition, or polymer entrapment, researchers have achieved improved selectivity and lower detection limits for target compounds. These CD-functionalized interfaces are further enhanced by combination with carbon nanotubes, graphene, metal nanoparticles, and redox mediators, providing synergistic effects that boost conductivity, catalysis, and signal amplification. Moreover, CD-based sensors exhibit reversible recognition, making them amenable to repeated use and continuous monitoring. Notably, derivatization of the CD ring expands its applicability, introducing functionalities such as chirality recognition, metal coordination, or improved solubility. Different detection modes, including voltammetry, impedance, and competitive displacement assays, have been reported for a variety of analytes, ranging from heavy metals and pesticides to pharmaceuticals and chiral compounds. The incorporation of CDs into advanced hybrid architectures also offers solutions to common issues like electrode fouling and limited selectivity, thus expanding their utility in harsh or complex sample environments. While challenges remain in ensuring reproducibility, large-scale manufacture, and robust performance in real-world applications, ongoing innovations in materials science and synthetic chemistry promise to make CD-based electrodes increasingly valuable for sensitive, portable, and cost-effective chemical analysis. Furthermore, novel integration with biological receptors, such as enzymes and aptamers, holds promise for multiplexed biosensing.

Electrospun nanofibers modified with zeolitic imidazolate framework-8 for electrochemiluminescent determination of terbutaline

For the first time it is demonstrated that zeolitic imidazolate framework-8 electrospun nanofibers (ZIF-8 NF) could serve as electrochemiluminescence (ECL) accelerator for the facile detection of terbutaline residual. A novel ECL sensor for the determination of terbutaline was fabricated based on ZIF-8 NF. The ZIF-8 NF were successfully prepared according to electrospinning and in-situ growth method. First, chitosan was modified on the surface of the electrode, and then the ZIF-8 NF was modified onto the upper layer of the chitosan. Taking advantages of chitosan and ZIF-8 NF in conductivity and electrocatalysis, the modified electrode presents obvious ECL phenomenon in 0.2 M PBS solution (pH 10.0) containing 0.025 M luminol. After the addition of terbutaline, ECL intensity decreased significantly, and the decreasing value showed a linear relationship with the logarithm of terbutaline concentration. The linear range was from 2.0 × 10^-10 to 2.0 × 10^-5 M, and the detection limit was 1.41 × 10^-11 M (3σ/m). The method had high sensitivity, good stability, and good applicability to actual pork samples.

A simple, sensitive and efficient electrochemical platform based on carbon paste electrode modified with Fe3O4@MIP and graphene oxide for folic acid determination in different matrices

A new biomimetic sensor selective to folic acid based on a carbon paste modified with graphene oxide and Fe₃O₄ nanoparticles coated with molecularly imprinted polymer in the core@shell format (Fe₃O₄@MIPs) was obtained using the polyol method. The sensing phase was synthesized in a simple way and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface area. In the binding experiments the selective material showed a high adsorption capacity (Q) of 30.4 mg g^-1 for MMIP, while the Q value for MNIP (magnetic non-imprinted polymer) was 15.3 mg g^-1 both of them following the Langmuir model to the adsorption procedure. After their efficiency was proven, these materials were used as modifiers in the electrochemical sensor (Fe₃O₄@MIP-GO/CPE). Under optimized conditions using the square-wave adsorptive voltammetry, the proposed sensor exhibited excellent response with a concentration linear range between 2.5 and 48 μmol L^-1 and limit of detection of 0.65 μmol L^-1 (S/σ = 3). The advantages obtained with the proposed method were high robustness, selectivity, and low cost being these characteristics due to the MIP; highly sensibility due to the high superficial area being the contribution of the magnetite in the core of material; and experimentally versatile since was possible carry out numerous reproductible analysis only make the renovation of the paste electrode surface by simple polishing. The sensor was applied successfully in pharmaceutical formulation and river water samples with recoveries percentages near 100%.

da Silva Alves D, Okeke C, Breslin CB. Cyclodextrins as Supramolecular Recognition Systems: Applications in the Fabrication of Electrochemical Sensors

Supramolecular chemistry, although focused mainly on noncovalent intermolecular and intramolecular interactions, which are considerably weaker than covalent interactions, can be employed to fabricate sensors with a remarkable affinity for a target analyte. In this review the development of cyclodextrin-based electrochemical sensors is described and discussed. Following a short introduction to the general properties of cyclodextrins and their ability to form inclusion complexes, the cyclodextrin-based sensors are introduced. This includes the combination of cyclodextrins with reduced graphene oxide, carbon nanotubes, conducting polymers, enzymes and aptamers, and electropolymerized cyclodextrin films. The applications of these materials as chiral recognition agents and biosensors and in the electrochemical detection of environmental contaminants, biomolecules and amino acids, drugs and flavonoids are reviewed and compared. Based on the papers reviewed, it is clear that cyclodextrins are promising molecular recognition agents in the creation of electrochemical sensors, chiral sensors, and biosensors. Moreover, they have been combined with a host of materials to enhance the detection of the target analytes. Nevertheless, challenges remain, including the development of more robust methods for the integration of cyclodextrins into the sensing unit.

An efficient and simple method using a graphite oxide electrochemical sensor for the determination of glyphosate in environmental samples

Excessive and indiscriminate use of the herbicide glyphosate (GLY) leaves the environment susceptible to its contamination. This work describes the development of a simple, inexpensive, and efficient electroanalytical method using graphite oxide paste electrode (GrO-PE) for the direct determination of GLY traces in groundwater samples, soybean extracts, and lettuce extracts. Under optimal experimental conditions, the developed sensor exhibited a linear response of the peak current intensity vs. the concentration, in the range of 1.8 × 10^-5 to 1.2 × 10^-3 mol L^-1 for GLY. The limits of detection and quantification are 1.7 × 10^-8 mol L^-1 and 5.6 × 10^-8 mol L^-1, respectively. The methodology developed here demonstrated a strong analytical performance, with high reproducibility, repeatability, and precision. Moreover, it successfully avoided interference from other substances, showing high selectivity. The GrO-PE sensor was effectively applied to determine GLY traces in real samples with recovery rates ranging from 98% to 102%. Results showed that the GrO-PE is effective and useful for GLY detection, with the advantage of not involving laborious modifications and complicated handling, making it a promising tool for environmental analysis.