A Novel Electrochemical Sensor Based on Graphene Oxide Decorated with Silver Nanoparticles–Molecular Imprinted Polymers for Determination of Sunset Yellow in Soft Drinks

Nitrogen-doped biomass-derived carbon dots for fluorescence determination of sunset yellow

Sunset Yellow (SY) is a widely used food coloring in the food industry. However, exceeding the allowable limit of this dye poses a significant threat to human health. To address this issue, we developed Lycium ruthenicum-derived nitrogen-doped carbon dots (N-CDs) with a stable blue fluorescence through hydrothermal treatment for SY determination. The quantum yield (QY) of these N-CDs was found to be up to 10.63%. Physical characterization of N-CDs was performed using various spectroscopic techniques to confirm their excellent photostability and non-toxic properties. Furthermore, the presence of SY had a substantial quenching effect on the fluorescence intensity (F0/F) of the N-CDs. Leveraging this observation, we developed a fluorescent sensor for the determination of SY in the concentration range of 0.05 to 35.0 μM, with a limit of detection (LOD, 3σ/K) of 17 nM. The excellent fluorescent sensor also showed satisfactory results in the practical drink samples. Moreover, the stability and cytotoxicity of N-CDs as a fluorescent probe were studied. Finally, the N-CDs were applied to cell imaging using A549 cells.

Highly stable electrochemical sensing platform for the selective determination of pefloxacin in food samples based on a molecularly imprinted-polymer-coated gold nanoparticle/black phosphorus nanocomposite

The overuse of pefloxacin (PEF) leaves residues in foods. Therefore, the development of robust analytical techniques for the selective detection of PEF is of great importance. In this study, a highly stable electrochemical sensing platform has been constructed, using molecularly imprinted polymer (MIP)-coated gold nanoparticle/black phosphorus nanocomposites (BPNS-AuNPs), for the selective detection of PEF. BPNS-AuNPs significantly enhance the black phosphorus (BP) stability and electrochemical activity and offer a larger surface area to accommodate more imprinted sites for selective PEF binding. MIP/BPNS-AuNPs exhibit a broad linear detection range (0.005-10 μM), low detection limit (0.80 nM), and high sensitivity (3.199 μA μM-1). The MIP/BPNS-AuNPs show a high binding affinity for PEF, even in the presence of structural analogs, and maintain stable voltammetric signals for at least 35 d. The MIP sensor exhibits consistent high sensitivity in the detection of PEF in real milk and orange juice samples.

Exploring the potential of molecularly imprinted polymers and metal/metal oxide nanoparticles in sensors: recent advancements and prospects

Metal/metal oxide nanoparticles have gained increasing attention in recent years due to their outstanding features, including optical and catalytic properties, as well as their excellent conductivity. The implementation of metal/metal oxide nanoparticles, combined with molecularly imprinted polymers (MIPs) has paved the way for a new generation of building blocks to engineer and enhance the fascinating features of advanced sensors. This review critically evaluates the impact of combining metal/metal oxide nanoparticles with MIPs in sensors. It covers synthesis strategies, advantages of coupling these materials with MIPs, and addresses questions about the selectivity of these hybrid materials. In the end, the current challenges and future perspectives of this field are discussed, with a particular focus on the potential applications of these hybrid composites in the sensor field. This review highlights the exciting opportunities of using metal/metal oxide nanoparticles along with MIPs for the development of next-generation sensors.

Application of Molecularly Imprinted Electrochemical Biomimetic Sensors for Detecting Small Molecule Food Contaminants

Environmental chemical contaminants in food seriously impact human health and food safety. Successful detection methods can effectively monitor the potential risk of emerging chemical contaminants. Among them, molecularly imprinted polymers (MIPs) based on electrochemical biomimetic sensors overcome many drawbacks of conventional detection methods and offer opportunities to detect contaminants with simple equipment in an efficient, sensitive, and low-cost manner. We searched eligible papers through the Web of Science (2000-2022) and PubMed databases. Then, we introduced the sensing mechanism of MIPs, outlined the sample preparation methods, and summarized the MIP characterization and performance. The classification of electrochemistry, as well as its advantages and disadvantages, are also discussed. Furthermore, the representative application of MIP-based electrochemical biomimetic sensors for detecting small molecular chemical contaminants, such as antibiotics, pesticides, toxins, food additives, illegal additions, organic pollutants, and heavy metal ions in food, is demonstrated. Finally, the conclusions and future perspectives are summarized and discussed.

Cu2+ modified Zr-based metal organic framework-CTAB-graphene for sensitive electrochemical detection of sunset yellow

A sensitive electrochemical sensor for sunset yellow (SY) was constructed based on cetyltrimethylammonium bromide (CTAB) functionalized graphene (Gr) and Cu/Zr-MOF electrode modified materials. The CTAB-Gr-Cu/Zr-MOF composites were synthesized by using a mild method and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and EDX spectrum. The combination of Cu/Zr-MOF and graphene exhibited synergetic effect of the strong accumulation efficiency, fast electron transfer rate and more sensing sites towards the oxidation of SY. The new modified materials remarkably increased the electrochemical response of SY to 6.53-fold when comparing with bare electrode. Under the optimized conditions, the oxidation peak currents of SY had a linear relationship with its concentration in a wide range from 0.10 to 8.00 μM and 40.00-1000.00 μM, and the limit of detection was 6.68 nM (S/N = 3). The electrochemical method shows high sensitivity, stability, reproducibility and is successfully applied in the determination of SY in soft drinks.

Synthesizing a surface-imprinted polymer based on the nanoreactor SBA-15 for optimizing the adsorption of salicylic acid from aqueous solution by response surface methodology

The molecularly imprinted polymer prepared on the nanoreactor SBA-15 displayed excellent ordered mesoporous structure and superior adsorption property for salicylic acid.

Sensitive and In Situ Hemoglobin Detection Based on a Graphene Oxide Functionalized Microfiber

The determination of hemoglobin (Hb) level is indispensable in the pathological study of many blood diseases. Graphene oxide (GO), with its excellent optical properties and great biocompatibility, has attracted significant attention and been widely utilized in biochemical detection. Here, we report an ultrasensitive Hb sensor based on a graphene oxide (GO)-coated microfiber. The GO was utilized as a linking layer deposited on the microfiber surface, which can provide an enhanced local evanescent light field and abundant bonding sites for Hb molecules. The optical microfiber with a compact structure and a strong evanescent light field served as the platform for biosensing. The surface morphology characterized by optical microscope, scanning electron microscope, and Raman spectroscopy offers detailed evidence for the success of GO deposition. The dynamic bonding between GO and target Hb molecules was monitored in real-time through an optical spectrum analyzer. An ultrahigh sensitivity of 6.02 nm/(mg/mL) with a detection limit of 0.17 μg/mL was achieved by tracking the resonant wavelength shift of spectra. It is important to highlight that the detection limit of GO-coated microfiber is 1–2 orders of magnitude lower than other reported fiber optic Hb sensors. Benefiting from high sensitivity, low cost, small size, and fast response, the proposed sensing microfiber coated with GO could be a competitive alternative in the diagnosis of blood diseases and a subject of further research in the medical field.

3-Aminobenzeneboronic Acid Functionalized MoS2 Quantum Dot as Fluorescent Nanoprobe for the Determination of o-Dihydroxybenzene

In this work, by functionalizing MoS₂ quantum dot with 3-aminobenzeneboronic acid, a novel multifunctional quantum dot (denoted as B-MoS₂ QD) was obtained and used successfully for a fluorescence nanoprobe for detecting o-dihydroxybenzene (o-DHB). Transmission electron microscopy, fluorescence spectrum, UV-vis spectrum and fluorescence lifetime were used to investigate the prepared nanoprobe. The results show that the B-MoS₂ QD nanoprobe can exhibit strong fluorescence and excellent light fastness owing to the coupled effect from the MoS₂ QDs and boronic acid; interestingly, the vicinal diols structure from its surface can bridge covalently with o-DHB, resulting in the fluorescence quenching of B-MoS₂ QDs and selective recognition toward o-DHB. With the increasing of o-DHB concentration, the nanoprobe fluorescence would gradually decrease. By measuring the fluorescence intensity of B-MoS₂ QDs, a wide linear range from 0.1 to 200.0 μM with a low detection limit of 0.025 μM was obtained for o-DHB analysis; meanwhile, this fluorescence nanoprobe possesses excellent selectivity for the selective detection of o-DHB from its analogues.

Novel Electrochemical Sensors Based on Cuprous Oxide-Electrochemically Reduced Graphene Oxide Nanocomposites Modified Electrode toward Sensitive Detection of Sunset Yellow

Control and detection of sunset yellow is an utmost demanding issue, due to the presence of potential risks for human health if excessively consumed or added. Herein, cuprous oxide-electrochemically reduced graphene nanocomposite modified glassy carbon electrode (Cu₂O-ErGO/GCE) was developed for the determination of sunset yellow. The Cu₂O-ErGO/GCE was fabricated by drop-casting Cu₂O-GO dispersion on the GCE surface following a potentiostatic reduction of graphene oxide (GO). Scanning electron microscope and X-ray powder diffractometer was used to characterize the morphology and microstructure of the modification materials, such as Cu₂O nanoparticles and Cu₂O-ErGO nanocomposites. The electrochemical behavior of sunset yellow on the bare GCE, ErGO/GCE, and Cu₂O-ErGO/GCE were investigated by cyclic voltammetry and second-derivative linear sweep voltammetry, respectively. The analytical parameters (including pH value, sweep rate, and accumulation parameters) were explored systematically. The results show that the anodic peak currents of Cu₂O-ErGO /GCE are 25-fold higher than that of the bare GCE, due to the synergistic enhancement effect between Cu₂O nanoparticles and ErGO sheets. Under the optimum detection conditions, the anodic peak currents are well linear to the concentrations of sunset yellow, ranging from 2.0 × 10⁻⁸ mol/L to 2.0 × 10⁻⁵ mol/L and from 2.0 × 10⁻⁵ mol/L to 1.0 × 10⁻⁴ mol/L with a low limit of detection (S/N = 3, 6.0 × 10⁻⁹ mol/L). Moreover, Cu₂O-ErGO/GCE was successfully used for the determination of sunset yellow in beverages and food with good recovery. This proposed Cu₂O-ErGO/GCE has an attractive prospect applications on the determination of sunset yellow in diverse real samples.