Droplet-Enhanced Chemiluminescence Strategy for Enrofloxacin Detection Based on Porous Carbon Z-8 Encapsulated Luminol

A droplet-enhanced chemiluminescence (CL) assay for enrofloxacin was fabricated. After preparation ZIF-8 carbonization, porous carbon material Z-800 was obtained and aptamer and cDNA were immobilizated onto the surface of Z-800. Luminol was encapsulated into Z-800 with the help of aptamer and cDNA. In the presence of enrofloxacin, aptamer accurately recognizes it, enrofloxacin specifically binds to aptamer, and the switch that encapsulateed luminol is turned on, causing luminol to be released into the supernatant. The supernatant reacts with H2O2 to produce a strong CL signal. The immiscible organic droplets, benzyl benzoate (Bnbzo), greatly enhances the CL signal. This assay shows a linear relationship between enhanced CL signals and enrofloxacin concentrations in the range from 0.1 to 500.0 nM with LOD of 30 pM (S/N = 3). The sample measurement was performed with the recoveries of 92.00% to 95.63% and relative standard deviation of 3.9%-5.2%. It proves that droplet-enhanced CL is a promising method for enhancing CL signals in real sample and trace analysis.

Pentacenequinone-Modulated 2D GdSn-PQ Nanosheets as a Fluorescent Probe for the Detection of Enrofloxacin in Biological and Environmental Samples

The fate and effects of fluoroquinolone antibacterial (FQ) on the environment are important since there appears to be a surge in FQ resistance like enrofloxacin (ENR) in both environmental and clinical organisms. Numerous reports indicate that the sensing capabilities of these antibiotics need to be improved. Here, we have investigated the interaction of ENR with our synthesized pentacenequinone-modulated gadolinium-tin (GdSn-PQ) nanosheets and the formation of intermolecular interactions that caused the occurrence of aggregation-induced emission enhancement. The concept for designing hybrid metallic nanosheets comes from the unique features inherited from the parent organic precursor. Due to the distinct interaction between ENR and GdSn-PQ, the interstate conversion (ISC) between GdSn-PQ and ENR induces a significant wavelength shift in photoluminescence (PL), improving reliability, selectivity, and visibility compared to quenching- or AIEE-based methods without peak shifts, allowing for highly sensitive and visually detectable analyses. The fluorescence signal of GdSn-PQ exhibited a linear relationship (R2 = 0.9911), with the added ENR concentrations ranging from 5 to 90 nM, with a detection limit of 0.10 nM. We have demonstrated its potential and wide use in the detection of ENR in biological samples (human urine and blood serum) and environmental samples (tap water and seawater) with a recovery rate of 98- 108%. The current approach has demonstrated that the 2D GdSn-PQ nanosheet is a novel and powerful platform for future biological and environmental studies.

Metal-Based Nanomaterials for the Sensing of NSAIDS

Cadmium sulfide and zinc oxide nanoparticles were prepared, characterized and used as electrode modifiers for the sensing of two non-steroidal anti-inflammatory drugs (NSAIDs): naproxen and mobic. The structural and morphological characterization of the synthesized nanoparticles was carried out by XRD, UV-Vis spectroscopy, FTIR and scanning electron microscopy. The electrode's enhanced surface area facilitated the signal amplification of the selected NSAIDs. The CdS-modified glassy carbon electrode (GCE) enhanced the electro-oxidation signals of naproxen to four times that of the bare GCE, while the ZnO-modified GCE led to a two-fold enhancement in the electro-oxidation signals of mobic. The oxidation of both NSAIDs occurred in a pH-dependent manner, suggesting the involvement of protons in their electron transfer reactions. The experimental conditions for the sensing of naproxen and mobic were optimized and, under optimized conditions, the modified electrode surface demonstrated the qualities of sensitivity and selectivity, and a fast responsiveness to the target NSAIDs.

A Novel Aptamer Biosensor Based on a Localized Surface Plasmon Resonance Sensing Chip for High-Sensitivity and Rapid Enrofloxacin Detection

Enrofloxacin, a fluoroquinolone widely used in animal husbandry, presents environmental and human health hazards due to its stability and incomplete hydrolysis leading to residue accumulation. To address this concern, a highly sensitive aptamer biosensor utilizing a localized surface plasmon resonance (LSPR) sensing chip and microfluidic technology was developed for rapid enrofloxacin residue detection. AuNPs were prepared by the seed method and the AuNPs-Apt complexes were immobilized on the chip by the sulfhydryl groups modified on the end of the aptamer. The properties and morphologies of the sensing chip and AuNPs-Apt complexes were characterized by Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, and scanning electron microscope (SEM), respectively. The sensing chip was able to detect enrofloxacin in the range of 0.01-100 ng/mL with good linearity, and the relationship between the response of the sensing chip and the concentration was Δλ (nm) = 1.288log ConENR (ng/mL) + 5.245 (R2 = 0.99), with the limit of detection being 0.001 ng/mL. The anti-interference, repeatability, and selectivity of this sensing chip were studied in detail. Compared with other sensors, this novel aptamer biosensor based on AuNPs-Apt complexes is expected to achieve simple, stable, and economical application in the field of enrofloxacin detection.

Sensitive electrochemical detection of enrofloxacin in eggs based on carboxylated multi-walled carbon nanotubes-reduced graphene oxide nanocomposites: Molecularlyimprintedrecognition versus direct electrocatalytic oxidation

A sensitive electrochemical method for detecting enrofloxacin was proposed using carboxylated multi-walled carbon nanotubes-reduced graphene oxide (MWCNT-COOH-RGO) nanocomposites. The MWCNT-COOH-RGO nanocomposites were firstly electrodeposited on a bare electrode, followed by electropolymerization of molecularly imprinted polymers. Enrofloxacin was determined by the mechanisms of direct electrocatalytic oxidation and molecularly imprinted recognition, respectively. Under the optimized conditions, a response range of 5.0×10^-7 M to 5.5×10^-5 M and limit of detection (LOD) of 2.3×10^-7 M were obtained by direct electrocatalytic oxidation of enrofloxacin using chronoamperometry. By contrast, the response range of 1.0×10^-10 M to 5.0×10^-5 M and LOD of 2.5×10^-11 M were achieved by molecularly imprinted recognition of enrofloxacin using square-wave voltammetry. Moreover, the proposed method exhibited good repeatability, stability and selectivity, and could be used for enrofloxacin detection in egg samples with satisfactory results.

Fluorescence turn off-on detection of Co2+ and enrofloxacin by N, Cl-carbon dots prepared in deep eutectic solvent and study of their photocatalytic antibacterial activity

Nitrogen, chloride doped carbon dots (N, Cl-CDs) were synthesized in deep eutectic solvent. TEM, XRD, FT-IR, XPS, EDAX, UV-Vis and fluorescence were used for characterization. Quantum yield and average size of N, Cl-CDs were 38.75 % and 2-3 nm, respectively. N, Cl-CDs fluorescence was turn off by cobalt ion and then turn on gradually after addition of enrofloxacin. Linear dynamic range and detection limit (DL) for Co²⁺ and enrofloxacin were (0.1-70 µM and 30 nM) and (0.05-50 µM and 25 nM), respectively. Enrofloxacin was detected in blood serum and water samples with the recovery of 96-103 %. Finally, Antibacterial activity of the carbon dots was also investigated.

Cadmium Sulfide Nanoparticles: Preparation, Characterization, and Biomedical Applications

Cadmium sulfide nanoparticles (CdS NPs) have been employed in various fields of nanobiotechnology due to their proven biomedical properties. They are unique in their properties due to their size and shape, and they are popular in the area of biosensors, bioimaging, and antibacterial and anticancer applications. Most CdS NPs are generally synthesized through chemical, physical, or biological methods. Among these methods, biogenic synthesis has attracted more attention due to its high efficiency, environmental friendliness, and biocompatibility features. The green approach was found to be superior to other methods in terms of maintaining the structural characteristics needed for optimal biomedical applications. The size and coating components of CdS NPs play a crucial role in their biomedical activities, such as anticancer, antibacterial, bioimaging, and biosensing applications. CdS NPs have gained significant interest in bioimaging due to their desirable properties, including good dispersion, cell integrity preservation, and efficient light scattering. Despite these, further studies are necessary, particularly in vivo studies to reduce NPs' toxicity. This review discusses the different methods of synthesis, how CdS NPs are characterized, and their applications in the biomedical field.

SERS determination and multivariate classification of antibiotics in chicken meat using gold nanoparticle-decorated electrospun PVA nanofibers

The fabrication of SERS substrate by gold nanoparticle-decorated polyvinyl alcohol electrospun nanofibers which has been used to detect trace sensing of two widely used poultry antibiotics doxycycline hydrochloride and enrofloxacin is demonstrated. The performance of the backscattered Raman signals from the proposed SERS substrate has been initially evaluated with two standard Raman active compounds namely malachite green and rhodamine-6G. The limit of detection of the proposed substrate is estimated to be 7.32 nM. Following this, the usability of the proposed SERS substrate has been demonstrated through the detection of the aforementioned antibiotics in chicken meat samples. The presence of antibiotics in chicken meat sample has been validated with the standard analytical tool of liquid chromatography-mass spectrometry and the results were compared with the proposed sensing technique. Further, principal component analysis has been performed to classify the antibiotics that are present in the field-collected meat samples.

A highly sensitive impedimetric sensor based on a MIP biomimetic for the detection of enrofloxacin

The benefits of molecularly imprinted polymer (MIP) technology in creating artificial receptors to replace natural counterparts have piqued the interest of numerous researchers in recent years. We propose a biomimetic enrofloxacin-MIP for enrofloxacin (ENRO) antigen detection using gold nanoparticles (AuNPs) and MIP methodologies in this study. A self-assembled monomer layer of aminothiophenol was used to immobilize a pre-formed complex of the anti-enrofloxacin monoclonal antibody and enrofloxacin antigen onto the surface of an AuNP coated screen-printed carbon ink electrode (SPCE). The poly-(aminothiophenol) layer thickness was adjusted to entrap and restrict enrofloxacin antigens near the surface. The imprinting and removal of the enrofloxacin antigen in the MIP film were strongly validated by the Raman spectra. The final mAb-MIP sensor had better sensitivity (302 Ω mL ng^-1) and a better detection limit (0.05 ng mL^-1) than self-assembled monolayer (SAM)-based immunosensors, which had 102 Ω mL ng^-1 and 0.1 ng mL^-1, respectively.

A novel electrochemical sensor for the detection of enrofloxacin based on a 3D flower-like metal tungstate-incorporated reduced graphene oxide nanocomposite

In recent times, metal tungstates have received a lot of attention in various research fields. Accordingly, the CaWO₄/RGO (CW/RGO) nanocomposite was prepared by a facile hydrothermal method. The electrocatalytic performance of the hydrothermally prepared CW/RGO nanocomposite was used for the electrochemical detection of the antibiotic medicine enrofloxacin (ENF). The electrocatalytic oxidation performance of ENF was examined by cyclic voltammetry (CV) and amperometry (AMP) techniques. The CV results showed the lowest anodic peak potential and the enhanced anodic peak current response compared to the other modified electrodes. Mainly, our newly proposed sensor exhibited excellent electrochemical performance with the lowest limit of detection (LOD) of 0.021 μM, and a significant linear range of 0.001-115 μM. Additionally, our proposed sensor exhibited good selectivity, great long-term stability, and excellent reproducibility. Then, our proposed sensor was successfully applied to detect the amount of ENF in a milk sample and river water, which exhibited good satisfactory results.

Simultaneous detection of enrofloxacin and ciprofloxacin in milk using a bias potentials controlling-based photoelectrochemical aptasensor

It is important to develop highly-active photoelectrochemical (PEC) materials and use novel sensing strategy for constructing high-PEC-performance sensors with multiplex detection abilities, owing to the simultaneous presence of multiple antibiotic residues in food. Herein, a bias-potential-based PEC aptasensor was prepared for the trace detection of dual antibiotic analytes, enrofloxacin (ENR) and ciprofloxacin (CIP), which often coexist in milk samples. Here, two materials were developed with excellent PEC performance: three-dimensional nitrogen-doped graphene-loaded copper indium disulfide (CuInS₂/3DNG) and Bi³⁺-doped black anatase titania nanoparticles decorated with reduced graphene oxide (Bi³⁺/B-TiO₂/rGO). By applying different bias potentials to the two materials near one ITO electrode, the cathodic current generated by CuInS₂/3DNH and the anodic current generated by Bi³⁺/B-TiO₂/rGO could be clearly distinguished without interfering with each other. Then, ENR and CIP aptamers were respectively modified onto the surface of CuInS₂/3DNH and Bi³⁺/B-TiO₂/rGO to construct a PEC aptasensor for the sensitive detection of ENR and CIP. Under optimal conditions, the proposed aptasensor exhibited wide linear ranges of ENR (0.01-10000 ng/mL) and CIP (0.01-1000 ng/mL), and relatively low detection limits of 3.3 pg/mL to ENR and CIP (S/N = 3). The aptasensor was successfully applied to the detection of ENR and CIP in milk samples.

Green synthesis of a deep-ultraviolet carbonized nanoprobe for ratiometric fluorescent detection of feroxacin and enrofloxacin in food and serum samples

A sensitive ratiometric fluorescent probe for EFC and FXC detection in milk and bovine serum samples based on the internal filtration effect.

Flexible Electrochemical Bioelectronics: The Rise of In Situ Bioanalysis

The amalgamation of flexible electronics in biological systems has shaped the way health and medicine are administered. The growing field of flexible electrochemical bioelectronics enables the in situ quantification of a variety of chemical constituents present in the human body and holds great promise for personalized health monitoring owing to its unique advantages such as inherent wearability, high sensitivity, high selectivity, and low cost. It represents a promising alternative to probe biomarkers in the human body in a simpler method compared to conventional instrumental analytical techniques. Various bioanalytical technologies are employed in flexible electrochemical bioelectronics, including ion-selective potentiometry, enzymatic amperometry, potential sweep voltammetry, field-effect transistors, affinity-based biosensing, as well as biofuel cells. Recent key innovations in flexible electrochemical bioelectronics from electrochemical sensing modalities, materials, systems, fabrication, to applications are summarized and highlighted. The challenges and opportunities in this field moving forward toward future preventive and personalized medicine devices are also discussed.

Rapid and sensitive detection of enrofloxacin hydrochloride based on surface enhanced Raman scattering-active flexible membrane assemblies of Ag nanoparticles

The abuse of antibiotics resulted in the pollution of river is more and more serious and it was necessary to exploit a sensitive detection method to improve the traditional analysis measurement. In this test, it is reported an Ag-based SERS sensing membrane synthesized by the technique of SERS detection and membrane separation. SERS analysis technique presented sensitive detection property, which could be applied into trace analysis. Membrane separation could effectively enrich the analytes to improve the sensitivity. The SERS membrane was synthesized by filtrating Ag nanoparticles (NPs) on the surface and investigating the amount of PVP and Ag NPs to the sensitivity. Meanwhile, the addition of Ag NPs effectively improved the hydrophilia to promote the detection effectivity in the water. By the investigations of optical analysis, the SERS membrane presented high sensitivity in the detection of antibiotics. Under the optimal condition, the SERS intensity presented good linear relationship with the concentration of antibiotics between 1.0 nmol L^-1 and 200 nmol L^-1. This method provided a sensitive detection approach and broadened the investigation field of antibiotics detection.