Optical Fiber-Mediated Immunosensor with a Tunable Detection Range for Multiplexed Analysis of Veterinary Drug Residues

A novel differential ratiometric molecularly imprinted electrochemical sensor for determination of sulfadiazine in food samples

Herein, we report a novel differential ratiometric molecularly imprinted polymer (MIP) electrochemical sensor for sulfadiazine (SDZ). An MIP membrane with double templates, SDZ and propyl gallate (PG), was fabricated on glassy carbon electrode (GCE) modified by CuInS2/ZnS nanocomposites. After adding PG in the samples as the reference, the current differences between MIP@CuInS2/ZnS/GCE and non-imprinted polymer@CuInS2/ZnS/GCE at the potentials of 0.18 V (ΔIPG) and 0.92 V (ΔISDZ) were measured. The ratio of ΔISDZ/ΔIPG was used for SDZ determination in the differential and ratiometric dual-mode. The influence of the variations in electrode modification and sample enrichment conditions on the determination of SDZ can be suppressed by 2.8 ∼ 13.2-fold, enhancing the reproducibility and stability of the MIP sensor. The interference level was reduced by one order of magnitude compared with the normal MIP mode. The proposed sensors were used to determine SDZ in food samples, with the detection limit of 2.1 nM.

Rapid and quantitative determination of deoxynivalenol in cereal through the combination of magnetic solid-phase extraction and optical fiber-based homogeneous chemiluminescence immunosensor

An integrated strategy for the rapid and sensitive detection of deoxynivalenol in cereals was developed by combining Fe₃O₄ magnetic nanoparticle-modified metal organic framework-5-based magnetic solid-phase extraction and the optical fiber-based homogeneous chemiluminescence immunosensor. The hybrid magnetic material was prepared and characterized, exhibiting good enrichment capacity up to 1.68 mg/g. The competitive immunoassay-based homogeneous chemiluminescence immunosensor enabled washing-free and high-sensitivity detection of deoxynivalenol. Under optimized conditions, this immunosensor could detect deoxynivalenol as low as 46.7 pg/mL with a quantitatively linear range of 0.1 to 1000 ng/mL. The recoveries of this integrated detection strategy in rice, corn, and wheat ranged from 80.0 % to 118.2 %, 91.1 % to 116.7 %, and 80.0 % to 91.5 %, respectively, with a relative standard deviation that did not exceed 9.11 %. More importantly, it shows great consistency with the high-performance liquid chromatography-mass spectrometry in blind sample analysis. This integrated detection strategy provides a convenient approach for mycotoxins screening in cereals.

DNA Tetrahedron-Based Valency Controlled Signal Probes for Tunable Protein Detection

Combined detection of multiple markers related to the same disease could improve the accuracy of disease diagnosis. However, the abundance levels of multiple markers of the same disease varied widely in real samples, making it difficult for the traditional detection method to meet the requirements of a wide detection range. Herein, three kinds of cardiac biomarkers, cardiac troponin I (cTnI), myoglobin (Myo), and C-reaction protein (CRP), which were from the pM level to the μM level in real samples, were selected as model targets. Valency-controlled signal probes based on DNA tetrahedron nanostructures (DTNs) and platinum nanoparticles (PtNPs) were constructed for tunable cardiac biomarker detection. PtNPs with high horseradish peroxidase-like activity and stability served as signal molecules, and DTNs with unique spatial structure and sequence specificity were used for precisely controlling the number of connected PtNPs. By controlling the number of PtNPs connected to DTNs, monovalent, bivalent, and trivalent signal probes were obtained and were used for the detection of cardiac markers in different concentration ranges. The limit of detection of cTnI, Myo, and CRP was 3.0 pM, 0.4 nM, and 6.7 nM, respectively. Furthermore, it performed satisfactorily for the detection of cardiac markers in 10% human serum. It was anticipated that the design of valency-controlled signal probes based on DTNs and nanozymes could be extended to the construction of other multi-target detection platforms, thus providing a basis for the development of a new precision medical detection platform.

Novel method in emerging environmental contaminants detection: Fiber optic sensors based on microfluidic chips

Recently, human industrial practices and certain activities have caused the widespread spread of emerging contaminants throughout the environmental matrix, even in trace amounts, which constitute a serious threat to human health and environmental ecology, and have therefore attracted the attention of research scholars. Different traditional techniques are used to monitor water pollutants, However, they still have some disadvantages such as high costs, ecological problems and treatment times, and require technicians and researchers to operate them effectively. There is therefore an urgent need to develop simple, inexpensive and highly sensitive methods to sense and detect these toxic environmental contaminants. Optical fiber microfluidic coupled sensors offer different advantages over other detection technologies, allowing manipulation of light through controlled microfluidics, precise detection results and good stability, and have therefore become a logical device for screening and identifying environmental contaminants. This paper reviews the application of fiber optic microfluidic sensors in emerging environmental contaminant detection, focusing on the characteristics of different emerging contaminant types, different types of fiber optic microfluidic sensors, methodological principles of detection, and specific emerging contaminant detection applications. The optical detection methods in fiber optic microfluidic chips and their respective advantages and disadvantages are analyzed in the discussion. The applications of fiber optic biochemical sensors in microfluidic chips, especially for the detection of emerging contaminants in the aqueous environment, such as personal care products, endocrine disruptors, and perfluorinated compounds, are reviewed. Finally, the prospects of fiber optic microfluidic coupled sensors in environmental detection and related fields are foreseen.

A REVIEW ON DETERMINATION OF THE VETERINARY DRUG RESIDUES IN FOOD PRODUCTS

In this paper, we discuss veterinary medicine and its applications in the food field as well as its risk to the health of humans and animals by the residues. We review how the veterinary residues enter and cause some detrimental effects. We also mention two techniques to determine the residue of veterinary medication that existed in food originating from animals, including classic and advanced techniques. Finally, we discuss the potential of various developed methods compared to some traditional techniques.

Smart Materials Enabled with Artificial Intelligence for Healthcare Wearables

Contemporary medicine suffers from many shortcomings in terms of successful disease diagnosis and treatment, both of which rely on detection capacity and timing. The lack of effective, reliable, and affordable detection and real‐time monitoring limits the affordability of timely diagnosis and treatment. A new frontier that overcomes these challenges relies on smart health monitoring systems that combine wearable sensors and an analytical modulus. This review presents the latest advances in smart materials for the development of multifunctional wearable sensors while providing a bird's eye‐view of their characteristics, functions, and applications. The review also presents the state‐of‐the‐art on wearables fitted with artificial intelligence (AI) and support systems for clinical decision in early detection and accurate diagnosis of disorders. The ongoing challenges and future prospects for providing personal healthcare with AI‐assisted support systems relating to clinical decisions are presented and discussed.

Direct Transverse Relaxation Time Biosensing Strategy for Detecting Foodborne Pathogens through Enzyme-Mediated Sol-Gel Transition of Hydrogels

In this work, we develop a direct transverse relaxation time (T₂) biosensing strategy and employ it for assaying foodborne pathogens relying on the alkaline phosphatase (ALP)-mediated sol-gel transition of hydrogels. ALP can catalyze the reaction to generate an acidic environment to transform the sol-state alginate solution to hydrogel, and this hydrogelation process can directly regulate the diffusion rate of water protons that results in a T₂ change of water molecules. By means of enzyme-modulated sol-gel transition and antigen-antibody interactions, this T₂ biosensor displays high sensitivity for detecting 50 CFU/mL S. enteritidis within 2 h. This biosensing strategy directly modulates the water molecules rather than magnetic probes in traditional methods, offering a straightforward, novel, and sensitive platform for pathogen detection.

Mesoporous silica-mediated controllable electrochemiluminescence quenching for immunosensor with simplicity, sensitivity and tunable detection range

Straightforward and accurate measurement of medical biomarkers is of essential importance in clinical diagnostics and treatments. However, the major challenge is the diversity in dynamic range of different biomarkers ranging from pg mL^-1 to μg mL^-1 in various body fluids and tissues among patients. Here, we develop a mesoporous silica (MS)-mediated controllable electrochemiluminescence (ECL) quenching of immunosensor that allows accurate immunoassays with simplicity, sensitivity and tunable sensing range. MS is employed to enhance the sensitivity and tune ECL quenching to broaden the detection range just by altering luminophore (Ru(bpy)₃²⁺) and coreactant (DBAE) concentration without additional modifications. The immunoassay is followed: homogeneous sandwich immunoreaction, magnetic separation, and ECL quenching detection. As a proof-of-concept, simple and sensitive detection of IgG is achieved ranging from pg mL^-1 to μg mL^-1, and applications of the strategy are extended by the combination of ECL immunosensor with commercial ELISA kit. This study will not only be expected to serve as a new avenue for the assay of physiological and clinical implications of immunological biomarkers, but also benefit a wide range of applications that require a tunable detection range and ultrahigh sensitivity.

Veterinary Drug Residues in Animal-Derived Foods: Sample Preparation and Analytical Methods

Veterinary drugs are used to treat livestock and aquatic diseases and thus are introduced into animal-derived foods, endangering consumer health and safety. Antibiotic resistance is rapidly becoming a major worldwide problem, and there has been a steady increase in the number of pathogens that show multi-drug resistance. Illegal and excessive use of veterinary drugs in animals and aquaculture has serious adverse effects on humans and on all other environmental organisms. It is necessary to develop simple extraction methods and fast analytical methods to effectively detect veterinary drug residues in animal-derived foods. This review summarizes the application of various sample extraction techniques and detection and quantification methods for veterinary drug residues reported in the last decade (2010-2020). This review compares the advantages and disadvantages of various extraction techniques and detection methods and describes advanced methods, such as those that use electrochemical biosensors, piezoelectric biosensors, optical biosensors, and molecularly imprinted polymer biosensors. Finally, the future prospects and trends related to extraction methods, detection methods and advanced methods for the analysis of veterinary drug residues in animal-derived foods are summarized.

Fabrication of an electrochemical sensor with Au nanorods-graphene oxide hybrid nanocomposites for in situ measurement of cloxacillin

In recent years, considering the increasing use of antibiotics, and their continued entry into the environment, extensive research has been conducted on the impact of antibiotics on human health, water resources, and the environment. In this study, a suitable method has been proposed for detecting and elimination the trace amounts of the antibiotic cloxacillin in aqueous. For identify trace amounts of cloxacillin in solution, a new electrochemical nanosensor based on a screen printed carbon electrode (SPCE) modified with gold nanorods/graphene oxide was proposed. This nanosensor, which was prepared by self-assembling method, was capable of measuring cloxacillin in the 5.0-775.0 nM with a detection limit of 1.6 nM. In order to reduce the amount of antibiotics in the environment, a novel carbon nanocomposite based on sol-gel method was prepared and its application as a high-capacity adsorbent for the removal of cloxacillin was studied. In the antibiotic removal experiments, the effect of pH, contact time, different mass ratios of SWCNT and amount of nanocomposite adsorbent were also optimized by response surface methodology (RSM). The prepared nanosensor and synthesized carbon nanocomposites were then characterized by commonly identical techniques involve SEM, EDAX, BET and FT-IR. The presented nanosensor was successfully used for the in situ determination of Clox in adsorptive tests with reliable recovery. As well, the AuNR/GO/SPC electrode presented well stability, repeatability and reproducibility. In addition, good performance and high adsorption capacity make developed adsorbent as a suitable case for the removal of water-soluble pharmaceutical contaminants.

A portable pencil-like immunosensor for point-of-care testing of inflammatory biomarkers

Portable devices for immunoassays are in high demand for point-of-care testing (POCT) of biomarkers. Here, we report a robust portable pencil-like immunosensor (PPS) platform for the determination of three inflammatory biomarkers including interleukin-6 (IL-6), procalcitonin (PCT), and C-reactive protein (CRP) in human serum samples. The PPS platform is composed of a unique pencil-like optical-fiber-based sensor, a reagent strip consisting of a series of pencil-cap-like wells, and a battery-powered photon counting detector for recording chemiluminescence. The PPS probe moves from well to well with a plug-into/out approach and goes through the immunoassay steps. Each fiber probe in the PPS platform can be sequentially used in up to 10 assays by simply propelling the intact probe out of the pencil body. The PPS platform is well-integrated into a portable suitcase-like device (32 cm × 23 cm × 11 cm) and is only 3 kg in weight. The sensor has good repeatability and can maintain 90% response after 14 days of storage at room temperature, showing its ability for assays in the field. The good linear relationship and efficient dynamic range with a limit-of-detection (LOD) of 1.05 pg/mL for IL-6, 10.64 pg/mL for PCT, and 29.40 ng/mL for CRP are obtained. The assay results are compared with clinical methods, and the findings confirm the high accuracy and precision of the proposed method. The proposed PPS platform is versatile and operable with minimal instruments and technical skills and simplifies the process of immune analysis, thus has great prospects for POCT of biomarkers. Graphical abstract.