Ultra-sensitive detection of ampicillin via dual-enzyme mediated cascade-signal amplified aptasensor

Surface-enhanced Raman spectroscopy substrates for monitoring antibiotics in dairy products: Mechanisms, advances, and prospects

Antibiotic residues in dairy products have become an undeniable threat to human health. Surface-enhanced Raman spectroscopy (SERS) has been widely used in efficiently detecting antibiotics because of its characteristics including fast response, high resolution, and strong resistance to moisture interference. However, as a core part of SERS technology, the design principle and detection performance of enhanced substrates used in monitoring antibiotics in dairy products have not yet received enough attention. Thus, it is necessary to give a critical review of the recent developments of SERS substrates for monitoring antibiotics in dairy products, which can be expected to provide inspiration for the efficient utilization of SERS technology. In this work, advances in various SERS substrates applied in sensing antibiotics in dairy products were comprehensively reviewed. First, the enhancement mechanisms were introduced in detail. Significantly, the types of enhanced materials (plasmonic metal particles [PMPs], PMPs/semiconductor composite materials) and biometric design strategies including immunoassay, aptamer, and molecularly imprinted polymers-based SERS biosensors applied in dairy products were systematically summarized for the first time. Meanwhile, the performance of SERS substrates used for the detection of antibiotics in dairy products was addressed from the aspects of dynamic linear range and detection restriction strategy. Finally, the conclusions, challenges, and future prospects of SERS substrates for antibiotic monitoring in dairy products were deeply discussed, which also provide new opinions and key points for constructing SERS substrates applied in complex food matrix in the future.

Bifunctional bovine serum albumin modification driven sensitivity-enhanced lateral flow immunoassay for small molecule hazards monitoring in food

Traditional lateral flow immunoassays (TLFIAs) are valued for their simplicity, speed, and user-friendliness. However, the specificity of conventional test strips often necessitates large quantities of antigen-protein conjugates for target detection, which can be resource-intensive. Here, we present a strategy aimed at enhancing the universality of test strips while reducing the consumption of antigen-protein conjugates, without compromising sensitivity. By coating streptavidin on the test line and employing bifunctional antigen-protein conjugates (competitor to target and immunoprobe linker), the test strip was thus served as a universal module. We developed three universal lateral flow immunoassays (ULFIAs) for the detection of aflatoxin B1 (AFB1), carbendazim (CBZ), and enrofloxacin (ENR). Compared to traditional methods based on the same aggregation-induced emission fluorescent microspheres, the proposed ULFIAs demonstrated a significant increase in sensitivity, with enhancements of 11.0-fold for AFB1, 10.9-fold for CBZ, and 4.1-fold for ENR. Additionally, this approach substantially reduced the consumption of antigen-protein conjugates by 19.1-fold, 40.9-fold, and 23.8-fold, respectively, thereby promoting greener detection methods. This bifunctional antigen conjugate strategy offers a promising pathway for the sensitive detection of small molecule hazards.

Gold nanoparticles-doped MXene heterostructure for ultrasensitive electrochemical detection of fumonisin B1 and ampicillin

Early transition metal carbides (MXene) hybridized by precious metals open a door for innovative electrochemical biosensing device design. Herein, we present a facile one-pot synthesis of gold nanoparticles (AuNPs)-doped two-dimensional (2D) titanium carbide MXene nanoflakes (Ti3C2Tx/Au). Ti3C2Tx MXene exhibits high electrical conductivity and yields synergistic signal amplification in conjunction with AuNPs leading to excellent electrochemical performance. Thus Ti3C2Tx/Au hybrid nanostructure can be used as an electrode platform for the electrochemical analysis of various targets. We used screen-printed electrodes modified with the Ti3C2Tx/Au electrode and functionalized with different biorecognition elements to detect and quantify an antibiotic, ampicillin (AMP), and a mycotoxin, fumonisin B1 (FB1). The ultralow limits of detection of 2.284 pM and 1.617 pg.mL-1, which we achieved respectively for AMP and FB1 are far lower than their corresponding maximum residue limits of 2.8 nM in milk and 2 to 4 mg kg-1 in corn products for human consumption set by the United States Food and Drug Administration. Additionally, the linear range of detection and quantification of AMP and FB1 were, respectively, 10 pM to 500 nM and 10 pg mL-1 to 1 µg mL-1. The unique structure and excellent electrochemical performance of Ti3C2Tx/Au nanocomposite suggest that it is highly suitable for anchoring biorecognition entities such as antibodies and oligonucleotides for monitoring various deleterious contaminants in agri-food products.

Aptamer-Based fluorescent DNA biosensor in antibiotics detection

The inappropriate employment of antibiotics across diverse industries has engendered profound apprehensions concerning their cumulative presence within human bodies and food commodities. Consequently, many nations have instituted stringent measures limiting the admissible quantities of antibiotics in food items. Nonetheless, conventional techniques employed for antibiotic detection prove protracted and laborious, prompting a dire necessity for facile, expeditious, and uncomplicated detection methodologies. In this regard, aptamer-based fluorescent DNA biosensors (AFBs) have emerged as a sanguine panacea to surmount the limitations of traditional detection modalities. These ingenious biosensors harness the binding prowess of aptamers, singular strands of DNA/RNA, to selectively adhere to specific target antibiotics. Notably, the AFBs demonstrate unparalleled selectivity, affinity, and sensitivity in detecting antibiotics. This comprehensive review meticulously expounds upon the strides achieved in AFBs for antibiotic detection, particularly emphasizing the labeling modality and the innovative free-label approach. It also elucidates the design principles behind a diverse array of AFBs. Additionally, a succinct survey of signal amplification strategies deployed within these biosensors is provided. The central objective of this review is to apprise researchers from diverse disciplines of the contemporary trends in AFBs for antibiotic detection. By doing so, it aspires to instigate a concerted endeavor toward the development of heightened sensitivity and pioneering AFBs, thereby contributing to the perpetual advancement of antibiotic detection methodologies.

A solid-phase capture probe based on upconvertion nanoparticles and inner filter effect for the determination of ampicillin in food

Ampicillin (AMP) is commonly used to treat diseases caused by bacterial infections as a veterinary drug. However, the abuse of AMP can lead to residues in food and ultimately cause harm to humans. Thus, it is significant to construct a reliable system for AMP detection. Here, we developed an inner filter effect system based on a solid-phase capture probe and the catalysis of platinum nanoparticles (PtNPs) for AMP determination in food. In the presence of AMP, PDMS captured AMP then combined with aptamer-functionalized PtNPs, which catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine, resulting in upconversion fluorescence quenching. The results showed the fluorescence intensity of upconversion nanoparticles was related to AMP concentration (0.5-100 ng·mL^-1) with an LOD of 0.32 ng·mL^-1, which made quantification of AMP possible. The method also achieved a satisfactory recovery rate (96.89-112.92%) and can be used for AMP detection in food samples with selectivity and sensitivity.

A Label-Free Electrochemical Aptasensor Based on Zn/Fe Bimetallic MOF Derived Nanoporous Carbon for Ultra-Sensitive and Selective Determination of Paraquat in Vegetables

Paraquat (PQ) has high acute toxicity, even at low concentrations. For most people, the main pathway of exposure to PQ is through the diet. Therefore, the development of simple and efficient methods for PQ testing is critical for ensuring food safety. In this study, a new electrochemical detection strategy for paraquat is proposed based on the specific binding of PQ to its nucleic acid aptamer. Firstly, the Zn/Fe bimetallic ZIF derived nanoporous carbon (Zn/Fe-ZIF-NPC) and nickel hexacyanoferrate nanoparticles (NiHCF-NPs) were sequentially modified onto the glassy carbon electrode (GCE). NiHCF-NPs served as the signal probes, while Zn/Fe-ZIF-NPC facilitated electron transfer and effectively enhanced the sensing signal of NiHCF-NPs. Au nanoparticles (AuNPs) were then electrodeposited on the NiHCF-NPs/Zn/Fe-ZIF-NPC/GCE and then the thiolated aptamer was assembled on the AuNPs/NiHCF-NPs/Zn/Fe-ZIF-NPC/GCE via Au-S bonding. When incubated with PQ, the formation of PQ–aptamer complexes delayed the interfacial electron transport reaction of NiHCF-NPs, which caused a decrease in the current signals. As a result, simple and highly sensitive detection of PQ can be readily achieved by detecting the signal changes. A linear range was obtained from 0.001 to 100 mg/L with a detection limit as low as 0.34 μg/L. Due to the recognition specificity of the aptamer to its target molecule, the proposed method has excellent anti-interference ability. The prepared electrochemical aptasensor was successfully used for PQ assay in lettuce, cabbage and agriculture irrigation water samples with recoveries ranging from 96.20% to 104.02%, demonstrating the validity and practicality of the proposed method for PQ detection in real samples.

Fluorescence resonance energy transfer-based aptasensor for sensitive detection of kanamycin in food

Kanamycin (KAN) is widely used in animal husbandry to treat bacterial infections. However, excessive KAN may cause residues and be transmitted to humans and the environment, causing serious adverse effects on humans. Herein, a simple fluorescence resonance energy transfer (FRET)-based aptasensor has been developed for sensitive detection of KAN in food. In the absence of KAN, UCNPs-aptamer hybridized with BHQ3-cDNA and quenched fluorescence was observed due to the FRET effect between BHQ3 and UCNPs. In the presence of KAN, double strands separated and the fluorescence intensity was recovered. Additionally, a linear relation (R² = 0.9926) was found in the range of 0.05-50 μM and the recovered fluorescence intensity at 654 nm with a detection limit of 18.9 nM. The method was verified by standard recovery method and HPLC with satisfactory recovery rate (87.0-109.6%) and accuracy (P > 0.05). These results showed the proposed method could be successfully applied to detect KAN in food samples.

A novel label-free photoelectrochemical aptasensor for the sensitive detection of ampicillin based on carbon-coated Bi2S3 nanorods

The prepared Bi2S3@C nanorods with remarkable photoelectrochemical properties served as a PEC sensor platform for the ultrasensitive analysis of ampicillin.