Self-Assembling Antibody Network Simplified Competitive Multiplex Lateral Flow Immunoassay for Point-of-Care Tests

Sensitive fluorescence detection based on dimeric G-quadruplex combined with enzyme-assisted solid-phase microextraction of streptomycin in honey

Streptomycin (STR), an aminoglycoside antibiotic with the potential to persist in honey and other food products, may induce allergy, toxicity and antibiotic resistance in humans. In this study, we developed a solid-phase microextraction (SPME) biosensor based on a quartz rod that was modified with double-stranded DNA structures consisting of partially complementary G-rich base DNA strand and STR aptamer. The STR isolated by SPME initially bound to the aptamer. Then the remaining double-stranded DNA structures were cleaved by the Nt.BstNBI enzyme, resulting in release of G-quadruplex dimers. The latter formed a complex with thioflain T fluorescent dye, resulting in an amplified fluorescence response. The method exhibited high sensitivity (a limit of detection of 10.84 pM), wide linear range (0.05 nM ∼ 500 nM (with determination coefficient > 0.99)), and simple operation, making it suitable and convenient for STR detection. Successful STR determination in genuine honey samples was demonstrated.

Ultrasensitive Ti3C2Tx@Pt-Based Immunochromatography with Catalytic Amplification and a Dual Signal for the Detection of Chloramphenicol in Animal-Derived Foods

Herein, a catalytic amplification enhanced dual-signal immunochromatographic assay (ICA) based on Pt nanoparticles (Pt NPs) modified with Ti3C2Tx MXene (Ti3C2Tx@Pt) was first developed for chloramphenicol (CAP) in animal-derived foods. Due to the large specific surface area and abundant active sites of Ti3C2Tx@Pt, they can be loaded with hundreds of Pt NPs to enhance their catalytic activity, resulting in a significant increase in the detection sensitivity; the sensitivity was up to 50-fold more sensitive than the reported ICA for CAP. The LODs of the developed method for milk/chicken/fish were 0.01 μg/kg, the LOQs were 0.03 μg/kg and the recovery rates were 80.5-117.0%, 87.2-118.1% and 92.7-117.9%, with corresponding variations ranging from 3.1 to 9.6%, 6.0 to 12.7% and 6.0 to 13.6%, respectively. The linear range was 0.0125-1.0 μg/kg. The results of the LC-MS/MS confirmation test on 30 real samples had a good correlation with that of our established method (R2 > 0.98), indicating the practical reliability of the established method. The above results indicated that an ICA based on the Ti3C2Tx@Pt nanozyme has excellent potential as a food safety detection tool.

Goat anti-mouse immunoglobulin as "crosslinker" assisted signal tracer assemble with intensive antibody utilization efficiency for sensitive paper-based strip nanobiosensors

Engineered collaborative biochemical techniques and regulated nanomaterials (NMs) offer extraordinary opportunities for improving the analysis performance of lateral flow immunoassay (LFIA). Herein, inspired by the ability of macromolecules (e.g., proteins) to assemble into new functional units and the remarkable optical performance of engineered regulated NMs, goat anti-mouse immunoglobulin (GAMI) serves as the "crosslinker" integrate with gold‑manganese oxide (Au-MnOx) to assemble the "signal tracers (STs)-crosslinker-antibody (mAb)" for elevating the mAb utilization efficiency. Notably, the "STs-crosslinker-mAb" assembly shows ~13.33-folds mAb utilization efficiency enhance, which perfectly response the challenge between limited sensitivity and sufficient signal intensity in competitive-type LFIA. The black color and rough structure of Au-MnOx offer higher colorimetric brightness (~2-folds than AuNPs) and enhanced mAb coupling efficiency (up to 92.47%), which further improves sensitivity under the premise of functional assembly to intensify the competitive immunoreaction. Additionally, the convenient synthesis conditions (~13 min at room temperature) even comparable to direct purchase commercial products indicate that using Au-MnOx undoubtedly increases the cost-effectiveness. Encouragingly, the Au-MnOx-GAMI-mAb based LFIA exhibited high sensitivity (LOD: 0.063 ng mL-1 for clenbuterol (CLE) monitoring) by elevating mAb utilization efficiency with the attendant enhancing immune competition response in a cost-effective manner, which provides an invigorating reference pathway in point-of-care immunoassay.

RNA-cleaving deoxyribozyme-linked immunosorbent assay for the ultrasensitive detection of chloramphenicol in milk

In this presented work, an artificial deoxyribozyme was employed as the substitute for horseradish peroxidase (or alkaline phosphatase) in ELISA for generating amplified signals. The feasibility of the proposed deoxyribozyme-based ELISA (DLISA) was demonstrated in the detection of a forbidden veterinary drug, chloramphenicol. And its efficiency was praised since that ultrahigh sensitivity was accomplished with a detection limit of 0.1 ng/L. The wide linear range from 0.000001 μg/mL to 1.0 μg/mL, as well as good recoveries from 86 % to 104 % in whole milk samples showed its excellent practical performances. Besides, the DLISA was worth popularizing due to the easy connection of antibody and DNAzyme through a facile functionalization process of gold nanoparticles. These advantages showed the possibility of DLISA for developing commercial kits, and the utilization of flexible DNA fluorescent probes in DLISA would inspire more work on innovations.

"Potential Scalpel": A Bioassisted Ultrafast Staining Lateral Flow Immunoassay from De Novo to Results

It is of great importance to overcome potential incompatibility problems between dyestuffs and antibodies (mAbs) for extensive commercial application of a dyestuff-chemistry-based ultrafast colorimetric lateral flow immunoassay (cLFIA). Herein, inspired by traditional staining technologies, a basic dyestuff gallocyanine (GC)-assisted biogenic "potential scalpel"-based cLFIA (GC-ABPS-based cLFIA) by employing clenbuterol (CLE) as proof-of-concept was proposed to solve a high degree of incompatibility between the same potential dyestuffs and mAbs. Goat antimouse immunoglobulin (Ab₂) could serve as the "potential scalpel" to form the positive potential value biomolecular network self-assemblers (BNSA) with anti-CLE mAbs (Ab_CLE) by noncovalent force. The cLFIA completed the entire detection process from de novo to detection results within 30 min thanks to the easy availability and ideal marking efficiency (≤1 min, saving 0.4-10 h) of GC. Encouragingly, the proposed ultrafast GC-ABPS-based cLFIA has also exhibited high sensitivity (0.411 ng mL^-1) and low cost (300 times) compared with other cLFIAs. Also, the feasibility of the proposed cLFIA was demonstrated by detecting CLE in beef, pork ham, and skim milk. Finally, the proposed GC-ABPS-based cLFIA has broadened the application range of dyestuffs and provided an effective reference strategy for the application of dyestuffs in food safety monitoring.

Multiplex immunochromatographic platform based on crystal violet tag for simultaneous detection of streptomycin and chloramphenicol

Antibiotic abuse has caused serious health risks for human beings for long. To address the problem, novel and facile detection techniques are highly desired. Here, an effective multiplex immunochromatographic platform (MICP) with synthesis-free and cost-effective merits is established for simultaneous detection of antibiotics on a single immunochromatographic assay (ICA) strip. Adopting crystal violet (CV) as a signal tag for multiplex ICA allows for direct coupling with multiple antibodies in several minutes. By combining CV and ICA perfectly, this convenient strategy offers improvements in convenience, speed, flexibility, and portability, eventually ensuring the optimized effectiveness of this approach. As a result, the established platform is successfully used to detect streptomycin (STR) and chloramphenicol (CAP) with visual detection mode, and the obtained total recoveries of milk and honey real samples changed from 83.82 to 113.38% with total RSD values of 0.48 to 4.15%.