A visual bio-barcode immunoassay for sensitive detection of triazophos based on biochip silver staining signal amplification

Strategies Employed to Design Biocompatible Metal Nanoparticles for Medical Science and Biotechnology Applications

The applicability of nanomaterials has evolved in biomedical domains thanks to advances in biocompatibility strategies and the mitigation of cytotoxic effects, allowing diagnostics, imaging, and therapeutic approaches. The application of nanoparticles (NP), particularly metal nanoparticles (mNPs), such as gold (Au) and silver (Ag), includes inherent challenges related to the material characteristics, surface modification, and bioconjugation techniques. By tailoring the surface properties through appropriate coating with biocompatible molecules or functionalization with active biomolecules, researchers can reach a harmonious interaction with biological systems or samples (mostly fluids or tissues). Thus, this review highlights the mechanisms associated with the obtention of biocompatible mNP and presents a comprehensive overview of methods that facilitate safe and efficient production. Therefore, we consider this review to be a valuable resource for all researchers navigating this dynamic field.

Plasmonic enzyme immunoassay via nanobody-driven controllable aggregation of gold nanoparticles for detection of ochratoxin A in pepper

Ochratoxin A (OTA) in food poses a serious challenge to public health. Herein, using the nanobody-driven controllable aggregation of gold nanoparticles (AuNPs) in a glucose oxidase-tyramine-horseradish peroxidase (GOx-TYR-HRP) system, we propose a direct competitive plasmonic enzyme immunoassay (dc-PEIA) for OTA detection. The OTA-GOx conjugate catalyzes glucose to produce hydrogen peroxide (H2O2), and then HRP catalyzes H2O2 to generate hydroxyl radical which induces the crosslink of TYR. Crosslinked TYR leads to aggregation of AuNPs through strong electrostatic interactions, which is tunable based on the competition of OTA-GOx and free OTA for binding the immobilized nanobody. The optimized dc-PEIA achieves an instrumental limit of detection (LOD) of 0.275 ng/mL and a visual LOD of 1.56 ng/mL. It exhibits good selectivity for OTA and accuracy in the analysis of pepper samples, with the confirmation of high-performance liquid chromatography. Overall, the dc-PEIA is demonstrated as a useful tool for detecting OTA in food.

Bio-barcode assay: A useful technology for ultrasensitive and logic-controlled specific detection in food safety: A review

Food safety is one of the greatest public health challenges. Developing ultrasensitive detection methods for analytes at ultra-trace levels is, therefore, essential. In recent years, the bio-barcode assay (BCA) has emerged as an effective ultrasensitive detection strategy that is based on the indirect amplification of various DNA probes. This review systematically summarizes the progress of fluorescence, PCR, and colorimetry-based BCA methods for the detection of various contaminants, including pathogenic bacteria, toxins, pesticides, antibiotics, and other chemical substances in food in over 120 research papers. Current challenges, including long experimental times and strict storage conditions, and the prospects for the application of BCA in biomedicine and environmental analyses, have also been discussed herein.

Integration of DNA barcoding and nanotechnology in drug delivery

In recent years' development in nanotechnology utilization of DNA barcodes with potential benefit of nanoparticulate system is a hallmark for novel advancement in healthcare, biomedical and research sector. Interplay of biological barcoding with nanodimensional system encompasses innovative technologies to offer unique advantages of ultra-sensitivity, error-free, accuracy with minimal label reagents, and less time consumption in comparison to conventional techniques like ELISA, PCR, culture media, electrophoresis. DNA barcoding systems used as universal novel tool for identification and multiplex structural detection of proteins, DNAs, toxins, allergens, and nucleic acids of humans, viruses, animals, bacteria, plants as well as personalized treatment in ovarian cancer, AIDS-related Kaposi sarcoma, breast cancer and cardiovascular diseases. Barcoding tools offer substantial attention in drug delivery, in-vivo screening, gene transport for theranostics, bioimaging, and nano-biosensors applications. This review article outlines the recent advances in nano-mediated DNA barcodes to explore various applications in detection of cancer markers, tumor cells, pathogens, allergens, as theranostics, biological sensors, and plant authentication. Furthermore, it summarizes the diverse newer technologies such as bio-barcode amplification (BBA), Profiling Relative Inhibition Simultaneously in Mixtures (PRISM) and CRISPR-Cas9 gene knockout and their applications as sensors for detections of antigens, allergens, and other specimens.

Nanozyme-encoded luminescent detection for food safety analysis: An overview of mechanisms and recent applications

With the rapid growth in global food production, delivery, and consumption, reformative food analytical techniques are required to satisfy the monitoring requirements of speed and high sensitivity. Nanozyme-encoded luminescent detections (NLDs) integrating nanozyme-based rapid detections with luminescent output signals have emerged as powerful methods for food safety monitoring, not only because of their preeminent performance in analysis, such as rapid, facile, low background signal, and ultrasensitive, but also due to their strong attractiveness for future sensing research. However, the lack of a full understanding of the fundamentals of NLDs for food safety detection technologies limits their further application. In this review, a systematic overview of the mechanisms of NLDs and their applications in the food industry is summarized, which covers the nanozyme-mimicking types and their luminescent signal generation mechanisms, as well as their applications in monitoring common foodborne contaminants. As demonstrated by previous studies, NLDs are bridging the gap to practical-oriented food analytical technologies and various opportunities to improve their food analytical performance to be considered in the future are proposed.

Magnetic covalent organic framework immobilized gold nanoparticles with high-efficiency catalytic performance for chemiluminescent detection of pesticide triazophos

Covalent organic frameworks (COFs) are considered to be a promising support material for catalyst due to their highly ordered porous structure. Here, a core-shell structured Fe₃O₄ magnetic covalent organic framework (Fe₃O₄@COF) was synthesized and employed to provide basic sites for immobilization of gold nanoparticles (AuNPs). The AuNPs was in-situ immobilized on the shell of Fe₃O₄@COF via a citrate reducing method. The Fe₃O₄@COF-AuNP had convenient magnetic separability and exhibited excellent mimicking peroxidase-like activity in catalyzing chemiluminescence (CL) reaction of luminol with hydrogen peroxide (H₂O₂). With acetylcholine chloride (ACh) as substrate of acetylcholinesterase (AChE), a CL method was exploited for sensitive detection of organophosphorus pesticide triazophos due to its irreversible inhibiting effect on the AChE activity and subsequently influences the production of H₂O₂ under the condition of choline oxidase (ChOx). This method gave a good linearity for triazophos in the range of 5.0-300.0 nmol L^-1, and a limit of detection (LOD) of 1 nmol L^-1 was acquired. The applicability of this method was verified by the determination of triazophos in different spiked vegetable samples.

A Simple Colorimetric Analytical Assay for the Determination of Tetracyclines Based on In-situ Generation of Gold Nanoparticles Coupling with a Gold Staining Technique

The development of simple and sensitive detection methods for tetracyclines (TCs) is crucial for their routine detection. The present study developed a colorimetric method for the detection of TCs based on the in-situ generation of AuNPs, which were subsequently coupled with a gold staining reaction. Briefly, TCs containing phenolic groups reduce HAuCl₄ to form gold nanoparticles (AuNPs) as gold seeds. In the gold staining process, the gold seeds catalyze the reduction of HAuCl₄ by NH₂OH to form gold atoms that deposit on the surface of AuNPs, resulting in the enlargement of AuNPs. Sensitive detection of TCs was achieved by employing the gold staining technique. As low as 14, 18.9, and 1.98 nM of oxytetracycline (OTC), tetracycline (TC), and doxycycline (DC), respectively, could be sensitively detected. The proposed method also exhibited good repeatability and specificity, and then was applied to the determination of OTC in milk samples.

Duplex-Specific Nuclease-Triggered Fluorescence Immunoassay Based on Dual-Functionalized AuNP for Acetochlor, Metolachlor, and Propisochlor

Given the great harm of pesticide residues to the environment and public health, exploring ultrasensitive and low-cost methods for their quantitative analysis becomes intensely necessary. Herein, we proposed a double-functionalized gold nanoparticle (AuNP) probe as a signal amplification immunoassay for the detection of acetochlor (ATC), metolachlor, and propisochlor. The AuNP was modified with IgG and fluorophore-labeled duplex DNA by a polyadenine-based freezing method. The quenched fluorescence can be effectively recovered via duplex-specific nuclease (DSN) with excellent cleaving activity. This approach provided limits of detection (LODs) down to 0.03 ng/mL for ATC, 0.10 ng/mL for metolachlor, 0.14 ng/mL for propisochlor, and 0.08 ng/mL for their mixture. The average recoveries of ATC, metolachlor, and propisochlor were 93.0-106.6% from a corn sample, which are in good agreement with the commercial kit (R² = 0.9995). This "turn-off" fluorescence immunoassay presents considerable potential in the analysis of chloroacetamide herbicide due to its simple process of probe preparing and ultrahigh sensitivity.