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Gold nanoparticles (AuNPs)-based immunochromatographic assay has gained popularity as a rapid detection method for food hazards. Synthesizing highly stable AuNPs in a rapid, simple and environmentally friendly manner is a key focus in this field. Here, we present a green microfluidic strategy for the rapid, automated, and size-controllable synthesis of pepsin-doped AuNPs (AuNPs@Pep) by employing glucose-pepsin as a versatile reducing agent and stabilizer. Through combining the colorimetric and photothermal (PoT) properties of AuNPs@Pep, both "signal-off" and "signal-on" formats of microfluidic paper analytical devices (PADs) were developed for detection of a small molecule antibiotic, florfenicol, and an egg allergen, ovalbumin. Compared to the colorimetric mode, a 4-fold and 3-fold improvement in limit of detection was observed in the "signal-off" detection of florfenicol and the "signal-on" detection of ovalbumin, respectively. The results demonstrated the practicality of AuNPs@Pep as a colorimetric/PoT dual-readout probe for immunochromatographic detection of food hazards at different molecular scales. [Display omitted] • Rapid and size-controlled green synthesis of AuNPs@Pep on a microfluidic device. • AuNPs@Pep has excellent biosensing stability as a colorimetric/photothermal probe. • High-performance "signal-on" and "signal-off" dual-readout PADs for food hazards. [ABSTRACT FROM AUTHOR]

With increasing concerns related to the abuse of antibiotics in livestock production worldwide, simple and rapid screening methods for monitoring antibiotics in animal-derived foods are highly desirable. In this study, we propose a facile synthesis strategy for gold nanoclusters (AuNCs) exhibiting remarkable optical properties by employing ovalbumin (OVA) as the template. The OVA-stabilized AuNCs (AuNCs@OVA) manifest intriguing multicolour fluorescence and a gradually declining fluorescence intensity at 650 nm with an increasing concentration of tetracycline family antibiotics (TCs) including tetracycline, chlorotetracycline, oxytetracycline, and doxycycline, which are a widely used class of antibiotics for treating infections in food-producing animals. This performance makes AuNCs@OVA particularly attractive as a broad-spectrum detector for TCs sensing, and we demonstrate that this simple sensing procedure can be realized in real time by directly mixing the target sample and AuNCs@OVA components. Based on this sensing strategy, a microfluidic lab-on-a-chip platform was constructed for the ultrarapid detection of TCs within 30 s. The detection limit was determined to be 0.09 μg/mL in chicken muscle extract, with the recovery ranging from 86.20% to 93.57% in spiked samples. This work provides not only a broad-spectrum sensing strategy for TCs but also a pump-free microfluidic chip with the advantages of being portable, ultrarapid, and low cost, offering a viable alternative for on-the-spot ultrarapid screening of TCs. • A facile synthesis strategy for ovalbumin-stabilized gold nanocluster (AuNCs@OVA). • A novel real-time sensing strategy for TCs using AuNCs@OVA as a broad-spectrum detector. • A single small lab-on-a-chip device for easy and ultrarapid detection of TCs. [ABSTRACT FROM AUTHOR]

Different types of nanomaterials used in (bio)sensors systems for the detection of pathogens and microbial toxins. [Display omitted] • One of the new and emerging strategies for safety assessment are nanomaterial-based sensors. • Nanosensors for detection of microorganisms and their toxins have been hugely probed. • Magnetic/gold nanoparticles, peptide nanotubes, quantum dots, etc. are the most common nanomaterials for nanosensors. • Challenges stay for the easy fabrication of nanosensors and their application in food matrices. Nowadays, because of the higher people's awareness for safe and healthy food consumption, there is a proliferating request to keep food products versus the hazardous effect of pathogens and harmful microbial metabolites. Indeed, these organisms and their toxins create a high risk for food safety and known as a crucial menace for public health due to the ability of triggering foodborne infections/intoxications. Common procedures have high cost for analyses, need a lot of time, are effortful and need new tools along with skilled staff. Therefore, to come cross such difficulties, it is essential to expand sensing methods including bio/nanosensors for detections and evaluations, which are quick, trustworthy, economical and beneficial. Nanosensors for detection of microorganisms and their toxins have been hugely probed with the emrging fields of nanotechnology and artificial intelligence. Nanomaterial-based sensors such as magnetic nanoparticles, gold nanoparticles, peptide nanotubes, quantum dots, etc are the most common sensors with broad application for detection of pathogens and their toxins; they have been discussed completely in this review. Nevertheless, challenges stay for the easy and simple fabrication of nanosensors and their functional application in food matrices. Hence, developments and innovation in sensing process will be a movement in the near future. [ABSTRACT FROM AUTHOR]

• An MOFs and AuNPs-based QCM aptasensor was fabricated for TC sensing. • MOFs-AuNPs nanocomposite were used to enhance the performance of QCM aptasensor. • The QCM aptasensor exhibited wide linear range, good sensitivity, selectivity, and applicability. • This is a first attempt of applying MOFs in the field of QCM aptasensor. A novel label-free point-of-care quartz crystal microbalance (QCM) aptasensing platform based on metal–organic frameworks (MOFs) and gold nanoparticles (AuNPs) was fabricated for tetracycline (TC) detection. MOFs (HKUST-1) and AuNPs were modified onto the sensing interface of QCM sensor to enhance the sensing performance of the QCM aptasensor. TC aptamer with sulfhydryl group was fixed through Au-S bond. The recognition performance of the aptasensor was predicted and verified by the computer simulation. At the optimal conditions, the frequency change of the sensor was adopted for quantitative detection of TC. The prepared QCM aptasensor exhibited a wide linear range from 1 × 10−10 g mL−1 to 1 × 10−5 g mL−1 with low limit of detection (0.8 × 10−11 g mL−1). High sensitivity, good selectivity, acceptable recoveries (87.6–91.4%) in real samples were obtained. For the first time, MOFs were utilized in the construction of QCM aptasensing platform, providing a promising application way of MOFs in the QCM sensing. [ABSTRACT FROM AUTHOR]