Development of a smartphone-integrated microfluidic paper-based optosensing platform coupled with molecular imprinting technique for in-situ determination of histamine in canned tuna.

We reported the development of a smartphone-integrated microfluidic paper-based optosensing platform for in-situ detection and quantification of histamine in canned tuna. Molecularly imprinted polymers were synthesized via precipitation polymerization and utilized as dispersive solid phase extraction sorbent to selectively extract histamine from canned tuna. Carbon quantum dots functioning as a fluorescent probe were synthesized and introduced onto the microzones of the microfluidic paper device. This facilitated a noticeable fluorescence color change from dark red to vivid blue upon the addition of histamine. The change in fluorescence on the paper device was converted into specific RGB values using a portable UV light box combined with a smartphone. This assay achieved the limit of detection of 14.04 mg/kg with the linear range from 20 to 100 mg/kg of histamine in canned tuna. The entire molecular imprinting-microfluidic optosensing test could be completed in 45 min including sample preparation.

Development of a microfluidic device to enrich and detect zearalenone in food using quantum dot-embedded molecularly imprinted polymers.

Mycotoxins are secondary metabolites of certain moulds, prevalent in 60-80% of food crops and many processed products but challenging to eliminate. Consuming mycotoxin-contaminated food and feed can lead to various adverse effects on humans and livestock. Therefore, testing mycotoxin residue levels is critical to ensure food safety. Gold standard analytical methods rely on liquid chromatography coupled with optical detectors or mass spectrometers, which are high-cost with limited capacity. This study reported the successful development of a microfluidic "lab-on-a-chip" device to enrich and detect zearalenone in food samples based on the fluorescence quenching effect of quantum dots and selective affinity of molecularly imprinted polymers (MIPs). The dummy template and functional polymer were synthesized and characterized, and the detailed microfluidic chip design and optimization of the flow conditions in the enrichment module were discussed. The device achieved an enrichment factor of 9.6 (±0.5) in 10 min to quantify zearalenone spiked in food with high recoveries (91-105%) at 1-10 mg kg-1, covering the concerned residue levels in the regulations. Each sample-to-answer test took only 20 min, involving 3 min of manual operation and no advanced equipment. This microfluidic device was mostly reusable, with a replaceable detection module compatible with fluorescence measurement using a handheld fluorometer. To our best knowledge, the reported device was the first application of an MIP-based microfluidic sensor for detecting mycotoxin in real food samples, providing a novel, rapid, portable, and cost-effective tool for monitoring mycotoxin contamination for food safety and security.