pH-triggered fluorogenic sensing for pork freshness monitoring using a microneedle array chip and smartphone

The rapid and accurate detection of pork freshness is critical for food safety and public health supervision, while conventional detection methods suffer from complicated pretreatment and reliance on large laboratory equipment. To overcome these drawbacks, a microneedle array chip (MAC) was successfully constructed through the composite assembly of a microneedle array (MA) and a pH-responsive red fluorescent carbon dots (R-CDs) electrospun membrane. Endowed with excellent tissue penetration capability and rapid interstitial fluid adsorption capacity, the MAC enables a sensitive fluorescence response to pH elevation within 10 min during pork spoilage, accompanied by a distinct fluorescence color transition from purple to pink and finally to red. Coupled with smartphone-based RGB analysis, a linear regression model was established to correlate R values with pH, showing a wide linear range of = 1144. Real-time monitoring of pork freshness at 4 °C and 25 °C confirmed that the MAC enables visual and efficient detection of pork freshness. The developed MAC holds great potential as a portable and point-of-care testing platform for on-site food quality control.