In this paper, a portable fluorescence-based functional hydrogel loaded with β-d-glucose pentaacetate (β-D-GP) is designed for high-sensitive quantification of amine vapor and visual monitoring of freshness of shrimp. We found for the first time that amine vapor can mediate β-D-GP to generate photoluminescent polymer-carbon nanodots (PCNDs) with good optical properties. On this basis, a functional hydrogel sensing platform is simply formed by solidifying β-D-GP in agarose hydrogels. When exposure to the volatile amines released from the spoilage of shrimp, β-D-GP in hydrogel is immediately mediated by amines to generate PCNDs, resulting in obvious fluorescence-based color variation of functional hydrogel. Notably, a smartphone is used to obtain digital photographs and RGB (Red/Green/Blue) information of hydrogels for on-site quantitative analysis. The gray value of G/(R + B) of hydrogel shows good linearity with trimethylamine (TMA) vapor concentration in the range of 0-59.49 × 10-9 mol dm-3. More importantly, the G/(R + B) value of functional hydrogel is successfully used to assess the freshness of shrimp. Consequently, this strategy provides a low-cost, portable fluorescence analysis device with promising applications in achieving high-sensitive, nondestructive, and on-site food safety evaluation of animal-derived aquatic products.
Keywords: Freshness of shrimp; Functional hydrogel; Polymer-carbon nanodots; Smartphone; Volatile amines.
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