monitoring meat freshness with a ratiometric fluorescence nanoprobe and a combinational logic gate

Abstract: monitoring meat freshness has always been an important topic in food safety and control. although significant advances have been made, there are still some challenges to meet [1]. probing markers of meat spoilage, particularly spermine (sp) and spermidine (sd), become even more challenging when rapid, sensitive and portable detections are desired [2]. herein, we have developed a ratiometric fluorescent nano probe with a wide color variation for visual determination of sp and sd in meat samples. the green emission of the ratiometric probe which is provided from the combination of the yellow emission of mpa-capped cdte quantum dots (yqds) and the blue emission of carbon dots (bcds), turns into pink when sp or sd are present. the higher sensitivity of the probe towards sp which eventually causes earlier color alterations, is manipulated for the quantification of their mixtures. the results show that the developed sensor has good linearity in the range of 0.5- 10 μm and 0.5-80 μm for sp and sd, respectively and suitable detection limits including 0.2 μm for sp and 2.1 μm for sd. the ratiometric probe also revealed high selectivity towards sp and sd in the presence of amino acids and other biogenic amines. moreover, the rgb indices of the fluorescence response were extracted to build a two input - two output combinational logic gate for visual and simultaneous detection of sp and sd. the dual functional logic gate was easy to design and convenient to operate. finally, a portable sensor was fabricated for visual, rapid and on-site monitoring of meat spoilage.