Novel Dual-Emission Carbonized Polymer Dot-Based Ratiometric Fluorescence Probe for the Sensitive Detection of...

Tertiary butylhydroquinone (TBHQ), one of the most common antioxidants in many foods, has attracted widespread attention due to its potential risk to human health. In this work, an "on-off-on" ratiometric fluorescent probe was prepared using dual-emission carbonized polymer dots (d-CPDs), which can be used to detect TBHQ in edible oils. The ratiometric fluorescent sensing system consisted of blue fluorescent CPDs (b-CPDs) as the response signal and yellow fluorescent CPDs (y-CPDs) as the internal reference material. The blue fluorescence of b-CPDs was gradually quenched with increasing Fe³⁺ ion concentration, while the yellow fluorescence was essentially unaffected. Interestingly, TBHQ can restore the fluorescence intensity of b-CPDs. Meanwhile, the fluorescence mechanism of Fe³⁺ on b-CPDs was investigated by density functional theory, both after the addition of TBHQ, and CPDs were released and their fluorescence was restored due to the competitive reaction of TBHQ-Fe³⁺. Thus, the d-CPDs probe was able to detect Fe³⁺ accurately in an "on-off" manner and thus TBHQ in an "off-on" manner. At an optimal Fe³⁺ concentration, the ratiometric sensing system provided fine linearities for determining TBHQ in the range from 0.2 to 2 μM and an ingenious detection limit of 0.052 μM. The CPDs ratiometric fluorescent probe designed in this work may have a broader application in the rapid, susceptive, and low-cost determination of TBHQ in various foods.