Jump to Main Content
Polymer Vesicle Sensor for Visual and Sensitive Detection of SO2 in Water
- Huang, Tong, Hou, Zhilin, Xu, Qingsong, Huang, Lei, Li, Chuanlong, Zhou, Yongfeng
- Langmuir 2017 v.33 no.1 pp. 340-346
- acetates, adsorption, alcohols, bicarbonates, binding capacity, bromides, chlorides, detection limit, fluorides, nitrites, oxalates, paper, polymers, sulfates, sulfides, sulfites, sulfur dioxide, surfactants, thiocyanates, thiosulfates
- This study reports the first polymer vesicle sensor for the visual detection of SO₂ and its derivatives in water. A strong binding ability between tertiary alkanolamines and SO₂ has been used as the driving force for the detection by the graft of tertiary amine alcohol (TAA) groups onto an amphiphilic hyperbranched multiarm polymer, which can self-assemble into vesicles with enriched TAA groups on the surface. The polymer vesicles will undergo proton exchange with cresol red (CR) to produce CR-immobilized vesicles (CR@vesicles). Subsequently, through competitive binding with the TAA groups between CR and SO₂ or HSO₃–, the CR@vesicles (purple) can quickly change into SO₂@vesicles (colorless) with the release of protonated CR (yellow). Such a fast purple to yellow transition in the solution allows the visual detection of SO₂ or its derivatives in water by the naked eye. A visual test paper for SO₂ gas has also been demonstrated by the adsorption of CR@vesicles onto paper. Meanwhile, the detection limit of CR@vesicles for HSO₃– is approximately 25 nM, which is improved by approximately 30 times when compared with that of small molecule-based sensors with a similar structure (0.83 μM). Such an enhanced detection sensitivity should be related to the enrichment of TAA groups as well as the CR in CR@vesicles. In addition, the CR@vesicle sensors also show selectivity and specificity for the detection of SO₂ or HSO₃– among anions such as F–, Br–, Cl–, SO₄²–, NO₂–, C₂O₄²–, S₂O₃²–, SCN–, AcO–, SO₃²–, S²–, and HCO₃–.