Xin Yu Deng,Kai Chen,Ming-Dong Chen,Li Bin Lü,Zhu Tao
Graphical The probe responds to Cs + cations in alkali metal systems, Ba 2+ and Sr 2+ cations in alkaline earth metal systems; Eu 3+ , Tm 3+ , and Yb 3+ cations in lanthanide systems, and Cr 3+ , Fe 3+ , and Hg 2+ cations in systems containing transition and other metal cations, by obvious fluorescence quenching. Based on the study of a known host–guest inclusion complex comprising cucurbit[6]uril (Q[6]) and a hemicyanine dye, trans -4-[4-(dimethylamino)styryl]-1-pyridinium iodide ( t -DSMI), a water-soluble symmetric tetramethylcucurbit[6]uril (TMeQ[6]), was selected to construct a t -DSMI-based probe to test the response to various metal cations in neutral water. The experimental results revealed that the probe responded to Cs + cations in alkali metal systems, Ba 2+ and Sr 2+ cations in alkaline earth metal systems, Eu 3+ , Tm 3+ and Yb 3+ cations in lanthanide systems, and Cr 3+ , Fe 3+ and Hg 2+ cations in systems containing transition and other metal cations, via obvious fluorescence quenching.
A novel strategy for cytochrome c selective recognition assisted with cucurbit[6]uril by host-guest interaction via N-terminal epitope imprinting and reversible addition-fragmentation chain transfer (RAFT) polymerization was developed. N-terminal nonapeptide of cytochrome c (GI-9) was used as the epitope template to achieve highly selective recognition of cytochrome c . As a common supramolecule in recent years, cucurbit[6]uril can encapsulate the butyrammonium group of lysine residue to capture the peptide and improve the corresponding spatial orientation by the host-guest interaction for GI-9 or cytochrome c recognition. After cucurbit[6]uril modification and epitope immobilization, the imprinted polymer was synthesized by RAFT polymerization with 2-dodecylsulfanylcarbothioylsulfanyl-2-methylpropanoic acid as chain transfer agent. After template removal, the obtained imprinted particles showed good binding ability to GI-9 (20.28 mg g −1 , IF = 4.11) and cytochrome c (36.12 mg g −1 , IF = 3.91). With the successive addition of cucurbit[6]uril and RAFT agent, the step-by-step improvement of the IF for cytochrome c recognition further illustrated the effects of supramolecular host-guest interaction and regulation of imprinted polymer chain. The imprinted polymers showed obvious advantages for cytochrome c recognition compared to competitive proteins and had good reusability with the repeated reproduction rate 80.8 % after five cycles of adsorption and desorption. Furthermore, the selective recognition for cytochrome c in adult bovine serum proved its potentiality to be applied in practical samples. All these results demonstrated that the combination of epitope imprinting, cucurbit[6]uril host-guest interaction and RAFT strategy presented an efficient new feasible control method for protein recognition with good selectivity, stability and reusability.
Ye Meng,Weiwei Zhao,Jun Zheng,Daofa Jiang,Jie Gao,Yanmei Jin,Peihua Ma
Since the first reportal on decamethylcucurbit[5]uril (Me10Q[5]) in 1992, substituted cucurbit[n]urils have attracted considerable research interest. In this study, the host–guest modes between the tetramethyl cucurbit[6]uril (TMeQ[6]) as a host and 4-chloroaniline and 4,4′-diaminostilbene (G1 and G2) as guests were investigated by single-crystal X-ray diffraction, NMR, ITC, UV-Vis spectrum, and MALDI-TOF mass spectrometry analyses. The experimental results showed that TMeQ[6] formed a 1 : 1 inclusion compound with G1, and the carbonyl portal of TMeQ[6] formed a 1 : 1 self-assembly with G2. Further, multi-dimensional supramolecular frameworks were formed driven by weak interaction forces in the system (hydrogen bonding, C–H⋯π interactions, ion–dipole interactions, and dipole–dipole interactions).
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