Guanglin Feng

Preparation of molecularly imprinted polymers using theanine as dummy template and its application as SPE sorbent for the determination of eighteen amino acids in tobacco.

In this paper, a novel dummy template molecularly imprinted polymer (DMIP) based on a vinyl-SiO2 microspheres surface for the simultaneous selective recognition and enrichment of 18 amino acids was prepared via a surface molecular imprinting technique using theanine as a dummy template. Compared to the imprinted polymers prepared using traditional polymerization techniques, the obtained DMIPs exhibited a regular spherical shape and were relatively monodisperse. The maximal sorption capacity (Qmax) of the resulting DMIPs for the 18 amino acids was up to 1444.3 mg g(-1). A kinetic binding study showed that the sorption capacity reached 85.40% of Qmax in 25 min and sorption equilibrium at 30 min. The imprint factors of the sorbents ranged from 2.86 to 6.9 for the 18 amino acids, which indicated that the DMIP sorbents have high selectivity. An HPLC-UV method for the simultaneous determination of 18 amino acids in tobacco and tobacco smoke was developed using the DMIPs as sorbents for solid phase extraction (SPE) in the sample pretreatment procedure. Under the optimum experimental conditions, the materials had enrichment factors of up to 200 for the amino acids, and the recoveries of the 18 amino acids in tobacco smoke were in the range from 79% to 104% with relative standard deviations of less than 7.4%. It indicated that the obtained DMIP sorbents could specifically recognize the amino acids from complicated samples.

The interaction of a cobalt porphyrin with cancer-associated nitrosamines

A cobalt porphyrin (CY-B) was presented, and its interaction with tobacco-specific nitrosamines (TSNAs) was investigated by UV-Vis spectroscopy and high-resolution mass spectrometry. The results revealed that the stoichiometry of the host-guest interaction was 1:2 and that the binding constant between CY-B and TSNAs was within the range of 0.78×10(8)-7.83×10(8)M(-2). The coordination strength between CY-B and TSNAs decreased in the sequence of NNN>NAB>NAT>NNK based on the binding constant. The interaction mechanism of CY-B with TSNAs involved a coordination interaction, and the π-π interaction between the porphyrin macrocycle and the aromatic frame of the TSNAs pyridines may also have been a driving force. The measured thermodynamic properties demonstrated that the reaction of CY-B with TSNAs was spontaneous and that the driving force for the interaction was a change in enthalpy. The reaction was exothermic, and an increasing temperature inhibited the interaction. The IR spectrum of the complex revealed that the NNO group of TSNAs and the metal cobalt of CY-B formed the six-coordinate complex.

Gingko biloba extract and cobalt porphyrin additive to remove harmful components from cigarette smoke and reduce its toxicity

Cigarette filters were modified with a combination of gingko biloba extract and cobalt porphyrin (CGC) to remove harmful components from the cigarette smoke and reduce its toxicity. Smoke analysis results indicated that CGC eliminated up to 32% of benzo[a]pyrene (B[a]P), 52% of N-nitrosonornicotine (NNN), 46% of N-nitrosoanabasine (NAB), 35% of 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanone (NNK), 31% of N-nitrosoanatabine (NAT), 30% of gas-phase free radicals, and 33% of solid-phase free radicals. Biological experiments, including the Ames test, neutral red cytotoxicity assay and chronic toxicity, were conducted for both CGC cigarettes and control cigarettes. Results showed that the toxicity of the CGC cigarettes was lower than those of the control cigarettes. The mechanism by which the CGC components could remove harmful components from cigarette smoke is discussed.