@article {YANG2020120885,
	title = {Characterization of interaction between Bcl-2 oncogene promoter I-Motif DNA and flavonoids using electrospray ionization mass spectrometry and pressure-assisted capillary electrophoresis frontal analysis},
	journal = {Talanta},
	year = {2020},
	pages = {120885},
	abstract = {B-cell lymphoma 2 (Bcl-2) is an antiapoptotic protein which is believed to be a triggering factor in developing human tumors. The Bcl-2 C-rich promoter element has been shown to form the i-motif (IM) via cytosine-cytosine (C{\textendash}C+) base pair building blocks, which can be targeted through the binding of ligands associated with Bcl-2 expression modulation. In this work, we monitored IM development and thermodynamic stability within the Bcl-2 promoter via circular dichroism (CD) spectroscopy and electrospray ionization mass spectrometry (ESI-MS). The results demonstrated that at an acidic pH, as well as in a crowded molecular environment, the Bcl-2 promoter element predominantly exists in a stable intramolecular IM folded state. We further explored the potential of targeting of the Bcl-2 IM to increase chemotherapeutic efficacy. We first used a rapid ESI-MS screening assay to identify possible ligands, finding that three natural flavonoids (P1, P5 and P6) exhibited a clear affinity for IM binding at 1:1 stoichiometry. Relative to P6, P1 and P5 were expected to form the more stable complexes with the Bcl-2 IM in gas phase according to MS/MS data. We further used ESI-MS and pressure-assisted capillary electrophoresis frontal analysis (PACE-FA) to assess the binding constants for these flavonoids in gas and liquid phases, respectively, with the latter considering both specific and non-specific binding. We found P5 and P6 to specifically bind the Bcl-2 IM with binding constants of \~{}104 M-1. P1 binding was confirmed to be due to both specific and nonspecific interactions, and the specific binding constant (8.67 {\texttimes} 103 M-1) was found much less significant than the binding constant in gas phase. Taken all these observations into consideration, the specific binding of selected flavonoids to the Bcl-2 IM may prove to be a potential ligand for modulating Bcl-2 gene expression.},
	keywords = {Bcl-2 oncogene, circular dichroism, Electrospray ionization mass spectrometry, Flavonoids, I-motif, Pressure-assisted capillary electrophoresis frontal analysis},
	issn = {0039-9140},
	doi = {https://doi.org/10.1016/j.talanta.2020.120885},
	url = {http://www.sciencedirect.com/science/article/pii/S0039914020301764},
	author = {Yang Yang and Hengqing Fu and Cheng Qian and Huihui Li and David D.Y. Chen}
}
@article {Fan201763,
	title = {Co-solvent enhanced adsorption with magnetic velvet-like carbon nitride for high efficiency solid phase extraction},
	journal = {Analytica Chimica Acta},
	volume = {960},
	year = {2017},
	pages = {63 - 71},
	abstract = {Abstract Magnetic velvet-like graphitic carbon nitride (V-g-C3N4/Fe3O4) was used for rapid 1~min extraction of flavonoids from different tea extracts by co-solvent enhanced adsorptive magnetic solid phase extraction. The nanocomposite can interact with flavonoids, in which Fe3O4 provide hydrogen bond and V-g-C3N4 has hydrophobic and π-π interaction to promote adsorption. The enhanced adsorptive magnetic solid phase extraction method is developed with the addition of a co-solvent (water) to dramatically change the solvent environment, which enhanced the speed of movement of target compounds from the solvent to the sorbent and increase the adsorption capacity. The synergistic effects improved the extraction rate of flavonoids with excellent reproducibility (88.2{\textendash}107.2\%), sensitivity (limits of detection (S/N~=~3): 0.075{\textendash}0.1~μg/mL) and recoveries (88.2{\textendash}107.2\%). This study demonstrated the potential to apply this method for various target analytes from complex sample matrices.},
	keywords = {Flavonoids},
	issn = {0003-2670},
	doi = {http://dx.doi.org/10.1016/j.aca.2017.01.020},
	url = {http://www.sciencedirect.com/science/article/pii/S0003267017300995},
	author = {Shanshan Fan and Jun Zhu and Lixuan Ren and Man Wang and Wentao Bi and Huihui Li and Xiaohua Huang and David Da Yong Chen}
}
