title: Nanosilica-based molecularly imprinted polymer nanoshell for specific recognition and determination of rhodamine B in red wine and beverages.
abstract: A new and facile rhodamine B (RhB)-imprinted polymer nanoshell coating for SiO2 nanoparticles was readily prepared by a combination of silica gel modification and molecular surface imprinting. The RhB-imprinted polymers (RhB-MIPs) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and UV-vis spectroscopy; the binding properties and selectivity of these MIPs were investigated in detail. The uniformly imprinted nanoparticles displayed a rather thin shell thickness (23nm) with highly effective recognition sites, showing homogenous distribution and monolayer adsorption. The maximum MIP adsorption capacity (Qm) was as high as 45.2mgg(-1), with an adsorption equilibrium time of about 15min at ambient temperature. Dynamic rebinding experiments showed that chemical adsorption is crucial for RhB binding to RhB-MIPs. The adsorption isotherm for RhB-MIPs binding could also be described by the Langmuir equation at different temperatures and pH values. Increasing temperature led to an enhanced Qm, a decreased dissociation constant (K'd), and a more negative free energy (ΔG), indicating that adsorption is favored at higher temperatures. Moreover, the adsorption capacity of RhB was remarkably affected by pH. At pH>7, the adsorption of RhB was driven by hydrogen bonding interactions, while at pH<7 electrostatic forces were dominant. Additionally, the MIPs also showed specific recognition of RhB from the standard mixture solution containing five structurally analogs. This method was also successfully employed to determine RhB content in red wine and beverages using three levels of spiking, with recoveries in the range of 91.6-93.1% and relative standard deviations lower than 4.1%.
authors.affiliation: Xinjiang Uygur Autonomous Region Product Quality Supervision and Inspection Institute, Urumqi, PR China. Electronic address: long8326rong@163.com.
authors.forename: Zerong
authors.initials: Z
authors.lastname: Long
authors.affiliation: Key Laboratory of Oil and Gas Fine Chemicals, Ministry of Education, Xinjiang University, Urumqi, PR China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Xu
authors.affiliation: Xinjiang Uygur Autonomous Region Product Quality Supervision and Inspection Institute, Urumqi, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou, PR China. Electronic address: hdqiu@licp.cas.cn.
authors.forename: Hongdeng
authors.initials: H
authors.lastname: Qiu
mesh_terms: D000327:Adsorption; D002253:Carbonated Beverages / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D057230:Limit of Detection; D054802:Molecular Imprinting / Q000379:methods*; D057145:Nanoshells / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D012235:Rhodamines / Q000032:analysis / Q000302:isolation & purification*; D012822:Silicon Dioxide / Q000737:chemistry; D052616:Solid Phase Extraction / Q000379:methods*; D013816:Thermodynamics; D014920:Wine / Q000032:analysis*
chemical_list: D011108:Polymers; D012235:Rhodamines; D012822:Silicon Dioxide; C029773:rhodamine B
keywords: Rhodamine B; Silica nanoparticle; Solid-phase extraction; Surface imprinting