Jingyao Qi

Synthesis of core-shell magnetic molecular imprinted polymer by the surface RAFT polymerization for the fast and selective removal of endocrine disrupting chemicals from aqueous solutions.

In this study, we present a general protocol for the making of surface-imprinted core-shell magnetic beads via reversible addition-fragmentation chain transfer (RAFT) polymerization using RAFT agent functionalized iron oxide nanoparticles as the chain transfer agent. The resulting composites were characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) analysis, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface-imprinted magnetic beads were demonstrated with a homogeneous polymer films (thickness of about 22 nm), spherical shape, and exhibited magnetic property (Ms = 0.41 mA m2 g(-1)) and thermal stability. Rebinding experiments were carried out to determine the specific binding capacity and selective recognition. The as-synthesized surface-imprinted core-shell magnetic beads showed outstanding affinity and selectivity towards bisphenol A over structurally related compounds, and easily reach the magnetic separation under an external magnetic field. In addition, the resulting composites reusability without obviously deterioration in performance was demonstrated at least five repeated cycles.

Density functional theory calculations and molecular dynamics simulations of the adsorption of biomolecules on graphene surfaces.

There is increasing attention in the unique biological and medical properties of graphene, and it is expected that biomaterials incorporating graphene will be developed for the graphene-based drug delivery systems and biomedical devices. Despite the importance of biomolecules-graphene interactions, a detailed understanding of the adsorption mechanism and features of biomolecules onto the surfaces of graphene is lacking. To address this, we have performed density functional theory (DFT) and molecular dynamics (MD) methods exploring the adsorption geometries, adsorption energies, electronic band structures, adsorption isotherms, and adsorption dynamics of l-leucine (model biomolecule)/graphene composite system. DFT calculations confirmed the energetic stability of adsorption model and revealed that electronic structure of graphene can be controlled by the adsorption direction of l-leucine. MD simulations further investigate the potential energy and van der Waals energy for the interaction processes of l-leucine/graphene system at different temperatures and pressures. We find that the van der Waals interaction between the l-leucine and the graphene play a dominant role in the adsorption process under a certain range of temperature and pressure, and the l-leucine molecule could be adsorbed onto graphene spontaneously in aqueous solution.

Selective recognition and removal of chlorophenols from aqueous solution using molecularly imprinted polymer prepared by reversible addition-fragmentation chain transfer polymerization

Molecularly imprinted polymer (MIP) for selective recognition and removal of chlorophenols from contaminated water was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization using RAFT agent functionalized silica gel as the chain transfer agent. The prepared MIP nano-film hybrid silica gel (silica-MIP) was characterized using Fourier transform infrared spectrometer (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and BET adsorption isotherm analysis. The proper adsorption and selective recognition ability of the silica-MIP were studied by an equilibrium-adsorption method. The resulting silica-MIP showed outstanding affinity towards 2,4-dichlorophenol (2,4-DCP) in aqueous solution. The silica-MIP bind the original template 2,4-DCP with an appreciable selectivity over structurally related compounds, and the molecular recognition of 2,4-DCP was analyzed in detail.

Selective recognition of veterinary drugs residues by artificial antibodies designed using a computational approach

In this work we introduce a simple and inexpensive veterinary drugs residues detection method. Molecular dynamics simulations and computational screening were used to identify functional monomers capable of interacting with sulfadimidine (SM2). A library of 15 kinds of common functional monomers for preparing molecular imprinted polymer (MIP) was built and their interactions with SM2 in acetonitrile were calculated using the molecular dynamics software (GROMACS 3.3). According to the theoretical calculation results, the surface molecularly imprinted silica (MIP-silica) with SM2 as template was prepared by surface-imprinting technique using methacrylic acid (MAA) as functional monomer and divinylbenzene as cross-linker in acetonitrile. The surface composition of the MIP-silica was determined by Fourier transform infrared spectrometer (FT-IR) and energy dispersive X-ray spectrometer (EDS). Scanning electron microscopy (SEM) was used to characterize the morphological properties of the MIP-silica. The synthesized MIP-silica was then tested by equilibrium-adsorption method, and the MIP-silica demonstrated high binding specificity to the SM2. The molecular recognition of SM2 was analyzed in detail by using molecular modeling software (Gaussian 03).

Selective removal of 2,4-dichlorophenol from contaminated water using non-covalent imprinted microspheres.

A molecularly imprinted polymer (MIP) for selective removal of 2,4-dichlorophenol (2,4-DCP) in water was prepared as microspheres by the reverse microemulsion polymerization method based on the non-covalent interactions between 2,4-DCP, oleic acid, and divinylbenzene in acetonitrile. Microspheres have been characterized by Fourier transform infrared spectrometer (FTIR) and energy dispersive X-ray spectrometer (EDS) studies with evidence of 2,4-DCP linkage in polymer particles and scanning electron microscopy (SEM) to study their morphological properties. The proper adsorption and selective recognition ability of the MIP were studied by an equilibrium-adsorption method. The MIP showed outstanding affinity towards 2,4-DCP in aqueous solution and the optimum pH value for binding has been found around the neutral range. The molecular recognition of 2,4-DCP was analyzed in detail by using molecular modeling software. In addition, by investigating the variation in the adsorption ability of the MIP, it clearly showed excellent reproducibility.

Preparation of core-shell molecularly imprinted polymer via the combination of reversible addition-fragmentation chain transfer polymerization and click reaction

In this paper, we demonstrated an efficient and robust route to the preparation of well-defined molecularly imprinted polymer based on reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. The alkyne terminated RAFT chain transfer agent was first synthesized, and then click reaction was used to graft RAFT agent onto the surface of silica particles which was modified by azide. Finally, imprinted thin film was prepared in the presence of 2,4-dichlorophenol as the template. The imprinted beads were demonstrated with a homogeneous polymer films (thickness of about 2.27 nm), and exhibited thermal stability under 255°C. The as-synthesized product showed obvious molecular imprinting effects towards the template, fast template rebinding kinetics and an appreciable selectivity over structurally related compounds.

Hydrothermal synthesis of CdS microparticles–graphene hybrid and its optical properties

A reduced graphene oxide–CdS microparticles (RGO–CdS) hybrid was prepared through a one-pot hydrothermal method in which graphene oxide (GO) served as the support and cadmium chloride as the starting material. GO was reduced to RGO during a hydrothermal reaction. The morphology, structure characterization, and crystal structure of the as-prepared hybrid were performed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. It was shown that in the composite, the CdS microparticles were dispersed uniformly in the RGO sheet, and the addition of GO did not influence the crystal structure of the hexagonal phase CdS. The as-prepared RGO–CdS hybrid shows efficient fluorescent features due to the size effect of the CdS microparticles. By combining the unique properties of RGO and CdS microparticles, the strategy presented in this study is expected to be useful to prepare highly efficient graphene-based hybrids for potential applications in various fields.

Preparation and theoretical study of functionalized single-wall carbon nanotubes used for water treatment

Single-wall carbon nanotubes (SWCNTs) were modified by chemical method and were employed as adsorbents to study adsorption of Cu2+ from water. The experiments demonstrated that the short time needed to reach equilibrium as well as the high adsorption capacity of Cu2+. The electronic and structural properties of Cu2+-SWNTs system was investigated by using density functional theory calculations, and the binding energies and the charge transfers between the Cu2+ and the tube are calculated and compared. It is found that that the Cu2+ attracted to the CNT surface in an effective physisorption way, which is important for wiping off the heavy metal ions in the water. It is suggesting that both SWCNTs and functionalized SWCNTs are efficient heavy metals sorbents and that they possess good potential applications in water treatment.