Hai-Dong Wang

A Thermoresponsive Membrane for Chiral Resolution

In this chapter, the design, fabrication and performance of thermo-responsive membranes for chiral resolution with a high performance are introduced. The membrane is designed with both chiral selectivity based on molecular recognition of beta-cyclodextrin (β-CD) and thermo-sensitivity based on phase transition of PNIPAM. Linear PNIPAM chains are grafted onto porous Nylon6 membrane substrates by using the plasma-graft pore-filling polymerization method, acting as micro-environmental adjustors for β-CD molecules. β-CD moieties are introduced into the linear PNIPAM chains by the chemical grafting polymerization method, acting as chiral selectors. The phase transition of grafted PNIPAM chains affects the micro-environment of β-CD molecules and then the association between β-CD and guest molecules. The chiral selectivity of the prepared thermo-responsive membranes in chiral resolution operated at a temperature below the LCST of PNIPAM is higher than that of membranes with no thermo-sensitivity, while the decomplexation ratio of enantiomer-loaded thermo-responsive membranes in decomplexation operated at a temperature above the LCST is much higher than that of membranes with no thermo-sensitivity. By simply changing the operating temperature, high selective chiral resolution and efficient membrane regeneration can be achieved.

Study on protein conformation and adsorption behaviors in nanodiamond particle–protein complexes

In the present research, the conformation of bovine serum albumin (BSA) in the nanodiamond particle (ND)-BSA complex was studied by Fourier transform infrared spectroscopy, fluorescence spectroscopy, UV-vis spectroscopy, and circular dichroism spectroscopy. The spectroscopic study revealed that most BSA structural features could be preserved in the complex though the BSA underwent conformational changes in the complex due to ND-BSA interaction. In addition, BSA adsorption isotherms and zeta-potential measurements were employed to investigate the pH dependence of the ND-BSA interaction. The changes in surface charge of the ND-BSA complex with pH variations indicated that the binding of BSA to ND might lead to not only the adsorption of BSA onto the ND surface but also the partial breakup of ND aggregates into relatively small ND-BSA aggregates because of the strong binding force between ND and BSA. The results show that ND is an excellent platform for protein immobilization with high affinity and holds great potential to be used for biosensor applications.