Investigation On The Interaction Of Protein With Surfactants Or Azobenzene-containing Copolymers

Protein, an important biological macromolecule in living organisms, is a critical research target in life sciences. It is an essential component of cells and can play many roles in the life activities of animals or plants. As the activity of a cell if dependent on one or several specific proteins, protein is the carrier of various biological functios and the specific performance of life activites. Investigations on the ineraction of proteins with amphiphilic surfactants are of immense importance for the detection of proteins or the improvement of the surfactants which are common components in our daily used goods. Azobenzene attached copolymers can self-assemble to form a variety of microstructures including micro-spheres, vesicles and azo moiety will undergo trans-cis isomerization, which can be regulated by photo-irradiation. Thus the study of the interaction between azo copolymer amd proteins will be helpful for drug delivery and site-specific drug release.In the present paper, various spectroscopic methods, including fluorescence spectra, UV-Vis spectra, FT-IR spectra, synsychros spectra, and fluorescence quenching techonique, resonance light scattering technique, TEM technique are we used to investigate the interaction of protein with amphiphilic surfactants or azobene-containing copolymers. The main contents of this paper are divided into three parts:1,The interaction between perfluorinated surfactant perfluorooctanesulfonic acid potassium salt (FC95) and bovine serum albumin (BSA) has been thoroughly investigated by UV-vis, FT-IR and fluorescence spectra. With the aid of two typical site markers- warfarin and ibuprofen, the binding sites are reported. Based on the enhanced resonance light scattering (RLS) signals, a new simple detection assay for BSA is then proposed with FC95 as probe. The optimal experimental conditions including pH values, ionic strength, FC95 concentration and effect of coexisting substances are discussed, respectively. Under the optimum conditions, a linear relationship are obtained and synthetic samples are analyzed by this assay.2,Amphiphilic azobene-attatched diblock copolymer (PAzoM26-b-PAA296) is synthesized by reversible addition-fragmentation transfers polymerization (RAFT) and the binding of this copolymer to bovine serum albumin (BSA) is investigated by TEM, UV-vis absorption spectra, spectrofluorimetry and synchronous fluorescence spectra techniques. The inherent binding information, such as the quenching mechanism, binding constants, number of binding sites, thermodynamic parameters and interaction driven forces, is presented by appling fluorescence quenching technique. The binding distance and energy transfer efficiency were obtained based on Forster non-radiation energy transfer theory. The copolymer can quench the fluorescence intensity of BSA by a dynamic quenching mechanism with complex formation and the main binding force is hydrophobic force. The interaction is spontaneous and entropy-driven. Energy may transfer from BSA to PAzoM26-b-PAA296 copolymer with high possibility.3,We have synthesized a new type amphiphilic diblock copolymer p(DMAEMA79-b-AZOM5) via RAFT polymerization technique and discussed the self-assemble behavior and potential application in drug delivery and site-specific drug release of this copolymer by TEM images. We have also studied its interaction with BSA by spectroscopic techniques. The inherent binding information is then revealed by using fluorescence quenching technique. With the aid of two typical site markers-ibuprofen and warfarinm the possible binding site is discussed. This copolymer primarily binds to Trp-214 tryptophan of BSA in the hydrophobic cavity named Sub-domainsⅡA (site I).