Modified Poly (3-Hydroxybutyrate-Co-4-by Droxybutyrate) Surface And Its Interaction With Protein

The biomedical material’s interaction is very complicated with protein, cells and tissues.And the foundational interaction is between biomedical materials and protein. Variousmaterials have different ways to interacte with proteins. Polyhydroxyalkanoates [P(3HB-4HB)] is novel bio-degradation polymer synthesized by microorganisms. Theapplication in medical clinical field of this polymer is limited because of its hydrophobicityand chemical inertness. Therefore, it is necessary to do surface modification and study theinteraction between protein and P (3HB-4HB) which has different electro polar. The resultwould provide theoretical basis in modification, enhance the application ofpolyhydroxyalkanoates.Different surfaces of P (3HB-4HB) films were prepared using NH3plasma and O2plasma separately. The numbers of electrical quantities on the surfaces of films were adjustedby changing the conditions of plasma modification. The interactions between material surface(before and after modification) and amino acid and/or protein were studied by quartz crystalmicrobalances with dissipation (QCM-D), solid surface zeta potential analyser (SurPass) andatomic force microscopy (AFM).Our results indicated that the surface modifications were successful. The aminated P(3HB-4HB) films with-NH-CO-、-C-N and-NH3+on the surface and carboxylated films with-C-O-、-COOH and-COOR on the surface were prepared. The hydrophilicity of those filmssurfaces were improved due to introduced polar functional groups. Because of plasma etching,the surface toughness of films were changed. The zeta potential of surfaces increased as basicfunctional groups, the more basic functional groups the higher zeta potential and isoelectricpoint. While introducing acidic functional groups the zeta potential of modified filmsdecreased, the more acidic functional groups the lower zeta potential. Isoelectric points ofcarboxylated films were not shown in the test coverage.The interaction between BSA and modified films surface was studied by QCM-D, theadsorption quantity, viscoelastic property, and desorption rate were analyzed especially. Theresults showed that in PBS, aminated films had low adsorption quantites and the modulus ofshearing drceased with the decrease of dgree of modification, but desorption rate increasedwith the increase of dgree of modification. In deionized water, the BSA adsorption quantites of carboxylated films was as twice as many with the un-modified films, and the adsorptionwas irreversible.Generally, the both positive and negative polar functional groups can improve P(3HB-4HB) films surface hydrophilic; the adsorption quantities of BSA on the surfaces of P(3HB-4HB) films with some positive charges decreased, while the adsorption quantities ofBSA on the ones with negative charges increased, which have good anticoagulationhemorrhagic.