Sum frequency generation studies on the surface structures of plasticized and unplasticized polyurethane in air and in water.

This study characterizes the molecular surface structures of polyurethane (PU) and plasticized PU films in air, in water, and in albumin solution in situ using a nonlinear optical technique, sum frequency generation (SFG) vibrational spectroscopy. Two different plasticizers are investigated: dioctyl sebacate (DOS) and o-nitrophenyl octyl ether (NPOE). Plasticization of PU is common for biosensors to achieve better adhesion, malleability, elasticity, and permeability; however, this can adversely affect biocompatibility.

Detection of amide I signals of interfacial proteins in situ using SFG.

In this Communication, we demonstrate the novel observation that it is feasible to collect amide signals from polymer/protein solution interfaces in situ using sum frequency generation (SFG) vibrational spectroscopy. Such SFG amide signals allow for acquisition of more detailed molecular level information of entire interfacial protein structures. Proteins investigated include bovine serum albumin, mussel protein mefp-2, factor XIIa, and ubiquitin.

Expression and identification of type 1 diabetes associated autoantigen IA-2.

Objectives: To obtain prokaryotic expressed IA-2 recombinant protein and to identify its immunological activity.

Methods: The complimentary DNA (cDNA) coding for the intracytoplasmic part of IA-2 (IA-2ic) was amplified from human fetal brain RNA, and was subcloned into the PinPoint Xa-1 T vector to construct recombinant expression plasmid, and was then expressed in E. coli JM109 cells as a fusion protein with a biotinylated peptide sequence at the aminoterminus.

The effect of surface coverage on conformation changes of bovine serum albumin molecules at the air-solution interface detected by sum frequency generation vibrational spectroscopy.

The air-BSA solution interface has been investigated by various techniques for years. From these studies we know that BSA molecules segregate at the BSA solution-air interface, and the surface coverage increases with the increase of the bulk solution concentration. However, questions still remain as to whether the protein changes conformation, orientation, or a combination of the two upon adsorption.

Molecular responses of proteins at different interfacial environments detected by sum frequency generation vibrational spectroscopy.

Sum frequency generation (SFG) vibrational spectroscopy has been applied to investigate molecular responses of bovine serum albumin (BSA) molecules adsorbed at different interfacial environments. Molecular level and in situ SFG studies demonstrate that albumin molecules have different adsorption behaviors when contact with fused silica, polystyrene, and poly(methyl methacrylate). Adsorbed albumin molecules exhibit different structural changes when exposed to different chemical environments, including air, water, and hydrophobic solvents.

Interaction of fibrinogen with surfaces of end-group-modified polyurethanes: a surface-specific sum-frequency-generation vibrational spectroscopy study.

Fibrinogen adsorption on polyurethanes with different surface-modifying end groups (SMEs) has been studied with sum-frequency-generation vibrational spectroscopy (SFG). The results show very different protein adsorption properties for different SMEs on the same backbone polymer. Fibrinogen binds weakly on the hydrophilic backbone of a poly(dimethyl siloxane) (PDMS)-modified polyurethane surface but leaves the hydrophobic PDMS part untouched.

Measuring polymer surface ordering differences in air and water by sum frequency generation vibrational spectroscopy.

Molecular structures of poly(n-butyl methacrylate) (PBMA) at the PBMA/air and PBMA/water interfaces have been studied by sum frequency generation (SFG) vibrational spectroscopy. PBMA surfaces in both air and water are dominated by the methyl groups of the ester side chains. The average orientation and orientation distribution of these methyl groups at the PBMA/air and PBMA/water interfaces are different, indicating that surface restructuring occurs when the PBMA sample contacts water.

Studies of polymer surfaces by sum frequency generation vibrational spectroscopy.

Recently, sum frequency generation (SFG) vibrational spectroscopy has been developed into a powerful technique to study surfaces of polymer materials. This review summarizes the significant achievements in understanding surface molecular chemical structures of polymer materials obtained by SFG. It reviews in situ detection at the molecular level of surface structures of some common polymers in air, surface segregation of small end groups, polymer surface restructuring in water, and step-wise changed polymer blend surfaces.