Jinn-Nan Lin

The influence of adsorption of native and modified antibodies on their activity.

Immobilization of biomolecules to solid phase materials has been widely used in many areas (e.g., purification, analytical chemistry, and catalysis). The interfacial properties of immobilized antibodies on pretreated silica and hydrogel surfaces were explored by comparing native and modified antibodies with respect to their surface activity. The antibody was modified by exposing it to a low pH solution prior to immobilization. Both physical adsorption and covalent immobilization methods were studied. It was found that the surface activity of the modified antibody is higher than that of the native antibody on two silica surfaces. The results of this study demonstrate that the adsorption properties of the antibodies play an important role in their covalent immobilization on certain types of solid supports.

Spatially resolved detection of antibody—antigen reaction on solid/liquid interface using total internal reflection excited antigen fluorescence and charge-coupled device detection

Spatially-resolved detection of antibody-antigen reactions at the solid/liquid interface was investigated by total internal reflection excited fluorescence from large area flat surfaces. Anti-HSA immunoglobulin G (IgG) antibody was immobilized at four spatially distinct spots. Binding of fluorescein-labeled human serum albumin (HSA) from the solution to immobilized antibody was detected by a cooled charge-coupled device (CCD) as a charge in the fluorescence intensity. A two-dimensional representation of the fluorescence was obtained during the binding reaction time of 25 mins. The contributions from bound and free antigen to the total signal were evaluated. The influence of the scattered excitation light and the normalization of fluorescence signal with respect to the two-dimensional incident light intensity distribution are discussed.

On-line sensors for coagulation proteins: concept and progress report

The assessment of blood damage and of the activation of the coagulation, complement and/or inflammatory systems by cardiovascular and extracorporeal devices is difficult at best. Immunoassay methods are now available for the measurement of many of the proteins, enzymes and peptides involved in coagulation, thrombosis, complement and inflammation. We present a long-range project and plan to develop an array of remote, on-line, semicontinuous immunosensors for selected coagulation proteins, based on fluoroimmunoassay principles. The free/bound separation step is performed optically. Excitation of fluorescence is performed via an evanescent wave produced by total internal reflection and waveguide optics. Fluorescence emission is collected only in the near field. Means to deliver fluorescently-labelled reagent and to modify the antigen-antibody binding constant are presented and discussed. The results of non-specific binding, plasma-blood fluorescence, and blood compatibility are also discussed.