Surface plasmon resonance (SPR) was used to screen the interaction between a variety of affinity ligands and hemagglutinin (HA) from human influenza virus, with the aim of identifying low affinity ligands useful for the development of a rapid bioanalytical sensor. Three sialic acid-based structures and four lectins were evaluated as sensor ligands. The sialic acid-based ligands included a natural sialic acid-containing glycoprotein, human α1-acid glycoprotein (α1-AGP), and two synthetic 6′-sialyllactose-conjugates, with varying degree of substitution. The interaction of HA with the four lectin-based ligands, concanavalin A (Con A), wheat germ agglutinin (WGA), Maackia amurensis lectin (MAL), and Sambucus nigra agglutinin (SNA), showed a wide variation of affinity strengths. Affinity and kinetics data were estimated. Strong affinities were observed for Con A, WGA, α1-AGP, and a 6′-sialyllactose-conjugate with a high substitution degree, and low affinities were observed for MAL and a 6′-sialyllactose-conjugate with low substitution.

The main objective, to identify a low affinity ligand which could be used for on-line monitoring and product quantification, was met by a 6′-sialyllactose–ovalbumin conjugate that had 0.6 mol ligand per mol carrier protein. The apparent affinity of this ligand was estimated to be 1.5 ± 0.03 μM (K_D) on the SPR surface. Vaccine process samples containing HA were analyzed in the range 10–100 μg HA mL⁻¹ and correlated with single-radial immunodiffusion. The coefficient of variation on the same chip was between 0.010 and 0.091.

Work with initial development towards in vitro toxicity assay for lactate dehydrogenase (LDH) using surface plasmon resonance is described. LDH is one of the important versatile biomarkers in in vitro hepatotoxicity. In this report LDH is detected by surface plasmon resonance using antibodies directly immobilized to the sensor surface. The assay is further extended with protein G immobilized to the surface to capture the antibody ligand. This has the advantage of simultaneously and on site purify and orient antibody ligand.

A surface plasmon resonance (SPR) sensor chip with immobilized protein G was used for simultaneously capturing, purifying and orienting antibody ligands. The ligands were further stabilized by chemical cross-linking. This procedure of designing the sensor chip improved efficient use of the ligands and could prolong the analytical use. less thanbrgreater than less thanbrgreater thanThe procedure was evaluated on standard dextran-coated sensor chips onto which commercial semi-purified antibodies towards human serum albumin and human troponin where captured and used for analysing their antigens. less thanbrgreater than less thanbrgreater thanThe procedure demonstrates a general design approach for presenting the biorecognition element on a biosensor surface which enhances sensitivity, stability and selectivity at the same time as an impure ligand is purified.