A novel assay for influenza virus quantification using surface plasmon resonance.

Quantification of hemagglutinin (HA) by single-radial immuno diffusion (SRID) is the predominant method to ensure product potency in seasonal influenza vaccines. Here a new method for quantification of influenza virus using biosensor technology is presented. The method employs quantification of virus via an inhibition assay format using HA proteins for H1N1, H3N2 and B immobilized on a sensor chip. Initial results showed the assay to have higher sensitivity (detection range 0.5-10 microg/ml), higher precision and significantly lower analysis and hands on time compared with SRID.

Predicting the intestinal absorption potential of hits and leads.

Today's pharma environment requires rapid and reliable methods of screening drug leads for intestinal permeability potential in the early stages of drug discovery. Techniques using excised tissues, Caco-2 cells, artificial membranes, 'in silico' techniques and surface plasmon resonance (SPR)-based biosensors are critically examined in terms of their reliability, measurement criteria, throughput and utility in identifying potentially successful or unsuccessful drug molecules.:

Biosensor analysis of the interaction between immobilized human serum albumin and drug compounds for prediction of human serum albumin binding levels.

The interactions between a set of drugs, selected on the basis of reported human serum albumin (HSA) binding levels, and immobilized HSA were investigated using surface plasmon resonance technology. Major HSA binding sites were available after immobilization. The intensity of the signal obtained from the interaction of the drug with the HSA surface was correlated with the reported HSA binding level. Drugs were classified into groups corresponding to high, medium, or low HSA binding based on the injection of the drug at 80 microM concentration. A set of 10 drugs binding to alpha(1)-acid glycoprotein (AGP) was also investigated and correlated with reported AGP binding data. The throughput of the presented assay is 100 compounds/24 h, and the sample consumption is less than 100 microL (8 nmol).

Lactose repressor-operator DNA interactions: kinetic analysis by a surface plasmon resonance biosensor.

Lactose repressor binding to operator DNA and subsequent dissociation of the complex was monitored continuously by a biosensor, measuring surface plasmon resonance. In this analysis a synthetic, double-stranded oligonucleotide containing the operator site was immobilized on the sensor surface and repressor protein was passed over the surface. The formation of the repressor-operator complex was specific and could be inhibited by isopropyl-beta-D-thiogalactopyranoside inducer. From the association curve, the apparent kass was determined to be 1.8 x 10(6) M-1 s-1. Dissociation of the complex was, for the first time for the lac repressor, determined as an uncatalyzed reaction and the kdiss was determined to be 3.4 x 10(-4) s-1. As a reference, the repressor-operator interaction was analyzed by electrophoretic mobility shift assay under similar reaction conditions. With this method the equilibrium binding constant was calculated to be 2.4 (+/- 0.2) x 10(8) M-1. The corresponding value calculated from biosensor data was 5.1 x 10(9) M-1.

Biospecific interaction analysis using surface plasmon resonance detection applied to kinetic, binding site and concentration analysis.

A system for real-time biospecific interaction analysis using biosensor technology based on the optical phenomenon surface plasmon resonance is described. The biospecific interface is a sensor chip covered with a hydrogel matrix. One component of the interaction to be studied is immobilized covalently to the hydrogel and other interactants are passed over the chip in solution. The mass change at the sensor surface, reflecting the progress of the interaction studied, is monitored in real time. The technique, which does not require molecular labels for detection, can measure mass changes down to 10 pg/mm2. Repeated analyses can be performed on the same sensor chip. Applications shown include kinetic measurements, binding site analysis and concentration determination.