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Bead Injection Spectroscopy (BIS), is based on monitoring of the change of optical properties of translucent  beads during their interaction with biomolecules in solution. The measurement starts by injection  of  a microliter volume of beads ( such as Agarose or Sephadex ) into a flow through cell, where the beads  are captured and monitored, while the analyte solution is passed through. The accumulation of the analyte on the bead surfaces ( furnished with a bioligand ), is measured in real time by UV- VIS spectroscopy, or by fluorescence. This unique feature of BIS allows simultaneous monitoring of non-labeled and labeled biomolecules. Since the beads can be automatically discarded after each measurement, the sensing layer does not need to be regenerated, and since the fresh beads are supplied from a uniform batch the repeatability within a series of measurements is superb. Also, because  the beads used for BIS are identical with those used for affinity chromatography, they are available with a  wide range of bioligands already attached, including Protein A, Protein G, as well as avidin or lecitin.

 For the study of non-labeled biomolecules  BIS provides a superb alternative to Surface Plasmon Resonance because:

non-labeled biomolecules can be monitored by absorbance at 280nm, while labeled biomolecules can be used as internal standards and monitored simultaneously and independently by fluorescence or by absorbance

sensing layer does not need to be regenerated – it is discarded

the cost of assay is a minute fraction of a sensor “chip” used in SPR systems

Simultaneous  monitoring of labeled and non-labeled biomolecules offers advantages to immunoassays such as:

saturation assay,  since native and  fluorescence labeled molecules can be measured as they  compete for limited sites

epitope mapping and and ligand ranking carried out with native non-labeled molecules can be verified  by using labeled analogues.

ELISA since the capture of enzyme label can be measured by UV spectroscopy and verified during subsequent  reaction with substrate by fluorescence or absorbance measurement.

Please email or phone FIAlab Instruments for additional product information. Email: fialab@flowinjection.com, Voice: 425-376-0450 or 1-800-963-1101,  Fax: 425-376-0451

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