The LiquiChip system is a bead-based platform that offers the potential to rapidly assay up to 100 different analytes in a single sample. A wide range of protein-based assays for proteomics and drug discovery research can be quickly and easily adapted to LiquiChip technology. The complete system includes instrumentation, software, a range of beads, and detection reagents.
| LiquiChip system components | |
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The LiquiChip Reader, Microplate Handler, and Fluid Module make up the LiquiChip workstation. |
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LiquiChip beads |
LiquiChip beads are used to immobilize capture molecules in LiquiChip assay procedures. LiquiChip
Ni-NTA beads — Immobilization of 6xHis-tagged proteins using
Ni-NTA technology |
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LiquiChip detection reagents are designed for simple and sensitive detection and quantification of bead-bound assay components. |
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LiquiChip accessories |
LiquiChip
Calibration And Control Beads – for calibration and validation of
the LiquiChip Reader |
LiquiChip assays are based on xMAP technology and involve the interaction of immobilized, bead-bound capture molecules with a reaction partner (analyte) in solution. A reporter molecule, specific for the analyte, is used to quantify the interaction.
The LiquiChip Assay Principle
Analytes free in solution interact with
bead-bound capture molecules and are detected using reporter molecules specific
for the analyte.
Different bead sets (see figure "Multiplex Assays — Liquid Assays"), each containing a defined mixture of two fluorescent dyes, are available. By coupling different capture molecules to different bead sets, multiplex assays can be performed.
Flexibility in Protein Immobilization
Multiplex Assays — "Liquid Arrays"
Multiplexing of LiquiChip assays. Bead sets with different color codes and capture molecules are added to an assay where they react with different analytes. The color code unique to each bead set allows the discrete quantification of each analyte in the LiquiChip Reader.
This multiplexing feature allows you to obtain a wealth of information using a minimum of sample. Multiplexing enables a comprehensive overview of complex biological systems, and the inclusion of in-process controls. In addition, sample volume requirements are reduced, and assay throughput is dramatically increased.
In the LiquiChip Reader, each reaction (bead set) is identified by its spectral signature after irradiation by the red classification laser. The attendant reporter signal from each reaction is simultaneously quantified by fluorescence generated by the green reporter laser.
Simultaneous Measurement of Classification and Reporter Fluorescence
Simultaneous detection of classification-code fluorescence (upper trace) and reporter fluorescence (lower trace). Only reporter fluorescence that is associated with a valid classification signal is recorded.
Virtually all types of protein-based interaction assay can be quickly and easily established using the LiquiChip System.
Using competitive assay techniques,
even unlabeled interaction partners can be screened by measuring the decrease of
signal.
Adaptable to a Wide Range of Assays
Assays that can be performed using the LiquiChip System.
Highly Sensitive Assays
Higher assay sensitivity using the LiquiChip System. Varying amounts of 6xHis-tagged thioredoxin were assayed using a conventional ELISA technique (blue squares) or were immobilized using LiquiChip Ni-NTA Beads and added to a LiquiChip assay (red squares). Detection was performed by measuring the OD 450 (ELISA) or by measuring the mean fluorescence intensity of an Alexa Fluor 532 reporter molecule (LiquiChip assay).
Multiplex ELISA Using the LiquiChip System
Titration of an antibody mixture into a multiplex ELISA. Three LiquiChip Ni-NTA Bead sets were coupled with 6xHis-tagged tumor necrosis factor-alpha (TNF-alpha); thioredoxin carrying a 6xHis tag at its N-terminus and the Tag·100 epitope at its C-terminus; and 6xHis-tagged thioredoxin (control) respectively. Protein-coupled beads were incubated with the indicated amount of biotinylated anti-TNF-alpha and Tag·100 Antibodies for 120 min. Streptavidin-R-PE was added to the sample, the reaction was incubated for a further 60 min, and protein-specific antibodies were detected using the LiquiChip Reader.
As reporter fluorescence is measured only in conjunction with classification fluorescence, signals from reporter molecules free in solution are not measured, allowing homogenous assays with no wash steps. The high signal-to-noise ratio enables highly sensitive protein assays.