Kelly J. Cassutt, Ph.D., application scientist at Hamamatsu (www.hamamatsu.com), says the FDSS6000 imaging-based plate reader is "an evolution not a revolution." It multiplexes both calcium mobilization and membrane potential cell-based assays on a 96- or 384-well plate, generating two results from the same cells.
Furthermore, two different cell lines can be dye-loaded with different fluorescent calcium detection dyes and combined to generate two independent results in the same well. Additional multiplexing assays with other dyes are in development.
For cell-based imaging, Cellomics (www.cellomics.com) offers high-content screening through its family of automated imaging systems, which includes the ArrayScan VTI HCS Reader, KineticScan HCS Reader, and cellWoRx High Content Cell Analysis System. The systems provide a complete picture of the cell for image-based analysis, with tens to hundreds of parameters for each cell, the company says.
Recently, Cellomics incorporated live cell imaging to its ArrayScan VTI HCS Reader. It also is launching high-content screening kits and expects to expand its portfolio of validated reagent kits during the next two years.
This month, Promega(www.promega.com) launches its cell viability assay, MultiTox, to simultaneously assay live and dead cells in culture in the same well. According to Pam Guthmiller, strategic marketing manager, users add one reagent directly to the wells, simplifying what otherwise is a multistep process.
"Other assays, like luminescent genetic reporter or caspase assay, can be multiplexed with this reagent," she says. In pharma, it would be used to screen compounds and provide a confirmatory, secondary assay, reducing cell culture costs and compound use.
Recent advances in nucleic acid lateral flow (NALF) multiplexing for PCR and other amplification technologies are making it "a serious contender in the future nucleic acid test market," according to Joanna Seal, Ph.D., senior project leader, nucleic acid division, BBInternational (www.britishbiocell.co.uk).
"Multiplexed NALF involves oligonucleotide probes and gold nanoparticle conjugation technology to simultaneously detect as little as one femtomole of each PCR amplicon in a single reaction," Dr. Seal says. Results can be visually interpreted by unskilled operators. Simple prototypes can detect up to seven targets. Using a bi-directional housing with two longer test strips can theoretically detect up to 25 targets. Commercialization is expected by 2007.
Another U.K. company SmartBead Technologies Limited (www.smartbead.com) attaches five-digit barcoded microparticles to biomolecules for a total of 99,999 unique codes.
As Chris Savory, director of sales and marketing, elaborates, "The UltraPlex barcoded microparticles have biomolecules, typically antigens or antibodies, attached to them, one biomolecule type per unique barcode. These are supplied in a lyophilized multiplexed kit format and the user incubates the microparticles with a sample. Reacting biomolecules attach to the microparticles. The reaction is incubated with a fluorescent reporter molecule, and the results of the assay are determined using our proprietary reader, which identifies each barcode and measures the amount of fluorescence associated with it."
By reading both the barcode and fluorescence, particle identification is permanent and not subject to photo-bleaching, thus eliminating reading errors. And, Savory says, because they are lyophilized in an accusphere format, pipetting of different bead types is eliminated before running an assay, and shelf-life, stability, and antigen binding are enhanced.
Also, SmartBead is developing a biological fingerprinting solution, based on advanced pattern recognition that will lead to megaplex assays, Savory GE Healthcare (www.gehealthcare.com) are focused bioarrays in flexible multiassay array formats, according to Hrissi Samartzidou, Ph.D., global marketing manager, gene expression. The first of GE’s catalog line of multiplexed arrays, a 16-assay panel for inflammation, is being introduced this month.
New CodeLink software is also being released this month, with normalization algorithms optimized for mid-to-low density arrays and an online tool, CodeLink iCenter, with all the information relevant to CodeLink products.
Earlier this year, Promega introduced its HaloTag technology for cell imaging and protein analysis, Guthmiller says. "A gene of interest can be placed next to the HaloTag gene, expressed as a protein fusion partner, and tracked with a multitude of ligands labeled with different fluorescent moieties and multiplexed with antibodies in live or fixed-cell imaging applications," she says. It also can be used in immobilization applications or protein-to-protein array applications using bead- or slide-based arrays.
Biacore (www.biacore.com) relies on surface plasmon resonance (SPR) for its label-free protein-interaction analysis systems, Biacore A100 and Flexchip. Biacore A100 offers a greater degree of system automation and can analyze up to 3,800 interactions in 24 hours, according to the company. It is used for protein-interaction analysis in processes demanding higher throughput, including discovery and development for small molecule drugs.
Flexchip is used for rapid screening, ranking, and profiling of large numbers of interactions and "is used for proteomics and early-stage candidate selection in biotherapeutic development," according to the company. Both systems provide such interaction information as kinetic rate constants and affinity constants.