What's new in assay technology?

The latest assay technologies are designed for speed, reliability and accuracy. Sean Ottewell highlights the best new entrants to the market.

Labcyte, the developer of acoustic liquid handling, and QIAGEN, a leading global provider of sample and assay technologies, have announced that QIAGEN FlexiPlate siRNA reagent libraries are now available in Labcyte Echo qualified microplates. These microplates enable researchers to use the Echo liquid handler to miniaturise the transfer of small interfering RNA (siRNA) reagents.

The Echo liquid handler uses acoustic energy to move fluids without physical contact or the possibility of cross-contamination. There are no pipette tips, pin tools or nozzles involved, which provides unsurpassed precision and accuracy while reducing volume.

The advantages afforded by the Echo liquid handler include applications in drug discovery, cell-based analyses, sample management, and assay miniaturisation.

"Our Echo platforms have revolutionised liquid handling," said Mark Fischer-Colbrie, ceo and president of Labcyte. "Researchers can now transfer significantly smaller volumes while maintaining excellence in precision and accuracy. The reduction in assay volumes and elimination of disposable tips dramatically reduces cost. Data show that siRNA screening at reduced volume is superior or equal to results obtained with traditional liquid handlers."

"As the first provider to offer flexible and targeted siRNA sets worldwide, QIAGEN is pleased that we have the opportunity to combine our FlexiPlate siRNA concept with Labcyte Echo qualified plates, which minimises volumes and reduces the risk of contamination during reagent transfer," says Jörg Dennig, global product manager RNAi at QIAGEN. "Our siRNAs are provided in highly flexible formats and scales with an unlimited possibility to arrange targeted siRNA libraries according to the researchers' needs, and with easy access via our GeneGlobe website."

"Providing siRNA libraries in acoustically compatible microplates makes it much easier to consider high-throughput, miniaturised siRNA screening," said Anthony Davies of the Institute of Molecular Medicine, Dublin University, Ireland.

"Echo liquid handlers have already had a significant impact on drug discovery efforts in the pharmaceutical industry. Our technology is now poised to bring similar advances across a wide range of genomic and cell-based applications," added Fischer-Colbrie. "We are pleased to work with QIAGEN in this effort."

New from BellBrook Labs is an HTS assay for screening the regulators of G-protein signalling (RGS) proteins that influence signalling of G protein-coupled receptors (GPCRs), an important class of proteins for the treatment of multiple diseases, such as cancer, cardiovascular disease, inflammation, and CNS disorders.

Offered as an assay development service, the RGScreen assay service opens up new therapeutic strategies for modulating GPCR pathways, including the potential to fine-tune the effects of existing GPCR ligands.

Though these proteins have been the focus of intense investigation as potential drug targets, the lack of suitable HTS assay methods has prevented large scale screening efforts. BellBrook overcame this technical hurdle by developing proprietary G variant proteins that enable direct detection of RGS catalytic activity using its Transcreener HTS assay platform.

The discovery of RGS proteins and their ability to attenuate GPCR signals opened up a new avenue for modulating the activity of GPCR ligands. The exploitation of this opportunity requires robust HTS assay methods. The most direct way to detect RGS function is by measuring the increased GTPase activity of the associated G protein. However, GTPase activity of isolated G proteins is limited by GDP dissociation, so RGS GAP activity cannot be measured using simple biochemical assays.

The BellBrook team, collaborating with David Siderovski, a co-discoverer of the RGS protein family at the University of North Carolina-Chapel Hill School of Medicine, overcame this kinetic constraint by creating G protein variants with altered GTP hydrolysis and GDP dissociation rates that enable detection of RGS GAP activity using the Transcreener GDP assay.

Assay certification

Renishaw Diagnostics, developer of the RenDx multiplex assay system for infectious disease research and diagnosis, has been certified to ISO 13485:2003 for the following scope: design, development, product manufacture and management of subcontracted manufacture of molecular diagnostic systems for infectious diseases.

ISO 13485 is a standard, published in 2003, that represents the requirements for a comprehensive management system for the design and manufacture of medical devices.

Allana Johstone, Renishaw Diagnostics' head of compliance, said: "The BSI assessor was very impressed with our QMS System, our good practices, everyone she interacted with, and the general atmosphere she observed here at RDL. Our staff should be very proud of themselves for the outstanding contribution they have all made towards this achievement. It is unusual for a company as young as ours to have manufacturing included in the scope of the certification, so we are very pleased indeed."

Rupert Jones, general manager, said: "We are delighted to have received this certification; it reflects a significant effort by all of our staff and reinforces our commitment to quality. The transition from an R&D company to a fully commercial organisation is a very challenging process and it is essential that we have the right people and systems in place to make this happen".

Renishaw Diagnostics, formerly D3 Technologies, was a Strathclyde University spin-out before being acquired by the Renishaw Group, which is a leading global supplier of engineering technologies, medical devices and Raman spectroscopy systems. It is focused on developing and commercialising its first in vitro diagnostic (IVD) and clinical research products, with the goal of establishing Renishaw Diagnostics as the premium provider of automated, multiplex, high sensitivity molecular diagnostics products for the detection of human infectious diseases.

Renishaw Diagnostics has launched its first RenDx research-use-only (RUO) multiplex assay system and is working towards the obtaining of CE marking for the system as an in vitro medical device in Europe and clearance in the US.

One major challenge in studying epigenetic enzymes and their corresponding modifications is their existence in multiprotein complexes and the complexes' impact on their activity. So the ability to study these enzymes and to identify compounds that translate into useful drugs in vivo is greatly facilitated by the ability to incorporate cell-based assays using therapeutically relevant cell backgrounds.

The BacMam Histone H3 cellular assay kits from Life Technologies allow users to choose the modifications that correspond to the enzymes of interest in the chosen cell background or multiple cell background.

The BacMam reagent is used to transduce cells and drives expression of GFP-Histone H3 fusion protein in the cell background of interest. The GFP-Histone H3 is now a substrate for a variety of epigenetic enzymes such as methyltransferases. In the presence of a terbium (Tb)-labelled modification-specific antibody (such as anti histone H3K4me2), the binding of the antibody to the Histone H3 substrate results in time-resolved fluorescence resonance energy transfer (TR-FRET) between the GFP and the Tb.

Monitoring the TR-FRET readout in the presence of cells treated with compounds enables the identification of inhibitors of epigenetic enzymes for that particular modification.

EMD Millipore's new Millicell µ-Migration assay kit is a slide-based platform that can be used to visualise and measure the effects of chemo-attractants on the migration of adherent cells in real time. The kit is useful for studying metastatic behaviour or the effects of toxins.

The Millicell µ-Migration assay replaces the filter used in traditional Boyden chambers with microchannels. Cells migrating in these channels can be directly observed and their progress can be quantitatively measured. The kit also provides a stable linear concentration gradient for up to 48 hours. With high optical properties similar to those of glass, the Millicell µ-Migration slide is suitable for the analysis of slow- or fast-moving cells by video microscopy. Up to three assays can be run in parallel on each slide with approximately 100 to 200 cells per assay. The kit comes assembled and ready to use with a Millicell µ-Migration slide and migration assay reagents.

Finally, Lonza's new NodeSensor assays are based on the protein-fragment complementation principle, and they enable visualisation of protein complex dynamics within living human cells. NodeSensor assays can directly measure the activity of undruggable targets such as transcription factors and proteasome components, as well as mainstream drug targets (such as GPCRs) within their natural cellular context. When combining different NodeSensor assays with high-content analysis, a range of cellular responses becomes visible.

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