NEW YORK (GenomeWeb) – Harnessing a microfluidic technology initially developed by researchers at the University of California, Irvine, startup Velox Biosystems plans to develop a clinical diagnostic device for rapid identification of rare targets in complex raw samples, such as blood.
The microfluidic technology, called Integrated Comprehensive Droplet Digital Detection, or IC 3D, was developed in the labs of UC Irvine professors Weian Zhao and Enrico Gratton. Velox was co-founded by Zhao and former UC Irvine postdoc Chris Heylman, who now serves as the company's CEO.
Heylman told GenomeWeb that Velox believes IC 3D offers a unique approach to detecting and quantifying targets present at very low frequency amidst a complex background like a blood sample, both in terms of its position relative to standard molecular testing technologies, and its comparability to existing commercial microfluidic platforms.
The approach essentially spatters a sample into micron-size droplets, each just bigger than a cell. Using DNAzyme-based sensors, fluorescent biomarkers, and a high-throughput particle counter, the system enables users to analyze an entire sample volume split into hundreds of millions of droplets in only a few minutes.
According to Heylman, unlike other existing droplet-based detection platforms, IC 3D makes possible the analysis of hundreds of millions and potentially up to 1 billion droplets within a 10- to 15-minute timeframe.
The systems fluidics advances came out of Zhao's lab. "They developed a method to do molecular detection in complex media like blood using a microfluidic generation of oil and water emulsion droplets, with the premise that you could do this directly in complex samples without preprocessing or culture or anything like that," Heylman said.
"But then they were faced with a problem, because doing that approach, you generate a larger number of droplets — hundreds of millions up to a billion — so the limiting factor becomes the ability to assess the chemistries in the droplets rapidly enough," he added.
The answer to this part of the IC 3D equation was enabled by Zhao's collaboration with Gratton's lab, which furnished the project with a high-throughput droplet counter that involves multiple lasers and shape-recognition algorithms.
"The end result is the marriage of the two technologies together, so you now have the ability to assess hundreds of millions of droplets in a short time," Heylman said.
As a result, IC 3D offers an improvement over other technologies or approaches on several fronts, he argued. In the context of infectious disease detection, for example, culture-based techniques, while sensitive, require multiple days to complete. Molecular detection methods like PCR, while fast, suffer in sensitivity because each purification or isolation step needed for the reaction squanders precious targets along the way.
And while other microfluidic technologies and droplet-based chemistries exist — droplet-based digital PCR, for instance — IC 3D's counting technology offers an ability to more rapidly detect more droplets, Heylman said.
The ability to analyze a raw sample partitioned into millions of droplets potentially offers a unique potential for rapid detection without losing out on sensitivity, he argued.
Heylman said that Velox has two main strategies as it moves forward to commercialize the IC 3D technology. One is sublicensing it to other entities interested in using it for their own purposes, whether research or clinical, for example in the pharmaceutical space.
Although he did not name any users, Heylman said that adoption at this point is mainly at a research level. "We have a number of co-development projects in academic labs, and also different businesses interested in the technology for specific purposes like bacterial detection in water," he said.
Meanwhile, Velox's second focus is on developing a diagnostic instrument of its own for specific clinical applications that Heylman said are still to be determined.
"The bulk of our work to date [as a company] has been market analysis and assessment of where the technology can best be applied," he said.
Although the flagship demonstration of IC 3D — a study published in November 2014 by Zhao and colleagues in Nature Communications — was infectious disease-focused, Heylman said that there are many other possible applications.
In their Nature Communications publication, Zhao and co-authors demonstrated that IC 3D could selectively detect bacteria directly from milliliters of diluted blood at single-cell sensitivity in a one-step, culture- and amplification-free process.
Using Escherichia coli as a target, the investigators demonstrated that IC 3D could provide absolute quantification of both stock and clinical isolates of the bacteria in spiked blood down to extremely low concentrations ranging from 10,000 to just a single bacteria per ml.
Although Heylman said that Velox is not yet pursing this commercially, Zhao and his lab are using a multi-year grant from the National Institute of Allergy and Infectious Diseases to determine whether IC 3D can also detect antimicrobial resistance.
According to the team's grant proposal, their study in this area aims to develop and validate new IC 3D tests for rapid detection of carbapenem-resistant Enterobacteriaceae.
As part of this project Zhao and colleagues also plan to work with industrial partners including ISS, Dolomite Microfluidics, and BioVenture Services to develop and validate an integrated, automated, portable IC 3D system, including product-development activities to support a submission to the US Food and Drug Administration and subsequent commercialization, according to the grant abstract.
Meanwhile, in another paper published last year in Lab on a Chip, Zhou and colleagues also showed how IC 3D might have applications in the oncology space, showing that it could specifically quantify target miRNA directly from blood plasma at extremely low concentrations ranging from 10 to 10,000 copies per mL in without the need for sample processing such as RNA extraction.