NEW YORK (GenomeWeb) – Researchers at AI Biosciences have developed a method to adapt a standard 3D printer into an automated sample prep and molecular detection device.
In a PLoS One study published late last month, the researchers also demonstrated the device could be used to purify and detect DNA- and RNA-based pathogens, including Chlamydia trachomatis and dengue virus.
Typical commercial sample prep equipment can cost up to $25,000 with reaction times of around 40 minutes. A 3D printer — which is essentially a robotic arm programmed to extrude thin lines of heated plastic — costs $750 or less as adapted for the proof-of-principle sample prep device, and had a sample prep processing time of 15 minutes, according to the PLoS One study.
Now, "High-quality, consistent nucleic acid extractions and amplification can be accomplished without breaking the bank," lead researcher Season Wong told GenomeWeb in an email.
Wong, co-founder and president of AI Biosciences, is also the developer of a nucleic acid amplification method that uses Thermoses for infectious disease detection, and he contributed to a lab-on-a-drone project by adapting the rotors on a quadcopter drone into centrifuges.
The general mission of AI Biosciences is to build low-cost yet high-quality, reliable molecular tools, he said, with a special focus on diagnostics.
As such, Wong began a collaboration with Charlotte Gaydos at Johns Hopkins, who is a co-author on the PLoS One study. Gaydos' lab provided expertise on molecular diagnostic testing for chlamydia as well as clinical urine samples.
The study showed the C. trachomatis was very efficiently extracted from urine samples, compared to a gold-standard spin column-based method from Qiagen, and the nucleic acids from both methods had similar Cq values across a range of dilutions. Similar results were seen with commercially available dengue virus, and all experiments demonstrated minimal cross-contamination.
Interestingly, the low-budget water bath PCR on dilutions of C. trachomatis took less time than a commercial thermal cycler — 24 minutes versus 36 minutes for a 35-cycle PCR run respectively.
The inspiration for the sample prep module came from observation, Wong said. The lab had purchased a low-cost model to print lab ware, but he realized the movements of the 3D printer were somewhat similar to automated sample prep devices.
"These devices usually cost $15,000 to $20,000 to process magnetic particle-based nucleic acid extraction, so I thought that we could try to convert the 3D printer into a sample preparation device to extract DNA and RNA at a fraction of the cost," he said.
The conversion involved replacing the device's extruder tip with a magnetic particle processing attachment (MPPA). The arm's movement was then programmed to mimic a sample prep instrument, including shaking.
Standard 3D printers also have a heated head element to melt the plastic, as well as a heated bed so that the growing 3D printed structure hardens evenly.
For nucleic acid amplification on the new platform, Wong and his group used the heated bed to heat water above 95 degrees Celsius in order to create a denaturing bath for DNA. They also created an annealing and extending bath by adding layers of aluminum foil between the bed and bath to reduce the heat transfer. They then programmed the robotic arm to shuttle a PCR tube holder between the two baths.
Notably, the changes to the 3D printer are "very simple and reversible," Wong said, and can be reversed so that the equipment can be used for 3D printing again.
The group is currently working under a Phase I Small Business Innovation Research grant to develop Chlamydia trachomatis and Neisseria gonorrhoeae diagnostics. "We will soon submit a Phase II SBIR proposal using the same 3D printer platform but with a specifically designed cartridge for molecular diagnostics applications," Wong said.
Overall, the firm is focused on low-resource settings, particularly diagnostics in less-developed countries, but it also sees opportunities in offering its technologies to university research laboratories or classrooms as part of STEM education curriculums, Wong said. "The next step is to promote the Thermos thermal cycler (TTC) as a Kickstarter project. Having more people who can use our devices will give us more feedback and validate that the TTC can work robustly in resource-limited settings," he said.
AI Biosciences will also use the 3D printer platform technology "to develop and commercialize medium-throughput molecular devices and assays," Wong said, using the aforementioned cartridges operated by the 3D printer platform to carry out molecular tests.