At Wageningen University & Research in the Netherlands, an ordinary, aluminium, Nespresso-type coffee capsule has been transformed into a home test device for COVID-19.
The test is the brainchild of Dr Vittorio Saggiomo, Assistant Professor of the BioNanoTechnology group (BioNT), and has been created in collaboration with the Netherlands Organisation for Applied Scientific Research (TNO).
A decentralised testing alternative
The CoronaEspresso responds to growing demand for decentralised COVID-19 testing methods.
While initial global efforts centred around centralised, fasting-acting test facilities, Dr Saggiomo suggested logistical bottlenecks soon altered such strategies. “Centralised testing is only useful and feasible in terms of capacity to a certain extent,” he explained.
“There were no good alternatives available for more efficient and effective decentralised testing,” he continued, whether that be at home, at school, or at work.
At the same time, Dr Saggiomo observed that current home testing methods are testing for antibodies, rather than antigens. While antibody tests work well with high virus concentrations, the researcher raised concerns that people with lower virus concentrations can receive a negative test result.
“Furthermore, antibody-type tests can only be used once and then they are discarded. That is exactly what we do not want.”
Spotlight on LAMP
Instead, Dr Saggiomo is an advocate for the LAMP (loop mediated isothermal amplification) test. Similarly to the well-known PCR (polymerase chain reaction) test, the LAMP method tests for the presence of an antigen. The two have comparable reliability.
So why opt for LAMP over PCR? The LAMP test is cheaper, less demanding in terms of laboratory infrastructure, and yields results faster. This, according to the Wageningen team, makes it possible to work at a constant process temperature.
The CoronaEspresso can handle both LAMP and PCR tests. To do so, a parrafin-based phase change material is placed inside the capsule, which is then covered with a 3D-printed sample holder with enough space to hold four test samples at once. A small tube (either PCR or LAMP) known as an Eppendorf tube is inserted into the capsule. The tube contains a mixture of chemicals and enzymes, to which the test sample is added.
The entire unit is then placed in water just come off the boil for 30 minutes. The paraffin warms the samples to 65 degrees and keeps them at that temperature for 25 minutes. According to the researchers, this allows a ‘LAMP reaction’ to occur. The result can then be read from a colour change in the samples.
“The thin aluminium is perfect for a taste increase of temperature for the amplification reaction to happen,” Dr Saggiomo told this publication. Another big plus is that the test result can be determined without the need for another lab.
A move away from single-use
According to the researcher, the CoronaEspresso is reusable, recyclable, and inexpensive.
Nespresso-style capsules, he explained, are ‘already massively produced’, and ‘easy to recycle because of the aluminium’. “That’s a huge improvement compared to single use plastics.”
CoronaEspresso can also be produced locally at low cost. The phase-transition material, which is not dissimilar to wax, can be reused in candles and other items, and the 3D-printed holder is biodegradable. It is also easy to design alternatives if a 3D printer is not available, he noted.
Ultimately, the CoronaEspresso is ‘not a single-use tool’. “It can be used several times to warm up samples as long as the wax does not come into contact with water and the cup remains undamaged.” It was been suggested that the CoronaEspresso could be particularly useful in more remote locations and/or lower-income countries.
The BioNT group has now made ‘hundreds’ of CoronaEspresso tests, which can be used for any RNA/DNA detection using LAMP. It has been successfully tested with synthetic SARS-CoV-2 RNA and with real human samples, and has been proven to be a ‘reliable indicator’ of the presence or absence of the virus.
Moving forward, Dr Saggiomo said there could be scope to partner with coffee capsule brands for the production of CoronaEspresso tests. In the meantime, Saggiomo and his co-workers are focused on optimising the sampling – based on nose/throat swabs or saliva – and the ‘practical matters’ regarding LAMP reaction mixtures.