Microcapsule technology could fast-track disease diagnosis and reduce plastic waste

Griffith University researchers have reported a new technology with multiple applications — from fast-tracking disease diagnosis such as COVID-19, to reducing plastic waste and for use in the pharmaceutical and cosmetic industries.

Published in AIP Advances, the technology encapsulates tiny droplets with a diameter smaller than a hair strand.

These microcapsules for the storage and delivery of substances are tiny versions of the type of capsule used for fish oil or other liquid supplements like vitamin D, and possess a solid shell protecting the liquid core from evaporation, oxidation and degradation.

Lead researcher Professor Nam-Trung Nguyen from the Queensland Micro-and Nanontechnology Centre said an important application of the tiny capsules was in laboratory tests such as disease diagnostics.

“This technology provides unparalleled control of small liquid volumes, which are invaluable in applications such as cell culture, immunoassays, and polymerase chain reactions (PCR), which is the “gold standard” for the detection of the coronavirus in the current COVID-19 pandemic,” he said.

Professor Nguyen’s team recently pioneered digital microfluidics with liquid marbles, which are droplets coated with hydrophobic powder.

The liquid marble with a porous shell is ideal for growing for three-dimensional tissue.

The team has also successfully developed a number of microfluidic PCR platforms. The microcapsules reported by the team will enable fast and cost-effective detection of RNA and DNA with a technology called digital PCR. In this technology, the test sample can be divided into thousands to a million microcapsules so that some capsules only contain 1 or 2 target DNA molecules.

“PCR can then be performed in the many tiny capsules to provide accurate results in a digital format. For example, some capsules with target DNA will brighten up for ON state, the others with no DNA targets remain dark for OFF state,’’ Professor Nguyen said.

“The small size of the capsules will allow for a fast reaction and thus reducing the test time for the DNA.”

He said the technology also represented a packaging solution for reagents and chemicals that will eventually reduce plastic waste, as conventional Petri dishes and vials could be replaced by capsules.

“Plastic waste is one of the major global environmental challenges. Biological laboratories around the world alone produced approximately 5.5 million tons of plastic waste in 2014,’’ he said.

The technology can also be used in the pharmaceutical and cosmetic industries — microencapsulated fragrances, bleach activators and anti-bacterial compounds are needed for personal care products. Drug ingredients can be delivered in a controlled dose with microcapsule.