Researchers have developed a surface to which biological material cannot stick for carrying out molecular biology experiments in a single droplet. A researcher says that the dream of carrying out droplet-sized molecular biology research is closer than ever.
Scientists have long dreamed of being able to carry out experiments on a microscopic scale, on a single droplet, to save material, time and money.
A droplet laboratory would enable advanced experiments on a chip, with a computer very precisely controlling entire experiments, such as what to mix together when and at what temperature.
Such processes include polymerase chain reaction (PCR), which amplifies small amounts of DNA for analysis to diagnose diseases or understand genetic sequences.
“We have already developed a digital microfluidics platform for experimenting with tiny droplets on the surface of a chip. The droplet laboratory can replace large machines and flasks, thereby enabling hundreds of experiments in the time normally required to perform just a few,” explains a researcher behind the new project, Winnie E. Svendsen, Professor, Department of Biotechnology and Bioengineering, Technical University of Denmark, Kongens Lyngby, Denmark.
The research has been published in Talanta.
Adapting existing technology to biological systems
The development of the digital microfluidics platform previously focused on its potential within chemistry, but now researchers are using slippery liquid-infused porous surfaces (SLIPS) with Teflon and silicone oil to align the platform closer for use within molecular biology research. SLIPS ensure that biological materials such as cells and proteins do not stick, which minimises the risk of contamination and makes experiments more precise.
“This shrinks experiments to microscopic size, which saves reagents and time, and SLIPS ensure that biological materials do not stick – preventing cross-contamination and making processes easier to control,” says Winnie E. Svendsen.
The process creates a chemical laboratory in a droplet on a chip. This reduces resource consumption and increases efficiency, which has inspired researchers to adapt the technology to biological systems.
“We investigated how to shrink a molecular biology laboratory to microscopic size. This is far more challenging for biological systems because complex processes must be controlled very precisely and sensitive materials protected,” adds Winnie E. Svendsen.
Colleague wanted to carry out micro-scale biological experiments
Winnie E. Svendsen has worked for many years to develop the microfluidics platform so that it can improve chemical experiments.
She was contacted by research colleague, Irina Borodina, who wanted to know whether a digital microfluidics platform could be developed for molecular biology research, such as cloning experiments or PCR, in which DNA is amplified in test tubes.
The standard for this type of research is to use pipettes, bottles, flasks and very large and expensive machines, but the Irina Borodina dreamed of shrinking the molecular biology experiments to droplet size.
However, chemical experiments and biological experiments differ in a digital microfluidics platform, and the new study addressed this.
“Processing biological materials differs from moving liquids of different colours around on a chip. Biological material placed on the surface of materials can stick, and this can transfer contamination from one experiment to the next. We had to solve this to carry out molecular biology research on a chip,” explains Winnie E. Svendsen.
Teflon surfaces prevent cross-contamination by biological materials
To solve the problem, the researchers developed SLIPS, which are as slippery as Teflon on a frying pan, and very little sticks to them.
However, Teflon alone was not good enough, since biological material such as cells and proteins could still get stuck in small holes on the Teflon surface.
To solve this problem, the researchers covered these holes with a thin silicone oil, creating a smooth surface on which nothing sticks – in a project called MagicBox: digital microfluidics platform for strain development in biotechnology.
“The MagicBox project aims to revolutionise strain development in molecular biology. By combining SLIPS technology with digital automation, the MagicBox is designed to automate the entire cloning process from PCR to transformation. In the future, this compact platform will be able to support parallel experiments, give small laboratories access to advanced technology and reduce costs by minimising manual interventions,” says Winnie E. Svendsen.
Avoiding surfactants in biological experiments
Winnie E. Svendsen explains that the new surface coating prevents cross-contamination between each step of the experimental protocol and between each experiment.
Molecular biology research must often use surfactants to enable ingredients in the biological experiments to move freely, but this is not necessary when using SLIPS.
In addition to avoiding cross-contamination, the modified Teflon surface also minimises the use of other chemicals not directly related to molecular biology experiments.
This integration provides more rapid workflow, higher accuracy by mitigating surface biofouling and saves substantial money by automation and reducing reagent use.
“By improving surfactant-free PCR, SLIPS automates the entire cloning process on a digital microfluidics platform. For example, we can copy DNA more rapidly without using chemicals that might contaminate the process,” says Winnie E. Svendsen.
Considerable industrial potential
Winnie E. Svendsen envisions several applications in which a microscopic molecular biology laboratory on a chip could be especially useful. For example, cloning experiments are standard in industrial research, with researchers trying to get bacteria and yeasts to produce dyes, fragrances, fuels or other useful substances.
These experiments currently take time, but a digital microfluidic platform based on SLIPS can perform everything on small chips, enabling researchers to perform thousands of automated cloning experiments at the same time without risking cross-contamination or material sticking from previous experiments.
“In the future, we hope to include sensors in our platform to not only carry out experiments in droplets but also analyse them in real time, including checking whether cloning has been performed correctly. Today, a laboratory technician must manually check each experiment, but integrating sensors into our platform could automate the entire process,” notes Winnie E. Svendsen.
The researchers also aim to develop the platform to automate, perform and analyse the entire biological research process – from PCR to transformation and cloning.
“We can eventually analyse the results and, for example, select the clone that produces the best fuel, without having to remove anything from the chip,” concludes Winnie E. Svendsen.
