色中色

DNA is the 鈥榗ode of life鈥� and contains the information that makes you you. If you ask a scientist where you鈥檒l find DNA, almost all will say inside the nucleus of a biological cell.

Yet, some researchers like B谩rbara Malheiros will tell you that DNA is not just for genetics and that DNA on the outside of tiny particles known as colloids can influence how colloids interact with each other.

DNA can have enormous influence on how a particle behaves.

B谩rbara Malheiros

Such DNA-coated colloids can bind to each other, respond to changes in their environment, and even move when exposed to light. And this is what Malheiros worked on as part of her PhD research.

鈥淒NA can have enormous influence on how a particle behaves,鈥� says Malheiros. 鈥淚t depends on how much DNA there is on the particle surface, how its distributed on the surface, and what type of DNA it happens to be.鈥�

A synthetic choice

Upon hearing of particles coated in DNA, one question some may have for Malheiros is 鈥榃hat is the source of the DNA?鈥�. Rest assured, the DNA does not come from any living entity.

鈥淚 used synthetic DNA, which was bought from a company. Sometimes, we must try out several DNA sequences until we find one that鈥檚 a good match for our goal. However, in most cases, it鈥檚 a DNA that has already worked in a previous study,鈥� says Malheiros.

DNA-coated history

DNA-coated particles have been studied for about 70 years to date. Using approaches from click chemistry (a topic which won the ), DNA strands can be attached to various tiny particles, like colloids.

鈥淲hen the art of attaching DNA to particles was developed, exciting things started to happen. These DNA-coated particles would start to assemble or stick together to create structures 鈥� which can have exciting possibilities in materials science and nanotechnology,鈥� notes Malheiros.

When the art of attaching DNA to particles was developed, exciting things started to happen.

B谩rbara Malheiros

In her thesis, Malheiros compared two different ways of attaching DNA to particles. One is click chemistry, while the second is a protein-binding approach known as biotin-streptavidin (BSP). 鈥淓ven though both approaches successfully placed DNA on the particles, they formed different crystal-like structures. This suggests that the way that DNA is attached to the surface influences how the particles interact with each other afterwards.鈥�

Smart applications

Once Malheiros looked at ways to stick DNA to the colloidal particles, she wanted to know how the particles stuck together when exposed to different types of light.

鈥淚 used blue and UV light in my study. To get the DNA to react to light I added a special molecule called azobenzene. This molecule changes shape in different light, and this can change how the particles stick together.鈥�

These light-sensitive particles could have future smart material applications, particularly in photonics. 鈥淵ou could use the same DNA-coated particles to create two completely different structures depending on the type of light illuminated on the particles. This could lead to tailored photonic devices that only work under specific lighting conditions and can be used in future computing devices,鈥� adds Malheiros. 

Added to that, the colloidal particles could be used in biosensing to improve disease diagnosis. 鈥淭he colloids could attach to biomarkers at low concentrations and help decrease the time for the diagnosis of diseases like cancer.鈥�

Sitting, Watching, Waiting

Of course, Malheiros wanted to see the DNA-coated colloids in action as they stuck together to form structures. This was made possible with optical and confocal microscopy.

鈥淚n optical microscopy, I could only see the assembly process take place and that led to big aggregates between 50 and 100 micrometers in size. With confocal microscopy though, I could follow individual particles and record the assembly process live 鈥� which is very useful when it comes to understanding assembly dynamics.鈥�  

Transition to research support

With her PhD now complete, Malheiros will remain at 色中色 as a project manager with the Research Support Office (RSO). In fact, she has been working in the new role already, even while she finished writing her PhD thesis.

My time and project management skills were put to test, and I learned a lot about myself over the past few months.

B谩rbara Malheiros

鈥淢y PhD contract ended in September of last year, and I started with RSO in October. It was a quick change to be honest. I had just finished my experimental work, so that meant that I still had data analysis and writing to do. All of this was completed during the evenings and weekends,鈥� says Malheiros. 鈥淢y time and project management skills were put to test, and I learned a lot about myself over the past few months.鈥�

According to Malheiros, her experience as a PhD researcher has proven invaluable in her new role. 鈥淢y PhD years taught me to learn quickly and put things into practice quickly, which has been important for my new role. And as I work with lots of PIs in my new role, I鈥檓 aware of how important time is to them and how I can help. It gave me a good sense of empathy towards researchers.鈥� 

A surprise change?

But was her change of career a surprise to those around her? 鈥淔or my colleagues in the research group, it came as a surprise since they saw me as a future researcher. My family were happy for me to find a role that offered more stability and certainty. They saw how demanding a research role can be in terms of working hours and funding.鈥�

Things don鈥檛 stop being exciting if you leave research.

B谩rbara Malheiros

As Malheiros takes on a new role away from fundamental research, what advice does she have for anyone who is thinking of exploring something new beyond research?

鈥淔ollow your heart. Things don鈥檛 stop being exciting if you leave research. It鈥檚 the opposite 鈥� a new role away from research might be what you need to find purpose. While in academia there is a limited vision of what non-research roles have to offer, mostly because we focus either on the academic path or R&D jobs. But we develop many different skills during a PhD, and those also deserve a chance to be developed if you find a nice opportunity to do so.鈥�