Nanotechnology holds promise for medicine, particularly for accessing cells and tissues in new ways. Claire O’Connell found out from Dr Anna Salvati why it’s important to understand how cells and nanoparticles get along.
It can be hard to get your head around just how small a nanoparticle is. There’s the standard description that a nanoparticle or nanomaterial has a dimension of less than 100 nanometres, and a nanometre is a billionth of a metre – but does that really get the point across?
Here’s another comparison that puts it into context: nanoparticles can be similar in size to large proteins, the kinds of molecules that drive activity in our cells, or to viruses, which seek to get inside cells. Now we’re getting somewhere.
Being that size means nanoparticles have all sorts of interesting properties that we could harness for medicine, explains Dr Anna Salvati, a post-doctoral researcher at the UCD Centre for BioNano Interactions.
She is looking closely at what happens when you expose living cells to various nanoparticles. “We see they can enter the cells very easily,” she says. “And if we manage to learn how that happens and how to control it, it could be used for medicine to be able to transport drugs into places where drugs don’t normally arrive – and only there, in a more specific way, to limit side effects.”
Knowing how nanoparticles behave around living cells and tissues is also important for understanding safety, she adds. “If nanoparticles or nanomaterials can get into the body, we want to know how they interact with the body. You are asking the same kinds of questions here, too.”
Biology and chemistry in the mix
Salvati has an interest in these ‘bionano interactions’ from both a chemical and biological perspective. She studied biology at the University of Florence, then did a PhD in physical chemistry, which she admits was an unusual switch. “I wanted to have a mix of competencies and this was a way to do it,” she says.
For her PhD in Italy and Sweden (at Lund University, she designed and made nanoparticles to ferry drugs into cells, and during this time she got to know Prof Kenneth Dawson at UCD. So she moved to UCD in 2007 to join his group, just when the research on bionano interactions got going.
At first, the team worked on building up the methods to set up and look at these nanoscale interactions, and this has allowed them in more recent years to ask some of the ‘tough questions’ about what is going on, explains Salvati, whose work has been supported by Science Foundation Ireland, IRCSET and European FP7 funding.
The group’s discoveries are now shedding light on the complexity of those interactions, not least how nanoparticles draw around them a ‘cloak’ of molecules from the environment, and this can affect their behaviour.
Salvati has also been looking at what happens to nanoparticles that are customised with transferrin, a molecule that should allow them to gain preferential access to some types of cancer cells.
She and colleagues found that if the environment around the cells was biologically complex or crowded – like it is in the blood – the nanoparticles were less likely to ‘find’ their target on the cells and gain access.
The findings, published recently in Nature Nanotechnology, could help to explain why nanoparticles might behave one way in the relatively simple environment of cells growing in a lab, but quite another way in the ‘busier’ environment of the human body, explains Salvati.
Spreading the load
But once nanoparticles do get inside cells, what happens then? Do they stay put? And when cells grow and divide, do the nanoparticles get moved along into the new cells? Salvati and colleagues came up with some answers by exposing cells in the lab to nanoparticles and carefully tracking what happened.
They saw that if nanoparticles went into a cell and later the cell divided, the nanoparticles would go into the ‘daughter’ cells. This could have important implications for how nanoparticles used for diagnosis or drug delivery would stick around inside different tissues and organs, explains Salvati.
“If cells divide quickly, that will dilute the amount of internalised nanoparticles quickly, because every time a cell divides it splits the load,” she says. “On the other hand, cells that divide at a slower rate might potentially accumulate more nanoparticles if there is no other method of clearing them.”
Informing the future
Getting a better handle on such bionano interactions should help to inform more effective designs in nanomedicine, according to Salvati. “There is a lot of interest in nanomedicine but success stories to date are limited,” she says. “I think that in order to design a successful drug carrier, firstly there is a need to focus on these interactions and to understand how a cell processes nanoparticles, and in my view the fact the ‘bionano’ field – which is focused on these questions – is growing is promising for nanomedicine.”
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