Nano probes: the future of drug delivery?

Scientists have developed an extremely small probing device that is capable of binding to a cells surface and eavesdropping on its internal electrical activity. This may help to provide insight into how cells communicate and how they respond to medication delivered through the probe.    

Ever think we could spy on a cell? We have been able to for almost thirty years now, but a new technique is purported to no do it substantially better. Stanford Researchers recently (March 30) published a paper describing their success in developing a nanometer-scale probe capable of binding and becoming a part of a single cell’s membrane.  The paper, published in Proceedings of the National Academy of Science, offers insight into the ability for researchers to eavesdrop on the inner electrical activity of individual cells. The use of the nano probe as a conduit for inserting medication into a cell’s interior is also being cited by the Stanford researchers.    

The study, spearheaded by Nick Melosh and Benjamin Almquist, focused on designing a probe in a way that allowed it to mimic a component of the cell membrane. The cell membrane, or cell wall, is the outermost encapsulating structure of a cell that protects it from the outside environment. The key to the probe’s easy insertion and the great affinity it has for the cell membrane is due to its engineering. The probe was engineered in a way that allowed it to mimic a type of cell membrane gatekeeper protein – a molecule naturally found in the cell membrane that regulates what enters and exits the cell.      

“What we have done is make an inorganic version of one of those membrane proteins, which sits  in the membrane without disrupting it,” said Melosh. “The probes fuse into the membranes spontaneously and form good, strong junctions there.” The attachment is so strong, “we cannot pull them out. The membrane will just keep deforming rather than let go of the probes.” The 600-nanometer-long probe has integrated so well into membranes that the researchers have dubbed it the “stealth” probe.    

Current methods involved in cell probing are limited in that they only allow access to the cell for few hours. Additionally, the methods are extremely destructive and damaging to cells. Melosh and Almquist are the first to implant a cell probe with very little damage to the cell.      

Up to now, poking a hole in a cell membrane has largely relied on brute force, Melosh said. “We can basically rip holes in the cells using suction, we can use high voltage to puncture holes in their membranes, both of which are fairly destructive […]; many of the cells don’t survive.” That limits the duration of any observations, particularly electrical measurements of cell function.    

“Ideally, what you’d like to be able to do is have an access port through the cell membrane that you can put things in or take things out, measure electrical currents … basically full control,” commented Melosh. “That’s really what we’ve shown – this is a platform upon which you can start building those kinds of devices.”    

Melosh and Almquist are currently working with human red blood cells, cervical and ovary cancer cells to demonstrate the functionality of the probes in living cells.    

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