The study “Lithography-Free Water Stable Conductive Polymer Nanowires” is about a simple, yet efficient, way to bring conductive polymers into a nanowire shape suitable to interface with living cells.
Conductive polymers conduct both electronic and ionic currents (different from traditional conductors which only transmit electronic signals). This mixed conductivity allows for more accurate capture and transmission of biological signals (such as neural or muscle activity), improves the efficiency of cell stimulation, and ensures better biocompatibility and integration with living tissues.
Nanowires have the best shape to interact with living cells and can be made to spontaneously penetrate the cell membrane. Due to processing challenges, conductive polymers have not previously been possible to process into nanowires without destroying the material in the process.
”In this paper, we show a way to make conductive polymer nanowires with maintained electrical conductivity and we use them to interface with cells,” Martin Hjort states.
Why are these results so interesting?
“This is the first time anyone has demonstrated that nanowires can be made from conductive polymers! These nanowires allow for controlling intracellular electronic and ionic functions,” says Martin Hjort.
Nanowires, albeit made from semiconductors, were for decades the main technology to be researched at NanoLund. Their shape has allowed the creation of efficient solar cells, light-emitting diodes, as well as playgrounds for quantum physics. Designed correctly, this type of structure can even spontaneously reach inside living cells and provide a healthy pipeline to electronically modify cell functions.
“The key problem has been that conductive polymers get damaged from the patterning and processing conditions when making small structures. Other researchers have instead focused on making a layer of polymer (two-dimensional, 2D) and within the past years stacked layers (3D). With our clever molding in nanoporous membranes, we present nanowires (1D),” says Martin Hjort.
What is the most important thing you have learned from this study?
“That it is possible to take a water-soluble conductive polymer solution, mold it in a nanopore, and then make it water stable through introduction of cations and small molecules. And that cells really like the nanowires, you can even see human blood stem cells reaching out trying to grab onto the nanowires as well as wrapping tightly around them in a cozy way,” says Martin Hjort.
The cells really like the nanowires, you can even see human blood stem cells reaching out trying to grab onto the nanowires as well as wrapping tightly around them in a cozy way.
He says that the results can be useful by the conductive polymer nanowires providing a way to access the intracellular space of living cells. This ‘information highway’ enables electrical stimulation and sensing to understand how electroactive cells respond to external cues. It also enables bioelectrical stimulation to manipulate ion flows which is the way cells normally communicate and operate. This can enable diverse areas such as more efficient neural implants to sense and control neurological signals, controlled differentiation of stem cells, and GMO-free ways to use algal cells for biomanufacturing.
“The applications are quite far into the future, but I think the possibility of reducing dimensionality in systems is always appealing. Going from 3D to 2D was fun, now 1D is available as well!” says Martin Hjort.
Was there something in the results that took you by surprise?
“The way the cells approved of and seemingly encouraged interaction with the nanowires. The processing and manufacturing of the wires are largely engineering and to some extent predictable. How they interface with living cells (both human and plant-based) is more challenging to predict and needs to be tried out. Luckily enough, the cells really liked the structures!”