Crab-derived material takes biosensors to the next level
New biocompatible materials have been combined, laying the foundations for the next generation of durable, sensitive, biocompatible biosensors.
A team of researchers, led by Prashant Sonar at the Queensland University of Technology (Brisbane, Australia) and supported by Nanyang Technological University (Singapore), has utilized vapor phase polymerization (VPP) to combine two cutting-edge materials and develop a next-generation wearable biosensor.
Wearable biosensors represent a vital opportunity to improve our ability to conduct real-time point-of-care testing and continuous health monitoring. However, to reach their full potential, developers will need the most biocompatible, flexible and functional materials to work together.
Biosensors are built around a core material known as the substrate, which essentially coats conductive materials like graphene, while also immobilizing sensory molecules such as antibodies, acting as the connection between the analyte detected and the materials that transmit the signal to a device for readout. Chitosan, a non-toxic polysaccharide derivative of the marine crustacean polymer chitin, has recently emerged as an effective biocompatible substrate material due to its mechanical stability and its ability to immobilize and protect sensory biomolecules, keeping them active for longer and enhancing device sensitivity.
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Another key component of these biosensors is the active channel material, conductive or semiconductive materials that provide the active sensory component of the biosensor. Poly(3,4-ethylene dioxythiophene):poly(styrene sulphonate) (PEDOT:PSS) is the most prevalent material used for this purpose; however, a new material using tosylate rather than PSS as the anion has recently emerged. Tosylate has a higher charge density and diffusivity, meaning that PEDOT:Tos can offer better conductivity and durability than its predecessor.
With these factors in mind, the researchers set out to combine these two materials to produce a new biosensor. First, the team evaluated the biocompatibility of chitin using an MTT assay to determine its impact on cultured human cells. Then they deployed VPP, which has previously been used to deposit PEDOT:Tos on other substrates, to layer the material onto the chitin substrate. VPP uses a spin coating approach to coat a substrate with an oxidant film, such as Fe(III) tosylate with butanol, before exposing it to ethylenedioxythiophene vapor to enable polymerization.
This produced a bendable, biocompatible electronic film, which the team could then use to create an organic electrochemical transistor before testing its performance. The team used the Bruker Dimension Icon atomic force microscope for nanomechanical mapping analysis to determine the material’s resistance to a series of bending tests, amid a series of other tests to determine factors such as the device’s transconductance, hybrid electronic and ionic transport capability.
Study first author, Chattarika Khamhanglit, commented on the device’s performance, stating that it “… retained up to 97% of its electrical performance after repeated bending tests.” Commenting further, Sonar declared that “Not only do these devices work electrically, they are biocompatible, meaning they can safely interact with human cells, and they are mechanically strong enough to withstand bending and movement. That makes them ideal for future wearable health monitors.”
Looking to the future, Sonar wants to work these devices into biosensing platforms for specific applications. “Imagine a lightweight patch that can comfortably adhere to the skin and provide continuous, accurate health information to doctors or patients.”
