Engineering a Fully Biodegradable Multiplexed Biosensing Platforms Based on Chitosan Lignin Composites to Detect Biomarkers

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Over the past decade, there have been significant advancements in wearable biosensors to fulfil the increasing need for rapid, personalized, non-invasive, and point-of-care monitoring. Nonetheless, with the prevalence and ubiquity of smart sensors, it is crucial to take into account the environmental consequences that may arise due to their extensive use1. Recently, there has been growing interest in using natural platforms for the development of biosensors that can also detect multiple biomarkers simultaneously2. Among verities of natural materials, chitosan and its derivatives are promising due to their biodegradability and sustainability. Additionally, the composition of these biopolymers could be easily tuned using other natural materials to meet any specific requirements for developing biosensors. Crucially, chitosan-based films are graphitisable by direct laser writing, as recently demonstrated by our group3. Recently we have successfully developed an electrochemical glucose biosensor based on pure chitosan based bioplastic film4. Although the proposed biosensor showed satisfactory characteristics, it can only be used as a disposable biosensor due to the solubility of chitosan films in water. Therefore, in order to extend the applicability of these platform especially for wearable purposes it is necessary to improve its water resistivity by introducing other natural components to its matrix. Due to its hydrophobic nature, lignin could be an excellent choice in order to overcome this drawback of pure chitosan films. Therefore, in this work, firstly, composites of chitosan and lignin were prepared. The formulations of the precursors in initial solutions were altered and optimized. Then, the electrical, electrochemical and spectral properties of the prepared bioplastic based films were investigated. Moreover, the mechanical stability, strength as well as water resistivity of the films were evaluated. Then, a glucose biosensor were constructed on optimized bioplastic platforms derived from natural precursors. The analytical features of the biosensor were evaluated in both phosphate buffer and artificial sweat. The proposed biosensor presented good stability for determination of glucose in both media compared to pure chitosan based biosensors.