An Eco-Friendly Disposable Plasmonic Biochip Based on Bacterial Cellulose for Interleukin-17A Detection at Atto-Femto Molar Level

The need for disposable, low-cost, biodegradable, small-size, and biocompatible sensor chips is crucial for the development of point-of-care tests (POCTs) in several bio/chemical sensing application fields. In this scenario, an eco-friendly sensor chip based on gold-coated bacterial cellulose (BC) nanostructures, which exploits localized surface plasmon resonance (LSPR) phenomena, is combined with a bioreceptor layer as a proof-of-concept for cytokine detection. The BC-based LSPR chip was developed and tested using a simple transmission-based experimental setup, enabling both bulk and binding sensitivity characterization. In particular, the optical analysis revealed a BC-based LSPR chip's bulk sensitivity of about 370 nm/RIU, comparable to that of more complex and expensive LSPR platforms reported in the literature. Following a functionalization process with an antibody specific for the interleukin 17A (IL-17A) protein, the BC-based LSPR biochip was tested, demonstrating an ultralow detection limit in the atto-femto molar range (detection limit of approximately 400 aM), an ultrawide detection range, and good selectivity toward other interleukins, making it a proof-of-principle useful in biomedical applications. The achieved results paved the way for the applicability of this eco-friendly biochip as a disposable chip useful for POCTs in several application fields, where the required disposable feature is due to contamination that occurs during measurements in real-world scenarios.