Cellulose-Based Biosensing Platforms—Fabrication and Detection Strategies

The development of accurate, reliable, and inexpensive analytical platforms is of utmost relevance to several fields from clinical diagnosis to environmental screening. Moreover, the use of inexpensive materials and cost-effective manufacturing processes for production of such devices is very attractive and must be aligned with the European Green Deal and the United Nation’s Sustainable Development Goals. In that sense, cellulosic materials are appealing candidates to be used as low-cost disposable materials for biosensing platforms, with great emphasis in point-of-care (POC) settings, particularly in resource-poor countries. Here, we show the use of cellulose-based substrates with both passive and active roles in biosensing platforms allied with cost-effective, energy-efficient and scalable fabrication routes. These biosensors were developed with both optical and electrochemical mechanisms, due to their meritorious ability to offer high selectivity and sensitivity, ease of fabrication and usage, easy miniaturization, low cost and versatility. Specifically, we present examples of (i) cellulose-based colourimetric biosensors using wax printing technology combined with colourimetric detection using both natural and biomimetic receptors for a multitude of applications, ranging from bacteria detection to diabetes control[1]; (ii) cellulose-based Surface-Enhanced Raman Scattering platforms, produced using both physical and chemical routes, for the detection of antibiotics, cancer biomarkers and spike protein from SARS-CoV-2 virus, where the influence of different types of cellulosic materials is demonstrated[2,3,4]; (iii) cellulose-based electrochemical biosensors, using laser-induced graphene electrodes with tailored conductive and electrochemical properties, applied for amperometric, enzymatic biosensing schemes for glucose detection and with potential for sensing of other metabolites [5]. In conclusion, the biosensing concepts explored herein pave the way toward developing robust analytical devices with the potential to be integrated with stand-alone multifunctional platforms to be used in POC settings.<br/><br/>[1] Pinheiro, T., et al, ACS Appl. Mater. Interfaces, 13, 2021.<br/>[2] Marques, A.C., et al, Scientific Reports, 9, 2019.<br/>[3] Ferreira, N. et al, ACS Sensors, 4, 2019.<br/>[4] Marques, A.C., et al, Applied Surface Science, 561, 2021.<br/>[5] Pinheiro, T., et al, Adv. Mater. Interfaces, 8, 2021.<br/><br/>National funds from FCT financed this work - Fundação para a Ciência e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. The authors also acknowledge funding from the European Research Council (ERC) ref 787410 -DIGISMART and from BEST project, ALT20-03-0247-FEDER-113469|LISBOA-01-0247-FEDER-113469. T. P. also acknowledge the funding from National Foundation for Science and Technology, through the PhD Grant 2020.08606.BD.