Review of Bacterial Nanocellulose-Based Electrochemical Biosensors: Functionalization, Challenges, and Future Perspectives

Abstract

Electrochemical biosensing devices are known for their simple operational procedures, low fabrication cost, and suitable real-time detection. Despite these advantages, they have shown some limitations in the immobilization of biochemicals. The development of alternative materials to overcome these drawbacks has attracted significant attention. Nanocellulose-based materials have revealed valuable features due to their capacity for the immobilization of biomolecules, structural flexibility, and biocompatibility. Bacterial nanocellulose (BNC) has gained a promising role as an alternative to antifouling surfaces. To widen its applicability as a biosensing device, BNC may form part of the supports for the immobilization of specific materials. The possibilities of modification methods and in situ and ex situ functionalization enable new BNC properties. With the new insights into nanoscale studies, we expect that many biosensors currently based on plastic, glass, or paper platforms will rely on renewable platforms, especially BNC ones. Moreover, substrates based on BNC seem to have paved the way for the development of sensing platforms with minimally invasive approaches, such as wearable devices, due to their mechanical flexibility and biocompatibility.

Keywords: bacterial nanocellulose; biosensors; ex situ; functionalization; in situ.

Figure 1

Representation of cellulose structure interconnected by a hydrogen bond. The cellulosic membrane exhibits different structures at different scales: the cellulose fibers consist of bundles of elementary fibrils, and these fibrils are composed of parallel stacked molecular cellulose chains [67].

Figure 2

Representative micrographs for each nanocellulose material focused on in this review. Transmission electron microscopy (TEM) image of (a) CNFs. Reproduced (adapted) with permission [87]. Copyright 2013, American Chemical Society; (b) CNCs. Reproduced with permission [59]. Copyright 2020. Reproduced with permission from the American Chemical Society; (c) BNC [88]. Copyright 2015.

Figure 3

Schematic representation of BNC composites synthesized through in situ synthetic and ex situ modification strategies. The example illustrates the penetration of particles in the BNC matrix through chemical, physical, and in situ methods.

Figure 4

Modified BNC prepared by agitation method for incorporation of nanoparticles. (a) (A) Field Emission Scanning Electron Microscopy (FE-SEM) images of transparent nanopaper. (B) FE-SEM images of ESNP; (b) Schematic representation for the fabrication of ESNPs. Adapted with permission from [94]. Copyright 2015. Reproduced with permission from Elsevier.

Figure 4

Modified BNC prepared by agitation method for incorporation of nanoparticles. (a) (A) Field Emission Scanning Electron Microscopy (FE-SEM) images of transparent nanopaper. (B) FE-SEM images of ESNP; (b) Schematic representation for the fabrication of ESNPs. Adapted with permission from [94]. Copyright 2015. Reproduced with permission from Elsevier.

Figure 5

(a) Nanocellulose biosynthesis by Komagataeibacter hansenii in a defined minimal culture medium. Membranes with increased optical properties are visible in the figure. Reproduced with permission [20]. Copyright 2018. Reproduced with permission from Springer; (b) Schematic illustration of steps involved in the fabrication in situ of BNC/RGO nanocomposites. Reproduced with permission [93]. Copyright 2019. Reproduced with permission from the American Chemical Society; (c) Biosynthesis of 6CF-BNC based on an in-situ microbial fermentation method [129].

Figure 5

(a) Nanocellulose biosynthesis by Komagataeibacter hansenii in a defined minimal culture medium. Membranes with increased optical properties are visible in the figure. Reproduced with permission [20]. Copyright 2018. Reproduced with permission from Springer; (b) Schematic illustration of steps involved in the fabrication in situ of BNC/RGO nanocomposites. Reproduced with permission [93]. Copyright 2019. Reproduced with permission from the American Chemical Society; (c) Biosynthesis of 6CF-BNC based on an in-situ microbial fermentation method [129].

Figure 6

A typical design of antibody-, enzyme-, and DNA-based electrochemical biosensors, based on information from [46].