ABSTRACT
Microbial cellulose paper treated with polyaniline and carbon nanotubes (PANI/CNTs) can be attractive as potential flexible capacitors in terms of further improvements to the conductivity and thermal resistance. The interactions between PANI and CNTs exhibit new electrochemical features with increased electrical conductivity and enhanced capacity. In this study, PANI/CNTs was incorporated into a flexible poly(4-vinylaniline)-grafted bacterial cellulose (BC/PVAN) nanocomposite substrate for further functionalization and processability. PANI/CNTs coatings with a nanorod-like structure can promote an efficient ion diffusion and charge transfer, with a significant enhancement of the electrical conductivity after CNTs reinforcement of 1 order of magnitude up to (1.0 ± 0.3) × 10-1 S·cm-1. An escalating improvement of the double charge capacity (â¼54 mF) of the grafted BC nanocomposites was also detected through electrochemical analysis. The multilayered electrical coatings also reinforce the thermal resistance, preventing anticipated thermal degradation of the BC substrate. The cell viability and differentiation assays using neural stem cells (SVZ cells) testified to the cytocompatibility of the grafted BC nanocomposites, while inducing neuronal differentiation over 7 days of culture with a neurite that was 77 ± 24.7 µm long. This is promising for meeting the requirements in the construction of high-performance bioelectronic devices that can actively interface biologically, providing a friendly environment for cells while tuning the device performance.
ABSTRACT
Bacterial cellulose (BC) has interesting properties including high crystallinity, tensile strength, degree of polymerisation, water holding capacity (98%) and an overall attractive 3D nanofibrillar structure. The mechanical and electrochemical properties can be tailored upon incomplete BC dehydration. Under different water contents (100, 80 and 50%), the rheology and electrochemistry of BC were evaluated, showing a progressive stiffening and increasing resistance with lower capacitance after partial dehydration. BC water loss was mathematically modelled for predicting its water content and for understanding the structural changes of post-dried BC. The dehydration of the samples was determined via water evaporation at 37 °C for different diameters and thicknesses. The gradual water evaporation observed was well-described by the model proposed (R2 up to 0.99). The mathematical model for BC water loss may allow the optimisation of these properties for an intended application and may be extendable for other conditions and purposes.
