Ion-Induced Nanopatterning of Bacterial Cellulose Hydrogels for Biosensing and Anti-Biofouling Interfaces

Abstract

Hydrogels provide a solution-mimicking environment for the interaction with living systems that make them desirable for various biomedical and technological applications. Because relevant biological processes in living tissues occur at the biomolecular scale, hydrogel nanopatterning can be leveraged to attain novel material properties and functionalities. However, the fabrication of high aspect ratio (HAR) nanostructures in hydrogels capable of self-standing in aqueous environments, with fine control of the size and shape distribution, remains challenging. Here, we report the synthesis of nanostructures with a HAR in bacterial cellulose (BC) hydrogel via directed plasma nanosynthesis using argon ions. The nanostructures in BC are reproducible, stable to sterilization, and liquid immersion. Using in-situ surface characterization and semiempirical modeling, we discovered that pattern formation was linked to the formation of graphitelike clusters composed of a mixture of C-C and C=C bonds. Moreover, our model predicts that reactive species at the onset of the argon irradiation accelerate the bond breaking of weak bonds, contributing to the formation of an amorphous carbon layer and nanopattern growth.

Surface Modification of Bacterial Cellulose for Biomedical Applications

“…The macromolecules hence organize in units producing subfibrils of 10–15 glucan chains that further assemble to form microfibrils, and finally microfibril bundles with diameter of 20–100 nm forms a gelatinous membrane. The microfiber diameter determines the properties and applications of the BC film [ 19 ]. Small diameters provide BC with high surface area for the interaction with biological molecules, and their characteristic stress strain nature closely mimic the inherent complexity and hierarchical structure of native tissues [ 31 ].…”

“…For example, BC subjected to ion-irradiation leads to the formation of self-organized nanostructures by reorganization of the fibrous surface structure ( Figure 6 ). In addition to this morphological transformation, ion irradiation of BC also induces chemical changes, including alteration of the atomic composition and crystallinity [ 19 ]. The properties of these nanopatterned surfaces make ion-irradiated BC a great candidate as a biocidal surface [ 20 , 97 ].…”

“…Moreover, BC possesses high purity with high water retaining capacity, easily modifiable biodegradability, biocompatibility with facile production, purification and mouldability. The micromorphology of BC has a distinctive network of cellulose nanofiber consisting of unique feature rendering them as oil absorbents, fuel cell, catalyst and biomedical applications such as drug delivery, tissue engineering, skin repair and wound dressing [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”

The effects of surface topography modification on hydrogel properties

“… 23,25,29,30 Another popular way to fabricate surface topographically patterned hydrogel is photolithographic patterning technique, where the mixed solution of photoinitiator and monomer are layered onto the photoactive hydrogel substrate and exposed to UV light through the photolithographic mask with desired patterns. 31,32 Other commonly used methods, such as nanoimprinting, 23,33–35 3D printing, 36–38 electrospinning, 39–41 multiphoton patterning, 42–45 e-beam lithographic patterning, 46,47 Self-assembly wrinkle technique, 48,49 ion-induced nanopatterning, 50 and swelling-induced patterning, 51,52 also have their own specific fabrication mechanism and process. In addition, many research groups have also developed effective methods to add patterns to hydrogel substrates.…”

Ion Beam Nanopatterning of Biomaterial Surfaces

“…While it is well established that topographically nanopatterned surfaces can exhibit contact-killing properties by inducing the rupture of the bacterial plasma membrane, such patterns typically require comparatively high aspect ratios [134,135]. To achieve such high aspect ratios, Arias et al irradiated dried bacterial cellulose (BC) hydrogels with 1 keV Ar + ions at normal incidence [136]. With increasing ion fluence, this resulted in a transition of the original BC morphology that is composed of interlaced ribbons to self-standing spike-like nanostructures 50-70 nm in width and about 400 nm in height.…”