Controlled Hydrophobic Biosurface of Bacterial Cellulose Nanofibers through Self-Assembly of Natural Zein Protein

Abstract

A novel, highly biocompatible bacterial cellulose (BC)-zein composite nanofiber with a controlled hydrophobic biosurface was successfully developed through a simple and green solution impregnation method, followed by evaporation-induced self-assembly (EISA) of adsorbed zein protein. The surface hydrophobicity of the zein-modified BC nanofibers could be controlled by simply changing the zein concentration, which is able to tune the morphology of self-assembled zein structures after EISA, thus affecting the surface roughness of composite membranes. Zein self-assembly at low concentrations (5 mg/mL) resulted in the formation of hierarchical zein structures (spheres and bicontinuous sponges) on the BC surface, thus increasing the surface roughness and leading to high hydrophobicity (the water contact angle reached 110.5°). However, at high zein concentrations, these large zein spheres assembled into a flat zein film, which decreased the surface roughness and hydrophobicity of membranes. The homogeneous incorporation of zein structures on the BC surface by hydrogen bonding did not significantly change the internal structure and mechanical performance of BC nanofibers. In comparison with pure BC, the BC-zein nanofibers had a better biocompatibility, showing a significantly increased adhesion and proliferation of fibroblast cells. This is probably due to the rough surface structure of BC-zein nanofibers as well as the high biocompatibility of natural zein protein. The novel BC-zein composite nanofibers with controlled surface roughness and hydrophobicity could be of particular interest for the design of BC-based biomaterials and biodevices that require specific surface properties and adhesion.

Development of novel bacterial cellulose composites for the textile and shoe industry

“…Further, the hydrophilic nature of BC hinders the combination with hydrophobic polymer matrixes, an obstacle to the development of composites where both BC and the added polymer contribute to the final desirable properties. Several studies have been conducted on the chemical modification/hydrophobization of cellulose and of BC in particular, attempting to overcome these issues (Tomita et al ., ; Nisoa and Wanichapichart, ; Tomé et al ., ; Wan et al ., ).…”

Improvement of bacterial cellulose nonwoven fabrics by physical entrapment of lauryl gallate oligomers

“…This increased crystallinity contributed to a decrease in moisture uptake, due to the long hydrophobic aliphatic groups entrapped in BC nonwoven fabric. 46,47 Das 48 reported that crystallinity provides strength to fibers and, thus, plays a significant role in fiber mechanical properties. Therefore, the increase of crystallinity by the physical entrapment of lauryl gallate oligomers can improve durability of BC nonwoven fabric.…”

Biological Engineered Living Materials: Growing Functional Materials with Genetically Programmable Properties

“…One common approach to develop new BC-based materials is to blend BC with another biological macromolecule to create a composite. In fact, many biological species have been used to modify BC material properties, including spider silk 61 , gelatin 62 , zein 63 , collagen 64 , hyaluronan 65 , alginate 66 , heparin 67,68 , antimicrobial peptides 69 and growth factors 70,71 . While some of these species were incorporated into the BC matrix by non-specific interactions, others have been specifically bound by fusion to a cellulose-binding domain (CBD) protein [72][73][74] .…”

“…Engineering co-secretion of these polysaccharides from BC-producing bacteria could enable the production of a variety of novel copolymer materials. Similarly, numerous reports have demonstrated that purified proteins can be externally added to BC to confer new and useful material properties, for instance, increased hydrophobicity or catalytic activity 63,87,88 . Going forwards, it may be possible to engineer BC-producing bacteria to secrete proteins themselves and therefore functionalise BC in situ.…”