Surface Modification of Bacterial Cellulose for Biomedical Applications

Abstract

Bacterial cellulose is a naturally occurring polysaccharide with numerous biomedical applications that range from drug delivery platforms to tissue engineering strategies. BC possesses remarkable biocompatibility, microstructure, and mechanical properties that resemble native human tissues, making it suitable for the replacement of damaged or injured tissues. In this review, we will discuss the structure and mechanical properties of the BC and summarize the techniques used to characterize these properties. We will also discuss the functionalization of BC to yield nanocomposites and the surface modification of BC by plasma and irradiation-based methods to fabricate materials with improved functionalities such as bactericidal capabilities.

Keywords: bacterial cellulose; bactericidal; interface; surface analysis; surface chemistry; surface functionalization; tissue engineering.

Figure 5

Magnetic BC. (A) Macroscopic appearance of a magnetic BC hydrogel loaded with ferromagnetic nanoparticles. SEM images of (B) Pristine (left) and (C) magnetite-functionalized BC (right). (D) Magnetization saturation curve for 100 mM MBC shows that composite is superparamagnetic and has a maximum magnetic saturation of 10 emu/g. Reproduced with permission from [18] (Copyright © 2022, Journal of Visualized Experiments), [21] (Copyright © 2022, Elsevier).

Figure 1

(A) Arrangement of microfibril in amorphous and crystalline region and its macroscopic appearance in wet conditions. (B) BC loaded with water and its SEM image. (C) Molecular structure of “cellobiose unit.” (D) H-bonding in the matrix of the BC. Reproduced with permission from [27] (Copyright © 2022, Elsevier), [32] (Open Access).

Figure 2

(A) X-ray diffraction spectrum (B) FTIR spectrum (C) Raman Spectra comparing BC, Sigma Aldrich and Avicel PH10 samples [29]. (D) CPMAS ¹³C-NMR spectrum of BC fully ¹³C labeled obtained without treatment and its carbon signal assignment. (E) GPC analysis of BC samples produced via batch cultivation in chemically defined medium (a), fed-batch cultivation of chemically defined medium (b), and fed-batch cultivation of waste from beer fermentation broth (WBFB) (c) in static conditions in a Jar fermenter, (F) table showing the molecular weight distribution obtained from GPS. Reproduced with permission from [38] (Copyright © 2022, Springer Science Business Media B.V., part of Springer), [39] (Copyright © 2022, Elsevier), [36] (Copyright © 2022 Elsevier).

Figure 3

(A,B) High Resolution XPS spectra of C1s and O1s of pure BC. (C,D) TGA and DSC analysis from 3-aminopropyl triethoxysilane treated BC membrane (BC-APS), vinyl-triethoxy silane treated BC membrane (BC-VS), acrylated BC membrane (BC-AA), acetylated BC membrane (BC-AC). Inset (C,D): initial degradation step. Reproduced with permission from [41] (Copyright © 2022, Elsevier), [37] (Open Access).

Figure 4

Schematic showing the ideal biomaterial as a combination of engineered bulk and surface properties that trigger adequate immune responses while minimizing the risk of infection, commonly referred as “the race for the surface”.

Figure 6

SEM images of (A) pristine BC (B) irradiated BC. (C) Chemical and physical sputtering of BC surface. Reproduced with permission from [19] (Copyright © 2022, American Chemical Society).

Figure 7

Silver-loaded nanopatterned BC fabricated via ion beam irradiation. (A) SEM images, and (B) nanoparticle size distribution at two different irradiation angles.

Figure 8

Bactericidal nanostructures fabricated in BC. (A) Typical antibiofouling and antimicrobial strategies implemented on hydrogels and very compliant materials. (B) Contact-killing via mechanical means can be the result of capillary forces in the air-liquid interface as well as tension-induced mechanical rupture. (C) Indentation of the bacterial envelope in Escherichia coli and Bacillus subtilis in contact with nanostructured BC. The asterisks and arrows indicate the indentation left on the bacterial envelope by the BC’s nanostructures before and after the cross-sectional cut, respectively; (D) average force values necessary to penetrate B. subtilis, E. coli, S. typhimurium, and HEK93 cells as a function of the membrane stiffness. Reproduced with permission from [20]. (Copyright © 2022, American Chemical Society).