Bacterial Cellulose Nanocomposites: Morphology and Mechanical Properties.

Natalia Pogorelova,Svetlana Chernigova,Dmitry Nardin,Ilya Digel,Evgeniy Rogachev

doi:10.3390/ma13122849

Natalia Pogorelova, Svetlana Chernigova + Show 3 more

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https://doi.org/10.3390/ma13122849

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Abstract

Bacterial cellulose (BC) is a promising material for biomedical applications due to its unique properties such as high mechanical strength and biocompatibility. This article describes the microbiological synthesis, modification, and characterization of the obtained BC-nanocomposites originating from symbiotic consortium Medusomyces gisevii. Two BC-modifications have been obtained: BC-Ag and BC-calcium phosphate (BC-Ca3(PO4)2). Structure and physicochemical properties of the BC and its modifications were investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and infrared Fourier spectroscopy as well as by measurements of mechanical and water holding/absorbing capacities. Topographic analysis of the surface revealed multicomponent thick fibrils (150–160 nm in diameter and about 15 µm in length) constituted by 50–60 nm nanofibrils weaved into a left-hand helix. Distinctive features of Ca-phosphate-modified BC samples were (a) the presence of 500–700 nm entanglements and (b) inclusions of Ca3(PO4)2 crystals. The samples impregnated with Ag nanoparticles exhibited numerous roundish inclusions, about 110 nm in diameter. The boundaries between the organic and inorganic phases were very distinct in both cases. The Ag-modified samples also showed a prominent waving pattern in the packing of nanofibrils. The obtained BC gel films possessed water-holding capacity of about 62.35 g/g. However, the dried (to a constant mass) BC-films later exhibited a low water absorption capacity (3.82 g/g). It was found that decellularized BC samples had 2.4 times larger Young’s modulus and 2.2 times greater tensile strength as compared to dehydrated native BC films. We presume that this was caused by molecular compaction of the BC structure.

Highlights

Cellulose is the most widespread natural polysaccharide, synthesized by plants, microorganisms, and some animals [1]
We studied the properties of different bacterial cellulose (BC) nanocomposites keeping in mind its possible future industrial production using Medusomyces gisevii
Drying of the BC even at room temperatures lead to a significant decrease in its later water absorption capacity (WAC = 3.82 ± 0.12 g/g), which may be due to significant rearrangements in the internal structure of the polymer matrix induced by water loss

Summary

Introduction

Cellulose is the most widespread natural polysaccharide, synthesized by plants, microorganisms, and some animals [1]. Due to their numerous advantageous properties, cellulose nanomaterials (CNs) have garnered a tremendous attention in engineering and medicine, as very promising components of various nanocellulose-integrated matrices, electrochromic systems, nanogenerators piezoelectric systems, etc. Cellulose grafting by silver nanoparticles and calcium salts has already opened many exciting possibilities. Silver nanoparticles are continuously gaining usage in antibacterial food packaging [6,7] and in medical materials, e.g., wound dressings, catheters, aprons, face masks, gloves etc. The unique bioactive properties of grafted cellulose encourage research teams around the world to focus their work on a more effective and safe cellulose-derived materials.

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