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The degree of crystallinity in cellulose significantly affects the physical, mechanical, and chemical properties of cellulosic materials, their processing, and their final application. Measuring the crystalline structures of cellulose is a challenging task due to inadequate consistency among the variety of analytical techniques available and the lack of absolute crystalline and amorphous standards. Our article reviews the primary methods for estimating the crystallinity of cellulose, namely, X-ray diffraction (XRD), nuclear magnetic resonance (NMR), Raman and Fourier-transform infrared (FTIR) spectroscopy, sum-frequency generation vibrational spectroscopy (SFG), as well as differential scanning calorimetry (DSC), and evolving biochemical methods using cellulose binding molecules (CBMs). The techniques are compared to better interrogate not only the requirements of each method, but also their differences, synergies, and limitations. The article highlights fundamental principles to guide the general community to initiate studies of the crystallinity of cellulosic materials. [ABSTRACT FROM AUTHOR]

Hydrogels have likely not made widespread penetration in biomedical engineering work due to several key hurdles such as poor mechanical strength and non-existent antimicrobial properties. A new semi-interpenetrating polymer network (Semi-IPN) hydrogel was prepared by interpenetrating carboxymethyl chitosan (CMCH) with acrylamide (AM) and maleic acid (MA) by covalent bond crosslinking enhanced by ionic (carboxylic–Fe3+) secondary crosslinks. These hydrogels show a good tensile stress of about 1.44 MPa as well as outstanding antibacterial activity against Staphylococcus aureus and Gram-negative E. coli because of CMCH. [ABSTRACT FROM AUTHOR]

Here, we report for the first time a one-pot in situ biosynthetic method to fabricate structurally controllable bacterial cellulose (BC)/reduced graphene oxide (RGO) composites. Graphene oxide (GO) was highly reduced during a standard autoclave process using a traditional mannitol culture medium as the reducing agent. The RGO sheets prepared exhibit a high carbon to oxygen ratio of 3.1, as compared to 1.8 for GO determined by X-ray photoelectron spectroscopy. The electrical conductivity of the RGO was found to be 23.75 S m-1. The final BC/RGO composites were developed in three distinct forms: sealed structures in water, aerogels characterized by a porous cross-section and an aligned longitudinal structure, and films embedded within the RGO sheets. Because of the simplicity and non-toxic nature of this work, this process can be used in biomedical and bioelectronics applications, which can be placed within the context of novel biocompatible materials. [ABSTRACT FROM AUTHOR]