A new approach to purification of bacterial cellulose membranes: What happens to bacteria in supercritical media?

Designed Microbial Biosynthesis of Hierarchical Bone-Mimetic Biocomposites in 3D-Printed Soft Bioreactors

The creation of 3D biomimetic composite structures has important applications in tissue engineering, lightweight structures, drug delivery, and sensing. Previous approaches in fabricating 3D biomimetic composites have relied on blending or assembling chemically synthesized molecules or structures, making it challenging to achieve precise control of the size, geometry, and internal structure of the biomimetic composites. Here, we present a new approach for the creation of 3D bone-mimetic biocomposites with precisely controlled shape, hierarchical structure, and functionalities. Our approach is based on the integration of programmable microbial biosynthesis with 3D printing of gas-permeable and customizable bioreactors. The organic and inorganic components are bacterial cellulose and calcium hydroxyapatite via a mineral precursor, which are generated by Komagataeibacter xylinus and Bacillus simplex P6A, respectively, in 3D-printed silicone bioreactors in consecutive culturing cycles. This study is of high significance to biocomposites, biofabrication, and tissue engineering as it paves the way for the synergistic integration of microbial biosynthesis and additive manufacturing.

Biosorption of bioactive compounds in bacterial nanocellulose: Mechanisms and physical-chemical properties

Bacterial cellulose (BC) is a biomaterial produced by Gluconacetobacter xylinus, with wide applicability in different areas, such as biomedical, pharmaceutical, and food. BC production is usually carried out in a medium containing phenolic compounds (PC), such as teas, however, the purification process leads to the loss of such bioactive. Thus, the innovation of this research consists of the reincorporation of PC after the purification of the BC matrices through the biosorption process. In this context, the effects of the biosorption process in BC were evaluated to maximize the incorporation of phenolic compounds from a ternary mixture of hibiscus (Hibiscus sabdariffa), white tea (Camellia sinensis), and grape pomace (Vitis labrusca). The biosorbed membrane (BC-Bio) showed a great concentration of total phenolic compounds (TPC = 64.89 mg L^-1) and high antioxidant capacity through different assays (FRAP: 130.7 mg L^-1, DPPH: 83.4 mg L^-1, ABTS: 158.6 mg L^-1, TBARS: 234.2 mg L^-1). The physical tests also indicated that the biosorbed membrane presented high water absorption capacity, thermal stability, low permeability to water vapor and improved mechanical properties compared to BC-control. These results index that the biosorption of phenolic compounds in BC efficiently increases bioactive content and improves physical membrane characteristics. Also, PC release in a buffered solution suggests that BC-Bio can be used as a polyphenol delivery system. Therefore, BC-Bio is a polymer with wide application in different industrial segments.

Bacterial Cellulose-A Remarkable Polymer as a Source for Biomaterials Tailoring

Nowadays, the development of new eco-friendly and biocompatible materials using ‘green’ technologies represents a significant challenge for the biomedical and pharmaceutical fields to reduce the destructive actions of scientific research on the human body and the environment. Thus, bacterial cellulose (BC) has a central place among these novel tailored biomaterials. BC is a non-pathogenic bacteria-produced polysaccharide with a 3D nanofibrous structure, chemically identical to plant cellulose, but exhibiting greater purity and crystallinity. Bacterial cellulose possesses excellent physicochemical and mechanical properties, adequate capacity to absorb a large quantity of water, non-toxicity, chemical inertness, biocompatibility, biodegradability, proper capacity to form films and to stabilize emulsions, high porosity, and a large surface area. Due to its suitable characteristics, this ecological material can combine with multiple polymers and diverse bioactive agents to develop new materials and composites. Bacterial cellulose alone, and with its mixtures, exhibits numerous applications, including in the food and electronic industries and in the biotechnological and biomedical areas (such as in wound dressing, tissue engineering, dental implants, drug delivery systems, and cell culture). This review presents an overview of the main properties and uses of bacterial cellulose and the latest promising future applications, such as in biological diagnosis, biosensors, personalized regenerative medicine, and nerve and ocular tissue engineering.

Green approach for fabrication of bacterial cellulose-chitosan composites in the solutions of carbonic acid under high pressure CO2

The functionalization of the bacterial cellulose (BC) surface with a chitosan biopolymer to expand the areas of possible applications of the modified BC is an important scientific task. The creation of such composites in the carbonic acid solutions that were performed in this work has several advantages in terms of being biocompatible and eco-friendly. Quantitative analysis of chitosan content in the composite was conducted by tritium-labeled chitosan radioactivity detection method and this showed three times increased chitosan loading. Different physicochemical methods showed successful incorporation of chitosan into the BC matrix and interaction with it through hydrogen bonds. Microscopy results showed that the chitosan coating with a thickness of around 10 nm was formed in the bulk of BC, covering each microfibril. It was found that the inner specific surface area increased 1.5 times on deposition of chitosan from the solutions in carbonic acid.