Plant-Derived Nanocellulose as Structural and Mechanical Reinforcement of Freeze-Cast Chitosan Scaffolds for Biomedical Applications

Abstract

Despite considerable recent interest in microand nanofibrillated cellulose as constituents of lightweight structures and scaffolds for applications that range from thermal insulation to filtration, few systematic studies have been reported to date on structure−property-processing correlations in freeze-cast chitosan−nanocellulose composite scaffolds, in general, and their application in tissue regeneration, in particular. Reported in this study are the effects of the addition of plant-derived nanocellulose fibrils (CNF), crystals (CNCs), or a blend of the two (CNB) to the biopolymer chitosan on the structure and properties of the resulting composites. Chitosan−nanocellulose composite scaffolds were freeze-cast at 10 and 1 °C/min, and their microstructures were quantified in both the dry and fully hydrated states using scanning electron and confocal microscopy, respectively. The modulus, yield strength, and toughness (work to 60% strain) were determined in compression parallel and the modulus also perpendicular to the freezing direction to quantify anisotropy. Observed were the preferential alignments of CNCs and/or fibrils parallel to the freezing direction. Additionally, observed was the self-assembly of the nanocellulose into microstruts and microbridges between adjacent cell walls (lamellae), features that affected the mechanical properties of the scaffolds. When freeze-cast at 1 °C/min, chitosan−CNF scaffolds had the highest modulus, yield strength, toughness, and smallest anisotropy ratio, followed by chitosan and the composites made with the nanocellulose blend, and that with crystalline cellulose. These results illustrate that the nanocellulose additions homogenize the mechanical properties of the scaffold through cell-wall material self-assembly, on the one hand, and add architectural features such as bridges and pillars, on the other. The latter transfer loads and enable the scaffolds to resist deformation also perpendicular to the freezing direction. The observed property profile and the materials' proven biocompatibility highlight the promise of chitosan−nanocellulose composites for a large range of applications, including those for biomedical implants and devices.

Development of Inula graveolens (L.) Plant Extract Electrospun/Polycaprolactone Nanofibers: A Novel Material for Biomedical Application

“…The major benefit of plant scaffolding is the obvious simplicity with which it can be produced and handled; the design of a variety of sizes and shapes is entirely foldable, easy to cut, shaped, rolled, or stacked. They can also be reused, are easy to use, and are relatively cheap [26]. The principle of plant material Electrospun comprising therapeutic characteristics especially wound healing on the polymer matrix, is impressive.…”

Ice Templating Soft Matter: Fundamental Principles and Fabrication Approaches to Tailor Pore Structure and Morphology and Their Biomedical Applications

“…As ice forms further away from the cooled base, displacement becomes the more likely mechanism; increasing the likelihood of lamellar pore formation at each point further away from the base. [112] Scale bar is 100 µm. A) Adapted with permission.…”

“…[111] Copyright 1986, John Wiley & Sons, Inc. B) Adapted with permission. [112] Copyright 2019, American Chemical Society.…”

“…Mainly explored in unidirectional freezing setups, coupling microscopy analysis in early optimization experiments with thermal profiles provides the framework required to develop material specific models [66,89] or understanding of how different cooling can be used to control ice crystal (i.e., pore) size and shape. [20,31,68,107,112] Especially important in unidirectional freezing setups, quantifying thermal profiles at different points away from the cooling element can be used to quantify ice front growth rate [20] and act as an optimization guide to achieve different pore morphologies within the same experimental setup. [124,132]…”

Green one-step synthesis of cellulose nanocrystal/ ZnO nanohybrid with high photocatalytic activity

“…Để khắc phục nhược điểm trên các nhà khoa học đang rất quan tâm đến việc tổng hợp ZnO NPs trên nền một vật liệu khác, đóng vai trò là giá mang giúp cải thiện sự phân tán ZnO NPs ở cấp độ nanomet. Cellulose là một trong những polymer sinh học có nguồn gốc tự nhiên phong phú nhất, được sử dụng rộng rãi làm pha gia cường cho pha nền là nhựa nhiệt dẻo trong lãnh vực chế tạo vật liệu composite [8][9][10][11][12] . Các tinh thể nano cellulose (CNC) được điều chế bằng cách thủy phân cellulose trong môi trường axit thường có dạng hình que cứng, hàm lượng tinh thể cao với đường kính thay đổi từ 1-100 nm, tùy thuộc vào nguồn sinh khối 13 .…”