The influence of versatile thiol-norbornene modifications to cellulose nanofibers on rheology and film properties

Magnetically-activated, nanostructured cellulose for efficient capture of circulating tumor cells from the blood sample of head and neck cancer patients

In this report, the relative efficiency of cellulose nanocrystals (CNCs) and nanofibers (CNFs) to capture circulating tumor cells (CTCs) from the blood sample of head and neck cancer (HNC) patients was evaluated. Detection and enumeration of CTCs are critical for monitoring cancer progression. Both types of nanostructured cellulose were chemically modified with Epithelial Cell Adhesion Molecule (EpCAM) antibody and iron oxide nanoparticles. The EpCAM antibody facilitated the engagement of CTCs, promoting entrapment within the cellulose cage structure. Iron oxide nanoparticles, on the other hand, rendered the cages activatable via the use of a magnet for the capture and separation of entrapped CTCs. The efficiency of the network structures is shown in head and neck cancer (HNC) patients' blood samples. It was observed that the degree of chemical functionalization of hydroxyl groups located within the CNCs or CNFs with anti-EpCAM determined the efficiency of the system's interaction with CTCs. Further, our result indicated that inflexible scaffolds of nanocrystals interacted more efficiently with CTCs than that of the fibrous CNF scaffolds. Network structures derived from CNCs demonstrated comparable CTC capturing efficiency to commercial standard, OncoDiscover®. The output of the work will provide the chemical design principles of cellulosic materials intended for constructing affordable platforms for monitoring cancer progression in 'real time'.

Application of polysaccharide biopolymers as natural adsorbent in sample preparation

Preparing samples for analyses is perhaps the most important part to analyses. The varied functional groups present on the surface of biopolymers bestow them appropriate adsorption properties. Properties like biocompatibility, biodegradability, presence of different surface functional group, high porosity, considerable absorption capacity for water, the potential for modification, etc. turn biopolymers to promising candidates for varied applications. In addition, one of the most important parts of determination of an analyte in a matrix is sample preparation step and the efficiency of this step in solid phase extraction methods is largely dependent on the type of adsorbent used. Due to the unique properties of biopolymers they are considered an appropriate choice for using as sorbent in sample preparation methods that use from a solid adsorbent. Many review articles have been published on the application of diverse adsorbents in sample preparation methods, however despite the numerous advantages of biopolymers mentioned; review articles in this field are very few. Thus, in this paper we review the reports in different areas of sample preparation that use polysaccharides-based biopolymers as sorbents for extraction and determination of diverse organic and inorganic analytes.

Chemically Modified Biopolymers for the Formation of Biomedical Hydrogels

Biopolymers are natural polymers sourced from plants and animals, which include a variety of polysaccharides and polypeptides. The inclusion of biopolymers into biomedical hydrogels is of great interest because of their inherent biochemical and biophysical properties, such as cellular adhesion, degradation, and viscoelasticity. The objective of this Review is to provide a detailed overview of the design and development of biopolymer hydrogels for biomedical applications, with an emphasis on biopolymer chemical modifications and cross-linking methods. First, the fundamentals of biopolymers and chemical conjugation methods to introduce cross-linking groups are described. Cross-linking methods to form biopolymer networks are then discussed in detail, including (i) covalent cross-linking (e.g., free radical chain polymerization, click cross-linking, cross-linking due to oxidation of phenolic groups), (ii) dynamic covalent cross-linking (e.g., Schiff base formation, disulfide formation, reversible Diels-Alder reactions), and (iii) physical cross-linking (e.g., guest-host interactions, hydrogen bonding, metal-ligand coordination, grafted biopolymers). Finally, recent advances in the use of chemically modified biopolymer hydrogels for the biofabrication of tissue scaffolds, therapeutic delivery, tissue adhesives and sealants, as well as the formation of interpenetrating network biopolymer hydrogels, are highlighted.

Hydrophobic functionalization reactions of structured cellulose nanomaterials: Mechanisms, kinetics and in silico multi-scale models

Nanoscale-interfaced cellulose nanomaterials are extracted from polysaccharides, which are widely available in nature, biocompatible and biodegradable. Moreover, the latter have a potential to be recycled, upcycled, and formulate therefore a great theoretical predisposition to be used in a number of applications. Nanocrystals, nano-fibrils and nanofibers possess reactive functional groups that enable hydrophobic surface modifications. Analysed literature data, concerning mechanisms, pathways and kinetics, was screened, compared and assessed with regard to the demand of a catalyst, different measurement conditions and added molecule reactions. There is presently only a scarce technique description for carbonOH bond functionalization, considering the elementary chemical steps, sequences and intermediates of these (non)catalytic transformations. The overview of the prevailing basic research together with in silico modelling approach methodology gives us a deeper physical understanding of processes. Finally, to further highlight the applicability of such raw materials, the review of the development in several multidisciplinary fields was presented.

Aqueous Polymer Modification of Cellulose Nanofibrils by Grafting-Through a Reactive Methacrylate Group

Modifying the surface of cellulose nanofibrils (CNFs) produced by mechanical refinement with a variety of polymer functional groups in an entirely water-based system is challenging because only surface hydroxyl groups are accessible. To address this limitation, an entirely water-based, polymer modification scheme is developed. CNFs are functionalized with a reactive methacrylate functional group followed by subsequent grafting-through polymerization. This modification worked with a variety of water-soluble and water-insoluble (meth)acrylates and (meth)acrylamides, grafting up to 45 wt% polymer on to the CNFs. The reaction conditions introducing the methacrylate functional group are adjusted to vary the degree of functionality. Soxhlet extraction of modified samples demonstrates that the reactive methacrylate group is necessary to facilitate polymer grafting. The degree of functionalization of the polymers is studied via quantitative transmission IR spectroscopy and the morphology of the resulting cellulose nanofibrils is studied via a combination of optical, scanning electron, and atomic force microscopy. High levels of polymer modification do not significantly affect the micrometer-scale fibril morphology.

Material Extrusion Additive Manufacturing of Wood and Lignocellulosic Filled Composites

Wood and lignocellulosic-based material components are explored in this review as functional additives and reinforcements in composites for extrusion-based additive manufacturing (AM) or 3D printing. The motivation for using these sustainable alternatives in 3D printing includes enhancing material properties of the resulting printed parts, while providing a green alternative to carbon or glass filled polymer matrices, all at reduced material costs. Previous review articles on this topic have focused only on introducing the use of natural fillers with material extrusion AM and discussion of their subsequent material properties. This review not only discusses the present state of materials extrusion AM using natural filler-based composites but will also fill in the knowledge gap regarding state-of-the-art applications of these materials. Emphasis will also be placed on addressing the challenges associated with 3D printing using these materials, including use with large-scale manufacturing, while providing insight to overcome these issues in the future.