Synthesis of PLA-co-PGMA Copolymer and its Application in the Surface Modification of Bacterial Cellulose

Graft onto approaches for nanocellulose-based advanced functional materials

The resurgence of cellulose as nano-dimensional 'nanocellulose' has unlocked a sustainable bioeconomy for the development of advanced functional biomaterials. Bestowed with multifunctional attributes, such as renewability and abundance of its source, biodegradability, biocompatibility, superior mechanical, optical, and rheological properties, tunable self-assembly and surface chemistry, nanocellulose presents exclusive opportunities for a wide range of novel applications. However, to alleviate its intrinsic hydrophilicity-related constraints surface functionalization is inevitably needed to foster various targeted applications. The abundant surface hydroxyl groups on nanocellulose offer opportunities for grafting small molecules or macromolecular entities using either a 'graft onto' or 'graft from' approach, resulting in materials with distinctive functionalities. Most of the reviews published to date extensively discussed 'graft from' modification approaches, however 'graft onto' approaches are not well discussed. Hence, this review aims to provide a comprehensive summary of 'graft onto' approaches. Furthermore, insight into some of the recently emerging applications of this grafted nanocellulose including advanced nanocomposite formulation, stimuli-responsive materials, bioimaging, sensing, biomedicine, packaging, and wastewater treatment has also been reviewed.

Enzymatic Ring-Opening Polymerization (ROP) of Polylactones: Roles of Non-Aqueous Solvents

Aliphatic polyesters such as polylactides (PLAs) and other polylactones are thermoplastic, renewable and biocompatible polymers with high potentials to replace petro-chemical-based synthetic polymers. A benign route for synthesizing these polyesters is through the enzyme-catalyzed ring-opening polymerization (ROP) reaction; this type of enzymatic process is very sensitive to reaction conditions such as solvents, water content and temperature. This review systematically discusses the crucial roles of different solvents (such as solvent-free or in bulk, organic solvents, supercritical fluids, ionic liquids, and aqueous biphasic systems) on the degree of polymerization and polydispersity. In general, many studies suggest that hydrophobic organic solvents with minimum water contents lead to efficient enzymatic polymerization and subsequently high molecular weights of polyesters; the selection of solvents is also limited by the reaction temperature, e.g. the ROP of lactide is often conducted at above 100 °C, therefore, the solvent typically needs to have its boiling point above this temperature. The use of supercritical fluids could be limited by its scaling-up potential, while ionic liquids have exhibited many advantages include their low-volatility, high thermal stability, controllable enzyme-compatibility, and a wide range of choices. However, the fundamental and mechanistic understanding of the specific roles of ionic liquids in enzymatic ROP reactions is still lacking. Furthermore, the lipase specificity towards l- and d-lactide is also surveyed, followed by the discussion of engineered lipases with improved enantioselectivity and thermal stability. In addition, the preparation of polyester-derived materials such as polyester-grafted cellulose by the enzymatic ROP method is briefly reviewed.

Melt free radical grafting of glycidyl methacrylate (GMA) onto fully biodegradable poly(lactic) acid films: effect of cellulose nanocrystals and a masterbatch process

This article reports the preparation, by means of a masterbatch procedure, of poly (lactic acid) (PLA)/cellulose nanocrystal (CNC) films via premixing 1% wt of CNC into PLA or glycidyl methacrylate (GMA) grafted PLA (g-PLA).

A review of bacterial cellulose-based drug delivery systems: their biochemistry, current approaches and future prospects

Objectives

The field of pharmaceutical technology is expanding rapidly because of the increasing number of drug delivery options. Successful drug delivery is influenced by multiple factors, one of which is the appropriate identification of materials for research and engineering of new drug delivery systems. Bacterial cellulose (BC) is one such biopolymer that fulfils the criteria for consideration as a drug delivery material.

Key findings

BC showed versatility in terms of its potential for in-situ modulation, chemical modification after synthesis and application in the biomedical field, thus expanding the current, more limited view of BC and facilitating the investigation of its potential for application in drug delivery.

Summary

Cellulose, which is widely available in nature, has numerous applications. One of the applications is that of BC in the pharmaceutical and biomedical fields, where it has been primarily applied for transdermal formulations to improve clinical outcomes. This review takes a multidisciplinary approach to consideration of the feasibility and potential benefits of BC in the development of other drug delivery systems for various routes of administration.

Present status and applications of bacterial cellulose-based materials for skin tissue repair

Bacterial cellulose (BC, also known as microbial cellulose, MC) is a promising natural polymer which is biosynthesized by certain bacteria. This review focused on BC-based materials which can be utilized for skin tissue repair. Firstly, it is illustrated that BC has unique structural and mechanical properties as compared with higher plant cellulose, and is thus expected to become a commodity material. Secondly, we summarized the basic properties and different types of BC, including self-assembled, oriented BC, and multiform BC. Thirdly, composites prepared by using BC in conjunction with other polymers are explored, and the research on BC for application in skin tissue engineering is addressed. Finally, experimental results and clinical treatments assessing the performance of wound healing materials based on BC were examined. With its superior mechanical properties, as well as its excellent biocompatibility, BC was shown to have great potential for biomedical application and very high clinical value for skin tissue repair.

Effect of Sisal Fiber Surface Treatment on Properties of Sisal Fiber Reinforced Polylactide Composites

Mechanical properties of composites are strongly influenced by the quality of the fiber/matrix interface. The objective of this study was to evaluate the mechanical properties of polylactide (PLA) composites as a function of modification of sisal fiber with two different macromolecular coupling agents. Sisal fiber reinforced polylactide composites were prepared by injection molding, and the properties of composites were studied by static/dynamic mechanical analysis (DMA). The results from mechanical testing revealed that surface-treated sisal fiber reinforced composite offered superior mechanical properties compared to untreated fiber reinforced polylactide composite, which indicated that better adhesion between sisal fiber and PLA matrix was achieved. Scanning electron microscopy (SEM) investigations also showed that surface modifications improved the adhesion of the sisal fiber/polylactide matrix.