Membrane Technological Pathways and Inherent Structure of Bacterial Cellulose Composites for Drug Delivery

This report summarizes efforts undertaken in the area of drug delivery, with a look at further efforts made in the area of bacterial cellulose (BC) biomedical applications in general. There are many current methodologies (past and present) for the creation of BC membrane composites custom-engineered with drug delivery functionality, with brief consideration for very close applications within the broader category of biomedicine. The most emphasis was placed on the crucial aspects that open the door to the possibility of drug delivery or the potential for use as drug carriers. Additionally, consideration has been given to laboratory explorations as well as already established BC-drug delivery systems (DDS) that are either on the market commercially or have been patented in anticipation of future commercialization. The cellulose producing strains, current synthesis and growth pathways, critical aspects and intrinsic morphological features of BC were given maximum consideration, among other crucial aspects of BC DDS.

Preparation of Graphene Oxide/Cellulose Composites with Microcrystalline Cellulose Acid Hydrolysis Using the Waste Acids Generated by the Hummers Method of Graphene Oxide Synthesis

The Hummers method is the most commonly used method to prepare graphene oxide (GO). However, many waste acids remain in the raw reaction mixture after the completion of this reaction. The aim of this study was to reuse these waste acids efficiently. In this study, microcrystalline cellulose (MCC) was directly dissolved in the mixture after the high-temperature reaction of the Hummers method. The residual acid was used to hydrolyze MCC, and the graphene oxide/microcrystalline cellulose (GO/MCC) composites were prepared, while the acid was reused. The effects of MCC addition (0.5 g, 1.0 g, and 1.5 g in 20 mL) on the properties of the composites were discussed. The structure, composition, thermal stability, and hydrophobicity of GO/MCC composites were characterized and tested by SEM, XRD, FTIR, TG, and contact angle tests. The results showed that MCC could be acid hydrolyzed into micron and nano-scale cellulose by using the strong acidity of waste liquid after GO preparation, and it interacted with the prepared GO to form GO/MCC composites. When the addition amount of MCC was 1 g, the thermal stability of the composite was the highest due to the interaction between acid-hydrolyzed MCC and GO sheets. At the same time, the hydrophobic property of the GO/MCC composite is better than that of the GO film. The freeze-dried GO/MCC composites are more easily dispersed in water and have stronger stability.

Synthesis of Titanium Dioxide/Cellulose Derived from Banana Peel for Sonocatalytic Degradation of Methylene Blue

Banana peel was used as the source of cellulose and titanium dioxide (TiO2)/cellulose composites with different weight ratios were successfully synthesised by using sol-gel method. The composites were then characterised by using the scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The synthesised TiO2 was found to be in anatase phase. TiO2 particles were spherical in shape and consisted of both titanium (Ti) and oxygen (O) elements only. Meanwhile, the morphology of extracted cellulose was found to have a rough surface. TiO2 particles were found to be covering the cellulose surface when preparing the composite samples and clusters of agglomerated TiO2 particles on cellulose surface could be observed. FTIR results indicated that the absorption peaks intensity of cellulose slowly reduced as compared to the composite materials. The sonocatalytic degradation of methylene blue in the presence of TiO2/cellulose at weight ratio of 1:2 showed the highest degradation efficiency of 74.14 % at the optimum conditions (initial dye concentration of 10 ppm, catalyst dosage of 1.0 g/L and solution pH of 8). Study on the degradation kinetics of methylene blue at different solution pH proved that the reaction kinetics fitted well into pseudo first-order. Additionally, a chemical oxygen demand (COD) removal of 94.44 % was also achieved after 30 minutes of ultrasonic irradiation under the prescribed optimum conditions.

The effect of chemically treated all-cellulose composites (ACCs) with dodecyltriethoxysilane (DTES) solution on the structural-property relationship

Cellulose is the most abundant natural polymer on the Earth that is widely used in bio-based composites due to its high mechanical properties, availability and biodegradability. All-cellulose composites (ACCs) are known as a new class monocomponent of biocomposites due to both reinforcing and matrix phases that are based on cellulose. However, a technical challenge for ACCs is observed due to their propensity for high moisture absorption (water uptake), leading to the instability and deterioration of the mechanical properties. Therefore, this research focussed towards the improvement of the surface of ACCs in order to increase the resistance to water absorption. Prior to the characterisations, ACCs were chemically treated using dodecytriethoxysilane (DTES) coating solution by dip coating method. In this present study, the effects of two control factors: (i) DTES concentration (1.5, 7.5, and 12.5 vol%), and (ii) heating temperature (50, and 100 °C), were investigated on the ACCs. Upon completion of this treatment, three possible characterisations were conducted including of Fourier Transform Infrared (FTIR) spectroscopy analysis, scanning electron microscopy (SEM), and water absorption (WA) testing. Creation of polysiloxane layer was expected to reduce the tendency to absorb water in ACCs while being applied in the outdoor applications.

Effect of Vulcanization Processes on Properties of Natural Rubber/Cellulose Composites

The effect of vulcanization processes and surface treatment of cellulose were investigated on tensile strength, degradation temperature, and morphological properties of cellulose/natural rubber composites. Cellulose was surface-treated with Si-69 silane coupling agent and used as reinforcing filler in natural rubber (NR). Different vulcanization processes including electron beam irradiation (EB-Cured) and sulphur vulcanization (S-Cured) were used to crosslink NR. The incorporation of both untreated and treated cellulose at various concentrations (5, 10, 15 and 20 phr) into NR was found to significantly improve the tensile strength and modulus. Notably, with addition of treated cellulose in NR, the tensile strength and modulus were considerably higher than that of the untreated cellulose for all curing system. SEM morphological analysis revealed a well dispersion of cellulose particles in NR matrix. Addition of cellulose slightly decreased the onset of degradation temperature of NR, however, the degradable temperature was found to be unchanged. The curing systems had shown an impact on tensile property of NR. S-Cured NR exhibited highest modulus of 2.23 MPa comparing to the EB-Cured NR (1.69 MPa) for the same amount of cellulose (20 phr), due to a stronger crosslink network. However, the curing system had no significant impact on degradation temperature of NR.

Fabricating Sustainable All-Cellulose Composites

Climate change, waste disposal challenges, and emissions generated by the manufacture of non-renewable materials are driving forces behind the production of more sustainable composite materials. All-cellulose composites (ACCs) originate from renewable biomass, such as trees and other plants, and are considered fully biodegradable. Dissolving cellulose is a common part of manufacturing ACCs, and currently there is a lot of research focused on effective, but also more environmentally friendly cellulose solvents. There are several beneficial properties of ACC materials that make them competitive: light weight, recyclability, low toxicity, good optical, mechanical, and gas barrier properties, and abundance of renewable plant-based raw material. The most prominent ACC applications are currently found in the food packing, medical, technical and vehicle industries. All-cellulose nanocomposites (ACNCs) expand the current research field and can offer a variety of more specific and functional applications. This review provides an overview of the manufacture of sustainable ACCs from lignocellulose, purified cellulose, and cellulosic textiles. There is an introduction of the cellulose dissolution practices of creating ACCs that are currently researched, the structure of cellulose during complete or partial dissolution is discussed, and a brief overview of factors which influence composite properties is presented.