Md. Minhajul Islam

Preparation of gelatin based porous biocomposite for bone tissue engineering and evaluation of gamma irradiation effect on its properties

Biodegradable porous hybrid polymer composites were prepared by using gelatin as base polymer matrix, β-tricalcium phosphate (TCP) and calcium sulfate (CS) as cementing materials, chitosan as an antimicrobial agent, and glutaraldehyde and polyethylene glycol (PEG) as crosslinkers at different mass ratios. Thereafter, the composites were subjected to γ-radiation sterilization. The structure and properties of these composite scaffolds were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), mechanical properties testing (compressive, bending, tensile and impact), thermogravimetry/differential thermal analysis (TG/DTA), and physical stability test in simulated body fluid (SBF). We found that TCP rich composites showed enhanced mechanical properties among all the crosslinked composites. γ-Radiation sterilization triggered further cross linking in polymer matrix resulting a decrease in pore size of the composites and an increase in pore wall thickness with improved mechanical and thermal properties. The chemically crosslinked composite with 40% TCP followed by γ-radiation sterilization showed the smallest pore size distribution with a mean pore diameter of 159.22μm, which falls in the range of 100-350μm - known to be suitable for osteoconduction. Considering its improved mechanical and thermal properties along with osteoconduction ability without cytotoxicity, we propose this biocomposite as a viable candidate for bone tissue engineering.

Preparation and Characterization of Jute Cellulose Crystals-Reinforced Poly(L-lactic acid) Biocomposite for Biomedical Applications

Crystalline cellulose was extracted from jute by hydrolysis with 40% H2SO4 to get mixture of micro/nanocrystals. Scanning electron microscope (SEM) showed the microcrystalline structure of cellulose and XRD indicated the Iβ polymorph of cellulose. Biodegradable composites were prepared using crystalline cellulose (CC) of jute as the reinforcement (3–15%) and poly(lactic acid) (PLA) as a matrix by extrusion and hot press method. CC was cellulose derived from mercerized and bleached jute fiber by acid hydrolysis to remove the amorphous regions. FT-IR studies showed hydrogen bonding between the CC and the PLA matrix. The X-ray diffraction (XRD) and differential scanning calorimetry (DSC) studies showed that the percentage crystallinity of PLA in composites was found to be higher than that of neat PLA as a result of the nucleating ability of the crystalline cellulose. Furthermore, Vicker hardness and yield strength were found to increase with increasing cellulose content in the composite. The SEM images of the fracture surfaces of the composites were indicative of poor adhesion between the CC and the PLA matrix. The composite with 15% CC showed antibacterial effect though pure films but had no antimicrobial effect; on the other hand its cytotoxicity in biological medium was found to be medium which might be suitable for its potential biomedical applications.

Preparation and characterization of poly (ethylene glycol) grafted Ca-alginate fibers by γ-irradiation for biomedical applications

Radiation processing, being a physical process, is an environmentally friendly alternative to chemical modifications. It is economically viable, safe, and possesses several advantages over other conventional methods employed for modification and grafting. To improve the physico-mechanical properties of Ca-alginate fiber (CaAF), poly (ethylene glycol) (PEG) was grafted by applying γ-radiation of different intensities. The effect of γ-irradiation on the physico-mechanical, thermal, morphological, thermal and water aging, water, and simulated body fluid (SBF) uptake were evaluated. FT-IR results confirmed that PEG was successfully grafted onto Ca-alginate fibers by γ-irradiation. From the detailed experimental results, irradiation doses and PEG concentration were optimized for grafting processes. The results showed that 50% PEG and 2.5 kGy irradiation dose yielded the highest tensile strength. Differential scanning calorimetric (DSC) analysis showed that with increasing γ-intensity a decrease of dehydration temperature of the fibers had occurred. On the other hand, the glass transition temperature (T g) increased with increasing irradiation dose. The tensile cracked surfaces of the grafted alginate fibers were analyzed by scanning electron microscope (SEM) in order to monitor their surface morphologies. The SEM images of the cracked surfaces demonstrated that spherical shape rods were present for irradiated fiber sample while no such rods were observed for non-irradiated fibers. The characteristic data obtained from SBF and water uptake, and water and thermal aging experiments indicated that CaAF grafted with 50% PEG by applying 2.5 kGy γ-irradiation can be potentially employed for biomedical purposes, such as surgical suture.

Preparation of Rayon Fiber-Reinforced Polypropylene Composites by Extrusion Techniques

Hybrid composites from rayon fibers (∼2–5 cm size) and polypropylene (PP) were fabricated by using an extruder. Fibre content of the composite was varied from 5–30% by weight and physico-mechanical properties of the composites were measured. Surface morphology as observed by SEM showed good interface adhesion between rayon and PP matrix. Furthermore inclusion of rayon (up to 15% fiber inclusion) in the composite increased tensile, bending and hardness properties. As the fiber content in the composite increased more than 15%, physico-mechanical properties decreased due to the decrease of fiber matrix adhesion. The change of tensile properties due to environmental aging was carried out by keeping the composite under soil for 1 month and tensile properties were measured periodically. The aging result suggests that composites retained about 75% of its original tensile and bending strength even after 1 month soil burial. The modified fibers were also used for the study. As such the fibers were treated with vinyl-trimethyoxysilane and methanol solution and irradiated under UV before being used with PP in extruder. The results showed retardation of the physico-mechanical properties for composites obtained from irradiated rayon fibers than the composites fabricated from non irradiated rayon fibers.

Recent Updates on Immobilization of Microbial Cellulase

Several new types of carriers and techniques have been implemented in recent years to improve the traditional cellulase immobilization process, which aims to enhance its loading, activity, and stability with reduced cost for various industrial applications. This chapter summarizes the recent advancements in all aspects of microbial cellulase enzyme like the types of cellulases, their microbial sources, structure, and properties, immobilization factors, and industrial applications. Common cellulase inducers and existing immobilization matrices are highlighted along with insights into the recent developments for each of them. Different immobilization techniques, the types of reactors used so far, and their effect on the immobilized cellulase are thoroughly discussed. More importantly, this review focuses on the future immobilization processes of cellulase and their potential for the most modern industrial applications.

Cellulase in Waste Management Applications

Our society produces a lot of voluminous waste of biomass every day, which are mainly lignocellulose in origin. It is the most abundant plant cell wall component of the biosphere and the most plentiful biological compound on terrestrial earth. The successful conversion of cellulosic waste from domestic, industrial, and municipal sources through economically feasible processes to valuable by-products has long been admitted as a desirable endeavor. The degradation of cellulosic materials has gained increasing attention due to its worldwide availability and enormous potential for transforming them into sugars, fuels, and chemical feedstocks. Enzymatic hydrolysis of cellulosic biomass holds tremendous promise due to the high specificity and production of high yields of glucose without generation of degradation products, unlike acid/alkali hydrolysis. It has lower utility cost and hydrolysis occurs under mild reaction conditions. Microorganisms that degrade cellulose are abundant and universal in nature. The enzymatic hydrolysis of cellulose requires the use of cellulase enzyme. Fungi and bacteria are the main cellulase-producing microorganisms. A “twofold” benefit could be achieved through a sustainable bioconversion of biomass by cellulase enzyme. First, it would reduce the amount of cellulosic waste and diminish its effects on our environment; and second, the bioconversion of waste would be an alternative source of fuel energy to shrink our growing dependence on fossil fuels.

Benefits of Renewable Hydrogels over Acrylate- and Acrylamide-Based Hydrogels

In recent years, renewable/biodegradable polymer-based hydrogels have attracted great interest in the field of hydrogel research and development. The reasons of this interest are their applications in versatile fields including personal care products; drug delivery systems; wound healing; tissue engineering; industrial, pharmaceutical, and biomedical, agricultures; water treatments; food packaging; etc. Other important reasons are the problems caused by synthetic sources to the environment. Therefore, it is our demand to develop natural materials that can be biocompatible and biodegradable with the environment, and important efforts are focused on finding alternatives to replace the synthetic one. Furthermore, A. K. Mallik (*) · M. Shahruzzaman · M. N. Sakib · A. Zaman · M. S. Rahman · M. M. Islam · M. S. Islam · P. Haque · M. M. Rahman Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering and Technology, University of Dhaka, Dhaka, Bangladesh e-mail: abulkmallik@du.ac.bd; shahruzzaman@du.ac.bd; nsakib@du.ac.bd; asad.acce@du.ac.bd; shiraj@du.ac.bd; minhajul.acce@du.ac.bd; sazid@du.ac.bd; papiahq@yahoo.com; mizanur. rahman@du.ac.bd # Springer International Publishing AG, part of Springer Nature 2018 Md. I. H. Mondal (ed.), Cellulose-Based Superabsorbent Hydrogels, Polymers and Polymeric Composites: A Reference Series, https://doi.org/10.1007/978-3-319-76573-0_10-1 1 renewable hydrogels display unique properties such as biodegradability, biocompatibility, stimuli-responsive characteristics and biological functions. Natural hydrogels are often based on polysaccharide or protein chains. Due to the hydrophilic structure of polysaccharides, they have a good property to form hydrogel. There are various polysaccharides like starch, cellulose, sodium alginate, chitosan, guar gum, carrageenan, etc. that have been focused and used for the preparation of environmental friendly hydrogels. Among them, cellulose and its derivatives revealed distinctive benefits because they are the most abundant natural polysaccharide having low cost and better biodegradability and biocompatibility. Protein chains, which form natural hydrogels, are collagen, silk, keratin, elastin, resilin, and gelatin. On the other hand, many synthetic polymers/ copolymers also form hydrogel like poly(vinyl alcohol), polyacrylamide, poly (ethylene oxide), poly(ethylene glycol), etc. Synthetic polymer-based hydrogels have one benefit of chemical strength than natural counterpart due to the slower degradation rate of the hydrolyzable moieties. However, biorenewable polymers usually present higher biocompatibility compared to synthetic polymers, as they undergo enzyme-controlled biodegradation by human enzymes (e.g., lysozyme) and produce biocompatible by-products. This chapter focused on the advantages of biorenewable hydrogels over synthetic (acrylateand acrylamide-based) hydrogels.

Facile Preparation of Biocomposite from Prawn Shell Derived Chitosan and Kaolinite-Rich Locally Available Clay

A novel composite material was prepared from prawn shell derived chitosan (CHT) and locally available kaolinite-rich modified Bijoypur clay (MC) using a facile technique in which dilute acetic acid was used as a solvent for dissolving chitosan and composite fabrication whereas distilled water was used for preparing the clay dispersion. Bijoypur clay mainly consists of kaolinite clay mineral and it was modified with the dodecyl amine to make it organophilic. Morphology and properties of the composites (different weight ratio of MC and CHT) have been studied and compared with those of pure CHT and MC. Purification and modification of Bijoypur clay were investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier transformed infrared spectroscopy (FTIR) analyses. The fabrication of CHT-MC composites was confirmed by FTIR analysis. Thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC) were used to investigate the thermal stability of the composites. It was observed that dispersed clay improves the thermal stability and enhances the hardness of the matrix systematically with the increase of clay loading. In this study, a better insolubility in both acidic and alkaline media of the composites is also observed compared to pure chitosan.

Preparation and characterization of bijoypur clay-crystalline cellulose composite for application as an adsorbent

Biocomposite prepared from cellulose and Bijoypur clay (Kaolinite) exhibited enhanced properties compared to their original counterparts. Cellulose extracted from jute fiber and Bijoypur clay modified with a surfactant were combined to fabricate a biocomposite by exfoliation-adsorption method. A comparative study was carried out to determine thermal stability and adsorption capacity of the composite and raw materials. Characterizations of the biocomposites were carried out by Fourier transform infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) analysis. FT-IR analysis showed successful modification of clay and incorporation of polymer and organoclay in the biocomposites. The composite has exhibited better thermal properties with increasing clay percentage in TGA analysis. Moreover, the composite showed improved adsorption capacity of hexavalent chromium in stock solution compared to natural adsorbent such as cellulose and clay. Correspondence to: Mohammed Mizanur Rahman, Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering and Technology, University of Dhaka, Dhaka, Bangladesh, Tel: +880-2-9661920-70/7392; Fax: +880-2-9667222; E-mail: mizanur.rahman@du.ac.bd