In this study, we aimed to prepare and characterise hydrogel formulations using cellulose nanocrystals (CNCs), alginate (Alg), and polyethylene glycol diacrylate (PEGDA). The CNC/Alg/PEGDA formulations were formed using a double network crosslinking approach. Firstly, CNC was extracted from oil palm trunk, and the size and morphology of the CNCs were characterised using TEM analysis. Secondly, different formulations were prepared using CNCs, Alg, and PEGDA. The mixtures were crosslinked with Ca2+ ions and manually extruded using a syringe before being subjected to UV irradiation at 365 nm. The shear-thinning properties of the formulations were tested prior to any crosslinking, while the determination of storage and loss modulus was conducted post extrusion after the Ca2+ ion crosslink using a rheometer. For the analysis of swelling behaviour, the constructs treated with UV were immersed in PBS solution (pH 7.4) for 48 h. The morphology of the UV crosslinked construct was analysed using SEM imaging. The extracted CNC exhibited rod-like structures with an average diameter and length of around 7 ± 2.4 and 113 ± 20.7 nm, respectively. Almost all CNC/Alg/PEGDA formulations (pre-gel formulation) displayed shear-thinning behaviour with the power-law index η < 1, and the behaviour was more prominent in the 1% [w/v] Alg formulations. The CNC/Alg/PEGDA with 2.5% and 4% [w/v] Alg displayed a storage modulus dominance over loss modulus (G′ > G″) which suggests good shape fidelity. After the hydrogel constructs were subjected to UV treatment at 365 nm, only the F8 construct [4% CNC: 4% Alg: 40% PEGDA] demonstrated tough and flexible characteristics that possibly mimic the native articular cartilage property due to a similar water content percentage (79.5%). In addition, the small swelling ratio of 4.877 might contribute to a minimal change of the 3D construct’s geometry. The hydrogel revealed a rough and wavy surface, and the pore size ranged from 3 to 20 µm. Overall, the presence of CNCs in the double network hydrogel demonstrated importance and showed positive effects towards the fabrication of a potentially ideal 3D bioprinted scaffold.

Abstract. The Burra Charter has defined building adaptation as modifying a place to suit the existing or proposed use. Many historical buildings in the world have been changed or transformed for alternative uses or functions to meet current needs while remaining of significant value to younger generations. In order to protect and manage the historical buildings in Malaysia, various relevant agencies adopted a few general statutory frameworks such as the National Heritage Act (2005) and the Town and Country Planning Act (1979) for implementation at the national level while, for use at the local level, the Guideline for Conservation Areas and Heritage Buildings (GCAHB) is used in George Town, Penang. Even though standards and guidelines have been made, there are still many buildings that have been adaptively reused without following the regulations, thereby, losing the building's authenticity and historical significance. This paper will focus on an evaluation of adaptive reuse buildings in Penang in compliance with the GCAHB.

Herein, we describe the first report of Pichia strain producing biocellulose (BC). This yeast was isolated from rotten pineapple and was identified as Pichia kudriavzevii USM-YBP2 using 18S rDNA analysis. The formation of pellicle was characterized using a scanning electron microscope (SEM). Based on SEM analysis, pellicles are presented as an interwoven network of fibers. Next, to produce high BC, optimization was conducted using different carbon and nitrogen sources, carbon and nitrogen concentrations, inoculum size, and cultivation condition. The optimized parameters for maximum BC production were as follows: glucose 8.0% (w/v), peptone 2.0% (w/v), yeast extract 0.5% (w/v), disodium phosphate 0.270% (w/v), citric acid 0.115% (w/v), ethanol 0.5% (v/v), and inoculum size 10% (v/v). The production yield is 12.24 ± 0.43 g/L and the productivity of 0.128 g/L/h. Then, BC was further treated using sulfuric acid to destructuring to bionanocellulose (BNC) and was characterized using the transmission electron microscope (TEM), attenuated total reflection-Fourier transform infrared spectroscopy, and X-ray diffraction (XRD) analysis. After acid hydrolysis treatment, BNC showed a spherical shape as in TEM. Interestingly, BNC characteristic band displayed high similarity with cellulose from other bacterial species. Moreover, BNC showed high crystallinity index (∼82%) as estimated using XRD. Thus, our findings substantiated that strain USM-YBP2 showed remarkable BNC production with unique BNC property that can be further explored in various applications.

No abstract

No abstract