The potential of electrospinning process to fabricate ultrafine fibers as building blocks for tissue engineering scaffolds is well recognized. The scaffold construct produced by electrospinning process depends on the quality of the fibers. In electrospinning, material selection and parameter setting are among many factors that contribute to the quality of the ultrafine fibers, which eventually determine the performance of the tissue engineering scaffolds. The major challenge of conventional electrospun scaffolds is the nature of electrospinning process which can only produce two-dimensional electrospun mats, hence limiting their applications. Researchers have started to focus on overcoming this limitation by combining electrospinning with other techniques to fabricate three-dimensional scaffold constructs. This article reviews various polymeric materials and their composites/blends that have been successfully electrospun for tissue engineering scaffolds, their mechanical properties, and the various parameters settings that influence the fiber morphology. This review also highlights the secondary processes to electrospinning that have been used to develop three-dimensional tissue engineering scaffolds as well as the steps undertaken to overcome electrospinning limitations.
The end-of-life vehicles (ELV) issue has become an essential topic in the fast-growing automotive industry. This study utilizes comprehensive content analysis to critically review the recent ELV research developments and underpinning issues in Malaysia. Fifty relevant ELV studies in Malaysia from the year 2006 to 2021 are selected and categorized based on three innovative sub-elements (product, process, system) of sustainable manufacturing. The literature review findings show that sustainable product recovery and recyclability issues in ELV treatments are still a major concern. Current studies overlook specific research on sustainable and integrated processes for ELV treatment. There is still lack of detailed ELV implementation framework equipped with the documented procedures and appropriate industrial practices in the ELV ecosystem to optimize the ELV supply chain. ELV policy is yet to be enacted in Malaysia, and public awareness of ELV is still low. There is inadequate alignment in ELV research developments with the current National Automotive Policy 2020 in Malaysia. The proposed integrated conceptual model will provide an extensive overview for scholars, policy-makers, and ELV stakeholders to implement appropriate actions to improve present ELV businesses in line with the public readiness to enact the potential ELV directives or legislation in Malaysia.
Valvular dysfunction as the prominent reason of heart failure may causes morbidity and mortality around the world. The inability of human body to regenerate the defected heart valves necessitates the development of the artificial prosthesis to be replaced. Besides, the lack of capacity to grow, repair or remodel of an artificial valves and biological difficulty such as infection or inflammation make the development of tissue engineering heart valve (TEHV) concept. This research presented the use of compound of poly-l-lactic acid (PLLA), thermoplastic polyurethane (TPU) and maghemite nanoparticle (γ-Fe₂O₃) as the potential biomaterials to develop three-dimensional (3D) aortic heart valve scaffold. Electrospinning was used for fabricating the 3D scaffold. The steepest ascent followed by the response surface methodology was used to optimize the electrospinning parameters involved in terms of elastic modulus. The structural and porosity properties of fabricated scaffold were characterized using FE-SEM and liquid displacement technique, respectively. The 3D scaffold was then seeded with aortic smooth muscle cells (AOSMCs) and biological behavior in terms of cell attachment and proliferation during 34 days of incubation was characterized using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and confocal laser microscopy. Furthermore, the mechanical properties in terms of elastic modulus and stiffness were investigated after cell seeding through macro-indentation test. The analysis indicated the formation of ultrafine quality of nanofibers with diameter distribution of 178 ± 45 nm and 90.72% porosity. In terms of cell proliferation, the results exhibited desirable proliferation (109.32 ± 3.22% compared to the control) of cells over the 3D scaffold in 34 days of incubation. The elastic modulus and stiffness index after cell seeding were founded to be 22.78 ± 2.12 MPa and 1490.9 ± 12 Nmm², respectively. Overall, the fabricated 3D scaffold exhibits desirable structural, biological and mechanical properties and has the potential to be used in vivo.
End-of-life vehicles (ELV) management is becoming a global concern in the automotive industry. However, there is still limited study on supply chain optimisation that focusses on specific ELV treatments. Therefore, this mini-review article analyses the supply chain optimisation for recycling and remanufacturing sustainable management in ELV. A total of 51 papers were reviewed from the year 2016 to 2021. The key topics in each article were assessed and classified into various themes, followed by the content analysis. The percentage breakdown for the six main themes are ELV recovery management system (37.25%), reverse logistic network design (29.41%), ELV economy analysis (15.69%), government regulation or subsidies (7.84%), ELV quantity forecast (5.88%) and ELV part design (3.92%). It can be concluded that ELV recovery management and reverse logistic network design are the top two key focusses of supply chain optimisation priorities that have been extensively applied to improve ELV development. The literature gap has shown that the study on remanufacturing in the ELV supply chain is minimal compared to recycling. The classification of ELV recycling and remanufacturing supply chain optimisation in this study will be beneficial in supporting real-life problem-solving for industrial applications. This study serves as a valuable reference guide to identifying more sustainable solutions in ELV management and promoting the critical focus area for academicians and industry players.
Nanocrystalline cellulose is an abundant and inexhaustible organic material on Earth. It can be derived from many lignocellulosic plants and also from agricultural residues. They endowed exceptional physicochemical properties, which have promoted their intensive exploration in biomedical application, especially for tissue engineering scaffolds. Nanocrystalline cellulose has been acknowledged due to its low toxicity and low ecotoxicological risks towards living cells. To explore this field, this review provides an overview of nanocrystalline cellulose in designing materials of bone scaffolds. An introduction to nanocrystalline cellulose and its isolation method of acid hydrolysis are discussed following by the application of nanocrystalline cellulose in bone tissue engineering scaffolds. This review also provides comprehensive knowledge and highlights the contribution of nanocrystalline cellulose in terms of mechanical properties, biocompatibility and biodegradability of bone tissue engineering scaffolds. Lastly, the challenges for future scaffold development using nanocrystalline cellulose are also included.