Browsing by Author "Zhu, Huijun"
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Item Open Access Assessment of nanoparticle release and associated health effect of polymer-silicon composites(2014-04-15) Zhu, Huijun; Irfan, Adeel; Sachse, Sophia; Njuguna, JamesThe fast advancement in the nanotechnology and manufacturing of engineering nanomaterials has inevitably caused concerns over their impact on environment and human health. Little information is currently available on possible release of nanomaterials or/and nanoparticles (NP) from conventional and novel products and associated health effect. The NEPHH project funded under the EU FP7 programme is aimed to assess the environment and health impact of polymer-silicon nanocomposites in comparison to conventional polymer composites from life cycle perspective. As part of the NEPHH project, this study focused on assessing the possible release of NP during the application stage of conventional and nanoproducts. NP release was monitored during physical processing of polymer-silicon composites, and the toxicity of both the released NP and the raw silica nanomaterials that were used as fillers in nanocomposites was assessed in vitro using human lung epithelial A549 cells.Item Open Access Development of novel flax bio-matrix composites for non-structural and structural vehicle applications(Cranfield University, 2015) Zhu, Jinchun; Abhyankar, Hrushikesh; Zhu, HuijunThe use of natural fibres (e.g. flax, hemp etc.) instead of synthetic fibres (carbon and glass etc.) as composite reinforcements not only benefits the environment, but also provides economical lightweight products for transports. Although there are a few studies reported in literature on use of flax fibres, there is no comprehensive guide on use of flax fibres with bio-resins to re-engineer bio- composite systems that can be used in vehicle structures. The state-of-art of the current research towards using natural fibre reinforced composites is reviewed by the thesis. The review covers the performances of flax composites, concentrating on the effect of matrix types and existing development methods. The review also identifies the rational of selecting tannin resins and bio-epoxy resins to combine with flax fibre reinforcements. In the experimental work, mimosa tannin resin (natural phenolic resin) and pine- oil derived supersap epoxy resin are selected to manufacture the fully renewable flax composites. By tailoring the fibre configurations and chemical surface treatments, the resultant composites were investigated to provide information for engineers to understand the composite behaviours and properties. Mechanical properties (tension, flexural, shear, impact etc.) and physical properties (moisture, ageing etc.) were assessed through adequate tests and analysing methods. In addition, bio-sandwich structures based on the novel studied composites and commercial bio-foams were evaluated to study the energy absorption which could be very important in vehicle design. Based on the results, flax/supersap epoxy and flax/tannin composites are suitable for possible exterior structural and interior non-structural applications, respectively. The developed flax fibre composites with innovative bio-matrices have a potential to prevail in modern vehicle applications, due to the competitive performances, economic viability and environmental acceptability.Item Open Access Effect of fibre treatments on mechanical properties of flax/tannin composites(Cranfield University Press, 2013-09-19) Zhu, Jinchun; Zhu, Huijun; Abhyankar, Hrushikesh; Njuguna, JamesDue to the inherent environmental benefits of using natural resin (tannin) and natural fibre (flax), flax/tannin composites could be potentially used for vehicle applications. One of the main limitations is the hydrophilic property of flax, resulting in the poor fibre/hydrophobic matrix interface quality. Alkali, acetylation, silane treatment and enzymatic treatment were selected to modify non-woven flax mats to prepare the composites. The fibre morphology was studied through scanning electronic microscopes (SEM). The effects of fibre pre-treatments on dynamic and static mechanical properties of composites were investigated through adequate experiments, such as dynamic mechanical analysis (DMA) and static tensile testing. The modified rougher fibre surface broadened the glass transition peaks of composites due to the improved surface adhesion. However, there is no big improvement of tensile strength after modifications. The pure NaOH (sodium hydroxide) treated composites remain the tensile properties and offer good flax/tannin wettability.Item Open Access The effect of nanoclay on dust generation during drilling process of polyamide 6 nanocomposites(Hindawi Publishing Corporation, 2012-06-10T00:00:00Z) Sachse, Sophia; Silva, Francesco; Zhu, Huijun; Irfan, Adeel; Leszczynska, Agneska; Pielichowski, Krzysztof; Ermini, Valentina; Blazquez, Maria; Kuzmenko, Oleksandr; Njuguna, James A. K.During the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. However, there is currently a lack of information available in the literature on the nano and ultrafine particle emission rates from these materials. In this study, influence of nanoclay on mechanical drilling of PA6 composites, in terms of dust generation has been reported. With the help of real-time characterization, submicrometer-sized particles (5.6-512 nm) size distribution and number concentration emitted from polyamide 6/nanoclay composites during mechanical drilling is studied. Total particle concentration for the PA6/nanoclay composites was 20,000 cm-3, while unreinforced panel measured a total concentration of approximately 400,000 cm-3. While the airborne particle concentration for the PA6/ nanoclay composites was 20 times lower than for the PA6 matrix, the concentration of deposited nanoparticles doubled for the nanocomposite. The results clearly shows that more particles in the size range between 175-350 nm are generated, during drilling of the nanocomposites and this particles deposit in a shorter time. It is likely that the presence of nanoclay in some way retains the formation of high quantity of airborne particles and promotes particle deposition.Item Open Access Encapsulation of cancer therapeutic agent dacarbazine using nanostructured lipid carrier(JOVE, 2016-04-26) Almoussalam, Musallam; Zhu, HuijunThe only formula of dacarbazine (Dac) in clinical use is intravenous infusion, presenting a poor therapeutic profile due to the low dispersity of the drug in aqueous solution To overcome this, a nanostructured lipid carrier (NLC) consisting of glyceryl palmitostearate and isopropyl myristate was developed to encapsulate Dac. NLCs with controlled size were achieved using high shear dispersion (HSD) following solidification of oil-in-water emulsion. The synthesis parameters, including surfactant concentration, the speed and time of HSD were optimized to achieve the smallest NLC with size, polydispersion index and zeta potential of 155 ± 10 nm, 0.2 ± 0.01, and -43.4 ± 2 mV, respectively. The optimal parameters were also employed for Dac-loaded NLC preparation. The resultant NLC loaded with Dac possessed size, polydispersion index and zeta potential of 190 ± 10 nm, 0.2 ± 0.01, and -43.5 ± 1.2 mV, respectively. The drug encapsulation efficiency and drug loading reached 98% and 14%, respectively. This is the first report on encapsulation of Dac using NLC, implying that NLC could be a new potential candidate as drug carrier to improve the therapeutic profile of Dac.Item Open Access Improving mechanical properties of novel flax/tannin composites through different chemical treatments(Elsevier, 2015-02-12) Zhu, Jinchun; Zhu, Huijun; Immonen, K.; Brighton, James; Abhyankar, HrushikeshDue to the inherent environmental benefits of using renewable materials, mimosa tannin resin (a natural phenolic resin) reinforced by flax fibres could offer desirable characteristics (lightweight, economic and low environmental impact) aiming at reducing carbon footprint of superlight electric vehicles. The non-woven flax mats were chemically treated (alkali, acetylation, silane and enzymatic treatment) to prepare tannin composites through compression moulding (130 °C/35 min/1.5 MPa). The change in fibre morphology was seen in SEM (scanning electronic microscope) images. The treatments (except enzymatic) showed significant improvement in tensile properties, along with enhancement (acetylation) in flexural properties, but little effect on impact resistance for all treatments. APS (aminopropyl triethoxy siloxane) treated composites showed highest tensile strength of 60 MPa and modulus of 7.5 GPa. BTCA (butanetetracarboxylic acid) treatment led to the highest flexural strength of up to 70 MPa. NaOH treatment retained the impact failure force of about 0.5 kN and sustained the saturation energy (4.86 J) compared to untreated composites (4.80 J).Item Open Access In vitro analysis of nanoparticles released from polyamide nanomaterial composites during drilling process(2011-05-10T00:00:00Z) Irfan, Adeel; Sachse, Sophia; Njuguna, James A. K.; Zhu, Huijun; Crump, DerrickNanomaterials provide a new avenue of progress into technological development. By manipulating materials on the very basic atomic and molecular levels the property of a given material can be specifically altered to suit the purpose of intended applications. However, nanomaterials (nanoparticles and nanolayers) have a more complex nature in physiochemical properties and surface reactivity than their larger counterparts. Therefore, the release of these nanomaterials as dust during crushing or drilling may lead to serious health hazards for humans and the surrounding environment. This study, supported by the NEPHH (Nanomaterial-related Environmental Pollution Health Hazards), addresses two important questions about nanomaterials: - Whether nanomaterials can be released from physical process of nanoproducts. - Toxicity potential of nanodusts generated from nanoproducts in comparison with reference products. Both questions address a massive gap in knowledge for toxicity and more specifically nanomaterial toxicity.Item Open Access In vitro functionality and toxicity of dacarbazine delivery nanosystem for melanoma.(2018-02) Almoussalam, Mousallam Mohammad; Tothill, Ibtisam E.; Zhu, HuijunDacarbazine (Dac) is a chemotherapeutic for melanoma. Its poor solubility, short half-life, and side effects limit its therapeutic use. Nanoparticles used as drug delivery systems (DDS) improve drug pharmacological properties, target site concentration, and stability. This study aimed to improve the therapeutic efficiency and decrease the systemic toxicity of Dacarbazine using nanostructured lipid carriers (NLC) for topical administration. Different NLC compositions were synthesised using a laboratory-based high sheer dispersion (HSD) method, and applying varying processes parameters. The preparations were optimized to achieve the desired NLC characteristics (average size 155±2 nm, polydispersity index (PDI) 0.1±0.05 and zeta potential -43.7±0.6) assessed using hydrodynamic light scattering (DLS), zetasizer and transmission electron microscopy (TEM). The optimized NLC (NLC/PI) were then used to encapsulate Dacarbazine. The resultant NLC/PI-Dac was characterized (average size 190±10 nm, PDI 0.2±0.03 and zeta potential -43.5 ± 1.2) and crystallinity determined using X-Ray Diffraction (XRD). The pharmacological properties of NLC/PI-Dac were then investigated and the percentage of encapsulation efficiency and drug loading capacity were determined to be 98.5±0.2% and 23.4±0.2%, respectively. The in vitro toxicity of NLC/PI-Dac was assessed using a melanoma cell line (A375). The in vitro drug release profile of NLC-Dac showed a biphasic pattern; 50% released over 2 hours and remainder within 30 hours. No toxicity was measured for the different NLC/PI concentrations after 24, 48 and 72 hours treatment, but there was an increase in toxicity of Dacarbazine after NLC/PI encapsulation (NLC/PI-Dac) at all concentrations and all-time points. NLC/PI and NLC/PI-Dac were stable in size, PDI and zeta potential when stored at 4°C for 3 months and the developed process was transferable to industrial-scale synthesis using the Micro Jet Reactor technique. NLCs were shown to be a suitable drug delivery system for Dacarbazine, achieving a desirable drug loading, encapsulation efficiency and drug release profile.Item Open Access In vitro toxicity of new engineered nanoparticles through their life cycle(Cranfield University, 2013-11) Irfan, Muhammad Adeel; Zhu, Huijun; Njuguna, JamesThe rapid development of nanotechnology has caused concerns about nanoproducts on human health throughout their lifecycle. As part of the consortium NEPHH (nanomaterial related environmental pollution on human health through their life cycle, funded by EU-FP7), this project aimed to assess the potential effect of novel polymer-silicon composites on human health from a lifecycle perspective, focusing on in vitro toxicity of raw silica nanoparticles (SiNP) and dust nanoparticles (NP) released from silicon-based polymer composites. The main objectives were to characterise a group of amorphous SiNP and dust NP in water and cell culture medium; assess NP toxicity potential in in vitro models; and establish mode of SiNP action. The selection of SiNP of size 7-14 nm was based on their wide use in developing polymer nanocomposites. Dust NP were generated from mechanical processing of polymer composites made of polyamide-6 (PA6), polyurethane (PU) and polypropylene (PP), each incorporated with SiNP or 3 other different silicon reinforcement materials. The dispersion and size of NP in water and in cell culture medium were characterized using dynamic light scattering, scanning electron microscopy and transmission electron microscopy. The chemical composition of NP was assessed by infra-red spectroscopy. NP were assessed in vitro for induction of membrane damage, intracellular reactive oxygen species (ROS), loss of cell viability, and cellular uptake by flow cytometry and confocal microscopy. In order to identify potential biomarkers for toxicity prediction, miRNA array and extracellular metabonomic assays were performed. The size of SiNP (10-100 µg/ml) ranged from ~200-500 nm in water and ~20- 500 nm in culture medium, indicating the presence of aggregates. The infra-red spectrum of SiNP dried from culture medium showed a slight difference as compared with that dried from water, indicating protein adsorption. SiNP induced acute ROS increase, cell membrane damage, and reduction in cell viability after 48 h in human lung carcinoma epithelial A549 cells, lung fibroblast MRC-5 cells and skin HaCaT keratinocytes. SiNP were up taken by all 3 cell types, and located in the cytosol. Six early (<48h) SiNP responsive miRNAs were identified in A549 cells. SiNP also induced early changes in metabolites including glucose, lactate, ethanol, phenylalanine, histidine and tyrosine. Dust NP generated from PA6 group materials were more toxic than those from other polymer composites when assessed at 25-100 µg/ml at 72 h in A549 cells. The results obtained from this study suggest that 1) both small and larger SiNP aggregates are taken up into the target cells; 2) conventional cytotoxicity assays combined with miRNA and metabonomic assays provide insight into the molecular mechanisms of the nanotoxicity; 3) metabonomics and miRNA assays can serve as robust tools for recognising sub-toxic dose-effect relationships; 4) the toxicity of dust NP from polymer composites depends on polymer type but not reinforcement materials. This study demonstrated the importance of lifecycle analysis as opposed to single stage analysis of novel materials. Further studies need to improve study design to enable interpretation of cytotoxicity in relation to NP size, physiochemical property and intracellular dose, and to simulate the health effect of polymer-silicon composites under more realistic scenarios.Item Open Access In vitro toxicological assessment of amorphous silica particles in relation to their characteristics and mode of action in human skin cells(Cranfield University, 2015-09) Moia, Claudia; Zhu, HuijunBackground: Silica is the common name for silicon dioxide (SiO2) materials and exists in both crystalline and amorphous forms. While crystalline silica is known for its severe health effects, amorphous silica has been considered safe and applied in many areas. However, some recent studies have showed evidence of their toxicity, raising concerns about its use as nanomaterial for biomedical applications. When nanomaterials enter the body, they are enveloped in biological fluids rich in biomolecules, which compete for binding to the nanomaterial. Such effect could alter their surface chemistry and therefore affect their bio-distribution and interaction with cells. Aim and objectives: As part of the EU-funded NANODRUG network programme, the aim of this project was the in vitro toxicity assessment of commercially-sourced fumed and colloidal amorphous silica particles in relation to their physico-chemical properties and potential application as carriers for drug delivery. The objectives were 1) characterization of silica particles hydrodynamic (Hd) size and dispersity in different cell culture media; 2) in vitro toxicological assessment of silica particles in human skin cells; 3) delineation of toxicity mechanisms in relation to their size; 4) assessment of the influence of Foetal Bovine Serum (FBS) on particle Hd size and toxicity; and 5) contributing to the overall objective of the NANODRUG programme - development of safe nanodrugs for skin application - through collaborations with different partners. ...[cont.]Item Open Access Nano-sized particles emission during drilling and low velocity impact of silica-based thermoplastic nanocomposites(Cranfield University, 2012-10) Sachse, Sophia; Njuguna, James; Zhu, HuijunDuring the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. Driven by the certainty that by the integration of low nano ller amounts, existing material properties can be improved and moreover new material properties can be developed. Despite the clear bene t and therefore, increasing research, production and utilisation of nanomaterials, little is known about how nanocomposites will perform over their whole life cycle, especially in the usage and end of life phase. Under the in uence of environmental factors such as ultraviolet light, moisture, temperature and mechanical actions, nano-sized particles can be potentially released from nanocomposites and thus may have negative e ects on the human health and the environment. Within the scope of this work an extensive literature review has been conducted in which polymer nanocomposites are brie y introduced and release scenarios of engineered nano-sized particles from nanocomposites during their life cycle are discussed. In the experimental part of this work silica based polypropylene, polyamide and polyurethane composites were manufactured and particle exposure mechanism during mechanical processing and testing were monitored and analysed. A series of comprehensive physical characterisation techniques were utilised to assess particle size distribution, shape, and concentration in di erent mediums, once emitted by the solid composite materials. It was observed that during drilling of PA6 composites, the airborne particle emission rates were 10 times higher than those for the PP based composites. However, the characterisation of deposited particles showed exactly the opposite behaviour, were the total number of particles emitted by the PP based composites was 10-100 times higher than those of the PA6 based composites. To the best of our knowledge, this is the rst time such work has been reported in the literature. Further, the addition of secondary ller into a polymer/glass- bre composites changed the micro-mechanism during crash testing and therefore controlled the energy absorption characteristics of the composites. However, it was shown that once subjected to higher impact energies the geometric particle size of the released particles increased from approx. 25 nm for the 530 J to approx. 60 nm for the 1560 J impact. Additionally, the tensile modulus increased by 0.31 GPa and the speci c energy absorbed during impact test increased from 20.7 kJ to 22.6 kJ by using nano-SiO2 alternative to micro-SiO2 particles in PP/glass- bre matrix. Even though a respective enhancement in mechanical properties were observed by using nano llers over micro llers, no signi cant di erence in particle emission during impact test were measured. Further, it could be shown that during drilling and testing, nano-sized particles were released from all materials studied, regardless of whether they had nanoparticles integrated or not. In one particular case, the neat polymer matrix generated more nano-sized particles during drilling than the exfoliated PA6/nanoclay nanocomposite. Hence, the addition of nanoclay can have bene cial impact in terms of controlled particle release. However, in general the addition of nano llers increased the particle emission rates during drilling and impact testing of the nanocomposites. Further, the emitted nano-sized particles were not all free engineered pristine nanoparticles but also hybrid particles consisting of matrix/nano ller material. A signi cant set of data was obtained during this study and hence the outcomes sets an excellent foundation for risk assessment and life cycle analysis of silica based polypropylene, polyamide and polyurethane nanocomposites.Item Open Access Novel hybrid flax reinforced supersap composites in automotive applications(MDPI, 2015-03-19) Zhu, Jinchun; Immonen, Kirsi; Avril, Christophe; Brighton, James; Zhu, Huijun; Abhyankar, HrushikeshFlax fibre bio-epoxy composites have not found many commercial uses in structural applications on account of their lack of cost efficiency and high susceptibility to environmental changes. Non-woven flax mats were subjected to alkali, acetylation, silane and enzymatic treatment, and then combined with untreated unidirectional (UD) flax fabrics to make hybrid flax bio-epoxy composites. Mechanical and environmental resistance (aging) tests were performed on the treated flax fibres. The glass transition temperature was detected at about 75 °C with little effect of treatments. Untreated composites were found to have a tensile strength of 180 MPa while no significant improvement was observed for any of the treatments, which are also not environmentally friendly. The amiopropyltriethoxysilane (APS) composites after Xenon aging, retained the tensile strength of 175 MPa and a modulus of 11.5 GPa, while untreated composites showed 35% reduction in elastic modulus.Item Open Access A rapid and high-throughput quantum dots bioassay for monitoring of perfluorooctane sulfonate in environmental water samples(Elsevier Science B.V., Amsterdam., 2011-12-31T00:00:00Z) Zhang, Jiong; Wan, Yanjian; Li, Yuanyuan; Zhang, Qiongfang; Xu, Shunqing; Zhu, Huijun; Shu, BaihuaCurrently HPLC/MS is the state of the art tool for environmental/drinking water perfluorooctane sulfonate (PFOS) monitoring. PFOS can bind to peroxisomal proliferator-activated receptor-alpha (PPARα), which forms heterodimers with retinoid X receptors (RXRs) and binds to PPAR response elements. In this bioassay free PFOS in water samples competes with immobilized PFOS in ELISA plates for a given amount of PPARα-RXRα. It can be determined indirectly by immobilizing PPARα-RXRα-PFOS complex to another plate coated with PPARα antibody and subsequent measuring the level of PPARα-RXRα by using biotin-modified PPARα- RXRα probes-quantum dots-streptavidin detection system. The rapid and high- throughput bioassay demonstrated a detection limit of 2.5ngL-1 with linear range between 2.5ngL-1 and 75ngL-1. Detection results of environmental water samples were highly consistent between the bioassay anItem Open Access Recent Development of Flax Fibres and Their Reinforced Composites Based on Different Polymeric Matrices(2013-11-12T00:00:00Z) Zhu, Jinchun; Zhu, Huijun; Njuguna, James A. K.; Abhyankar, HrushikeshThis work describes flax fibre reinforced polymeric composites with recent developments. The properties of flax fibres, as well as advanced fibre treatments such as mercerization, silane treatment, acylation, peroxide treatment and coatings for the enhancement of flax/matrix incompatibility are presented. The characteristic properties and characterizations of flax composites on various polymers including polypropylene (PP) and polylactic acid, epoxy, bio-epoxy and bio-phenolic resin are discussed. A brief overview is also given on the recent nanotechnology applied in flax composites. Keywords: flax composites; mechanical properties; modificationsItem Open Access Safety assessment of novel polymer-silicon composites - from LCA perspective(Publications Office of the European Union, 2012-12) Zhu, Huijun; Irfan, Adeel; Sachse, Sophia; Njuguna, JamesThe fast growing trend in the development of novel materials with potential applications in many industrial sectors has caused concerns over the environment and human health effect of the emerging activities and associated products. It is imperative that these concerns are addressed in a holistic manner as early as possible. As part of the NEPHH project, this study applied the LCA concept aiming to identify hazardous nanoparticles (NP) that could be released during the development and application of novel products, focusing on polymeric-silicon composites in recognition of their attractions to a wide range of industries, including construct engineering, automotive and aerospace.