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- Electrospinning of food-grade nanofibres from whey proteinPublication . Zhong, Jie; Mohan, Saeed D.; Bell, Alan; Terry, Ann; Mitchell, Geoffrey R.; Fred, DavisIn this study, electrospinning has been employed to produce micro to nano scale fibres of whey protein in order to investigate their potential for use in the food industry. Initially, spinning of purewhey protein proved challenging; so in order to facilitate the spinning of freshly prepared aqueous solutions, small amounts of polyethylene oxide (as low as 1% w/w in solution) were incorporated in the spinning solutions. The electrospun composite polyethylene-oxide/whey fibres exhibited diameters in the region of 100 to 400 nm, showing the potential to build fibre bundles from this size up. Time-dependent examinations of pure whey protein aqueous solutions were conducted using rheometery and small angle neutron scattering techniques, with the results showing a substantial change in the solution properties with time and stirring; and allowing the production of fibres, albeit with large diameters,without the need for an additive. The spinability is related to the potential of thewhey protein composites to form aggregate structures, either through hydration and interaction with neighbouring proteins, or through interaction with the polyethylene oxide.
- Protein Nanocarriers for Targeted Drug Delivery for Cancer TherapyPublication . Kariduraganavar, Mahadevappa Y.; Heggannavar, Geetha B.; Amado, Sandra; Mitchell, Geoffrey R.This chapter describes how proteins can be used to provide effective targeted nanocarriers for drugs to target tumors. This approach offers an exciting framework for cancer therapies in the future, allowing multiple therapeutic agents and other functions to be combined in the same particle and ensuring a lower toxicity for the patient. The use of proteins provides a rich library of functional molecules to exploit in this methodology. The role of computer simulation to identify the best combination of protein, ligand, and drugs is highlighted.
- The Exploitation of Polymer Based Nanocomposites for Additive Manufacturing: A Prospective ReviewPublication . Khan, Imran; Kamma-Lorger, Christina S.; Mohan, Saeed D.; Mateus, Artur; Mitchell, GeoffreyAdditive manufacturing (AM) is a well-known technology for making real three dimensional objects, based on metal, ceramic and plastic material used for various applications. The aim of this review is to explore and offer an insight in to the state of the art polymer based nanocomposites in to additive manufacturing applications. In context to this, the developing efforts and trends in nanocomposites development particularly for additive manufacturing processes were studied and summed up. The scope and limitations of nanocomposites into Stereolithography, selective laser sintering and fused deposition modeling was explored and highlighted. The review highlights widely accepted nanoparticles for range of applications including mechanical, electrical, flame retardance and crossing over into more biological with the use of polymer matrices. Acquisition of functional parts with limitations in regard to printing is highlighted. Overall, the review highlights successes, limitations and opportunities that the union of AM and polymer based nanocomposites can bring to science and technology.
- Measuring in-situ X-ray scattering of natural rubber biaxial deformation: A new equipment for polymer studiesPublication . Silva, Daniel P. da; Lamolinara, Barbara; Costa, André; Gameiro, Fábio; Pascoal-Faria, Paula; Mateus, Artur; Martinez, Juan Carlos; Phinyocheep, Pranee; Amornsakchai, Taweechai; Mitchell, Geoffrey R.Understanding biaxial deformation is essential for a more realistic evaluation of rubber elasticity compared to the more usual uniaxial deformation. To study crystallisation occurring during biaxial deformation of natural rubber films, a new simple equipment has been designed and assembled. The equipment, mounted in the beamline of ALBA synchrotron light source facility, allowed the in-situ measurement of X-ray scattering of natural rubber during biaxial deformation. This work provides, for the first time, quantitative information on crystallisation during biaxial extension.
- A pilot plant scale testing of the application of seaweed-based natural coating and modified atmosphere packaging for shelf-life extension of fresh-cut applePublication . Augusto, Ana; Miranda, Andreia; Costa, Leonor; Pinheiro, Joaquina; Campos, Maria J.; Raimundo, Délio; Pedrosa, Rui; Mitchell, Geoffrey; Niranjan, Keshavan; Silva, Susana F.J.Codium tomentosum hydroethanolic extract was obtained using a pilot solid–liquid extractor to validate the anti-browning functionality of the extract under industrial conditions. Fresh-cut apple slices were coated by immersion in: (1) a seaweed extract solution (0.5% w/v) and (2) a commercial coating, and the two sets of samples were compared with a control (immersion in water). Packaged samples were stored, under ambient and modified atmosphere conditions at 4°C. After 30 days of storage, the samples that were coated with the seaweed extract and packaged under modified atmosphere, demonstrated lower peroxidase activity and polyphenol oxidation when compared with the samples treated with the commercial additive. These results confirm, at pilot scale and under industrial production conditions, the efficacy of the seaweed extract as a bio-based substitute for the synthetic coatings, which are currently used to prevent browning in fresh-cut apples.
- Additive manufactured Poly("-caprolactone)-graphene scaffolds: Lamellar crystal orientation, mechanical properties and biological performancePublication . Biscaia, Sara; Silva, João C.; Moura, Carla; Viana, Tânia; Tojeira, Ana; Mitchell, Geoffrey R.; Pascoal-Faria, Paula; Ferreira, Frederico Castelo; Alves, NunoUnderstanding the mechano–biological coupling mechanisms of biomaterials for tissue engineering is of major importance to assure proper scaffold performance in situ. Therefore, it is of paramount importance to establish correlations between biomaterials, their processing conditions, and their mechanical behaviour, as well as their biological performance. With this work, it was possible to infer a correlation between the addition of graphene nanoparticles (GPN) in a concentration of 0.25, 0.5, and 0.75% (w/w) (GPN0.25, GPN0.5, and GPN0.75, respectively) in three-dimensional poly("-caprolactone) (PCL)-based scaffolds, the extrusion-based processing parameters, and the lamellar crystal orientation through small-angle X-ray scattering experiments of extruded samples of PCL and PCL/GPN. Results revealed a significant impact on the scaffold’s mechanical properties to a maximum of 0.5% of GPN content, with a significant improvement in the compressive modulus of 59 MPa to 93 MPa. In vitro cell culture experiments showed the scaffold’s ability to support the adhesion and proliferation of L929 fibroblasts (fold increase of 28, 22, 23, and 13 at day 13 (in relation to day 1) for PCL, GPN0.25, GPN0.5, and GPN0.75, respectively) and bone marrow mesenchymal stem/stromal cells (seven-fold increase for all sample groups at day 21 in relation to day 1). Moreover, the cells maintained high viability, regular morphology, and migration capacity in all the different experimental groups, assuring the potential of PCL/GPN scaffolds for tissue engineering (TE) applications.
- Crosslinked nanocomposite sodium alginate-based membranes with titanium dioxide for the dehydration of isopropanol by pervaporationPublication . Premakshi, P. G.; Kariduraganavar, Mahadevappa Y.; Mitchell, GeoffreySodium alginate (NaAlg) based membranes were prepared using a solution technique, crosslinked with poly(styrene sulfonic acid-co-maleic acid) (PSSA-co-MA). Subsequently, the membranes were modified by the incorporation of 0, 10, 20, 30 and 40% w/w of titanium dioxide with respect to sodium alginate. The membranes thus obtained were designated as M, M-1, M-2, M-3 and M-4, respectively. An equilibrium swelling experiment was performed using dfferent compositions of the water and isopropanol mixtures. Subsequently, we used a pervaporation cell fitted with each membrane in order to evaluate the extent of the pervaporation dehydration of isopropanol. Among the membranes studied, the membranes containing 40 mass% of titanium dioxide exhibited the highest separation factor() of 24,092, with a flux(J) of 18.61x10-² kg/m².h at 30ºC for 10 mass%w/w of water in the feed. The total flux and the flux of water were found to overlap with each other, indicating that these membranes can be e ectively used to break the azeotropic point of water–isopropanol mixtures. The results clearly indicate that these nanocomposite membranes exhibit an excellent performance in the dehydration of isopropanol. The activation energy values obtained for the water permeation were significantly lower than those of the isopropanol permeation, underlining that these membranes have a high separation ability for the water isopropanol system. The estimated activation energies for total permeation (EP) and total di usion (ED) values ranged between 10.60 kJ.mol-¹ and 3.96 kJ.mol-¹, and 10.76 kJ.mol-¹ and 4.29 kJ.mol-¹, respectively. The negative change in the enthalpy values for all the membranes indicates that sorption was mainly dominated by Langmuir’s mode of sorption.
- Rosin Based Composites for Additive ManufacturingPublication . Sousa, Dora; Biscaia, Sara; Viana, Tânia; Gaspar, Miguel Belbut; Mahendra, Vidhura; Mohan, Saeed D.; Mateus, Artur; Mitchell, GeoffreyRosins are the non-volatile exudates of pine resins with hydrophobic characteristics that are widely used as a precursor for many industrial applications. In this paper we discuss the nature, process and its applications as a matrix for a composite material for additive manufacturing. The composite material has been tailored to chemical and mechanical properties with respect to their applications.
- Orthogonal templating control of the crystallisation of Poly("-Caprolactone)Publication . Mitchell, Geoffrey R.; Olley, Robert H.The crystal growth of poly("-caprolactone) can be very effectively directed through the use of small amounts of dibenzylidene sorbitol in conjunction with modest flow fields to yield extremely high levels of the preferred polymer crystal orientation. We show that by introducing small quantities of a terpolymer, based on polyvinyl butyral we can switch the symmetry axis of the final lamellar orientation from parallel to perpendicular to the melt flow direction. During shear flow of the polymer melt, the dibenzylidene sorbitol forms highly extended nanoparticles which adopt a preferred alignment with respect to the flow field and on cooling, polymer crystallisation is directed by these particles. The presence of the terpolymer, based on polyvinyl butyral, limits the aspect ratio of the dibenzylidene sorbitol (DBS) particles, such that the preferred orientation of the particles in the polymer melt changes from parallel to normal to the flow direction. The alignment of lamellar crystals perpendicular to the flow direction has important implications for applications such as scaffolds for tissue engineering and for barrier film properties.
- Development of novel 3D scaffolds using BioExtruder by varying the content of hydroxyapatite and silica in PCL matrix for bone tissue engineeringPublication . Pattanashetti, Nandini A.; Viana, Tânia; Alves, Nuno; Mitchell, Geoffrey; Kariduraganavar, Mahadevappa Y.Polycaprolactone (PCL) is considered as a most widely used biodegradable polymers in tissue engineering. But, PCL is also associated with certain limitations like, low stiffness, hydrophobic nature and limited cell affinity. These drawbacks are addressed in the present study by incorporating different wt% of silicon dioxide (SiO2) and hydroxyapatite (HAp) in the PCL matrix. 3D scaffolds were developed using a novel BioExtruder. The physicochemical properties, thermal stability and wettability of the composite scaffolds were studied systematically. Optical and Scanning Electron Microscopic images were analysed for morphological evaluation of the scaffolds. The pore size of the developed scaffolds increased from 290 to 315 μmwith increasing SiO2 content, as examined by scanning electron microscope. An improved compressive modulus of 68.82 MPa was observed for 15 wt% SiO2 incorporated composite scaffold. The in-vitro degradation study of the composite scaffolds demonstrated an increase in the degradation rate for PCL/HAp scaffolds, while no significant change was observed for SiO2 incorporated scaffolds. Further, the cytotoxicity and cell proliferation studies were carried out using L929 Mouse Fibroblasts and MG-63 Osteoblasts respectively. The developed scaffolds revealed no toxic effects towards the cellular response and an increase in cell proliferation of ≥90% was observed during 7 days of cell culture. Thus, the scaffolds were proved to be potential candidate for bone tissue engineering application, particularly the scaffold with 10 wt% SiO2 incorporation into PCL/HAp (75/15) composite has resulted into higher cell proliferative % and improved mechanical strength.