Browsing by Author "Edirisinghe, M."
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Item Metadata only Bioinspired bubble design for particle generation(Royal Society Publishing, 2012) Gunduz, Oguzhan; Ahmad, Z.; Stride, E.; Tamerler, Candan; Edirisinghe, M.Item Metadata only Continuous Generation of Ethyl Cellulose Drug Delivery Nanocarriers from Microbubbles(Springer, 2013) Gunduz, Oguzhan; Ahmad, Z.; Stride, E.; Edirisinghe, M.Item Metadata only A device for the fabrication of multifunctional particles from microbubble suspensions(Elsevier, 2012) Gunduz, Oguzhan; Ahmad, Z.; Stride, E.; Edirisinghe, M.Item Metadata only Direct Writing of Polycaprolactone Polymer for Potential Biomedical Engineering Applications(Wiley, 2011) Rasekh, M.; Ahmad, Z.; Day, R.; Wickam, Abeni; Edirisinghe, M.Item Metadata only Electrohydrodynamic Bubbling: An Alternative Route to Fabricate Porous Structures of Silk Fibroin Based Materials(ACS Publications, 2013) Ekemen, Z.; Ahmad, Z.; Stride, E.; Kaplan, David; Edirisinghe, M.Item Metadata only Electrohydrodynamic Printing of Silk Fibroin Fiber Structures(2013) Bayram, C.; Ahmad, Z.; Denkbas, E.; Stride, E.; Edirisinghe, M.Item Metadata only Fabrication of Biomaterials via Controlled Protein Bubble Generation and Manipulation(2011-11-01) Ekemen, Z.; Chang, H.; Ahmad, Z.; Bayram, C.; Rong, Z.; Denkbas, E.; Stride, E.; Vadgama, P.; Edirisinghe, M.In this work, we utilize a recently developed microbubbling process to generate controlled protein (bovine serum albumin, BSA) coated bubbles and then manipulate these to fabricate a variety of structures suitable for several generic biomedical applications, tissue engineering, and biosensor coatings. Using BSA solutions with varying concentrations (20, 25, and 30 wt%) and cross-linking (terephthaloyl chloride) mechanisms, structures were fabricated including porous thin films with variable pore sizes and thickness (partially cross-linked coupled to bubble breakdown), scaffolds with variable pore morphologies (fully cross-linked), and coated bubbles (no cross-linking), which can be used as stand-alone delivery devices and contrast agents. The movement of typical biosensor chemicals (catechol and hydrogen peroxide) across appropriate film structures was studied. The potential of formed scaffold structures for tissue engineering applications was demonstrated using mouse cell lines (L929). In addition to low cost, providing uniform structure generation and high output, the size of the bubbles can easily be controlled by adjusting simplistic processing parameters. The combination of robust processing and chemical modification to uniform macromolecule bubbles can be utilized as a competing, yet novel, tool with current technologies and processes in advancing the biomaterials and biomedical engineering remits.Item Metadata only Generation of multi-layered structures for biomedical applications using a novel tri-needle co-axial device and electrohydrodynamic flow(2008) Ahmad, Z.; Zhang, H.; Farook, U.; Edirisinghe, M.; Stride, E.; Colombo, P.In this short communication, we describe the scope and flexibility of using a novel device containing three coaxially arranged needles to form a variety of novel morphologies. Different combinations of materials are subjected to controlled flow through the device under the influence of an applied electric field. The resulting electrohydrodynamic flow allows us to prepare doublelayered bubbles, porous encapsulated threads and nanocapsules containing three layers. The ability to process such multilayered structures is very significant for biomedical engineering applications, for example, generating capsules for drug delivery, which can provide multistage controlled release.Item Metadata only How Do Microbubbles and Ultrasound Interact? Basic Physical, Dynamic and Engineering Principles(Bentham Science Publishers, 2012) Azmin, Mehrdad; Harfield, Caroline; Ahmad, Z.; Edirisinghe, M.; Stride, E.Item Metadata only Nanoparticle delivery systems formed using electrically sprayed co-flowing excipients and active agent.(2011) Bakhshi, R.; Ahmad, Z.; Soric, M.; Stride, E.; Edirisinghe, M.Item Metadata only Preparation and characterisation of a novel bioactive restorative composite based on covalently coupled polyurethane-nano-hydroxyapatite fibres(2008) Khan, A.; Ahmad, Z.; Edirisinghe, M.; Wong, F.; Rehman, I.Nanohydroxyapatite (n-HAp) was prepared using a sol–gel method. n-HAp powder was obtained from the gel form by heat treatment followed by grinding using ball milling. A novel polyurethane composite material was prepared by chemically binding the hydroxyapatite to the diisocyanate component in the polyurethane backbone through solvent polymerization. The procedure involved the stepwise addition of monomeric units of the polyurethane and optimizing the reagent concentrations. The resultant composite material was electrospun to form fibre mats. The fibres were less than 1 lm in thickness and contained no beads or irregularities. Chemical structural characterization of both the ceramics and the novel polymers were carried out by Fourier transform infrared and Raman spectroscopy. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy and Brunauer–Emmett–Teller surface area analysis were also employed to observe the crystal lattice and size and surface area of the n-HAp. Further characterization (by energy-dispersive X-ray analysis and SEM) of the spun fibres revealed the presence of elements associated with hydroxyapatite and polyurethane without the presence of any loose particles of hydroxyapatite, indicating the formation of the covalent bond between the ceramics and the polymer backbone.Item Metadata only The role of electrosprayed nanoapatites in guiding osteoblast behaviour(2008) Thian, E.; Ahmad, Z.; Huang, J.; Edirisinghe, M.; Jayasinghe, S.; Ireland, D.; Brooks, R.; Rushton, N.; Bonfield, W.; Best, S.Apatite nanocrystals, which mimic the dimensions of natural bone mineral, were electrosprayed on glass substrates, as a suitable synthetic biomedical material for osteoblast outgrowth was explored. A variety of topographic patterns were deposited and the influence of these designs on osteoblast alignment and cell differentiation was investigated. Patterned cell growth and enhanced cell differentiation were seen. Osteoblasts were also cultured on apatite nanocrystals chemically modified with either carbonate or silicon ions. Enhanced cell proliferation and early formation of mineral nodules were observed on apatite nanocrystals with silicon addition. This work highlights the importance of the combined effects of surface topography and surface chemistry in the guidance of cell behaviour.Item Metadata only Spatial and temporal evaluation of cell attachment to printed polycaprolactone microfibres.(2012) Rasekh, M.; Ahmad, Z.; Frangos, C.; Bozec, L.; Edirisinghe, M.; Day, R.Surface topography plays a crucial role in influencing cellular responses and has therefore been utilized in the development of numerous implantable devices. Whilst numerous studies have either investigated cell attachment or migration post-attachment, few have looked at the early-stages of this process temporally. The aim of this study was to evaluate the use of time-lapse microscopy to study the behaviour of fibroblasts cultured with polycaprolactone microfibres and to assess spatially and temporally the cell–structure interaction over a 24 h period. Ordered polymeric structures were printed (predetermined) onto glass substrates using an electrohydrodynamic direct write process to produce fine (3–5 lm wide) structures. Fibroblast attachment and migration were characterized as a function of distance perpendicular from structures ( 17.3, 34.6 and 51.9 lm). The use of time-lapse microscopy revealed a gradual decrease in cell attachment as the distance from the microfibres was increased. The technique also revealed that some cells were attaching and detaching from the microfibre multiple times. Our findings demonstrate that time-lapse microscopy is a useful technique for evaluating early-stage cell–biomaterial interaction that is capable of recording important events that might otherwise be overlooked.