Browsing by Author "Rasekh, M."
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item Open Access Broad Scale & Structure Fabrication of Healthcare Materials for Drug and Emerging Therapies Via Electrohydrodynamic Techniques(Wiley, 2018-09) Mehta, P.; Zaman, A.; Smith, A.; Rasekh, M.; Haj-Ahmad, R.; Arshad, M. S.; van der Merwe, S.; Chang, M-W.; Ahmad, Z.The engineering of advanced healthcare materials provides a platform to address challenges facing interdisciplinary scientists, clinicians, pharmacists, biomaterial scientists and biomedical engineers. Niche and timely developments arising from the synthesis or extraction of more biocompatible materials, new biologically active components, clearer insights into disease mechanisms and novel therapies or strategies provide several timely opportunities. These include enhanced therapies with greater patient compliance, improved disease targeting, better diagnosis and bespoke medications for individuals. Electrohydrodynamic atomisation (EHDA) engineering comprises several processes making use of electric fields (e.g. through an applied voltage) interplaying with several forces (e.g. gravity and surface tension). Coupled to advanced materials (e.g. formulated media) and specifically configured apparatuses (e.g. nozzles, collectors and downstream processes); effective and controlled fabrication of various structures (fibers, particles, bubbles, grids, droplets) on various scales (macro, micro and nano) possessing various dimensions (2D, 3D and 4D) is readily achieved. The processes have distinct advantages compared to established engineering methods (ambient environment engineering, low shear, scalability, compartmentalisation etc.). This detailed review focuses on key concepts and developments in EHDA engineering pertaining to underlying principles, enabling tools and engineered structures specifically for healthcare remits. From initial experiments involving the behaviour of non-formulated liquids on charged amber to recent developments in complex 3D matrix printing; the EHDA route has progressed significantly, most rapidly in the last two decades, and is capable of providing timely platform opportunities to tackle several global healthcare challengesItem 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 Embargo Electrospun PVP-indomethacin constituents for transdermal dressings and drug delivery devices(Elsevier, 2014-07) Rasekh, M.; Karavasili, Chirstina; Soong, Yi Ling; Bouropoulos, Nikolaos; Morris, M. A.; Armitage, David; Li, Xiang; Fatouros, Dimitrios; Ahmad, Z.A method in layering dressings with a superficial active layer of sub-micrometer scaled fibrous structures is demonstrated. For this, polyvinylpyrolidone (PVP) - indomethacin (INDO) fibres (5% w/v PVP, 5% w/w indomethacin, using a 50:50 ethanol-methanol solvent system) were produced at different flow rates (50μL/min and 100μL/min) via a modified electrospinning device head (applied voltage varied between 15±2kV). We further assessed these structures for their chemical, physical and morphological properties using SEM, AFM, DSC, XRD, FTIR and HPLC-UV. The average diameter of the resulting 3D (∼500nm in height) PVP-INDO fibres produced at 50μL/min flow rate was 2.58±0.30μm, while the diameter almost doubled (5.22±0.83μm) when the flow rate was doubled. However, both of these diameters were appreciably smaller than the existing dressing fibres (∼30μm), which were visible even when layered with the active spun fibres. Indomethacin was incorporated in the amorphous state. The encapsulation efficiency was 75% w/w, with complete drug release in 45minutes. The advantages are the ease of fabrication and deposition onto any existing normal or functionalised dressing (retaining the original fabric functionality), elimination of topical product issues (application, storage and transport), rapid release of active and controlled loading of drug content (fibre layer). Electrospun PVP-indomethacin constituents for transdermal dressings and drug delivery devices.Item Open Access Facile Preparation of Drug-Loaded Tristearin Encapsulated Superparamagnetic Iron Oxide Nanoparticles Using Coaxial Electrospray Processing(ACS American Chemical Society, 2017-04-26) Rasekh, M.; Ahmad, Z.; Cross, R. B. M.; Hernandez-Gil, Javier; Wilton-Ely, James D. E. T.; Miller, Philip W.Item Open Access Fibrous polymeric buccal film formulation, engineering and bio-interface assessment(Elsevier, 2017-10-03) Nazari, K.; Kontogiannidou, Eleni; Haj-Ahmad, R.; Andreadis, Dimitrios; Rasekh, M.; Bouropoulos, Nikolaos; van der Merwe, Susanna M.; Chang, Ming-Wei; Fatouros, Dimitrios; Ahmad, Z.Polymer based dosages form the mainstay of drug delivery systems either as simple matrix carrier materials or active release behavior modulating agents. In addition, several techniques have been developed further to deliver novel polymeric structures. One such method is electrospinning (ES); a maturing process which is operational at the ambient environment and enables drug loading (in molecularly dispersed form) directly into a fibrous polymer matrix system. Since there is an impending need to address healthcare challenges arising from an increase in the aging population (requiring enhanced treatments), the ES method was used to develop fibrous polymer composite-indomethacin (INDO) films for potential use in the buccal region. Films were assessed for their inter-facial behavior at bio-interfaces (in-vitro and ex-vivo). Polymeric excipients possessing an established profile for commercial dosage form development were selected. Fibrous films (all fibre components <400 nm) were characterised using DSC, TGA, FTIR, Raman and XRD. DSC and XRD demonstrated INDO change from crystalline to amorphous state. FTIR and Raman data suggest INDO, PVP and co-polymers (Methocel™ E5, Methocel™ E15 and Tween® 80) were integrated in stable fashion into filamentous structures via ES. Variable INDO release behavior from several matrices was observed suggesting a potential route to tailor drug release based on polymeric excipient use and ratio. Furthermore, permeation studies using a porcine buccal model demonstrated sustained permeation once dosages are attached to the buccal mucosa. The insoluble nature of cellulose excipients were used to promote sustained release while the use of Tween® 80 surfactant was used to enhance permeation of INDO through polymer interaction with excised tissue. Finally, histology studies indicate polymer excipient selection impacts the bio-interface. In summary, a facile approach to formulate, encapsulate and engineer fibrous polymeric buccal films (on demand) is shown. The method enables drug dispersion directly within the composite polymeric system, which has a clear impact on drug release, in-vitro and ex-vivo bio-interaction.Item Embargo Hollow-layered nano particles for therapeutic delivery of peptide prepared using electrospraying.(Springer US, 2015-10-08) Rasekh, M.; Young, Christopher N. J.; Roldo, M.; Lancien, F.; Mevel, J.C.; Hafizi, S.; Ahmad, Z.; Barbu, E.; Gorecki, DariuszThe viability of single and coaxial electrospray techniques to encapsulate model peptide-angiotensin II into near mono-dispersed spherical, nanocarriers comprising N-octyl-O-sulphate chitosan and tristearin, respectively, was explored. The stability of peptide under controlled electric fields (during particle generation) was evaluated. Resulting nanocarriers were analysed using dynamic light scattering and electron microscopy. Cell toxicity assays were used to determine optimal peptide loading concentration (~1 mg/ml). A trout model was used to assess particle behaviour in vivo. A processing limit of 20 kV was determined. A range of electrosprayed nanoparticles were formed (between 100 and 300 nm) and these demonstrated encapsulation efficiencies of ~92 ± 1.8%. For the single needle process, particles were in matrix form and for the coaxial format particles demonstrated a clear core-shell encapsulation of peptide. The outcomes of in vitro experiments demonstrated triphasic activity. This included an initial slow activity period, followed by a rapid and finally a conventional diffusive phase. This was in contrast to results from in vivo cardiovascular activity in the trout model. The results are indicative of the substantial potential for single/coaxial electrospray techniques. The results also clearly indicate the need to investigate both in vitro and in vivo models for emerging drug delivery systems.Item Open Access Microneedle Coating Techniques for Transdermal Drug Delivery.(Pharmaceutics, 2015-11-05) Haj-Ahmad, R.; Khan, H.; Arshad, M. S.; Rasekh, M.; Hussain, A.; Walsh, Susannah E.; Li, X.; Chang, M-W.; Ahmad, Z.Item Metadata only Pharmaceutical and biomaterial engineering via electrohydrodynamic atomization technologies(Elsevier, 2016-09-28) Mehta, P.; Haj-Ahmad, R.; Rasekh, M.; Arshad, Muhammad Sohail; Smith, Ashleigh; van der Merwe, Susanna M.; Li, Xiang; Chang, M-W.; Ahmad, Z.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.Item Open Access Stable Increased Formulation Atomisation Using a Multi-Tip Nozzle Device(Springer, 2018-06-05) Ahmad, Z.; Haj-Ahmad, R.; Rasekh, M.; Nazari, K.; Onaiwu, E.V.; Yousef, B.; Morgan, S.; Evans, D.; Chang, Ming-Wei; Hall, John; Samwell, C.Electrohydrodynamic atomisation (EHDA) is an emerging technique for the production of micron and nano-scaled particles. The process often involves Taylor cone enablement, which results in a fine spray yielding formulated droplets, which then undergo drying during deposition. In this work novel multi-tip emiiter (MTE) devices were designed, engineered and utilised for potential up-scaled EHDA, by comparison with a conventional single needle system. To demonstrate this, the active ketoprofen (KETO) was formulated using polyvinylpyrrolidone (PVP) polymer as the matrix material. Here, PVP polymer (5% w/v) solution was prepared using ethanol and distilled water (80:20) as the vehicle. KETO was incorporated as 5% w/w of PVP. Physical properties of resulting solutions (viscosity, electrical conductivity, density and surface tension) were obtained. Formulations were electrosprayed through both single and novel MTEs under EHDA conditions at various flow rates (5-300 μl/min) and applied voltages (0-30 kV). The atomization process using MTEs and single nozzle was monitored at using various process parameters via a digital optical camera. Resulting particles were collected 200mm below processing heads and were analyzed using differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Digital recordings confirmed stable MTE jetting at higher flow rates. Electron micrographs confirmed particle size variation arising due to nozzle head design and evidenced stable jetting derived greater near uniform particles. DSC, XRD and TGA confirm KETO molecules were encapsulated and dispersed into PVP polymer particles. In conclusion, novel MTE devices enabled stable atomisation even at higher flow rates when compared to the conventional single needle device. This indicates an exciting approach for scaling-up (EHDA) in contrast to current efforts focusing on multiple nozzle and pore based processing outlets.