Abstract: This paper present the results of (experiments and models) biosynthesized prodigiosin (PG) released from an implantable biomedical device on the viability of cancer cells. The implantable biomedical devices were obtained from poly-di-methyl-siloxane (PDMS) packages with well-controlled micro-channels and drug storage compartments, along with a drug storing polymer core (which contains thermosensitive Poly (N-isopropylacrylamide)(PNIPA)-based gels). The results were compared with drugs elution from devices loaded with paclitaxelTM. The effects of localized release of PG and paclitaxel (PTx) on cell viability were elucidated via clonogenic assay testing on MDA-MB-231 breast cancer cell line. The effects of PG and PTx released were also tested over a range of temperatures (37-45 ̊C) in which localized hyperthermia is applicable. The trends in the results were analysed using statistical models before discussion their implications for localized treatment of breast cancer.
Abstract: This paper presents the biosynthesis of gold nanoparticles from the bacteria, Serratia marcescens. The intra-and extra-cellular synthesis of gold nanoparticles is shown to occur over a range of pH and incubation times in cell-free exracts and biomass of serratia marcescens that were reacted with 2.5mM Tetrachloroauric acid (HAuCl4). The formation of gold nanoparticles was identified initially via color changes from yellow auro-chloride to shades of red or purple in gold nanoparticle solutions. UV-Visible spectroscopy (UV-Vis), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray spectroscopy (EDS), Helium Ion Microscopy (HIM) and Dynamic Light Scattering (DLS) were also used to characterize gold nanoparticles produced within a range of pH conditions. The results show clearly that the production of gold nanoparticles from cell-free extracts require shorter times than the production of gold nanoparticles from the biomass.
Abstract: The biosynthesis of gold nanoparticles from Nauclea latifolia leaf/plant extract is presented in this paper. The synthesis is shown to produce gold nanoparticles from hydrogen Tetra-chloro auric acid (HAuCl4) in less than 1 minute. The resulting gold nanoparticles are characterized using UV/Visible spectrophotometry (UV-Vis), Energy Dispersive X-ray Spectroscopy (EDX), Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). The implications of the results are discussed for potential applications of biosynthesized gold nanoparticles in cancer detection and treatment.
Abstract: This paper presents concepts for the modeling of cell deformation and cell detachment from biocompatible biomedical materials. A combination of fluid mechanics and fracture mechanics concepts is used to model the detachment of cells under shear assay conditions. The analytical and computational models are validated by shear assay experiments in which human-osteo-sarcoma (HOS) cell are detached from surfaces that are relevant to bio-micro-electro-mechanical systems (BioMEMS), bio-microelectronics and orthopaedic/dental implants. The experiments revealed that cell detachment occurs from patches in which of α/β integrins are separated from the extracellular matrix that is left on the substrate. The stress/strain distribution and energy release rates associated with the observed detachments are also computed using elastic cell deformation, fluid/structure interactions and linear fracture mechanics (LEFM) model. The simulations reveal show that cancer cells generally experience higher levels of deformation than normal cells. The simulations also revealed that the cell-extracellular matrix interface was prone to cell detachment (interfacial failure), as observed in the shear assay experiments. The critical energy release rates for normal cell detachment were also found to be greater than those required for the detachment of cancer cells. The implications of the results are discussed for the design of biomedical implants and their interfaces.
Abstract: This paper presents the results of an experimental study of the effects of adhesion between gold nanoparticles and surfaces that are relevant to the potential applications in cancer detection and treatment. Adhesion is measured using a dip coating/atomic force microscopy (DC/AFM) technique. The adhesion forces are obtained for dip-coated gold nanoparticles that interact with peptide or antibody-based molecular recognition units (MRUs) that attach specifically to breast cancer cells. They include MRUs that attach specifically to receptors on breast cancer cells. Adhesion forces between anti-cancer drugs such as paclitaxel, and the constituents of MRU-conjugated Au nanoparticle clusters, are measured using force microscopy techniques. The implications of the results are then discussed for the design of robust gold nanoparticle clusters and for potential applications in localized drug delivery and hyperthermia.
Abstract: This paper presents the results of a study of the adhesion and optical properties of layered structures that are relevant to stretchable organic solar cells. A combination of modeling and experiments is used to investigate the effects of adhesion and stretching on failure mechanisms and optical properties. The adhesion between the possible bi-layers is determined by incorporating force microscopy measurements of pull-off forces into adhesion models. The failure mechanisms associated with the tensile stretching of the structures are then investigated using a combination of in-situ/ex-situ microscopy observations and analytical/computational models. The resulting changes in optical properties are elucidated before discussing their implications for the design of stretchable organic solar cells
Abstract: In this paper, we present the results of a combined theoretical, computational and experimental study of failure mechanisms in model multilayers that are relevant to stretchable organic solar cells. The deformation of these structures is elucidated under monotonic loading that simulates possible stretching phenomena. The stress distributions within the layers and the possible interfacial crack driving forces are computed for model layered structures with well controlled thicknesses and elastic properties. The implications of the results are discussed for the improved design of stretchable organic solar cells with reliable optical properties.
Abstract: This research investigates the effects of bending on the electrical, optical, structural and mechanical properties of flexible organic photovoltaic (OPV) cells. Bulk heterojunction organic solar cells were fabricated on Polyethylene terephthalate (PET) substrates using Poly-3-hexylthiophene: [6, 6]-phenyl-C61-butyric acid methyl ester (P3HT: PCBM) as the active layer and Poly (3, 4-ethylenedioxythiophene) Polystyrenesulfonate (PEDOT: PSS) as the hole injection layer. All the organic layers were deposited by spin coating while the Al cathode was vacuum thermally evaporated. The Indium Tin Oxide (ITO) anode has an average optical transmittance of 85% in the visible spectrum, a sheet resistivity of 60 ohms per square and an average surface roughness of 3nm. The relationship between the optoelectronic performance of the various device layers and the applied mechanical strains has been analyzed. The effects of stress and strain on the current-voltage characteristics of the device and its failure were modeled using the Abaqus software.
Abstract: This paper examines the effects of cyclic bending on the deformation and failure of layers that are relevant to flexible organic solar cells (with Polyethylene Terephthalate (PET) substrates and Poly-3-hexylthiophene: [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) active layers). The deformation and cracking mechanisms are elucidated along with the stresses and crack driving forces associated with the bending of flexible organic solar cells. The changes in the optical properties (transmittance) of the individual layers and multilayers are then explored for layers/multilayers deformed to flexural strains and stresses that are computed using finite element models. The implications of the results are then discussed for the design of flexible organic solar cells.