http://hdl.handle.net/10468/3239 2017-10-30T17:58:25Z http://hdl.handle.net/10468/4826 A review of physical activity monitoring and activity trackers for older adults Barton, John; O'Flynn, Brendan; Tedesco, Salvatore Cudd, Peter; de Witte, Luc The objective assessment of physical activity levels through wearable inertial-based motion detectors for an automatic, continuous and long-term monitoring of people in free-living environments is a well-known research area in literature. However, their application to older adults can present particular constraints. This paper reviews the methods of measuring physical activity, adoption of wearable devices in older adults, describes and compares existing commercial products encompassing activity trackers tailored for older participants. 2017-09-01T00:00:00Z http://hdl.handle.net/10468/4752 Branched PEI capped gold nanoparticles in water for siRNA delivery to cancer cells Rahme, Kamil; Guo, Jianfeng; Biswas, Subhajit; O'Driscoll, Caitríona M.; Holmes, Justin D. Herein we describe a simple method for the synthesis of different sizes of polyethylenimine-capped gold nanoparticles (AuNPs-PEI) in water and assess their potential to deliver siRNA or other therapeutic agents to cancer cells. AuNP-PEI with diameters ranging between 25-150 nm have been synthesised in aqueous solutions using PEI (25 KD and 2KD) as capping ligands and using hydroxylamine-O-sulfonic acid or ascorbic acid as reducing agents. Different parameters were found to affect the final size of nanoparticles core (i.e. gold salt concentrations, PEI molecular weight/concentrations, and temperature). The obtained AuNP-PEIs were fully characterized using UV-visible spectroscopy, Electron Microscopy (EM), and Dynamic Light Scattering (DLS). UV-visible spectra clearly showed that the synthesized particles have size dependent optical properties with a plasmon band shift to longer wavelengths, as the size of the AuNP core was increased. In addition, DLS analysis indicated that all samples were nearly monodisperse with one size distribution and a polydispersity index (PDI) of about 0.15 (Std 0.03). EM analysis indicated that AuNPs-PEI were nearly spherical in shape. Zeta (ζ) potential measurements showed that all AuNPs-PEI samples were positively charged with a ζ-potential in the range of 38 (Std 5 mV), leading to a very high stability of the colloidal solution for several months when stocked at 4 C. Furthermore, the potential application of AuNP-PEIs in siRNA delivery to PC-3 prostate cancer cells was investigated. The ability of AuNP-PEIs to complex siRNA was analysed by gel electrophoresis. Results indicated that AuNP-PEI 2KD and AuNP-PEI 25KD could complex siRNA at MR0.5 and MR0.25 onwards, respectively, suggesting that AuNP-PEI 25KD has a better siRNA binding capacity than AuNP-PEI 2KD. Cellular uptakes were also performed using PC-3 cancer cells. Results following 24 h incubation indicated that AuNP-PEI 25KD achieved significantly higher fluorescein-positive cells (~ 98%) relative to that of AuNP-PEI 2KD (~ 5%), suggesting that AuNP-PEI 25KD, but not AuNP-PEI 2KD, could deliver siRNA into cells. Finally, we have also demonstrated that the surface of AuNPs-PEI can be further conjugated with thiolated polyethylene glycol (SH-PEG) onto AuNPs surface. Moreover, we have previously showed that covalently bonded targeting ligand (such as Anisic Acid or Folic acid) could be also chemically grafted on PEI, leading therefore to a multifunctional nanoparticle that may be promising in the field of Nanobiotechnology and Nanomedicine. 2017-05-01T00:00:00Z http://hdl.handle.net/10468/3965 Fabrication and characterization of microfabricated on-chip microelectrochemical cell for biosensing applications Said, Nur Azura Mohd; Twomey, Karen; Herzog, G.; Ogurtsov, Vladimir I. The fabrication of on-chip microelectrochemical cell on Si wafer by means of photolithography is described here. The single on-chip microelectrochemical cell device has dimensions of 100 × 380 mm with integrated Pt counter electrode (CE), Ag/AgCl reference electrode (RE) and gold microelectrode array of 500 nm recess depth as the working electrode (WE). Two geometries of electrode array were implemented, band and disc, with fixed diameter/width of 10 µm; and varied centre-to-centre spacing (d) and number of electrodes (N) in the array. The on-chip microelectrochemical cell structure has been designed to facilitate further WE biomodifications. Firstly, the developed microelectrochemical cell does not require packaging hence reducing the production cost and time. Secondly, the working electrode (WE) on the microelectrochemical cell is positioned towards the end of the chip enabling modification of the working electrode surface to be carried out for surface bio-functionalisation without affecting both the RE and CE surface conditions. The developed on-chip microelectrochemical cell was examined with scanning electron microscopy (SEM) and characterised by two electrochemical techniques. Both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed in 1 mM ferrocenecarboxylic acid (FCA) in 0.01 M phosphate buffered saline (PBS) solution at pH7.4. Electrochemical experiments showed that in the case of halving the interspacing distance of the microdisc WE array (50 nm instead of 100 nm), the voltammogram shifted from a steady-state CV (feature of hemispherical diffusion) to an inclined peak-shaped CV (feature of linear diffusion) albeit the arrays had the same surface area. In terms of EIS it was also found that linear diffusion dominates the surface instead of hemispherical diffusion once the interspacing distance was reduced, supporting the fact that closely packed arrays may behave like a macroelectrode. 2017-03-13T00:00:00Z http://hdl.handle.net/10468/3617 Piezo-force and vibration analysis of ZnO nanowire arrays for sensor application Christian, B.; Volk, J.; Lukàcs, I. E.; Sautieff, E.; Sturm, C.; Graillot, A.; Dauksevicius, Rolanas; O'Reilly, Eoin P.; Ambacher, O.; Lebedev, V. To estimate the potential of ZnO nanostructures for force sensing applications, arrays of single nanowires and arrays of nanowire bundles have been fabricated by wet chemical growth method. The piezoelectrical and electrical properties of the single nanowires have been investigated by atomic force microscopy based techniques. The piezoelectric constant d(33) = 15 pm/V has been determined from vibration analyses. The electrical response in the range up to 400 fA upon applying force between 40 nN and 1 mu N has been recorded. The nanowire bundles were studied by electro-mechanical macro probing technique within the force range 1 - 10 mN, where a reproducible response in pA range has been measured. 2017-01-04T00:00:00Z