Browsing by Author "Hood, Robert L."

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    Development of a Fiberoptic Microneedle Device for Simultaneous Co-Delivery of Fluid Agents and Laser Light with Specific Applications in the Treatment of Brain and Bladder Cancers
    Hood, Robert L. (Virginia Tech, 2013-10-16)
    This dissertation describes the development of the fiberoptic microneedle device (FMD), a microneedle technology platform for fluid and light delivery, from general engineering characterization to specific applications in treating bladder and brain cancers. The central concept of the FMD is physical modification of silica fiberoptics and capillary tubes into sharp microneedles capable of penetrating a tissue's surface, enabling light and fluid delivery into the interstitial spaces. Initial studies sought to characterize the mechanical penetration and optical delivery of multimode fiberoptics and capillary tubes modified through a custom, CO2 laser melt-drawing technique. Additional work with multimode fibers investigated using an elastomeric lateral support medium to ensure robust penetration of small diameter fibers. These early experiments laid an engineering foundation for understanding the FMD technology. Subsequent studies focused on developing the FMD to treat specific diseases. The first such investigation sought to leverage the high aspect ratio nature of FMDs made from long capillary tubes as a therapy delivery device deployable through the instrument channel of a urological cystoscope. The therapeutic strategy was to infuse single-walled carbon nanohorns (SWNHs), a carbon-based nanoparticle allowing surface modification and drug encapsulation, into the infiltrating front of later stage bladder tumors. The SWNHs primarily serve as exogenous chromophores, enabling a fluid-based control of photothermal heat generation created when the SWNHs interacted with laser energy from an interstitial FMD or a light-emitting fiber in the bladder's interior. The study described here primarily sought to characterize the dispersal of the infused SWNHs and the photothermal response of the particles when heated with a 1064 nm laser. The FMD was also developed as a platform capable of conducting convection-enhanced delivery (CED), a therapeutic approach to treat invasive tumors of the central nervous system such as malignant glioma (MG). Intracranial CED involves the placement of small catheters local to the tumor site and slow infusion of a chemotherapeutic over long timeframes (12-72 hours). A primary challenge of this treatment approach is infused chemotherapeutics not dispersing sufficiently to reach the infiltrating cells in the tumor's margins. The hypothetical improvement provided by the FMD technology is using sub-lethal photothermal heating to sufficiently increase the diffusive and convective transport of an infusate to reach infiltrative cells in the tumor's periphery. Initial experiments sought to demonstrate and characterize a heat-mediated increase of volumetric dispersal in Agarose tissue phantoms and ex vivo tissue. Subsequent studies with in vivo rodent models determined the best laser parameters to achieve the desired levels of diffuse, sub-lethal heat generation and then demonstrated the hypothesis of increasing the rate of volumetric dispersal though concurrent local hyperthermia. This research was the first demonstration of photothermal augmentation of an interstitially infused fluid's dispersal rate, which may have uses outside of the CED approach to brain cancer exhibited here. Taken in sum, this manuscript describes the potency and versatility of the FMD technology platform through its development in various biomedical applications.
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    Development of a Hollow-Core Fiberoptic Microneedle Device for the Treatment of Invasive Bladder Cancer
    Hood, Robert L. (Virginia Tech, 2011-08-11)
    The hydraulic resistance characterization manuscript chronicles the early development of the hollow-core fiberoptic microneedle device (FMD). The study determined that for straight tubing with an inner bore of 150 ?m and a length greater than 50 mm long, Poiseuille's Law was shown to be accurate within 12% of experimental data for the pressure range of 69-517 kPa. Comparison between different needle design geometries indicated that tip diameters <55 ?m cause a significant increase in hydraulic resistance. Tubing length should be kept to a minimum and tip diameter should be kept above this threshold to reduce overall hydraulic resistance. The bladder treatment study describes the fabrication and testing of the FMD for treatment of invasive urothelial cell carcinomas (UCCs). Experiments investigating the fluid dispersal of single-walled carbon nanohorns (SWNHs) in the wall of inflated, healthy ex vivo bladders demonstrated that perfusion of 2 cm° on the bladder wall's surface can be achieved with a 5 minute infusion at 50 ?L/min. Irradiation of the SWNH perfused bladder wall tissue with a free space, 1064 nm laser at an irradiance of 0.95 W/cm° for 40 seconds yielded a 480% temperature increase relative to similar irradiation of a non-infused control. Co-delivery experiments demonstrated both SWNH and light delivery though a single hollow-core fiber to heat the bladder wall 33 °C with an irradiance of 400 W/cm°, demonstrating that the FMD can be used to achieve hyperthermia-based therapeutic effects via interstitial irradiation.
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    Fiber array for optical imaging and therapeutics
    (United States Patent and Trademark Office, 2019-03-05)
    The present invention relates to the field of optical imaging and therapeutics. More particularly, embodiments of the present invention provide minimally-invasive Fiberoptic Microneedle Devices (FMDs) for light-based therapeutics, which physically penetrate tissue and deliver light directly into the target area below the skin surface. Embodiments of the invention enable depth-selective and deep photothermal therapeutics and include methods of treating cancer, methods of re-shaping or removing adipose tissue, and methods of delivering drugs or co-delivering drugs and energy to selected tissue.