Performance studies of a conical nozzle designed for the macromolecular skin delivery.

Human skin is an attractive site for the delivery of protein and peptide-based macromolecular drugs for the treatment of topical and systemic diseases as well as for DNA immunisation. However, the delivery of those macromolecules in or across the skin is undesirably limited due to its permeation property. To expand the number of macromolecules to be delivered to specific targeting tissue/cells, a unique biomedical device, the handheld powdered injection system, has been developed.

Characteristics of a micro-biolistic system for murine immunological studies.

With an advanced computational fluid dynamics (CFD) technique, we have numerically developed and examined a micro-biolistic system for delivering particles to murine target sites. The micro-particles are accelerated by a high speed flow initiated by a traveling shock wave, so that they can attain a sufficient momentum to penetrate in to the cells of interest within murine skin (or mucosa). In immunization application, powdered vaccines are directly delivered into the antigen presenting cells (APCs) within the epidermis/dermis of the murine skin with a narrow and highly controllable velocity range (e.

Femtosecond two-photon high-resolution 3D imaging, spatial-volume rendering and microspectral characterization of immunolocalized MHC-II and mLangerin/CD207 antigens in the mouse epidermis.

Langerhans cells (LCs) play a sentinel role by initiating both adaptive and innate immune responses to antigens pertinent to the skin. With the discovery of various LCs markers including antibodies to major histocompatibility complex class II (MHC-II) molecules and CD1a, intracellular presence of racket-shaped "Birbeck granules," and very recently Langerin/CD207, LCs can be readily distinguished from other subsets of dendritic cells. Femtosecond two-photon laser scanning microscopy (TPLSM) in recent years has emerged as an alternative to the single photon-excitation based confocal laser scanning microscope (CLSM), particularly for minimally-invasive deep-tissue 3D and 4D vital as well as nonvital biomedical imaging.

Multiphoton high-resolution 3D imaging of Langerhans cells and keratinocytes in the mouse skin model adopted for epidermal powdered immunization.

Langerhans cells (LCs) can be targeted with DNA-coated gold micro-projectiles ("Gene Gun") to induce potent cellular and humoral immune responses. It is likely that the relative volumetric distribution of LCs and keratinocytes within the epidermis impacts on the efficacy of Gene Gun immunization protocols. This study quantified the three-dimensional (3D) distribution of LCs and keratinocytes in the mouse skin model with a near-infrared multiphoton laser-scanning microscope (NIR-MPLSM).

Characterization of powdered epidermal vaccine delivery with multiphoton microscopy.

Multiphoton laser scanning microscopy (MPLSM) has been adapted to non-invasively characterize hand-held powdered epidermal vaccine delivery technology. A near infrared femtosecond pulsed laser, wavelength at approximately 920 nm, was used to evoke autofluorescence of endogenous fluorophores within ex vivo porcine and human skin. Consequently, sub cellular resolution three-dimensional images of stratum corneum and viable epidermal cells were acquired and utilized to observe the morphological deformation of these cells as a result of micro-particle penetration.

Identification of second harmonic optical effects from vaccine coated gold microparticles.

This study investigates the optical effects observed from uncoated and protein vaccine coated gold microparticles while imaging with two-photon excitation in the Mie scattering regime. When observed with time correlated single photon counting fluorescence lifetime microscopy, the emission from the gold microparticles appeared as an intense instrument-limited temporal response. The intensity of the emission showed a second-order dependence on the laser power and frequency doubling of the emitted light was observed for fundamental light between 890 and 970 nm.

Modelling of the flow-through dye-ligand affinity membrane process using bovine serum albumin as the model protein.

This paper presents the application of a mathematical model for the prediction of the performance of a dye-ligand affinity membrane. Cibacron Blue F3G-A was utilised as the capturing ligand and bovine serum albumin as the target molecule. The dye molecules were immobilised covalently via spacer molecules (polyethlenimine) onto the pores of a microfiltration membrane with a pore size rating of 0.

Development of a dye-ligand affinity membrane for the separation of bovine serum albumin.

This study reports the development and testing of a dye-ligand membrane. A synthetic dye called Cibacron Blue F3G-A was utilized as the capturing ligand. Bovine serum albumin acted as the target protein.

Transdermal and transmucosal powdered drug delivery.

High-velocity powder injection is a promising new drug-delivery technique that provides needle- and pain-free delivery of traditional drugs, drugs from biotechnology such as proteins, peptides, and oligonucleotides as well as traditional and genetic vaccines. The energy of a transient helium gas jet accelerates fine drug particles of 20 microns-100 microns diameter to high velocities and delivers them into skin or mucosal sites. This review describes the configuration and operating principles of devices that accelerate the particles, the required properties of the particles, the characteristics of the target tissues, and features of the developmental test methods.

Oral PowderJect: a novel system for administering local anaesthetic to the oral mucosa.

Objective: To assess the feasibility of using an Oral PowderJect (OPJ) to safely deliver a dose of dry powdered anaesthetic to the oral mucosa, producing an analgesic effect.

Design: Single centre: Part 1. An open, non-randomised safety study to check for mucosal damage; Part 2.

Effect of oscillatory flow on the performance of a novel cross-flow affinity membrane device.

This paper presents the results of an investigation into the effect of oscillatory flow in a membrane-based affinity contactor. This device was designed to accommodate a tubular affinity membrane, and the flow direction of working fluid was tangential to the surface of the membrane. Cibacron Blue F3G-A was utilized as the capturing ligand and bovine serum albumin as the target molecule.

Mammalian cell damage in a novel membrane bioreactor.

The experimental study has assessed a novel membrane bioreactor for mammalian cell culture. In the absence of a gas phase, the key features of cell damage associated with laminar and turbulent flow have been identified. The bioreactor employs a dimpled membrane in order to enhance transverse mixing in a narrow channel, but a fall in viable cell density has been observed at Reynolds numbers above Re = 83.

Enhanced filtration using flat membranes and standing vortex waves.

The performance of membrane filters is limited by concentration polarisation and membrane fouling. High shear rates reduce these effects but can damage delicate cells and proteins in biological fluids. Secondary flows to promote fluid mixing, and hence enhance filtration, can be highly effective, but usually carry the penalty of complexity.

A novel membrane bioreactor for microbial growth.

A novel membrane bioreactor, previously assessed for its gas transfer characteristics, was used in various size and membrane configurations for the growth of the strictly aerobic bacterium Pseudomonas aeruginosa. The bioreactor was found to readily support growth, and the initial growth rates showed the previously demonstrated enhanced effect in gas O2 mass transfer of the dimpled membrane bioreactor over flat membrane bioreactors. The production of a secondary metabolite by a Pseudomonas sp.

Quantitative optical determination of the viability of platelet concentrates.

An optical method to assess platelet viability in platelet transfusion concentrates has been developed which is based on the observation that healthy, discoid platelets transmit more light in shear flow than aged, spherical cells. Using a specially designed glass channel, the rise in transmission of light through platelet samples with agitation is referenced against a measurement of transmission without flow. Referencing the measurements may minimize the effects of red blood cell contamination, as well as other variations among platelet packs such as plasma characteristics and plastic container variability.

Gas transfer characteristics of a novel membrane bioreactor.

We show the design features of a membrane bioreactor based on pulsatile flow across dimpled membranes. Results show an enhanced mass transfer of air of at least five-fold magnitude as compared with flat membranes. An increased working volume form 20 mL to 120 mL reduced the k(L)A at a given Reynolds number because of axial mixing of fluid from the deoxygenated end chamber.

Comparative study of reaction kinetics in membrane and agarose bead affinity systems.

Compared to conventional agarose bead affinity supports, a microporous nylon membrane exhibits greatly improved reaction kinetics as quantified in the reaction between gamma-globulin and immobilised protein A. The improvement is only observed when the solution of gamma-globulin is forced through the membrane pores. In the absence of flow in the pores, it is possible to relate approximately the rate of uptake onto either type of affinity support to independently determined diffusion coefficients.

Effective endothelialization of polyurethane surfaces. Response to shear stress and platelet adhesion.

Biomer and Mitrathane are thromboresistant polyurethane ureas that are suitable for coating artificial valves. Degeneration of the surface coatings, however, does occur over time, and in experimental animal studies adherent thrombi have been observed as a complication. In this study, morphometric techniques applied to scanning electron microscopy were used to assess whether vascular endothelial cells harvested from jugular veins of fetal lambs could be grown to confluence on these polyurethane surfaces, whether the monolayer would remain intact under conditions of shear stress (104 dynes/cm2), and whether this would result in decreased platelet adherence of sheep platelets relative to nonendothelialized surfaces.

A high efficiency membrane separator for donor plasmapheresis.

The shortfall in human plasma for therapeutic use can be met satisfactorily only by donor plasmapheresis. Membrane blood plasma separators of conventional design work poorly at low rates of blood flow, and performance decreases rapidly as the membrane becomes fouled. To overcome these problems, membrane separators have been developed that employ vortex mixing to prevent blood cells obstructing the membrane pores.

Separation of plasma from whole blood by membrane filtration in oscillatory flows.

This paper describes the performance of a microfiltration plasmapheresis unit operating with reversing oscillatory flows. The device consists of a flat channel duct between cellulose nitrate membranes and was used to extract plasma from anticoagulated fresh whole bovine blood. Measurements were made of plasma flux, haematocrit concentration, haemolysis and protein sieving coefficients.

Extracorporeal oxygen and CO2 transfer of a polypropylene dimpled membrane lung with variable secondary flows: partial bypass in the dog.

In vivo gas transfer performance, during veno-venous bypass, is presented for one form of the Oxford membrane lung in which vortex mixing is induced in blood flow across a dimpled polypropylene membrane. Good agreement has been found with in vitro data presented in an earlier paper. Two experiments were extended to attain total extracorporeal CO2 removal with apnoeic diffusion oxygenation to motionless lungs.

Oxygen and CO2 transfer of a polypropylene dimpled membrane lung with variable secondary flows.

Gas transfer performance is presented for one form of the Oxford membrane lung in which vortex mixing is induced in blood flow across a dimpled polypropylene membrane. Dimensional analysis has been used to define the parameters characterizing mass transfer in the device, and of three fluid mechanical parameters: Reynolds number based on peak pulsation velocity, Strouhal number, and ratio of mean to oscillatory flows, only the first has been found to affect mass transfer significantly in the ranges studied. For oxygenation, rated flows in excess of 5 l min-1 m-2 are measured.

Initial in vitro evaluation of a pediatric vortex-mixing membrane lung.

A new design for a pediatric membrane lung is described in this paper. The lung consists of eight blood compartments, each having six U-shaped blood channels, with microporous PTFE membranes supported on rigid plates in such a way that the membranes form furrowed blood channels. Two rolling diaphragm pumps are attached to the open ends of the U-shaped blood channels; these pumps are operated in antiphase.