Paul Galvin

Magnetic core-shell nanoparticles for drug delivery by nebulization

BackgroundAerosolized therapeutics hold great potential for effective treatment of various diseases including lung cancer. In this context, there is an urgent need to develop novel nanocarriers suitable for drug delivery by nebulization. To address this need, we synthesized and characterized a biocompatible drug delivery vehicle following surface coating of Fe3O4 magnetic nanoparticles (MNPs) with a polymer poly(lactic-co-glycolic acid) (PLGA). The polymeric shell of these engineered nanoparticles was loaded with a potential anti-cancer drug quercetin and their suitability for targeting lung cancer cells via nebulization was evaluated.ResultsAverage particle size of the developed MNPs and PLGA-MNPs as measured by electron microscopy was 9.6 and 53.2 nm, whereas their hydrodynamic swelling as determined using dynamic light scattering was 54.3 nm and 293.4 nm respectively. Utilizing a series of standardized biological tests incorporating a cell-based automated image acquisition and analysis procedure in combination with real-time impedance sensing, we confirmed that the developed MNP-based nanocarrier system was biocompatible, as no cytotoxicity was observed when up to 100 μg/ml PLGA-MNP was applied to the cultured human lung epithelial cells. Moreover, the PLGA-MNP preparation was well-tolerated in vivo in mice when applied intranasally as measured by glutathione and IL-6 secretion assays after 1, 4, or 7 days post-treatment. To imitate aerosol formation for drug delivery to the lungs, we applied quercitin loaded PLGA-MNPs to the human lung carcinoma cell line A549 following a single round of nebulization. The drug-loaded PLGA-MNPs significantly reduced the number of viable A549 cells, which was comparable when applied either by nebulization or by direct pipetting.ConclusionWe have developed a magnetic core-shell nanoparticle-based nanocarrier system and evaluated the feasibility of its drug delivery capability via aerosol administration. This study has implications for targeted delivery of therapeutics and poorly soluble medicinal compounds via inhalation route.

Emerging optofluidic technologies for point-of-care genetic analysis systems: a review

This review describes recently emerging optical and microfluidic technologies suitable for point-of-care genetic analysis systems. Such systems must rapidly detect hundreds of mutations from biological samples with low DNA concentration. We review optical technologies delivering multiplex sensitivity and compatible with lab-on-chip integration for both tagged and non-tagged optical detection, identifying significant source and detector technology emerging from telecommunications technology. We highlight the potential for improved hybridization efficiency through careful microfluidic design and outline some novel enhancement approaches using target molecule confinement. Optimization of fluidic parameters such as flow rate, channel height and time facilitates enhanced hybridization efficiency and consequently detection performance as compared with conventional assay formats (e.g. microwell plates). We highlight lab-on-chip implementations with integrated microfluidic control for “sample-to-answer” systems where molecular biology protocols to realize detection of target DNA sequences from whole blood are required. We also review relevant technology approaches to optofluidic integration, and highlight the issue of biomolecule compatibility. Key areas in the development of an integrated optofluidic system for DNA hybridization are optical/fluidic integration and the impact on biomolecules immobilized within the system. A wide range of technology platforms have been advanced for detection, quantification and other forms of characterization of a range of biomolecules (e.g. RNA, DNA, protein and whole cell). Owing to the very different requirements for sample preparation, manipulation and detection of the different types of biomolecules, this review is focused primarily on DNA–DNA interactions in the context of point-of-care analysis systems.

Allozyme variation in populations of Atlantic salmon located throughout Europe: diversity that could be compromised by introductions of reared fish

A comprehensive understanding of the population structure of Atlantic salmon (Salmo salar L.) throughout the species range would help to determine the impact that cultured fish could have on wild populations. To help achieve this aim, Atlantic salmon samples were obtained from 14 locations throughout Europe (including Iceland) and screened for variation at 32 allozyme loci. A sample was also obtained from Canada to serve as an out-group. Seventeen allozyme loci were found to be variable in one or more of the populations studied and three, s AAT-4 * , IDDH-2 * , and m MEP-2 * were variable across the range. This is the widest-ranging study to include ESTD-2 * , FBALD-3 * , and TPI-3 * , which combined contributed 28% to the total genetic diversity detected. Genotype frequencies complied with Hardy-Weinberg expected proportions. Over all loci, highly significant heterogeneity was observed between samples. Alternate alleles segregating at ESTD-2 * were found to be largely exclusive to Europe or North America. A neighbour-joining dendrogram was constructed to visualize relationships between populations and was consistent with previous findings that revealed Baltic and European clusters, with the Canadian population being the most genetically distinct. A significant association was observed between geographic and genetic distance, which suggests the potential for local adaptation, thus highlighting the need for conservation of wild populations.

Surface chemical and physical modification in stent technology for the treatment of coronary artery disease

Coronary artery disease (CAD) kills millions of people every year. It results from a narrowing of the arteries (stenosis) supplying blood to the heart. This review discusses the merits and limitations of balloon angioplasty and stent implantation, the most common treatment options for CAD, and the pathophysiology associated with these treatments. The focus of the review is heavily placed on research efforts geared toward the modification of stent surfaces for the improvement of stent-vascular compatibility and the reduction in the occurrence of related pathophysiologies. Such modifications may be chemical or physical, both of which are surveyed here. Chemical modifications may be passive or active, while physical modification of stent surfaces can also provide suitable substrates to manipulate the responses of vascular cells (endothelial, smooth muscle, and fibroblast). The influence of micro- and nanostructured surfaces on the in vitro cell response is discussed. Finally, future perspectives on the combination of chemical and physical modifications of stent surfaces are also presented.

Emerging technologies for point-of-care genetic testing

In the coming years, genetic test results will be increasingly used as indicators that influence medical decision making. Novel instrumentation that is able to detect relevant mutations in a point-of-care setting is being developed to facilitate this increase, frequently as a spin-off from recent research in the area of biothreat monitoring. This market review will describe the current generation of instrumentation that is most suitable for use in a point-of-care setting; it will also try to identify some of the technologies that will make-up the next generation of instrumentation currently being prepared for the market.

A versatile multi-platform biochip surface attachment chemistry

A versatile DNA spotting and immobilization method for covalent attachment of amino-modified probe oligonucleotides in microarray format at glass, native silicon dioxide and CVD silicon nitride substrates is reported. Optimal probe spot printing and attachment buffers are identified for each substrate. Relative areal densities of immobilized probes as measured by epi-fluorescence microscopy vary with substrate type reflecting differences in surface morphology and chemistry. Target oligonucleotide hybridization occurs at glass and nitride supported probe microarrays in an efficient and reproducible manner with excellent measured fluorescence signal-to-background.

Fast and accurate temperature control of a PCR microsystem with a disposable reactor

The paper presents a micro polymerase chain reaction (PCR) device consisting of a miniature thermal cycler incorporating Pt thin layers used as heater and temperature sensors, screen-printed on a ceramic plate and a disposable PDMS part with a 1 µl chamber. Using a heating power of only 0.3 W at 95 °C and 1.5 W during heating transitions, the device can provide a 7.7 °C s−1 heating rate. For temperature control, a two-degree-of-freedom proportional–integral–derivative controller in conjunction with an anti-windup algorithm was designed and implemented. The obtained performances (such as the use of the maximum/minimum power level during almost all of the transition time, overshoots and undershoots below 0.1 °C, very short settling time with no oscillation, steady error less than ±0.05 °C and excellent robustness against the process changes) exceed those published so far. In addition, the proposed controller is much simpler to implement and tune in comparison to other previously described controllers. A dynamical correction of the difference between the sensor and chamber temperatures is introduced and several profiles for set-point shaping are proposed and compared. The delayed preshaped profile, based on the inverse of the corresponding transfer function, was found to give the best results. Forced convection cooling is handled as a heat switch providing a cooling rate of 6.6 °C s−1 while preserving the low power requirement for heating. With the device described cycle times of 12 s (if the dwell times are not considered) are possible. PCR amplification with 32 cycles was successfully carried out in less than 25 min.

A nanobiotechnology roadmap for high-throughput single nucleotide polymorphism analysis.

Genetic analysis based on single nucleotide polymorphisms (SNPs) has the potential to enable identification of genes associated with disease susceptibility, to facilitate improved understanding and diagnosis of those diseases, and should ultimately contribute to the provision of new therapies. To achieve this end, new technology platforms are required that can increase genotyping throughput, while simultaneously reducing costs by as much as two orders of magnitude. Development of a variety of genotyping platforms with the potential to resolve this dilemma is already well advanced through research in the field of nanobiotechnology. Novel approaches to DNA extraction and amplification have reduced the times required for these processes to seconds. Microfluidic devices enable polymorphism detection through very rapid fragment separation using capillary electrophoresis and high-performance liquid chromatography, together with mixing and transport of reagents and biomolecules in integrated systems. The potential for application of established microelectronic fabrication processes to genetic analyses systems has been demonstrated (e.g. photolithography-based in situ synthesis of oligonucleotides on microarrays). Innovative application of state-of-the-art photonics and integrated circuitry are leading to improved detection capabilities. The diversity of genotyping applications envisaged in the future, ranging from the very high-throughput requirements for drug discovery through to rapid and cheap near-patient genotype analysis, suggests that several SNP genotyping platforms will be necessary to optimally address the different niches.

Silicon microfluidic flow focusing devices for the production of size-controlled PLGA based drug loaded microparticles.

The increasing realisation of the impact of size and surface properties on the bio-distribution of drug loaded colloidal particles has driven the application of micro fabrication technologies for the precise engineering of drug loaded microparticles. This paper demonstrates an alternative approach for producing size controlled drug loaded PLGA based microparticles using silicon Microfluidic Flow Focusing Devices (MFFDs). Based on the precise geometry and dimensions of the flow focusing channel, microparticle size was successfully optimised by modifying the polymer type, disperse phase (Qd) flow rate, and continuous phase (Qc) flow rate. The microparticles produced ranged in sizes from 5 to 50 μm and were highly monodisperse (coefficient of variation <5%). A comparison of Ciclosporin (CsA) loaded PLGA microparticles produced by MFFDs vs conventional production techniques was also performed. MFFDs produced microparticles with a narrower size distribution profile, relative to the conventional approaches. In-vitro release kinetics of CsA was found to be influenced by the production technique, with the MFFD approach demonstrating the slowest rate of release over 7 days (4.99 ± 0.26%). Finally, MFFDs were utilised to produce pegylated microparticles using the block co-polymer, PEG-PLGA. In contrast to the smooth microparticles produced using PLGA, PEG-PLGA microparticles displayed a highly porous surface morphology and rapid CsA release, with 85 ± 6.68% CsA released after 24h. The findings from this study demonstrate the utility of silicon MFFDs for the precise control of size and surface morphology of PLGA based microparticles with potential drug delivery applications.

An Integrated Optofluidic Platform for DNA Hybridization and Detection

There has been extensive research into micro total analysis systems (micro-TAS) and lab-on-a-chip research due to the benefits of increased sample throughput, reduced sample consumption, and rapid analysis times. The integration of low-cost fluidic and optical components offers the possibility of complex systems with increased functionality on a single detection platform. For the development of an integrated optofluidic system for DNA hybridization, the key areas are optical/fluidic integration and the efficiency of surface chemistry integration within the system. The impact of fluidic parameters such as flow rate, channel height, and time on hybridization performance is to optimize detection performance over conventional assay (microtiter plate formats). The use of a passive waveguide device means DNA binding events can be monitored using fluorescence excitation or refractive index measurement. The integration of the three areas is enhanced by the robustness of the waveguide material (oxide, nitride), enabling chemical functionalization by initial silanization followed by addition of a linker molecule 1,4 phenylene diisothiocyanate (PDITC) for covalent immobilization of DNA probes together with the possibility to define microfluidics on the waveguide substrate using standard SU8 photolithography. The fluidic design requires 240 nl of analyte to fill the integrated optofluidic system. Here, we report the novel integration and optimization of a covalent surface chemistry with microfluidic channels for fluidic delivery, and a standard resonant mirror (RM) waveguide detection platform. The optofluidic detection platform was tested using fluorescence and refractive index to monitor binding events between target and probe DNA. We describe the detection system, using simulations to explain the response to changes in refractive index and outline a method for covalent attachment of DNA probes surface chemistry protocol to immobilize probe DNA on the sensor surface and the optimization of fluidic design, achieving pM detection limit. We highlight the benefit of optimizing the fluidic component and its benefit in hybridization efficiency an approach often overlooked in sensor design and performance.