Development of evanescent wave based sensor platforms for use in immunosensing

Two optical sensor platforms based on evanescent wave interactions for detection of biomolecules are presented. The first, a sol-gel derived planar waveguide, employs a grating coupler to couple light into a guided mode. The evanescent field of the mode interrogates the sensing layer. The platform employing mono-mode waveguides is described and applied to the imaging of fluorescently labelled antibodies which are immobilised on the waveguide surface. The antibodies, immunoglobulin G, are immobilised via an avidin-biotin bridge. First avidin is coated onto a silanized waveguide via a crosslinker. Then the surface is incubated with biotinylated fluorescently labelled antibodies. Compact optics image the evanescently excited fluorescence onto a large area, cooled CCD array. The image data is processed and corrected for local background levels. The second, a Surface Plasmon Resonance (SPR) refractive index sensor comprises of an integrated miniature SPR device interfaced to a computer. The sensor combines all of the necessary electro-optical components to excite a surface plasmon wave and quantify the resonance condition, within a single platform. This sensor is applied to liquid refractive index sensing and the monitoring of biomolecular interactions. Finally, work leading to the development of disposable sensor chips for use on the TI SPR sensor is presented

Magnetic core-shell nanoparticles for drug delivery by nebulization

BACKGROUND: Aerosolized 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 Fe(3)O(4) 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. RESULTS: Average 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. CONCLUSION: We 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

Detection of clinical biomarkers using a novel parabolic microchip diagnostic platform

A polymer paraboloid microchip is utilised for performing fluorescence detection in point-of-care devices, employing a mass producible and effective strategy. The chip consists of a single piece of moulded plastic containing nine parabolic elements, with planar upper surfaces. The chip is illuminated from below with collimated light which is then reflected from the edges of the paraboloid to the focal point on the upper plane. The light incident on the upper plane is supercritically reflected, so excitation of fluorophores on the plane occurs due to the evanescent wave, which extends only tens of nanometres above the surface, providing good surface discrimination. Light from the fluorophores is emitted preferentially into supercritical angles due to the nature of the dipoles oscillating on a planar dielectric interface. This is then collected again by the paraboloid edges reflecting light towards the detector. By counting the number of photons incident on the detector, a relationship between the analyte concentration and fluorescence can be found. Herein, we demonstrate a model assay developed to test the feasibility of using this technology to facilitate improved detection of clinically relevant biomarkers. A sandwich immunoassay based on the traditional ELISA format to the microchip platform for a detection of a specific cardiac biomarker was rapidly and efficiently transferred onto the paraboloid chips. An aldehyde-activated dextran surface coating was utilised to ensure an optimal capture antibody immobilisation. Reliable data was generated, quantifying the cardiac biomarker protein under physiological conditions. Low cost fabrication, dedicated optical interrogation instrumentation and antibody-compatible surface derivatisation, allied with the clear amenability for incorporation of a microfluidic sample delivery component, indicate that this device offers a very real alternative to traditional diagnostic assay platforms and has significant potential for application in a point-of-care settin

Magnetic core-shell nanoparticles for drug delivery by nebulization

Background: Aerosolized 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. Results: Average 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 mu g/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. Conclusion: We 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

Novel disposable biochip platform employing supercritical angle fluorescence for enhanced fluorescence collection

This paper presents an overview of development of a novel disposable plastic biochip for multiplexed clinical diagnostic applications. The disposable biochip is manufactured using a low-cost, rapid turn- around injection moulding process and consists of nine parabolic elements on a planar substrate. The optical elements are based on supercritical angle fluorescence (SAF) which provides substantial enhancement of the fluorescence collection efficiency but also confines the fluorescence detection volume strictly to the immediate proximity of the biochip surface, thereby having the potential to discriminate against background fluorescence from the analyte solution. An optical reader is also described that enables interrogation and fluorescence collection from the nine optical elements on the chip. The sensitivity of the system was determined with a biotin-avidin assay while its clinical utility was demonstrated in an assay for C-reactive protein (CRP), an inflammation marker