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Functionalization of the plastic chips for selective immobilization of biomolecules is one of the key challenges to be addressed in commercialization of the next-generation point-of-care (POC) diagnostics devices. Multistep liquid-phase deposition process requires a large quantity of solvent to be used in anhydrous conditions, providing quantity of industrial liquid waste. We, in this work, have demonstrated a solventless plasma-based process that integrates low-cost, high throughput, high reproducibility and ecofriendly process for the functionalization of POC device platforms. Amine functionalities have been deposited by plasma-enhanced chemical vapour deposition 2 (PECVD) using a new precursor. For a successful and efficient plasma functionalization process, an understanding of the influence of plasma process parameters on the surface characteristics is essential. The influence of the plasma RF power and the deposition time on the deposited amount of amino functionalities and on their capacity to immobilize nano-objects (i.e., nanoparticles) and biomolecules (i.e. DNA) was examined. Surfacial properties were related to the binding capacity of the films and to the amino content, as revealed by the Ònanoparticle approachÓ and DNA attachment experiments. The key process determinants were to have a sufficient power in the plasma to activate and partially fragment the monomer but not too much as to lose the reactive amine functionality, and sufficient deposition time to develop a reactive layer but not to consume or erode the amine reactivity. An immunoassay performed using human immunoglobulin (IgG) as a model analyte shows an improvement of the detection limit by two orders of magnitude beyond that obtained using devices activated by liquid-phase reaction.

Naturally occurring macromolecules have the potential for providing non-fouling coatings on substrates based on a steric entropic principle. In order for this effect to occur, the macromolecules that adhered to the surface must have the correct chemical conformation. This article reports on the immobilisation of hyaluronic acid (HA) onto polystyrene substrates for the purpose of repelling cellular adhesion thereon. In order to create a polystyrene surface capable of adhering HA in the required orientation substrates were treated by atmospheric pressure plasma processing in air. The resulting oxidised surfaces were then aminated by the chemisorption of the 3-aminopropyltrimethoxysilane (APTMS) linker molecule. Three distinct chemical states were found for the APTMS amine group: a neutral, a protonated and a hydrogen bonded state, as determined by X-ray photoelectron spectroscopy (XPS). Carbodiimide coupling of HA at two different macromolecular concentrations (1 mg cm À3 and 3 mg cm À3) to the aminated surfaces on oxidized polystyrene resulted in covalent immobilisation of the polysaccharide. The chemistry and topography of the polymer surface at each stage of the coating process were analysed by a combination of XPS, ToF-SIMS, and AFM. XPS demonstrates that HA was successfully grafted to the aminated PS surfaces. The degree of chemical homogeneity on the surfaces was determined by ToF-SIMS. Changes in topography resulting from the immobilization process were evident in the AFM images. In vitro studies of the response of human lens epithelial cells (LEC) to the HA-modified polystyrene indicated a significant reduction in cell numbers at all time points post-seeding compared to the control. These results coupled with the surface analysis data indicate that the immobilization method based on atmospheric plasma activation of the polymer surface creates a HA layer with a steric conformation capable of inhibiting cellular attachment.

In early stage disease diagnosis, an accurate and reliable measurement of low concentrations of specific biomarkers is a key need. The detection technique requires the reaction of an antibody, which is generally covalently bound to the biosensor platform, with its antigen. The application of Zeonor®, a cyclo olefin copolymer (COP) with very low autofluorescence, good optical properties and high precision molding characteristics, as a biosensor platform has been demonstrated recently. Highly reproducible, industrial scale surface chemical modification of the COP plastic for covalent attachment of the biomolecules for specific recognition of the target, together with low non specific binding of other proteins that may be present in the sample is a key challenge. In this work, the applicability of plasma enhanced chemical vapor deposition (PECVD) process has been demonstrated by depositing varying surface functionalities including amines, carboxylic, mercapto, epoxy and polyethylene glycol functionalities.The plasma functionalized coatings thus created possess both reactive and repellent sites on the biosensor chip, allowing the chip to be configured either for fluorescence or light scattering-based detection or for label-free surface plasmon resonance detection techniques. The versatility of the gas phase deposition process for building sequential chemistries on low cost and disposable plastic chips is presented in detail. * Corresponding Author: Vladimir.gubala@dcu.ie , Ph: +35317006337 IntroductionWith parameters. The effect of ion bombardment on the growing film and the plasma electron density are crucial and could lead to dissociation of functional groups in the plasma as well as on the growing film. In this article, synthetic approaches for modification of COP substrates with -NH 2 and -SH functional groups will be discussed. Perhaps more importantly, we will also provide a review on the analytical tools used to assess the quality of the prepared films. For a design of sensitive bioassay device, it is critical to understand interaction forces in real systems, and how these relate on the one hand to the surface composition and chemistry, and on the other hand to the specificity, sensitivity and resistance to non-specific binding. 2.Materials and methods Plasma Enhanced Chemical Vapor DepositionThe vacuum chamber is an aluminum based container. The pressure in the chamber was measured using a Granville-Phillips gauge. An Edwards EH mechanical booster pump backed by an Edwards E1M40 rotary pump was used to pump down the chamber.The rotary pump was connected through a port at the bottom of the chamber.The powered electrode, 24cm x 21cm plate with a 6cm diameter with a hole in the middle, was placed slightly below the top of the chamber and the chamber wall was grounded. The powered electrode is cooled with running water. Also a 24cm X 21cm X 1.2cm electrically isolated, water cooled hollow metallic setup placed 10 cm away from the powered electrode is used as the substrate holder. The powered electrod...