Introducere. Obiective generale
Obiectivul general al proiectului il constituie efectuarea de cercetari pentru realizarea unui prototip de instrument avand capacitate de detectie si masurare a unor molecule biologice specifice hemoglobinopatiilor si organismelor modificate genetic cu aplicatii in industria alimentara si diagnosticarea clinica de rutina. Un astfel de prototip necesita crearea si armonizarea de tehnologii diverse, realizarea fiecareia din ele fiind un obiectiv care trebuie atins in cadrul proiectului. In cazul proiectului de fata, obiectivul care trebuia atins de participantul roman (INFLPR) este realizarea de suprafete functionalizate, constand din grupari amino, aldehide sau carboxil legate chimic pe suprafete de cristal de cuart piezoelectric, suprafete capabile sa interactioneze cu entiitati biologice, molecule sau celule. Cristalele de cuart piezoelectric sunt utilizabile, de catre celelate echipe de cercetare partenere in proiectul Eureka din Turcia (Middle East University (METU) din Ankara; Hacettepe University (HU) din Ankara; Pamukkale University (PU) din Denizli, VASCO Ltd din Ankara), cu experienta in manipularea moleculelor biologice, elaborarea tipurilor de anticorpi specifici pentru hemoglobinopatie si pentru recunoasterea materialului genetic, legarea acestora la suprafata functionalizata a detectorului de cuart, realizarea si testarea dispozitivului. Pentru realizarea obiectivului proiectului INFLPR a recurs la tehnologii si metode de functionalizare a suprafetelor (inclusiv cuart) in plasma descarcarilor in amestecuri de gaze si vapori ai unor substante organice continand grupari tip amina, aldehida, carboxil.
Rezultate
In scopul crearii de suprafete functionalizate au fost abordate tehnicile de procesare cu plasma. Dispozitivele de plasma utilizate au fost bazate pe descarcari de radiofrecventa in configuratie afterglow, in configuratie cu electrozi plan-paraleli, si scanare cu surse de plasma rece tip jet la presiune atmosferica. Au fost investigate schimbarile de topografie, unghi de contact si compozitie chimica ale suprafetelor de sticla, cuart, siliciu, aur si polmerice - PVC, teflon, PET si PE in gaze nepolimerizabile (argon, azot, amoniac) si in prezenta gazelor polimerizabile ( acid acrilic, dietilamina). S-a demonstrat ca in conditiile experimentale utilizate (tratamente la puteri mici) plasma nu induce modificari topografice majore pe substraturile semiconductioare, sticla, cuart, dar produce schimbari semnificative ale topografiei substraturilor polimerice. In cazul tratarii in gaze polimerizabile se constata aparitia filmelor subtiri si functionalizarea suprafetelor cu grupari amino (in cazul dietilaminei) sau carboxilice (in cazul acidului acrilic). A fost demonstrata utilitatea sistemelor tip microbalanta cu cristal de cuart pentru studiul interactiei suprafetelor modificate in plasma cu molecule organice. Astfel s-a putut pune in evidenta grefarea unor cantitati foarte mici de vapori organici pe cristale de cuart tratate in plasma (activate sau depuse cu filme subtiri polimerice). In scopul testarii acestei abordari pentru realizarea de detectori capabili de interactie cu molecule biologice bazati pe cristal de cuart au fost realizate experimente de interactie a suprafetelor de cristal de cuart acoperite cu electrozi de aur activate in plasma si grefate cu vapori de tiofen, cu celule vii (osteoblaste si fibroblaste). S-a demonstrat ca in cazul probelor de cuart acoperit cu aur (probe similare capetelor de detectie cu cristal piezoelectric) tratate in plasma la presiune atmosferica prin scanare si grefate in vapori de tiofen, celulele au interactionat cu suprafata si s-au atasat de aceasta. Tehnicile elaborate conduc la realizarea de cristale oscilatoare de cuart (cu electrozi de aur acoperite cu PVC de uz medical sau grefate cu tiofen) capabile de interactie si atasare a proteinelor din celule. Aceste cristale pot fi utilizate pentru realizarea unui prototip de monitorizare a prezentei in produse a substantelor provenite de la organisme modificate genetic si in aplicatii clinice de rutina.
Summary
In this project plasma based techniques have been approached in order to obtain functionalized surfaces suitable for interaction with biological entities. The used plasma sources have been based on radiofrequency discharges in afterglow configuration, direct discharges in plan parallel configuration and atmospheric pressure cold plasma jets in conjunction with scanning procedures. The modification of topography, wetability and chemical composition of glass, quartz, metallic, and polymers (PVC, teflon, PET, PE) surfaces following the plasma treatments in non-polymerizing (argon, nitrogen, ammonia) and polymerizing (ethylendiamine, acrylic acid, tiophene) gases was investigated. It was demonstrated that in the used experimental conditions (low power) plasma does not produce major topographical changes of the semiconductor, glass or metallic substrates, but induces significant changes of topography of polymeric substrates. In the case of treatments in polymerizing gases the surface functionalization with amino or carboxylic functional groups is obtained. The utility of Crystal Quartz Microbalance (QMC) systems for the study of interaction of plasma modified surfaces with organic molecules was demonstrated. It was possible to detect the grafting of very small amounts of organic vapors on quartz crystals treated by plasmas (activated or deposited with plasma polymer thin films) In order to test the plasma approaches for preparing surfaces able to be used in detection of biological molecules with QMCs have been performed experiments of interaction of cells (osteoblasts and fibroblasts) with gold covered quartz crystals activated by plasma, or grafted with thiophene vapors. These devices are similar with the detection heads in Quartz Crystal Microbalances. A good adherence and cell proliferation was obtained on these surfaces. This way it was demonstrated that the atmospheric pressure plasma treatments realized by scanning, followed by grafting with tiophene vapors are appropriate procedures for creating functionalized surfaces suitable for interaction with biological entites. These crystals can be used for developing instrumentation to detect genetically modified organisms or for clinical applications.
Lucrari stiintifice publicate in reviste ISI
1. G. Dinescu, A. Lazea, L. Kravets, S. Dimitrev, Morphological, chemical and permeation characteristics of plasma modified polymeric track membranes, Journal of Optoelectronics and Advanced Materials, 9, 6, 1645-1648, (2007)
2. E.R. Ionita, M.D. Ionita, C. Stancu, M. Teodorescu, G. Dinescu, Small size plasma tools for material processing at atmospheric pressure, 255, 10, 5448-5452, (2009 )
Comunicari stiintifice:
1. C. Petcu, B. Mitu, G. Dinescu, Y. Segui, Crystallization aspects of diparaxylene composite organic materials during plasma processing, International Conference of Plasma Surface Engineering (PSE), Garmisch-Partenkirchen, Germany, 10-15 September, 2006
2. G. Dinescu, C. Ruset, M. Dinescu, Trends in combining techniques for deposition of new application tailored thin films, International Conference of Plasma Surface Engineering (PSE), Garmisch-Partenkirchen, Germany, 10-15 September, 2006, invited lecture
3. G. Dinescu, Basic Plasma Spectroscopy, Low Temperature Plasma Physics: Basics and Applications European Summer School, Bad Honnef, Germany, 8-13 October 2006, invited lecture
4. R. Ionita, I. Luciu, G. Dinescu, Jet type capacitively coupled RF plasma sources for material processing at atmospheric pressure, European Summer School, Bad Honnef, Germany, 8-13 October 2006, poster presentation
5. S. Vizireanu, B. Mitu, L. Nistor, C. Ghica, A. Malesevic, 2- and 3-D carbon nanostructures obtained by Low presure RF plasma Jet, European Summer School, Bad Honnef, Germany, 8-13 October 2006, poster presentation
6. E.C. Stancu, M.D. Ionita, G. Dinescu, L.M. Stefan, L. Moldovan, Atmospheric pressure plasma preparation of polymeric surfaces for interaction with cells, 9th Advanced Summer Course in Cell-Materials Interactions, Porto, Portugal, 16-20 June 2008, poster presentation
