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Title:NANOMETRIC CELLULOSIC LAYERS FOR SPECIFIC ADSORPTION OF POLYSACCHARIDES AND IMMOBILIZATION OF BIOACTIVE MOLECULES
Authors:Mohan, Tamilselvan (Author)
Stana Kleinschek, Karin (Mentor) More about this mentor... New window
Ribitsch, Volker (Co-mentor)
Files:.pdf DR_Mohan_Tamilselvan_2012.pdf (6,46 MB)
MD5: A9094A6300E6BC3E855C12C9FB733457
 
Language:English
Work type:Dissertation (m)
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:The aim of the thesis is to investigate the applicability of nanometric amorphous cellulose model films for the immobilization of functional DNA molecules and to apply this knowledge in the field of DNA microarray preparation. To achieve this aim, the whole thesis work is divided into three major parts, namely part I (partly and fully regenerated cellulose film preparation and its characterization), part II (functional polysaccharide conjugates preparation) and part III (DNA microarray preparation from polysaccharide functional conjugates). The first part of the work mainly focuses on the preparation of cellulose model films from spin coated trimethylsilyl cellulose (TMSC) using an in-situ and ex-situ regeneration methods and its characterization. In the in-situ method, the conversion of TMSC to pure cellulose via acid vapor hydrolysis is investigated at the gas-solid interface in real time and at ambient conditions employing quartz crystal microbalance with dissipation (QCM-D). For this purpose, a permanent flow of gaseous HCl is employed which reacts with TMSC coated surface to form pure cellulose. The kinetics behind this reaction is elucidated and reveals first order. Moreover, the influence of the acid concentration on the kinetics and on changes in mass and film thickness of TMSC is studied. In the case of an ex-situ method, partly and fully regenerated cellulose model films are prepared from spin coated TMSC films through acid vapor phase hydrolysis. This is done by exposing the TMSC films placed in a closed container to vapors of HCl. The regeneration is carried out on one hand by exposing the films to different time intervals and on the other hand to different volume of HCl. The changes in surface morphology, structure, surface composition and film thickness in the course of regeneration (i.e. desilylation) is studied by using various surface analytical techniques like atomic force microscopy (AFM), attenuated total reflectance infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and ‘Sarfus’-technique. In order to gain detailed insight into the desilylation reaction of the films the results from ATR-IR, XPS and thickness measurements are compared with data from static contact angle (SCA) and surface free energy (SFE) determination. Besides, to verify the completion of regeneration of cellulose from TMSC the partly and fully regenerated films prepared using ex-situ method are interacted with cellulase enzymes from Trichoderma viride using QCM-D technique. The changes in mass and energy dissipation due to the interaction of the enzymes with the substrates are correlated with the surface wettability and elemental composition of the regenerated films. The enzymatic degradation rate correlated well to the rate of regeneration. It is demonstrated that capillary zone electrophoresis (CZE) can be used to support QCM-D data via the detection of enzyme hydrolysis products in the eluates of the QCM-D cells. It is also shown that a combination of QCM-D together with enzymatic digestion is a reliable method to monitor the time dependent regeneration of TMSC to pure cellulose. Furthermore, the effect of heat treatment on partly and fully regenerated cellulose films prepared using ex-situ method is investigated by exposing the films to elevated temperature (105 °C) for a prolonged time (6 hours). Upon heating, a structural rearrangement in the films from a featureless to a fibrillar-like structure is observed as evidenced by AFM. Several analytical methods, namely GIXRD, ATR-IR, Sarfus, XPS and SCA data are employed to analyze the alteration in the structure, surface composition, film thickness, wettability and SFE of the time dependent regenerated films before and after heat treatment. Results from solvent (D2O/H2O) exchange studies proved that water content and water uptake capacity of heat treated cellulose films are significantly reduced compared to non heated films.Additionally, a new method is developed to structure nanometric cellulose films via vapor phase acid hydrolysis and enzymat
Keywords:Cellulose model films, carboxymethyl cellulose, trimethylsilyl cellulose, microarrays, quartz crystal microbalance, carbodiimide coupling, aminofluorescein, DNA
Year of publishing:2012
Publisher:T. Mohan]
Source:[Maribor
UDC:547.458.8.544.023.22(043.3)
COBISS_ID:264442624 New window
NUK URN:URN:SI:UM:DK:X4Z6UV2D
Views:1978
Downloads:133
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:KTFMB - FS
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Secondary language

Language:Slovenian
Title:NANOMETRSKE CELULOZNE PLASTI ZA SPECIFIČNO ADSORPCIJO POLISAHARIDOV IN IMOBILIZACIJO BIOAKTIVNIH MOLEKUL
Abstract:Namen predstavljenega doktorskega dela je razvoj nanometrskih amorfnih celuloznih modelnih filmov za imobilizacijo funkcionalnih DNA molekul in uporaba pridobljenega znanja za pripravo DNA mikromrež. Doktorska disertacija je razdeljena v tri dele in sicer; priprava in karakterizacija delno in popolnoma regeneriranih celuloznih filmov; priprava funkcionalnih polisaharidnih konjugatov in priprava DNA mikromrež s polisaharidnimi funkcionalnimi konjugati. Prvi del se nanasa predvsem na in-situ in ex-situ regeneracijo celuloznih filmov in njihovo karakterizacijo. Z uporabo kremenove mikrotehtnice (QCM-D metoda) smo podrobno spremljali hidrolizo in konverzijo trimetilsililne celuloze (TMSC) v celulozo v hlapih klorovodikove kisline. Plinasta HCl v neprekinjenem dotoku reagira s plastjo TMSC in na taksen nacin tvori plast celuloze. Raziskali smo kinetiko procesa regeneracije in dolocili reakcijo prvega reda. Poleg tega smo raziskali tudi vpliv koncentracije kisline na kinetiko reakcije ter na maso in debelino formiranega sloja celuloze. Za potrebe študija ex-situ regeneracije smo prav tako pripravili TMSC filme s tehniko ''spin coat''. V nasprotju z in-situ metodo regeneracije smo v tem primeru položili substrate s TMSC filmi v zaprto posodo, kjer so bili izpostavljeni hlapom klorovodikove kisline. Postopek regeneracije je potekal pri različnih časih izpostavitve kislinskim hlapom ter volumnih kisline. Spremembe v strukturi, debelini filmov, površinski elementni sestavi ter površinski prosti energiji regeneriranih celuloznih filmov (pri različnih časih regeneracije) smo raziskali z uporabo, ATR-IR, Sarfus, XPS tehnik ter z merjenjem stičnih kotov. Z interakcijo med delno ter popolnoma regeneriranimi celuloznimi filmi in encimom celulazo (Trichoderma viride) smo dodatno raziskali stopnjo hidrolize TMSC filmov in posledično stopnjo njihove regeneracije. Spremembe v masi filma in disipaciji energije, kot posledice delovanja celulaze, smo korelirali s sposobnostjo omakanja filmov in njihovo elementno sestavo. Stopnja encimske razgradnje regeneriranih celuloznih filmov je v dobri korelaciji s stopnjo regeneracije. V kombinaciji s kvarčno mikrotehtnico smo uporabili tudi kapilarno consko elektroforezo, s katero smo določili razgradne produkte encimske hidrolize celuloznih filmov. Kombinacija QCM-D tehnike in postopek encimske razgradnje celuloznih filmov se je izkazala koz zanesljiva metoda spremljanja regeneracije TMSC filmov v odvisnosti od časa. Vpliv toplotne obdelave na tako pripravljene filme smo dolocili z naknadno izpostavitvijo celuloznih filmov povišani temperaturi za daljši čas (6 ur). Segrevanje povzroci preureditev filmov, ki se ne ponašajo s posebnimi strukturnimi artefakti, v fibrilarno strukturo, kar je razvidno iz AFM posnetkov. Uporabili smo različne analitske metode, s katerimi smo raziskali spremembe v strukturi, elementni sestavi, debelini, sposobnosti omakanja ter prosti površinski energiji regeneriranih celuloznih filmov pred in po toplotni obdelavi; GIXRD, ATR-IR, Sarfus tehnika, XPS in goniometrija. Z izvedbo postopka izmenjave topila (D2O/H2O) smo dokazali, da se vsebnost vode in sposobnost navzemanja vode toplotno obdelanih regeneriranih celuloznih filmov občutno zmanjša v primerjavi z neobdelanimi filmi...
Keywords:celulozni modelni filmi, karboksimetilna celuloza, trimetilsililna celuloza, mikromreža, kremenova mikrotehtnica, karbodiimidna vezava, aminofluorescein, DNA


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