Mezoporozni delci kot osnova za razvoj kolorimetričnih indikatorjev za makromolekule

Šifrer, Klara (author), Švara Fabjan, Erika (mentor), Cerc Korošec, Romana (comentor)

Mezoporozni delci so porozni materiali, ki vsebujejo kanale por premera med 2 nm in 50 nm. Zaradi visoke specifične površine, ozke porazdelitve velikosti por in možnosti modifikacije porozne matrice s kovalentno vezavo različnih funkcionalnih skupin (t.i. reakcijo funkcionalizacije) in/ali adsorpcijo barvil, so zanimiva osnova za uporabo na različnih področjih, tudi v senzoriki. V magistrski nalogi sem sintetizirala in preučevala lastnosti modificiranih mezoporoznih delcev MCM-41 kot osnovo za razvoj kolorimetričnih indikatorjev za makromolekule, ki bi delovali po mehanizmu sistema vrat z zapiralnim mehanizmom (ang. Molecular gate system). Najprej sem sintetizirala mezoporozne delce tipa MCM-41. Nato sem jih modificirala na način, da sem najprej adsorbirala barvilo krezol rdeče, nato pa funkcionalizirala površino s 3-aminopropilnimi skupinami. Sintetiziranim delcem smo določili lastnosti z UV-Vis in FT-IR spektroskopijo, rentgensko praškovno difrakcijo, dušikovo fizisorpcijo, termogravimetrijo, sklopljeno z masno spektrometrijo, meritvami zeta potenciala in pH. Za namen uporabe delcev v sistemu vrat z zapiralnim mehanizmom sem preverila sproščanje barvila (desorpcijo) v medij s kontroliranim in nekontroliranim pH. Prav tako sem izvedla preliminarne teste vezave fluorescenčno označenega izbranega proteina na nefunkcionalizirano in funkcionalizirano matrico MCM-41. Ugotovila sem, da so nefunkcionalizirani delci MCM-41 z adsorbiranim barvilom krezol rdeče v različnih masnih razmerjih oranžne do oranžne-rjave barve, barvilo je v večji meri prisotno v enkrat deprotonirani obliki. Delcem se ohrani mezoporozna struktura, se jim pa zniža specifična površina in volumen por, kar potrjuje, da se je barvilo adsorbiralo v pore. Ocenjena izoelektrična točka materialov je pri približno pH 3,8. Funkcionalizirani delci MCM-41 z adsorbiranim barvilom so vijolične barve, barvilo je v večji meri prisotno v popolnoma deprotonirani obliki. Tem delcem nismo več potrdili mezoporozne strukture, volumen por in specifična površina sta se znižali, izoelektrična točka pa je bila približno pri pH 9. S testom desorpcije smo ugotovili, da je desorbirano barvilo iz vseh funkcionaliziranih in nefunkcionaliziranih delcev v medijih s kontroliranim pH v obliki, ki je značilna za pH medija ne glede na obliko, prisotno v matrici MCM-41, kar smo tudi potrdili s spremembo barve. Fluorescenčno označen protein A se je vezal na delce SiO2, vendar kanalov por s proteinom nismo popolnoma zaprli.

• Language: Slovenian
• Keywords: mezoporozni delci, MCM-41, kolorimetrični indikatorji, krezol rdeče
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2024
• PID: 20.500.12556/RUL-155268
• COBISS.SI-ID: 190564099
• Publication date in RUL: 22.03.2024

Secondary language

• Language: English
• Title: Mesoporous particles as a basis for the development of colorimetric indicators for macromolecules

Abstract

Mesoporous particles are porous materials containing pores with diameters from 2 nm to 50 nm. Due to their high specific surface area, narrow pore size distribution, and the possibility of modification of the porous matrix by covalent bonding of various functional groups (functionalization) and/or dye adsorption, they are an interesting basis for applications in various fields, including sensor technology. In this master's thesis, I synthesized and investigated the modified mesoporous MCM-41 particles as a basis for developing colorimetric indicators for macromolecules with a gate system. Firstly, I synthesized mesoporous particles type MCM-41. In the next step, I modified them by adsorbing the cresol red dye, followed by functionalizing the surface using 3-aminopropyl groups. The synthesized particles were characterized using UV-Vis and FT-IR spectroscopy, X-ray powder diffraction, nitrogen physisorption, thermogravimetry with mass spectrometry, zeta potential and pH measurements. For the purpose of using the particles in a molecular gate system, I studied the release of dye (desorption) into media with controlled and uncontrolled pH. Additionally, preliminary tests of binding the fluorescently labelled protein A to modified MCM-41 particles were performed. It was found that MCM-41 particles with adsorbed cresol red dye in various mass ratios were orange to orange-brown in colour, with the dye mostly present in monodeprotonated form. Non-functionalized particles with adsorbed dye retained their mesoporous structure, but their specific surface area and pore volume were reduced, confirming dye adsorption into the pores. The estimated isoelectric point of the materials was around pH 3.8. Functionalized MCM-41 particles with adsorbed dye were purple in colour, with the dye present mostly in fully deprotonated form. In the functionalized particles the mesoporous structure was no longer confirmed, pore volume and specific surface area were also reduced. An isoelectric point was at approximately pH 9. Desorption tests showed that desorbed dye from all functionalized and non-functionalized particles in media with controlled pH exhibited a characteristic form typical for the pH of the medium, independently of its form in the modified MCM-41, which was confirmed by visual colour changes. Fluorescently labelled protein was bound to SiO2 particles, although pores were not completely closed with protein.

• Keywords: Mesoporous particles, MCM-41, Colorimetric sensor, Cresol red