Preparation and photophysical characterisation of pH sensitive sol-gel thin films doped with curcumin

master's thesis

• Title (croatian): Priprema i fotofizička karakterizacija pH osjetljivih sol-gel tankih filmova dopiranih kurkuminom
• Author: Marija Šiprak
• Mentor: Ivana Steinberg (mentor)
• Committee member: Ivana Steinberg (predsjednik povjerenstva)
• Committee member: Svjetlana Krištafor (član povjerenstva)
• Committee member: Ante Jukić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Granter: University of Split; Faculty of Chemistry and Technology; Split
• Defense date and country: 2022-09-20, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Due to its desirable qualities, such as simplicity, portability, disposability and affordability, optical chemical sensors have been the focus of intensive study and development, including employment of microfluidic devices and lab-on-a-chip technologies. Due to its compatibility, affordability, user-friendliness and abundance, paper, alongside glass, has been used as a substrate material, and paper-based microfluidics have been mostly combined with colorimetric readouts. Furthermore, employment of natural “green” dyes as pH-sensing colorants is rising due to environmental reasons, and curcumin is therefore attracting major interest. Curcumin's various pharmacological actions have been proven by different scientific studies, establishing its ability to operate as a chemo-preventive, as well as potential therapeutic agent against a variety of chronic diseases. Furthermore, curcumin has a bright yellow color in acidic and neutral conditions that turn into a brownish-orange color on exposure to a basic pH solution. This makes it a promising tool for instantaneous detection of analyte with the naked eye, without the need to use the sophisticated instruments. In this study, optical sensors for quick sensing were created utilizing curcumin as pH indicator, immobilized by sol-gel method and deposited on two different types of substrates, glass and paper. Curcumin-based sensors were characterized by UV-Vis absorption and reflectance spectroscopy as well as colorimetry, on exposure to solutions of pH ranging from 4 to 13. In conclusion, curcumin-based paper sensors achieved better results than curcumin-based glass thin films, which lead to their further characterization in terms of stability and reversibility of response.

Abstract (croatian)

Zbog svojih poželjnih kvaliteta, kao što su jednostavnost, prenosivost, jednokratnost i pristupačnost, optički kemijski senzori su u središtu intenzivnog proučavanja i razvoja, uključujući korištenje mikrofluidnih uređaja i takozvanih tehnologija laboratorija na čipu. Zbog svoje kompatibilnosti, cjenovne pristupačnosti, lakoće korištenja i obilja, papir se, uz staklo, koristi kao materijal za supstrat, a papirna mikrofluidika se uglavnom kombinira s kolorimetrijskim očitanjima. Nadalje, uporaba prirodnih „zelenih“ boja kao pH osjetljivih bojila konstantno raste zbog ekoloških razloga, a među njima se ističe kurkumin, koji je privukao veliko zanimanje. Različita farmakološka djelovanja kurkumina dokazana su znanstvenim studijama, utvrđujući njegovu sposobnost za kemoprevenciju, kao i moguće terapeutsko djelovanje protiv raznih kroničnih bolesti. Nadalje, kurkumin ima jarko žutu boju u kiselim i neutralnim uvjetima, koja se pretvara u smeđe-narančastu kada je izložen bazičnom pH što ga čini obećavajućim alatom za trenutnu detekciju analita golim okom, bez upotrebe sofisticiranih instrumenata. U ovoj studiji, optički senzori za brzo očitavanje pripremljeni su korištenjem kurkumina kao pH bojila, imobiliziranog sol-gelom metodom i položenog na dvije različite vrste podloga, staklo i papir. Izrađeni senzorski materijali temeljeni na kurkuminu karakterizirani su primjenom UV-Vis apsorpcijske i reflektancijske spektroskopije, a kolorimetrijska detekcija ispitana je u rasponu pH vrijednosti od 4 do 13. Zaključeno je da su papirnati senzori na bazi kurkumina postigli bolje rezultate od staklenih senzora, što je dovelo do dodatnog testiranja njihove stabilnosti i reverzibilnosti.

• Keywords: optical chemical sensors; paper-based microfluidics; natural “green” dyes; pH-sensing colorants; curcumin
• Keywords (croatian): optički kemijski senzori; papirna mikrofluidika; prirodna “zelena” bojila; pH osjetljiva bojila; kurkumin
• Language: english
• URN:NBN: urn:nbn:hr:149:033117
• Study programme: Title: Chemical and environmental technology - graduate - university; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-04-03 07:22:13