Primjena prirodnih materijala u razvoju nosivih (bio)kemijskih senzora

undergraduate thesis

• Title (english): Application of natural materials in development of wearable (bio)chemical sensors
• Author: Rafaela Kovačević
• Mentor: Ivana Steinberg (mentor)
• Committee member: Ivana Steinberg (predsjednik povjerenstva)
• Committee member: Svjetlana Krištafor (član povjerenstva)
• Committee member: Juraj Šipušić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2022-09-20, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

U današnje vrijeme sve je veći interes za korištenjem prirodnih materijala pri izradi nosivih kemijskih senzora (engl. wearable chemical sensors), uslijed njihove netoksičnosti, biorazgradivosti i općenito manjeg utjecaja na okoliš. Antocijanini su pigmenti topljivi u vodi, koji se dobivaju izoliranjem iz biljaka, poput voća i povrća. Pokazuju širok spektar boja ovisno o pH medija, zbog čega se mogu koristiti kao pH indikatori. Spektroskopske karakteristike otkrivaju mnogo o kemijskom ponašanju pigmenata te su neizostavan korak prilikom izrade optičkih senzora. Najčešće korištene su UV-Vis apsorpcijska, reflektancijska, fluorescencijska spektroskopija te kolorimetrija. Celuloza je najrašireniji prirodni polimer glukoze, koji pokazuje razna korisna svojstva, primjerice obnovljivost, visoku adsorpciju i mogućnost modifikacije. Njena mikrofibrilna struktura čini pogodni matriks za imobilizaciju antocijanina u senzorima baziranim na prirodnim materijalima. Od mnogobrojnih derivata, karboksimetilceluloza (CMC) pokazuje velik potencijal zbog topivosti u vodi, čime se izbjegava korištenje toksičnih otapala. U ovom radu istraživana su optička svojstva antocijanina izoliranog iz crvenog kupusa, otopljenog u otopini, imobiliziranog u CMC trakicama te CMC filmovima osušenim na stakalcima. UV-Vis spektrofotometrija je korištena za karakterizaciju antocijanina u otopini te imobiliziranog u CMC trakicama, dok je za karakterizaciju CMC filmova osušenih na stakalcima korištena reflektancija. Promjena boje pri različitim pH imobiliziranog antocijanina usporediva je s promjenom boje u otopini. Najpogodnija svojstva u vidu najprimijetnije promjene boje, jasno definiranog reflektancijskog spektra i prikladne konzistencije filma postignuta su za filmove s najvećom korištenom koncentracijom antocijanina. Prikazani rezultati najavljuju mogućnost daljnjih istraživanja ove teme i razvoja nosivih pH osjetljivih materijala u potpunosti načinjenih od prirodnih, netoksičnih, štoviše jestivih materijala, čija primjena bi bila posebno atraktivna u nosivim kemijskim senzorima.

Abstract (english)

Nowadays there is a growing interest to apply natural materials into wearable chemical sensors, due to their lower impact on the environment, nontoxicity and biodegradability. Anthocyanins are water soluble pigments isolated from plants, like fruits and vegetables. They exhibit a broad spectrum of color depending on the pH, therefore could be used as pH indicators. Spectroscopic characteristics are important for defining chemical properties of the pigments and are a mandatory step in preparing an optical sensor. Characterization methods usually include UV-Vis absorbance, reflectance and fluorescence spectroscopy, as well as colorimetry. Cellulose is the most abundant glucose polymer, which shows great variety of properties, namely reusability, high adsorption and reactivity with other chemicals. Its microfiber structure allows to be utilized as an ideal matrix to immobilize anthocyanin in sensors based on natural materials. Out of many derivatives, carboxymethylcellulose shows great potential due to its solubility in water, thus avoiding the use of toxic solvents. In this work the optical properties of anthocyanin isolated from red cabbage are investigated in solution as well as in immobilized forms as carboxymethylcellulose (CMC) film strips and as dried CMC spots on glass slides. To characterize the anthocyanin in solution and immobilized in CMC film strips UV-Vis spectroscopy was used, while reflectance spectroscopy measurements were used to characterize spots dried on glass slides. Color change of immobilized anthocyanin films exposed to solution of different pH value was comparable with changes obtained with anthocyanins dissolved in solution. Best properties in terms of most noticeable color change, well defined reflectance spectra and appropriate consistency were achieved for the films with highest concentration of anthocyanins. The results obtained here show great promise for development of new pH sensitive materials entirely made of natural, nontoxic and even edible materials, especially suitable for wearable sensing applications.

• Keywords: senzor; antocijanin; celuloza; reflektancija; pH indikator
• Keywords (english): sensor; anthocyanin; cellulose; reflectance; pH indicator
• Language: croatian
• URN:NBN: urn:nbn:hr:149:859973
• Study programme: Title: Applied Chemistry - Undergraduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-03-02 08:19:24