Vpliv fosfonskih prevlek na biokompatibilnost fluorescenčnih nanodelcev

Vozlič, Maša (author), Žiberna, Lovro (mentor), Lisjak, Darja (comentor)

Nanodelci na osnovi NaYF4, dopirani z lantanoidi, so predmet številnih raziskav, saj imajo velik potencial za uporabo v medicinski diagnostiki. Njihova prednost pred klasičnimi organskimi fluorofori je fluorescenca z energijsko pretvorbo navzgor, ki omogoča vzbujanje z bližnjo infrardečo svetlobo. Kljub obetavnim optičnim lastnostim pa so nanodelci na osnovi NaYF4 kemijsko nestabilni in se v vodnih medijih počasi raztapljajo. Tako je treba pred njihovo možno uporabo v humani medicini opraviti še nadaljnje izboljšave ter preizkuse varnosti in učinkovitosti. Magistrska naloga je tematsko razdeljena na dva dela. V prvem sklopu smo optimizirali sintezo zaščitnih fosfonskih prevlek alendronske kisline in etilendiamino (tetrametilenfosfonske) kisline (EDTMP) na nanodelcih s kubično (α-NaYF4) oziroma heksagonalno (β-NaYF4) kristalno strukturo. Proučevali smo vpliv sinteznih parametrov, kot so temperatura, čas sinteze in intenzivnost mešanja na učinkovitost zaščite sintetizirane prevleke pred raztapljanjem nanodelcev. Sintetiziranim nanodelcem smo določili povprečno velikost in jih morfološko analizirali s pomočjo presevne elektronske mikroskopije. Z meritvami zeta potenciala in Kaiserjevim testom smo sledili nastanku zaščitnih prevlek. Izmerili smo optične lastnosti nanodelcev. Učinkovitost zaščitnih prevlek smo preverjali s testi raztapljanja v fosfatnem pufru (PBS) in celičnem mediju Dulbecco's Modified Eagle Medium (DMEM) z visoko vsebnostjo glukoze pri fizioloških pogojih. Stopnja raztapljanja je bila znatna v PBS, v DMEM pa zelo majhna. Povišana temperatura sinteze prevlek je imela pozitiven učinek na zaščito nanodelcev pred raztapljanjem. V drugem sklopu smo se osredotočili na študije akutne toksičnosti sintetiziranih nanodelcev. Na celični liniji humanega endotelija EA.hy926 smo izvedli teste celične viabilnosti pod različnimi pogoji. Delež viabilnih celic v vzorcu smo določili fluorometrično z dodatkom barvila resazurin. Prevleka EDTMP, sintetizirana z direktno metodo na heksagonalnih nanodelcih, je značilno povečala celično viabilnost nanodelcev v primerjavi z izhodnimi nanodelci.

• Language: Slovenian
• Keywords: biokompatibilnost, celična viabilnost, citotoksičnost, fluorescenčni nanodelci, fosfonske prevleke, raztapljanje
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2021
• PID: 20.500.12556/RUL-126399
• Publication date in RUL: 21.04.2021

Secondary language

• Language: English
• Title: The effect of phosphonic coatings on the fluorescent nanoparticles biocompatibility

Abstract

Nanoparticles based on NaYF4, co-doped with lanthanides, have been extensively studied. Their unique optical properties show great potential for use in human medicine, mostly as bioimaging probes in medicinal diagnostics. Their main advantage over traditional organic fluorophores is their ability to exhibit upconversion fluorescence after an excitation by near infrared light. Despite their promising optical properties, the NaYF4 nanoparticles slowly dissolve in aqueous media. Therefore thorough safety and efficacy assessments need to be done before use in human medicine. This master thesis is thematically divided into two parts. Firstly, we focused on optimizing the synthesis of protective phosphonic coatings based on alendronic acid and ethylenediamino(tetramethylenephosphonic) acid (EDTMP) on nanoparticles with either cubic (α-NaYF4) or hexagonal (β-NaYF4) crystal structure. The effect of synthesis parameters, such as temperature, time, and stirring intensity on the quality of the coatings was studied. We discovered that the coatings synthesized at higher temperatures were more efficient in preventing nanoparticle dissolution. The average size and surface morphology of the nanoparticles were determined using transmission electron microscopy. The coatings formation was followed with the zeta-potential measurements and Kaiser test. We examined the effect of the coatings on the optical properties of synthesized nanoparticles. The quality of the coatings was studied by the dissolution tests under physiological conditions in phosphate buffered saline (PBS) and Dulbecco's Modified Eagle Medium (DMEM) with high glucose content. In the second part of the thesis, we focused on acute toxicity studies. Cell viability tests were performed on human endothelial cell line EA.hy926 under different conditions. The percentage of viable cells was determined by measuring the fluorescence of resazurin. We found that EDTMP coating, which was synthesized with a direct method on nanoparticles with the hexagonal crystal structure, was successful in preventing deleterious effects of bare nanoparticles on cell viability.

• Keywords: biocompatibility, cell viability, cytotoxicity, fluorescent nanoparticles, phosphonic coatings, dissolution