Utjecaj veličine, oblika i površinske strukture nanočestica srebra na njihovu interakciju s modelnim proteinima

doctoral thesis

• Title (english): Effect of size, shape and surface structure of silver nanoparticles on their interaction with model proteins
• Author: Ivona Capjak
• Mentor: Ivana Vinković Vrček (mentor)
• Mentor: Sandra Šupraha-Goreta (komentor)
• Committee member: Tin Weitner (predsjednik povjerenstva)
• Committee member: Jasna Jablan (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; Zagreb
• Defense date and country: 2019-05-15, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy
• Universal decimal classification (UDC): 615 - Pharmacology. Therapeutics. Toxicology

Abstract

Zbog svojstava na nano razini, primjena nanosrebra (AgNP) u potrošačkim i medicinskim proizvodima je
u stalnom porastu što nužno zahtijeva stalnu procjenu njihovih učinaka na ljudsko zdravlje.
Cilj ovog doktorskog rada bio je utvrditi kako različita fizikalno-kemijska svojstva AgNP određuju
njihovo ponašanje, stabilnost i interakcije u različitim biološkim medijima. U tu svrhu je sintetizirano
šesnaest vrsta AgNP različitih oblika i površinske stabilizacije u veličinama od 10 nm i 50 nm. Sve AgNP
vrste su pažljivo karakterizirane obzirom na raspodjelu veličina, površinski naboj, topljivost i ponašanje u
vodi, u ultra čistoj vodi, pri različitim pH i ionskim jakostima, uz dodatak površinski aktivnih tvari, u
fiziološkoj otopini, fosfatnom puferu i fosfatnom puferu uz dodataka 0.9% NaCl. AgNP vrstama određen
je antibakterijski učinak na sojevima E. coli i S. aureus. Nano-bio interakcije istraživane su koristeći dva
modelna proteina: albumin i α-1-kiseli glikoprotein. U tu je svrhu određeno kako različita fizikalnokemijska
svojstva AgNP utječu na konstante vezanja ta dva proteina na površinu nanočestica, te što se
događa sa sekundarnom strukturom proteina uslijed vezanja na AgNP.
Utvrđeno je da osim naboja površinskog stabilizatora, značajnu ulogu u nano-bio interakcijama
ima nominalni promjer AgNP. S porastom ionske jakosti ili značajnom promjenom pH medija mijenja se
površinski naboj, a AgNP se destabiliziraju. Ukoliko u mediju nema biomolekula kao što su proteini,
AgNP su nestabilne i podložne aglomeraciji i otapanju. Proteini se vežu na AgNP površinu čim se AgNP
izlože mediju koji sadrže proteine, a konstante vezanja proteina na površinu AgNP slične su vezanju tih
proteina s nekim lijekovima. Promjena sastava medija ne uzrokuje značajne promjene u tim nano-bio
interakcijama. Vezanje albumina s AgNP rezultira većom i raznolikijom promjene sekundarne/tercijarne
strukture proteina u odnosu na onu koja se događa s α-1-kiselim glikoproteinom.

Abstract (english)

Due to properties of silver at a nano level, silver nanoparticles (AgNP) are currently being used in an
increasing number of consumer and medical products, which necessitate their safety assessment for
human health.
The aim of this doctoral work is to determine how different physico-chemical properties of AgNP affect
their behaviour and interaction in different biological media. For this purpose, sixteen types of AgNP of
different shape, size (10 and 50 nm) and surface stabilization were prepared. Careful characterization of
their size distribution, surface charge, dissolution, and behaviour in water, at different pH and ionic
strength, in the presence of surface active agents, in phosphate buffer, in 0.9 % NaCl solution, and in
phosphate buffer with addition of 0.9 % NaCl was carried out. Antimicrobial efficacy of AgNP were
tested using two bacterial strains, E. coli i S. aureus. Nano-bio interactions were investigated using two
model proteins: albumin and α-1-acid glycoprotein. For this purpose, effect of various physical-chemical
properties of AgNP on the binding constants of these two proteins on the AgNPs surface was evaluated, as
well as the changes in the secondary protein structure due to binding to AgNP.
Obtained results demonstrated that the surface charge and nominal diameter of AgNP both have a
significant role in nano-bio interactions. The surface charge and AgNP changes upon increase in ionic
strength or significant changes in pH of the inclusion media, which lead to AgNP destabilization. In media
without biomolecules like proteins, AgNP are unstable and susceptible to agglomeration and dissolution.
Proteins present in the media bind to the AgNP surface as soon as AgNP are suspended in these media.
Binding constants of proteins to AgNP surface are similar to binding between these proteins and some
drugs. Changing the media composition does not cause significant changes in these nano-bio interactions.
Binding of albumin to AgNP results in a greater and more varied alteration of the secondary / tertiary
protein structure compared to α-1-acid glycoprotein.

• Keywords: nanosrebro; proteini; interakcije; albumin; α-1-kiseli glikoprotein; stabilnost; antibakterijska aktivnost; nano-bio međuprostor
• Keywords (english): nanosilver; stability; ionic strength; electrolytes; antibacterial efficacy; coating; logKa; BSA; AGP
• Language: croatian
• URN:NBN: urn:nbn:hr:163:157944
• Promotion: 2019
• Study programme: Title: Pharmacy and biochemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor znanosti (doktor znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-16 10:12:42