Pojačanje Ramanova raspršenja na nanočesticama zlata pripremljenim u puferu HEPES

master's thesis

• Title (english): Enhancement of Raman scattering on gold nanoparticiples prepared in hepes buffer
• Author: Ivana Radoslavić
• Mentor: Adriana Kenđel (mentor)
• Committee member: Đani Škalamera (predsjednik povjerenstva)
• Committee member: Snežana Miljanić (član povjerenstva)
• Committee member: Adriana Kenđel (član povjerenstva)
• Committee member: Biserka Prugovečki (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2022-09-30, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Istražena je SERS (spektroskopija površinski pojačanog Ramanova raspršenja) učinkovitost i
stabilnost koloida zlata pripravljenih redukcijom tetraklorozlatne(III) kiseline 4–(2–
hidroksietil)–1–piperazinetilensulfonskom kiselinom (pufer HEPES) pomoću modelnih
molekula rodamina 6G (R6G), (E)-1,2-di(piridin-4-il)etena (BPE) i dinatrijeva fluoresceinata
(Na2Fl). Koloidi su sintetizirani na dva načina: sinteza „bez sjemena“ u kojoj su samo
pomiješani metalna sol i pufer, te sinteza „sa sjemenom“ u koju se dodaje, osim metalne soli i
pufera, i srebrov nitrat. Istražen je i utjecaj dodatka polimera poli(vinil-pirolidona) (PVP) na
stabilnost pripravljenih koloida i pojačanje raspršenja zračenja. U svim koloidima zlata najjače
pojačanje raspršenja nađeno je za molekulu BPE, vrlo vjerojatno zbog njezine neutralnosti i
strukturnih značajki. Modelne molekule s nabojem elektrostatski odbija HEPES koji stabilizira
nanočestice i nalazi se na površini zlata u obliku zwitter iona. Uvođenje stabilizirajućeg
polimera PVP u sustav stvara steričku barijeru i dobiveni spektri modelnih molekula pokazuju
vrlo slabe vrpce. No, takvi modificirani koloidi su najstabilniji kroz vrijeme.

Abstract (english)

The SERS (surface–enhaced Raman scattering) efficiency and stability of gold colloids prepared
by reduction of tetrachloroauric(III) acid with 4-(2-hydroxyethyl)-1-piperazineethylenesulfonic
acid (HEPES buffer) were investigated using rhodamine 6G (R6G), (E)-1,2-di(pyridin-4-yl)ethene
(BPE) and disodium fluoresceinate (Na2Fl). Colloids were synthesized in two ways: the "seedless"
synthesis, in which the metal salt and buffer are mixed, and the "seeded" synthesis, in which, in
addition to the metal salt and buffer, silver nitrate was added. The influence of the poly(vinylpyrrolidone) - PVP addition on the stability of the prepared colloids and the scattering enhancement
were investigated. In all gold colloids, the strongest SERS effect was found for the BPE molecules,
most likely due to its neutrality and structural features. The charged model molecules are
electrostatically repelled by HEPES, which stabilizes the nanoparticles and was located on the gold
surface as zwitter ion. Introduction of the polymer PVP into the system resulted with a steric barrier
and the obtained spectra of the model molecules show very weak bands. However, such modified
colloids are the most stable over time.

• Keywords: površinski pojačano Ramanovo raspršenje; koloid zlata; HEPES; PVP
• Keywords (english): surface-enhanced Raman scattering; gold colloid; HEPES; PVP
• Language: croatian
• URN:NBN: urn:nbn:hr:217:606055
• Study programme: Title: Graduate university studies in chemistry; specializations in: Research programme; Course: Research programme; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra kemije (magistar/magistra kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2024-09-30
• Created on: 2022-10-24 13:34:54