Lithuanian Journal of Physics article / Lietuvos fizikos žurnalo straipsnis

PROTEIN STABILIZED Au NANOCLUSTERS: SPECTRAL PROPERTIES AND PHOTOSTABILITY
Vilius Poderys^a, Marija Matulionytė-Safinė^a,b, Dainius Rupšys^b, and Ričardas Rotomskis^a,b
^aBiomedical Physics Laboratory, National Cancer Institute, P. Baublio 3b, LT-08406 Vilnius, Lithuania
^bBiophotonics Group of Laser Research Centre, Vilnius University, Saulėtekio 9, LT-10222 Vilnius, Lithuania
E-mail: ricardas.rotomskis@nvi.lt

Received 26 November 2015; revised 22 January 2016; accepted 25 March 2016

Bovine serum albumin stabilized gold nanoclusters (BSA-Au nanoclusters) have been widely studied due to their possible applications in biomedicine as sensors, fluorescent or multi-modality markers, and therapeutic agents. Synthesis and optical properties of these nanoclusters have been extensively investigated; however, there is still very little data on photostability of BSA-Au nanoclusters. Photostability of BSA-Au nanoclusters is of major importance for a variety of applications, such as material sensing and fluorescence imaging. Herein we demonstrate that after synthesis the BSA-Au solution has two photoluminescence (PL) bands peaking at 468 and 660 nm. Nevertheless, a different behaviour of the PL bands at 468 and 660 nm upon irradiation indicates that only band at 660 nm is related to PL of Au nanoclusters. BSA-Au nanoclusters exhibit great colloidal stability and do not undergo irreversible changes when heated up to 65 °C. However, irradiation of BSA-Au nanoclusters causes a wavelength dependent decrease of intensity and a hypsochromic shift of the PL band at 660 nm which is proportional to the delivered dose. The shift of the PL band at 660 nm could occur due to loss of several gold atoms in Au nanoclusters and/or due to deterioration of a nanoparticle coating layer. We have also demonstrated that the photostability of BSA-Au nanoclusters increases in the cell growth medium.

Keywords: photoluminescent gold nanoclusters, bovine serum albumin, spectral properties, stability, irradiation,
atomic force microscopy
PACS: 78.67.Bf

BALTYMU STABILIZUOTI AUKSO NANO KLASTERIAI: SPEKTRINIŲ SAVYBIŲ IR FOTOSTABILUMO TYRIMAI

Vilius Poderys^a, Marija Matulionytė-Safinė^a,b, Dainius Rupšys^b, Ričardas Rotomskis^a,b
^aNacionalinio vėžio instituto Biomedicininės fizikos laboratorija, Vilnius, Lietuva
^bLazerinių tyrimų centro Biofotonikos grupė, Vilnius, Lietuva

Pastaruoju metu jaučio serumo albuminu stabilizuoti aukso nanoklasteriai (JSA-Au NK) sulaukė didelio susidomėjimo dėl galimo šių nanodalelių taikymo biomedicinoje. Šio tipo nanodalelės gali būti taikomos kaip fluorescenciniai ar daugiafunkciai žymenys, jutikliai, terapiniai agentai. JSA-Au nanoklasterių sintezė ir optinės savybės plačiai tiriamos, tačiau iki šiol literatūroje yra labai mažai duomenų apie šių nanodalelių fotostabilumą. Žinios apie švitinimo poveikį JSA-Au NK yra itin svarbios norint juos sėkmingai taikyti optinėje diagnostikoje ir terapijoje. Šviežiai susintetintas JSA-Au NK tirpalas turi dvi fotoliuminescencijos juostas: ties 468 ir 660 nm. JSA-Au NK pasižymi dideliu koloidiniu stabilumu, išlieka stabilūs juos kaitinant iki 65 °C. Mūsų atlikti tyrimai parodė, kad švitinant JSA-Au nanoklasterių tirpalą skirtingo bangos ilgio spinduliuote švitinimo poveikis fotoliuminescencijos juostoms ties 468 ir 660 nm yra skirtingas ir juosta ties 468 nm nepriklauso baltyme susidariusiam Au nanoklasteriui. Švitinant JSA-Au NK stebimas fotoliuminescencijos juostos ties 660 nm trumpabangis poslinkis. Šis efektas (tikriausiai susijęs su Au NK irimu) yra didesnis, kai švitinama trumpesnio bangos ilgio spinduliuote.

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