[PDF]    http://dx.doi.org/10.3952/lithjphys.51206

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 51, 163–171 (2011)

V. Kulvietis a,b, G. Streckytė b, and R. Rotomskis a,b
a Biomedical Physics Laboratory, Institute of Oncology of Vilnius University, P. Baublio 3b, LT-08406 Vilnius, Lithuania
b Biophotonics group of Laser Research Center of Vilnius University, Saulėtekio 9, LT-10222 Vilnius, Lithuania
E-mail: giedre.streckyte@ff.vu.lt

Received 5 May 2011; revised 7 June 2011; accepted 21 June 2011

For the successful use of quantum dots (QDs) in biomedicine their chemical and optical stability is of great importance. In this study the changes of photoluminescence parameters of CdTe QDs coated with mercaptopropionic acid (MPA) dependently on time and environment are presented. The presence of salt ions in the QD water solution decreases photoluminescence band intensity and induces red shift. The pH value of the solution also influences spectroscopic properties of QDs. In the pH range from 2.5 to 9 a decrease of photoluminescence intensity is observed. The fastest one, leading to the complete luminescence bleaching, occurs in the most acidic medium. Changes of QD spectral properties in cell growth media were studied as well. The results imply that spectroscopic changes of CdTe–MPA QDs are caused by the interactions between the ions present in the solution and ligand coating of QDs. The model of possible processes is proposed.
Keywords: quantum dots, photoluminescence, ions, pH
PACS: 87.64.kv, 87.85.Rs

V. Kulvietis a,b, G. Streckytė b, and R. Rotomskis a,b
a Vilniaus universiteto Onkologijos institutas, Vilnius, Lietuva
b Vilniaus universiteto Lazerinių tyrimų centras, Vilnius, Lietuva

Kvantiniai taškai (KT) yra puslaidininkinės nanodalelės, pasižyminčios išskirtinėmis optinėmis savybėmis. Pastaraisiais metais sparčiai plečiasi jų taikymas biologijoje ir medicinoje. Siekiant sėkmingai taikyti KT įvairiose biomedicinos srityse, būtina nuodugniai ištirti jų cheminių ir spektrinių savybių stabilumą įvairiose vandeninėse terpėse. Šiame darbe spektroskopiniais metodais buvo tirti merkaptopropiono rūgštimi dengtų CdTe KT fotoliuminescencijos savybių pokyčiai einant laikui ir keičiantis terpės sudėčiai. Nustatyta, kad tirpale esantys druskų jonai mažina KT fotoliuminescencijos intensyvumą ir sukelia ilgabangį emisijos juostos postūmį. Terpės rūgštingumas taip pat veikia KT spektrines savybes. Kai tirpalo pH < 9, KT fotoliuminescencijos intensyvumas mažėja. Šis kitimas ypač išryškėja didėjant vandenilio jonų koncentracijai tirpale. Taip pat buvo tirti KT spektrinių savybių pokyčiai ląstelių auginimo terpėse. Gauti rezultatai rodo, kad KT spektrinių savybių pokyčius lemia tirpaluose esančių jonų sąveika su KT paviršių dengiančiais ligandais. Pateikiamas galimas šių procesų modelis.

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