SPECTRAL STUDY ON THE FORMATION OF QUANTUM DOTS AND CHLORIN E6 COMPLEX IN THE PRESENCE OF PROTEIN

Transcription

1 SPECTRAL STUDY ON THE FORMATION OF QUANTUM DOTS AND CHLORIN E6 COMPLEX IN THE PRESENCE OF PROTEIN Artiom SKRIPKA 1, Jurga VALANČIŪNAITĖ 2, Ričardas ROTOMSKIS 1, 2 1 Vilnius University Physics faculty, Saulėtekio 9, c.3, LT-10222, Vilnius, Lithuania 2 Laboratory of Biomedical Physics of Vilnius University institute of Oncology, Baublio 3B LT , Vilnius

2 Content Materials and methods Introduction Experiments and results Conclusions References

3 Norm. optical density Norm. Intensity, a.u. Quantum dots (QD) CdSe/ZnS-amino(PEG) quantum dots were used for the experiments purchased from Invitrogen Corp., USA with photoluminescence peak at 545nm. 1.0 Pure QDs: Absorption Photoluminescence , nm Fig. 1 Normalized absorption and photoluminescence spectra of pure QDs in PBS.

4 Norm. optical density Norm. Intensity, a.u. Clorin e 6 ( ) Chlorine e 6 obtained from Frontier Scientific Inc., USA was used as a photosensitizer with fluorescence peak at 660nm in aqueous solutions. 1.0 Pure : Absorption Fluorescence , nm 0.0 Fig. 2 Normalized absorption and photoluminescence spectra of pure in PBS.

5 Bovine Serum Albumin (BSA) As a protein bovine serum albumin was chosen for the experiments as a simulator of biological medium. BSA was provided by Sigma (Germany).

6 Methods All experiments were conducted in phosphate buffer solution (PBS) ph=7 in dark at room temperature. Absorption measurements were carried out with Cary 50 spectrophotometer (Varian Inc, USA) Fluorescence measurements were performed on Cary Eclipse fluorescence spectrophotometer (Varian Inc., USA)

7 Intensity, a.u. Intensity, a.u. Introduction to the experiment QD c=0.05 M c=0.5 M QD: 1: , nm x , nm Fig. 3 Fluorescence spectra λ ex =465nm of pure QD, and mixed QD- solutions. Inset shows the enlarged area of fluorescence. Intensity of pure is multiplied 5 times.

8 Intensity, a.u. Intensity, a.u. Control measurements QD c=0.05 M QD:BSA 1: c=0.5 M :BSA 1:2 using: ex = 400nm ex = 465nm , nm, nm Fig. 4 Photoluminescence spectra λ ex =465nm of QD and QD:BSA solutions (left). And fluorescence spectra of, :BSA solutions (right) using λ ex =400,465nm.

9 Intensity, a.u. Changes in time QD QD em =545nm em =660nm QD: : em =545nm em =670nm t, min Fig. 5 Fluorescence intensity change in the course of time at λ em =545nm of pure QDs and in QD- complex and λ em =660, 670nm respectively for pure and bound to QDs molecules

10 Intensity, a.u. QD+BSA QD(BSA) c=0.05 M, em =545nm (BSA) c=0.5 M, em =660nm QD:BSA: : em =545nm em =670nm 750 was added 500 QD:BSA 1: QD:BSA 1: t, min Fig. 6 Fluorescence intensity change in the course of time at λ em =545nm of pure QDs and in QD- complex and λ em =660, 670nm respectively for pure and bound to QDs molecules all in the presence of BSA.

11 Intensity, a.u. +BSA+QD 1000 QD was added QD(BSA) c=0.05 M, em =545nm (BSA) c=0.5 M, em =660nm :BSA:QD : em =545nm em =670nm t, min Fig. 7 Fluorescence intensity change in the course of time at λ em =545nm of pure QDs and in QD- complex and λ em =660, 670nm respectively for pure and bound to QDs molecules all in the presence of BSA.

12 Intensity, a.u. QD+ +BSA 1000 QD(BSA) c=0.05 M, em =545nm (BSA) c=0.5 M, em =660nm QD: :BSA : em =545nm em =670nm 750 BSA was added t, min Fig. 8 Fluorescence intensity change in the course of time at λ em =545nm of pure QDs and in QD- complex and λ em =660, 670nm respectively for pure and bound to QDs molecules all in the presence of BSA.

13 Conclusions The CdSe/ZnS-amino(PEG) quantum dots can form a stable complex with chlorin e 6 in the presence of protein and undergo FRET The protein added to QD- solution does not disrupt the QD- complex Protein stabilizes the QD- complex from aggregation

14 Acknowledgements The work was supported by the projects Promotion of Students Scientific Activities (VP1-3.1-ŠMM-01-V )

15 References E. Yaghini, A. M. Seifalian, A. J. MacRobert, Quantum dots and their potential biomedical applications in photosensitization for photodynamic therapy, Nanomedicine 4, (2009) R.Rotomskis, V.Karabanovas, V.Poderys, S.Bagdonas, J.Didžiapetrienė, Įvadas į nanomedicina, 2008 Joseph R. Lakowicz, Principles of fluorescence spectroscopy, third edition, Springer, B. Cunderlikova, L. Gangeskar, J. Moan, Acid-base properties of chlorin e(6): relation to cellular uptake. Journal of Photochemistry and Photobiology B-Biology 53, (1999). K. Das, B. Jain, A. Dube, P.K. Gupta, ph dependent binding of chlorin p-6 with phosphatidyl choline liposomes, Chem. Phys. Lett. 401 (2005)

16 Thank you for your attention.