Effect of Serum Albumin on Porphyrin-Quantum Dot Complex Formation, Characteristics and Spectroscopic Analysis

André L S Pavanelli,Iouri E Borissevitch,Leandro N C Máximo,Roberto S Da Silva

doi:10.3390/nano11071674

Abstract

The effect of bovine serum albumin (BSA) upon interaction between CdTe QD functionalized by 3-Mercaptopropionic Acid (CdTe-3-MPA QD) and two water soluble porphyrins: positively charged meso-tetra methyl pyridyl porphyrin (TMPyP) and negatively charged meso-tetrakis(p-sulfonato-phenyl) porphyrin (TPPS4), was studied in function of pH using the steady-state and time resolved optical absorption and fluorescence spectroscopies. It was shown that, depending on the charge state of the components, interaction with albumin could either prevent the formation of the QD…PPh complex, form a mixed QD…PPh…BSA complex or not affect PPh complexation with QD at all. The obtained results may be of interest for application in photomedicine.

Highlights

Photodynamic therapy (PDT) is a method of treatment of various diseases, including several types of cancer [1,2,3,4,5,6]
PDT is based on mutual application of a photoactive compound, visible or infrared light and molecular oxygen to generate reactive oxygen species (ROS)
We have studied the effect of bovine serum albumin on interaction between CdTe QD functionalized by 3-mercaptopropionic acid (CdTe-3-MPA QD) and two water soluble porphyrins: positively charged meso-tetra methyl pyridyl porphyrin (TMPyP)

Summary

Introduction

Photodynamic therapy (PDT) is a method of treatment of various diseases, including several types of cancer [1,2,3,4,5,6]. Porphyrin-type compounds are of a special interest among PS Due to their intensive optical absorption in the required spectral regions, high quantum yield of the triplet state and relative intense fluorescence, high dark and photostability and affinity with biological structures, such as proteins, nucleic acids and cell membranes, porphyrins (PPh) are widely applied as PS in Photodynamic Therapy (PDT) [1,2,3,4,5,6] and as fluorescence probes in Fluorescence Diagnostics (FD) [7,8]. A great disadvantage of PPh for these applications lies in their relatively low optical absorption in the spectral region of the so-called phototherapeutic window (600–800 nm), where biological tissues are the most transparent. The problem could be corrected by PPh complexation with certain structures, able to absorb light energy in this spectral range and transfer this energy to PPh molecules

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