Stimulation of Cysteine-Coated CdSe/ZnS Quantum Dot Luminescence by meso-Tetrakis (p-sulfonato-phenyl) Porphyrin

Abstract

Interaction between porphyrins and quantum dots (QD) via energy and/or charge transfer is usually accompanied by reduction of the QD luminescence intensity and lifetime. However, for CdSe/ZnS-Cys QD water solutions, kept at 276 K during 3 months (aged QD), the significant increase in the luminescence intensity at the addition of meso-tetrakis (p-sulfonato-phenyl) porphyrin (TPPS4) has been observed in this study. Aggregation of QD during the storage provokes reduction in the quantum yield and lifetime of their luminescence. Using steady-state and time-resolved fluorescence techniques, we demonstrated that TPPS4 stimulated disaggregation of aged CdSe/ZnS-Cys QD in aqueous solutions, increasing the quantum yield of their luminescence, which finally reached that of the fresh-prepared QD. Disaggregation takes place due to increase in electrostatic repulsion between QD at their binding with negatively charged porphyrin molecules. Binding of just four porphyrin molecules per single QD was sufficient for total QD disaggregation. The analysis of QD luminescence decay curves demonstrated that disaggregation stronger affected the luminescence related with the electron-hole annihilation in the QD shell. The obtained results demonstrate the way to repair aged QD by adding of some molecules or ions to the solutions, stimulating QD disaggregation and restoring their luminescence characteristics, which could be important for QD biomedical applications, such as bioimaging and fluorescence diagnostics. On the other hand, the disaggregation is important for QD applications in biology and medicine since it reduces the size of the particles facilitating their internalization into living cells across the cell membrane.Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2449-x) contains supplementary material, which is available to authorized users.

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

“…As it has been shown recently [ 13 , 26 , 27 , 28 , 29 ], the short-lived component of the CdTe-3-MPA QD luminescence is associated with the electron-hole annihilation in the QD core, while the long-lived one is due to the electron-hole annihilation in the QD functionalizing (protective) shell. Therefore, the increase of the QD luminescence intensity in the presence of BSA can be due to interaction of BSA with 3-MPA groups on the QD surface.…”

“…Therefore, the complexes of porphyrins with quantum dots are of great interest for medicine. PPh and QD complexation can occur via energy, electron or proton transfer, depending on the structural characteristics of the participants [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ].…”

<p>Synthesis of meso-tetra-(4-sulfonatophenyl) porphyrin (TPPS₄) – CuInS/ZnS quantum dots conjugate as an improved photosensitizer</p>

“…However, TPPS 4 has four sulfonyl groups available for binding and CuInS/ZnS has amine groups which when combined (sulfonyl and amine group) would aid the formation of sulfonamide bond between TPPS 4 and CuInS/ZnS via the negatively charged oxygen of the sulfonate and positive charge of the amine on the GSH-capped QDs (S1). Furthermore, the high affinity of the porphyrin π-conjugated systems for metal surfaces9 could further foster the formation of the sulfonamide bond. To further confirm the conjugate formation, FTIR analysis was done on the purified and dried CuInS/ZnS QDs, TPPS 4 and the dried TPPS 4 –CuInS/ZnS conjugate.…”

“…In addressing these inherent shortcomings of TPPS 4 and porphyrins at large, much research has focused on conjugated systems for their biological applications 8,9,11. Moreover, conjugation of TPPS 4 has shown to improve the QY of QDs and disaggregation of aged QDs which allows for a wider application range of TPPS 4 –nanomaterial conjugates 9. However, binary quantum dots (QDs) adopted to conjugate with porphyrins have added much distress due to their toxic nature attributed to the presence of heavy metals such as Cd and Pb 12.…”

Synthesis strategies and application of ternary quantum dots — in cancer therapy

“…On the other hand, most cancer drugs suffer from inherent shortcomings such as limited absorption, insolubility and aggregation. However, these shortcomings can be overcome when these drugs are applied in the form of conjugated systems [3,4].…”