Institute of Oncology of Vilnius University, Biomedical Physics Laboratory, Baublio 3b, LT-08406 Vilnius, Lithuania.
J Biomed Opt. 2013 Jul;18(7):078002. doi: 10.1117/1.JBO.18.7.078002.
The excitation-related problems in photodynamic therapy of cancer might be solved by combining two-photon (TP) irradiation and quantum dots (QDs) as effective energy donors for conventional photosensitizers (PS). Here, it is demonstrated for the first time that QD-chlorin e6 (Ce6) complex formed due to the hydrophobic interaction between Ce6 molecules and lipid coating of QDs can be effectively excited via TP irradiation at 1030 nm, which spectrally coincides with the biological tissue optical window. TP absorption cross-section for free QDs and Ce6 at 1030 nm was 3325 and 13 Goeppert-Mayer, respectively. Upon TP excitation of QD-Ce6 solution, the fluorescence band of bound Ce6 molecules was observed via energy transfer from excited QDs. Increasing concentration of Ce6 resulted in quenching of the photoluminescence of QDs and an increase in the fluorescence intensity of bound Ce6 molecules. These intensity changes coincided well with those observed upon single-photon excitation of QD-Ce6 solution when QDs alone are excited. The efficiency of energy transfer in QD-Ce6 complex upon TP excitation was about 80% (QD∶Ce61∶5). These results indicate that the effective excitation of PS with a low TP absorption cross-section is possible in such type noncovalent complexes via energy transfer from TP excited QDs.
在癌症的光动力疗法中，激发相关的问题可以通过将双光子（TP）辐照和量子点（QD）结合起来来解决，QD 可以作为传统光敏剂（PS）的有效能量供体。在这里，首次证明了由于 Ce6 分子与 QD 脂质涂层之间的疏水相互作用而形成的 QD-叶绿素 e6（Ce6）复合物可以通过在 1030nm 处的 TP 辐照有效激发，这与生物组织光学窗口光谱相吻合。在 1030nm 处，自由 QD 和 Ce6 的 TP 吸收截面分别为 3325 和 13 个 Goeppert-Mayer。在 QD-Ce6 溶液的 TP 激发下，通过从激发的 QD 到结合的 Ce6 分子的能量转移观察到结合的 Ce6 分子的荧光带。Ce6 浓度的增加导致 QD 的光致发光猝灭和结合的 Ce6 分子的荧光强度增加。这些强度变化与单独激发 QD 时观察到的 QD-Ce6 溶液的单光子激发时的变化非常吻合。在 QD-Ce6 复合物中，TP 激发的能量转移效率约为 80%（QD∶Ce61∶5）。这些结果表明，在这种非共价复合物中，通过从 TP 激发的 QD 到能量转移，具有低 TP 吸收截面的 PS 的有效激发是可能的。
