Gold Nanoparticles Conjugated with Methylene Blue for Photodynamic Therapy
Date Issued
2014
Date
2014
Author(s)
Hsu, Che-Hao
Abstract
Photodynamic therapy (PDT) mainly involves cellular uptake of photosensitizer (PS) and excitation of light at specific wavelength to induce generation of reactive oxygen species (ROS) inside the targeted cells. This approach usually suffers from two main deficiencies: dark toxicity of PS and poor selectivity of cellular uptake between targeted cells and normal tissues.
In this work, a known effective PS, methylene blue (MB) which can be excited by 660 nm red light source was chosen. Hela cells were used as targeted cells for PDT. To address obstacles in PDT, the MB conjugated Au nanocomposites were prepared via a hydrothermal synthesis method following by an intermolecular interaction between a poly styrene-alt-maleic acid (PSMA) layer on the Au nanoparticles (AuNPs) and MB.
The structure and optical property of MB-AuNP conjugate were characterized by UV-visible spectrometer, transmission electron microscopy (TEM), X-ray diffraction pattern, and zeta-potential analysis. Furthermore, generation of ROS from MB-AuNP conjugate after excitation of 100 mW hand-held laser at 660 nm wavelength was detected by using 9, 10-Anthracenediyl-bis(methylene) dimalonic acid (ABDA). Results indicated that the MB-AuNP conjugate was successfully prepared by wet-chemistry reaction since the optical property of MB was remained after conjugation. Then toxic effect of MB-AuNP conjugate on Hela cell was examined. With a single 4 min hand-held 100 mW laser treatment, cell works proved that AuNPs as goodness carrier could effectively reduce the cell toxicity of MB and still remain the PDT efficiency. Moreover, transferrin (Tf) was grafted on the particles via EDC/NHS reaction and followed by MB attachment as Tf-MB-AuNP conjugate to enhance the selectivity of cellular uptake between cancer cells (Hela cell) and non-malignant cells (3T3 cell, fibroblast). Atomic absorption spectroscopy (AA) was used for cellular uptake quantification. In vitro ROS generation was also monitored by 2′, 7′-Dichlorofluorescin diacetate (DCFH-DA). It was shown that Tf could effectively promote cancer cell targeting. In addition, Tf-MB-AuNP was proved that could enhance PDT efficiency significantly in cell works. Finally, cell death pathway was found to be mainly apoptosis by Annexin V-FITC/PI staining.
We proposed that by applying this biocompatible and cancer cell targeting Tf-MB-AuNP conjugate for PDT treatment could simultaneously reduce dark toxicity of MB and enhance the photodynamic therapy efficiency. This multi-functional AuNP could provide a less harmful alternative for PDT in cancer treatments.
Subjects
金奈米粒子
自由基
亞甲基藍
運鐵蛋白
光動力治療
SDGs
Type
thesis
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