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Theranostics 2014; 4(8):798-807. doi:10.7150/thno.8934 This issue Cite

Research Paper

Enhanced Plasmonic Resonance Energy Transfer in Mesoporous Silica-Encased Gold Nanorod for Two-Photon-Activated Photodynamic Therapy

Nai-Tzu Chen^1,2, Kuo-Chun Tang², Ming-Fang Chung¹, Shih-Hsun Cheng¹, Ching-Mao Huang¹, Chia-Hui Chu¹, Pi-Tai Chou², Jeffrey S. Souris³, Chin-Tu Chen³, Chung-Yuan Mou^2✉, Leu-Wei Lo^1✉

1. Institute of Biomedical Engineering and Nanomedicine (I-BEN), National Health Research Institutes, Zhunan, Miaoli 350, Taiwan.
^2. Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.
3. Department of Radiology, The University of Chicago, Chicago IL, 60637, USA.

✉ Corresponding author: Leu-Wei Lo, Institute of Biomedical Engineering and Nanomedicine (I-BEN), National Health Research Institutes, Zhunan, Miaoli 350, Taiwan, Phone: +886-37-246-166 ext. 37115, Fax: +886-37-586-440. E-mail: lwloorg.tw; or Chung-Yuan Mou, Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, Phone: +886-2-3366-8205, Fax: +886-2-3366-8670. E-mail: cymouedu.tw. More

Abstract

The unique optical properties of gold nanorods (GNRs) have recently drawn considerable interest from those working in in vivo biomolecular sensing and bioimaging. Especially appealing in these applications is the plasmon-enhanced photoluminescence of GNRs induced by two-photon excitation at infrared wavelengths, owing to the significant penetration depth of infrared light in tissue. Unfortunately, many studies have also shown that often the intensity of pulsed coherent irradiation of GNRs needed results in irreversible deformation of GNRs, greatly reducing their two-photon luminescence (TPL) emission intensity. In this work we report the design, synthesis, and evaluation of mesoporous silica-encased gold nanorods (MS-GNRs) that incorporate photosensitizers (PSs) for two-photon-activated photodynamic therapy (TPA-PDT). The PSs, doped into the nano-channels of the mesoporous silica shell, can be efficiently excited via intra-particle plasmonic resonance energy transfer from the encased two-photon excited gold nanorod and further generates cytotoxic singlet oxygen for cancer eradication. In addition, due to the mechanical support provided by encapsulating mesoporous silica matrix against thermal deformation, the two-photon luminescence stability of GNRs was significantly improved; after 100 seconds of 800 nm repetitive laser pulse with the 30 times higher than average power for imaging acquisition, MS-GNR luminescence intensity exhibited ~260% better resistance to deformation than that of the uncoated gold nanorods. These results strongly suggest that MS-GNRs with embedded PSs might provide a promising photodynamic therapy for the treatment of deeply situated cancers via plasmonic resonance energy transfer.

Keywords: Gold nanorods, photodynamic therapy, plasmonic resonance energy transfer, surface plasmon resonance, two-photon luminescence.

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