title: Plasmon-Enhanced Photodynamic Cancer Therapy by Upconversion Nanoparticles Conjugated with Au Nanorods.
abstract: Photodynamic therapy (PDT) based on photosensitizers (PSs) constructed with nanomaterials has been widely applied to treat cancer. This therapy is characterized by an improved PS accumulation in tumor regions. However, challenges, such as short penetration depth of light and low extinction coefficient of PSs, limit PDT applications. In this study, a nanocomposite consisting of NaYF4:Yb/Er upconversion nanoparticles (UCPs) conjugated with gold nanorods (Au NRs) was developed to improve the therapeutic efficiency of PDT. Methylene blue (MB) was embedded in a silica shell for plasmon-enhanced PDT. UCPs served as a light converter from near-infrared (NIR) to visible light to excite MB to generate reactive oxygen species (ROS). Au NRs could effectively enhance upconversion efficiency and ROS content through a localized surface plasmon resonance (SPR) effect. Silica shell thickness was adjusted to investigate the optimized MB loading amount, ROS production capability, and efficient distance for plasmon-enhanced ROS production. The mechanism of plasmon-enhanced PDT was verified by enhancing UC luminescence intensity through the plasmonic field and by increasing the light-harvesting capability and absorption cross section of the system. This process improved the ROS generation by comparing the exchange of Au NRs to Au nanoparticles with different SPR bands. NIR-triggered nanocomposites of UCP@SiO2:MB-NRs were significantly confirmed by improving ROS generation and further modifying folic acid (FA) to develop an active component targeting OECM-1 oral cancer cells. Consequently, UCP@SiO2:MB-NRs-FA could highly produce ROS and undergo efficient PDT in vitro and in vivo. The mechanism of PDT treatment by UCP@SiO2:MB-NRs-FA was evaluated via the cell apoptosis pathway. The proposed process is a promising strategy to enhance ROS production through plasmonic field enhancement and thus achieve high PDT therapeutic efficacy.
authors.affiliation: Department of Chemistry, National Taiwan University , Taipei 106, Taiwan.
authors.forename: Chieh-Wei
authors.initials: CW
authors.lastname: Chen
authors.affiliation: Genomics Research Center, Academia Sinica , Taipei 115, Taiwan.
authors.forename: Yung-Chieh
authors.initials: YC
authors.lastname: Chan
authors.affiliation: Genomics Research Center, Academia Sinica , Taipei 115, Taiwan.|Department of Biochemistry, College of Medicine, Kaohsiung Medical University , Kaohsiung, Taiwan.
authors.forename: Michael
authors.initials: M
authors.lastname: Hsiao
authors.affiliation: Department of Chemistry, National Taiwan University , Taipei 106, Taiwan.|Genomics Research Center, Academia Sinica , Taipei 115, Taiwan.|Department of Mechanical Engineering and Graduate Institute of Manufacturing Technology, National Taipei University of Technology , Taipei 106, Taiwan.
authors.forename: Ru-Shi
authors.initials: RS
authors.lastname: Liu
mesh_terms: D006046:Gold; D053758:Nanoparticles; D043942:Nanotubes; D010778:Photochemotherapy; D017319:Photosensitizing Agents; D012822:Silicon Dioxide
chemical_list: D017319:Photosensitizing Agents; D006046:Gold; D012822:Silicon Dioxide
keywords: gold nanorod; localized surface plasmon resonance; near-infrared light triggering; photodynamic therapy; plasmonic enhancement; upconversion nanoparticle