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Proceedings Paper

Induced structural defects in Ti-doped ZnO and its two-photon-excitation
Author(s): Milton A. Martínez Julca; Ivonnemary Rivera ; Jaime Santillan Mercado; Heidy Sierra; Oscar Perales-Pérez
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Paper Abstract

ZnO is a well-known luminescent material that reacts with light to generate free radicals enabling its use in cancer treatment by Photodynamic Therapy (PDT). Unfortunately, up to know, the photo-excitation of ZnO-based materials’ requires excitation with ultraviolet light, which limits their biomedical applications. In this regard, this work investigates the effect of Ti species incorporation into the lattice of ZnO nanoparticles (NPs) with the aim of improving the corresponding optical properties and enabling the two-photoexcitation with 690nm-light (near infrared light). A modified polyol-based route was used to synthesize pure and Ti-doped (9% at.) ZnO NPs. X-ray diffraction confirmed the formation of ZnO-wurtzite whereas Scanning Electron Microscopy confirmed the formation of monodispersed 100-nm NPs. Raman Spectroscopy measurements evidenced the presence of zinc interstitials (Zni) and oxygen vacancies (VO) in the host oxide strcuture. Asynthesized NPs were excited using the technique of two-photon fluorescence microscopy (TPFM). The photoluminescence (PL) spectra generated from the analysis of TPFM images revealed a high emission peak presence in the green region (555 nm) that was assigned to VO. Also, a weak but noticeable band at 420 nm was detected, which is attributed to electron transition from the shallow donor level of Zni to the valence band. These PL transitions will favor triplet states formation necessary to yield cytotoxic reactive oxygen species. Furthermore, the presence of the PL peaks confirmed the Ti-ZnO NPs capacity to be excited by 690-nm light, thus, opening new possibilities for this NPs to be used in lightinduced bio-medical applications.

Paper Details

Date Published: 22 April 2016
PDF: 7 pages
Proc. SPIE 9722, Colloidal Nanoparticles for Biomedical Applications XI, 97221E (22 April 2016); doi: 10.1117/12.2213750
Show Author Affiliations
Milton A. Martínez Julca, Univ. de Puerto Rico Mayagüez (United States)
Ivonnemary Rivera , Univ. de Puerto Rico Mayagüez (United States)
Jaime Santillan Mercado, Univ. de Puerto Rico Rio Piedras (United States)
Heidy Sierra, Memorial Sloan-Kettering Cancer Ctr. (United States)
Oscar Perales-Pérez, Univ. de Puerto Rico Mayagüez (United States)

Published in SPIE Proceedings Vol. 9722:
Colloidal Nanoparticles for Biomedical Applications XI
Wolfgang J. Parak; Marek Osinski; Xing-Jie Liang, Editor(s)

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