Hostname: page-component-76fb5796d-22dnz Total loading time: 0 Render date: 2024-04-25T16:36:48.964Z Has data issue: false hasContentIssue false
  • English
  • Français

Li-Doped ZnO Nanoparticles as Novel Direct Generator of Singlet Oxygen for Potential Photodynamic Therapy Applications

Published online by Cambridge University Press:  19 June 2015

Milton A. Martínez Julca ,
Ivonnemary Rivera ,
Oscar Perales-Pérez ,
Sonia Bailón  and
Melina Pérez
Milton A. Martínez Julca
Affiliation:
Department of Physics, University of Puerto Rico, Mayaguez Campus Department of Engineering Science and Materials, University of Puerto Rico, Mayaguez Campus
Ivonnemary Rivera
Affiliation:
Department of Chemical Engineering, University of Puerto Rico, Mayaguez Campus Department of Engineering Science and Materials, University of Puerto Rico, Mayaguez Campus
Oscar Perales-Pérez
Affiliation:
Department of Engineering Science and Materials, University of Puerto Rico, Mayaguez Campus
Sonia Bailón
Affiliation:
Department of Chemistry, University of Puerto Rico in Ponce, P.R.
Melina Pérez
Affiliation:
Food Science & Technology Program, University of Puerto Rico, Mayaguez , P.R.
Get access

Abstract

Photodynamic therapy (PDT) is an alternative to traditional cancer treatments. This approach involves the use of photosensitizer (PS) agents and their interaction with light. As a consequence, cytotoxic reactive oxygen species (ROS) are generated that, in turn will destroy tumors. On the other hand, ZnO is a biocompatible, nontoxic, and biodegradable material with the capability to generate ROS, specifically singlet oxygen (SO), which makes this material a promising candidate for 2-photon PDT. Doping ZnO with Li species is expected to induce defects in the host oxide structure that favors the formation of trap states that should affect the electronic transitions related to the generation of SO. The present work reports the effect of the level of Li-doping on the ZnO structure and its capability to generate SO. Li-doped ZnO nanoparticles were synthesized under size-controlled conditions using a modified version of the polyol method. XRD measurements confirmed the development of well-crystallized ZnO Wurtzite; the average crystallite sizes ranged between 13.3nm and 14.2 nm, with an increase in Li content. The corresponding band gap energy values, estimated from UV-vis measurements, decreased from 3.33 to 3.25 eV. Photoluminescence (PL) measurements of Li-ZnO revealed the presence of emission peaks centered on 363nm, 390nm, and 556 nm; these emission peaks correspond to the exciton emission, transition of shallow donor levels near of the conduction band to valence band such as interstitial Zn, and oxygen vacancies, respectively. The observed increase of the emission intensity of the 390 nm emission peak, relative to the intensity of the main emission peak at 363nm, was attributed to the promote of trap states due to interstitial Zn or Li-incorporation into the host oxide lattice. SO measurements evidenced the enhancing effect of the Li concentration on the capability of the doped ZnO to generate this species. This Li-dependence of SO generation can be attributed to the enhancement of the concentration of trap states in the host ZnO, as suggested by PL measurements. Accordingly, Li-ZnO would become cytotoxic to cancer cells via photo-induced ROS generation enabling this nanomaterial to be considered as a potential direct PS agent for the 2-photon PDT route.

Keywords

defectsluminescencebiomedical
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1784: Symposium R – Photoactive Nanoparticles and Nanostructures , 2015 , mrss15-2136565
Copyright
Copyright © Materials Research Society 2015 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Robertson, C., Hawkins, D., Abrahamse, H.. Photodynamic therapy (PDT): a short review on cellular mechanisms and cancer research applications for PDT. J Photochem Photobiol B. 96, 1–8 (2009).CrossRefGoogle Scholar
Garg, A., Nowis, D., Golab, J., Agostinis, P.. Photodynamic therapy: illuminating the road from cell death towards anti-tumor immunity. Apoptosis. 15, 1050–1071 (2010).CrossRefGoogle Scholar
Hudson, R., Boyle, R.. Strategies for selective delivery of photodynamic sensitisers to biological targets. J Porphyrins Phthalocyanines. 8, 954 (2004).CrossRefGoogle Scholar
Almeida, R., Manadas, B., Carvalho, A., Duarte. Biochim. Biophys. Act. 1704, 59(2004).Google Scholar
Klaus, D.. Handbook of Nanophysics. Nanomedicine and Nanorobitcs, edited by Klaus D. (CRC Press, 2011), Chap. 22 p. 17.Google Scholar
Mansoor, M.. Nanotechnology for Cancer Therapy. (CRC Press, 2006), p.59.Google Scholar
Braj, R., Brahma, N., Khan, W., Singh, H., Naqvi, A.. ROS-mediated apoptotic cell death in prostate cancer LNCaP cells induced by biosurfactant stabilized CdS quantum dots. Biomaterials. 33, 5753 (2012).Google Scholar
Honglin, L., Zhong, Z., Jinzhao, H., Ruxi, L., Qingbao, W.. Optical and structural analysis of rare earth and Li co-doped ZnO nanoparticles. Journal of Alloys and Compounds, 550, 526–530(2013).Google Scholar
Xia, Y., Huali, S., Weirong, L., Weizhong, G., Xiaoli, S., Yiqun, M.. Endoplasmic reticulum stress and oxidative stress are involved in ZnO nanoparticle-induced hepatotoxicity. Toxicology Letters 234, 40–49(2015).Google Scholar
Hal, A., Vecchio-Sadus, A.. Toxicity of lithium to humans and the environment-A literature review. Ecotoxicology and Environmental, 70, 349–356(2008).Google Scholar
Yu-Chih, T., Yow-Jon, L., Hsing-Cheng, C., Ya-Hui, C., Chia-Jyi, L., Yi-Yan, Z.. Dependence of luminescent properties and crystal structure of Li-doped ZnO nanoparticles upon Li content. Journal of Luminescence 132, 1896–1899(2012).Google Scholar
Collantes, Y., Perales- Pérez, O.. Structural and Functional Properties of Iron (II, III)-Doped ZnO Monodisperse Nanoparticles Synthesized by Polyol Method. Materials Research Society, 2013.CrossRefGoogle Scholar
Cullity, B.. Elements of X-Ray Diffraction, edited by Cohen, Morris (Addison Wesley, MA, 1972), p. 102.Google Scholar
Awan, S., Hasanain, S., Bertino, M. and Hassnain, G.. Effects of subtitutional Li on the ferromagnetic response of Li co-doped ZnO: Co nanoparticles. J.Phys.: Condens. Matter,25, 156005(2013).Google Scholar
Jeong, E., Yu, H., Kim, Y., Yi, G., Choi, Y., Han, S.. Local structural and optical properties of ZnO nanoparticles. Journal of Nanoscience and Nanotechnology, 10, 3562–3565(2010).CrossRefGoogle ScholarPubMed
Ischenko, V., Polarz, S., Grote, D., Stavarache, V., Fink, K., and Driess, M.. Zinc oxide Nanoparticles with Defects. Advanced Functional Materials, 15, 1945–1954(2005).CrossRefGoogle Scholar