title: Hybrid systems based on gold nanostructures and porphyrins as promising photosensitizers for photodynamic therapy.
abstract: Gold nanostructures of two different shapes (spheres and rods) were synthesized to form a colloidal hybrid system with 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin tosylate salt (H2TM4PyP(OTs)4) (POR) for applications in photodynamic therapy (PDT) using light in the visible spectral range. Electron paramagnetic resonance (EPR) experiments in combination with spin trapping were used for the detection of reactive oxygen species (ROS) and evaluation of the efficiency of these novel hybrid systems as photosensitizers. It is shown that the hybrid system consisting of gold nanorods (AuNR) and porphyrin (POR) is by far more efficient than its isolated components. This enhanced efficiency is explained by a synergetic effect between the AuNR and the porphyrin, wherein a rapid energy transfer from the former to the latter produces a large amount of singlet oxygen followed by its conversion into hydroxyl radicals. The mechanism was investigated using different spin traps and different ROS inhibitors. On the other hand, spherical gold nanoparticles (AuNP) do not show this synergetic effect. The synergetic effect for gold nanorods/POR hybrid is attributed to a larger field enhancement close to the gold nanorod surface in addition to the electrostatic attraction between the components of the hybrid system.
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil. Electronic address: daniele.c.fer@gmail.com.
authors.forename: Daniele C
authors.initials: DC
authors.lastname: Ferreira
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil.
authors.forename: Camila S
authors.initials: CS
authors.lastname: Monteiro
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil.
authors.forename: Claudilene R
authors.initials: CR
authors.lastname: Chaves
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil.
authors.forename: Gustavo A M
authors.initials: GAM
authors.lastname: Sáfar
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil.
authors.forename: Roberto L
authors.initials: RL
authors.lastname: Moreira
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil.
authors.forename: Maurício V B
authors.initials: MVB
authors.lastname: Pinheiro
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil.
authors.forename: Dayse C S
authors.initials: DCS
authors.lastname: Martins
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil.
authors.forename: Luiz Orlando
authors.initials: LO
authors.lastname: Ladeira
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais, Belo Horizonte-MG, 31270-901, Brazil.
authors.forename: Klaus
authors.initials: K
authors.lastname: Krambrock
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D006046:Gold / Q000737:chemistry*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D043942:Nanotubes / Q000737:chemistry; D009369:Neoplasms / Q000628:therapy*; D010778:Photochemotherapy / Q000295:instrumentation* / Q000379:methods; D017319:Photosensitizing Agents / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry; D019097:Spin Trapping
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins; D017382:Reactive Oxygen Species; D026082:Singlet Oxygen; D006046:Gold
keywords: Gold nanoparticles; Gold nanorods; Photodynamic therapy (PDT); Porphyrin; Reactive oxygen species (ROS)