Sensibilization of fullerene C60 immobilized at silica nanoparticles for cancer photodynamic therapy
Introduction
The supramolecular composites containing fullerenes immobilized at silica nanoparticles can be used as a new and promising class of pharmaceutical compositions with wide spectrum of therapeutic action due to their size and innate properties [1]. Fullerenes and their derivatives manifest unique physical and chemical properties that allow usage in biological systems as medical preparations or for targeting delivery of biologically active compounds and medicines in a cell. In addition to being nontoxic, they are also capable to contact biological molecules showing influence on biological processes at rather low (even physiological) concentration [1], [2], [3], [4], [5], [6]. Fullerenes are effective antioxidants; on the other hand, under photoexcitation, they can assist a formation of singlet oxygen and other reactive oxygen species (ROS), which are the endogenous factors of biological molecule damage especially nucleic acids. This fact testifies a perspective of using fullerene-based materials in photodynamic therapy.
The aim of present work was to use the spectral investigations for design of the molecular system possessing the following properties: high living cell permittivity, high efficiency of singlet oxygen generation, the ability of intracellular visualization with the help of luminescent microscopy, and nontoxicity.
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Materials and methods
To make fullerene active in biological solutions, they were anchored through covalently bonded spacers to hydrophilic nanoparticles of fumed silica, whose surface was modified by γ-aminopropyl groups. Concentrations of amino groups on the nanoparticle surface were 0.14, 0.23, 0.5, and 0.98 mmol/g. Fullerene concentration in all cases was 0.1–0.14 mmol/g.
To strengthen the property of fullerene to generate active forms of oxygen to destruct transformed cells, composites were modified by
Nanocomposites with immobilized fullerene
Photoluminescence spectra were measured for nanocomposites with concentration of amino groups on the surface 0.23, 0.5 and 0.98 mmol/g. The red shift of the luminescence maximum under the increasing of concentration was observed (Fig. 2). It can be explained through the dense arrangement of fullerenes in fullerene islets in the case of higher concentrations of amino groups on the surface and through the exhausted arrangement for lower concentrations. TEM studies of immobilized fullerene C60 on
Conclusions
A number of new functional fullerene-based supramolecular complexes were obtained and studied. Some of the proposed systems are perspectives for further investigations in order to use them as luminescent probes of cancer cells (fullerene-containing nanosilica with all luminescent antennas), as nanodevices in photodynamic therapy (fullerene-containing nanosilica with antracenonimine, antracenalimine, luminescent biscrownether) and drug delivery.
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