Due to the strong surface fields of noble metal nanoparticles, absorption and scattering of electromagnetic radiation is greatly enhanced. Noble metallic nanoparticles represent potential novel optical probes for simultaneous molecular imaging and photothermal cancer therapy using the enhanced scattering and absorption of light. Further, gold nanoparticles can affect molecular fluorescence via chemical, electronic, or photonic interactions. Live cells generate fluorescence due to intracellular and extracellular molecules. Differences in the biochemical composition between healthy and malignant cells can be exploited in vivo to help identify cancer spectroscopically. The interaction of gold nanoparticles with cellular autofluorescence has not yet been characterized. We hypothesized that gold nanoparticles delivered to live cells in vitro would alter cellular autofluorescence and may be useful as a novel class of contrast agent for fluorescence based detection of cancer. The fluorescence of two fluorophores that are responsible for tissue autofluorescence, NADH and collagen, and of two oral squamous carcinoma cell lines and one immortalized benign epithelial cell line were measured in vitro. Gold nanoparticles of different shapes, both spheres and rods, quenched the fluorescence of the soluble NADH and collagen. Reduction of NADH fluorescence was due to oxidation of NADH to NAD+ catalyzed by gold nanoparticles (results we previously published). Reduction of collagen fluorescence appears due to photonic absorption of light. Furthermore, a mean quenching of 12/8% (p<0.00050) of the tissue autofluorescence of cell suspensions was achieved in this model when nanospheres were incubated with the live cells. Gold nanospheres significantly decrease cellular autofluorescence of live cells under physiological conditions when excited at 280nm. This is the first report to our knowledge to suggest the potential of developing targeted gold nanoparticles optical probes as contrast agents for fluorescence based diagnoses of cancer.
"El-Sayed et al. treated two oral squamous carcinoma cell lines and one immortalized benign epithelial cell line with gold nanoparticles of different shapes, both spheres and rods and monitored changes in autofluorescence caused by soluble NADH and collagen. They significantly quenched the autofluorescence of both compounds based on the oxidation of NADH to NAD+ catalyzed by NPs surface and photonic absorption of light by collagen . This knowledge suggests new potential of NPs in cell and tissue imaging. "
[Show abstract][Hide abstract] ABSTRACT: The requirements for early diagnostics as well as effective treatment of insidious diseases such as cancer constantly increase the pressure on development of efficient and reliable methods for targeted drug/gene delivery as well as imaging of the treatment success/failure. One of the most recent approaches covering both the drug delivery as well as the imaging aspects is benefitting from the unique properties of nanomaterials. Therefore a new field called nanomedicine is attracting continuously growing attention. Nanoparticles, including fluorescent semiconductor nanocrystals (quantum dots) and magnetic nanoparticles, have proven their excellent properties for in vivo imaging techniques in a number of modalities such as magnetic resonance and fluorescence imaging, respectively. In this article, we review the main properties and applications of nanoparticles in various in vitro imaging techniques, including microscopy and/or laser breakdown spectroscopy and in vivo methods such as magnetic resonance imaging and/or fluorescence-based imaging. Moreover the advantages of the drug delivery performed by nanocarriers such as iron oxides, gold, biodegradable polymers, dendrimers, lipid based carriers such as liposomes or micelles are also highlighted.
"Plasmonic resonance of nanoshells subjected to near-infrared (NIR) light has generated sufficient heat to kill cancer cells in a murine model. These results raise the possibility that this technique may facilitate the visualization and local destruction of malignant cells under endoscopic examination in humans . Utilization of nanoparticles tuned to frequencies of light with greater tissue penetration may allow similar therapy for less accessible tumors. "
[Show abstract][Hide abstract] ABSTRACT: The field of nanotechnology has exploded in recent years with diverse arrays of applications. Cancer therapeutics have recently seen benefit from nanotechnology with the approval of some early nanoscale drug delivery systems. A diversity of novel delivery systems are currently under investigation and an array of newly developed, customized particles have reached clinical application. Drug delivery systems have traditionally relied on passive targeting via increased vascular permeability of malignant tissue, known as the enhanced permeability and retention effect (EPR). More recently, there has been an increased use of active targeting by incorporating cell specific ligands such as monoclonal antibodies, lectins, and growth factor receptors. This customizable approach has raised the possibility of drug delivery systems capable of multiple, simultaneous functions, including applications in diagnostics, imaging, and therapy which is paving the way to improved early detection methods, more effective therapy, and better survivorship for cancer patients.
"For instance, gold nanoparticles quench fluorescence of molecules when covalently bound to the molecule, but enhance the scattering and fluorescence of molecules on their surface is separated from the nanoparticles by a distance sufficient to minimize quenching. In OSCC cell culture models, El-Sayed et al.  found that gold nanoparticles quench cellular autofluorescence approximately 15% when incubated or immunoconjugated to cells. This effect was interpreted to be due to intense light absorption of the particles that were restricted in cellular compartments from accessing strong cellular fluorophores. "
[Show abstract][Hide abstract] ABSTRACT: Rapid advances in the ability to produce nanoparticles of uniform size, shape, and composition have started a revolution in the sciences. Nano-sized structures herald innovative technology with a wide range of potential therapeutic and diagnostic applications. More than 1000 nanostructures have been reported, many with potential medical applications, such as metallic-, dielectric-, magnetic-, liposomal-, and carbon-based structures. Of these, noble metallic nanoparticles are generating significant interest because of their multifunctional capacity for novel methods of laboratory-based diagnostics, in vivo clinical diagnostic imaging, and therapeutic treatments. This review focuses on recent advances in the applications of nanotechnology in head and neck cancer, with special emphasis on the particularly promising plasmonic gold nanotechnology.
Current Oncology Reports 03/2010; 12(2):121-8. DOI:10.1007/s11912-010-0087-2 · 2.89 Impact Factor
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