Apr 16 2010
Small metallic nanocages and pulsed laser-based ultrasensitive medical imaging methodology are likely to facilitate the detection and treatment of cancer at an early stage.
This methodology does not result in damage of the imaged tissues due to heat like previously used methodologies that utilized miniature metallic nanospheres and nanorods. Purdue University’s associate professor of chemistry and biomedical engineering, Ji-Xin Cheng, revealed that this methodology also does create a background auto fluorescent glow for the tissues that surround the imaged tissue. Cheng added that this glow causes interference to the imaging process, resulting in lower brightness and contrast. The miniature gold-silver cages could also be utilized in anticancer drug delivery to diseased tissue.
The near-infrared (IR) laser pulses are made to pass though the skin by this system to identify solid nanoparticles and hollow nanocages, which have been earlier injected in the bloodstream. These nanoparticles and nanocages are made of gold and silver alloys. Initially the nanocages were injected into mice through intravenous injections by researchers. These researchers then took images of minute structures present in tissue samples. These samples were taken from the organs like the spleen and the liver. When compared to other imaging research experiments utilizing nanorods and nanospheres, this silver gold alloy structure produces images that are 10 times brighter. This technique offers contrast and brightness that is many times better when compared to the traditional fluorescent dyes being utilized for a broad range of biological imaging for understanding the inner functioning of molecules and atoms.
A phenomenon known as ‘three-photon luminescence,’ is utilized by this imaging methodology. This phenomenon offers brighter and higher contrast images as compared to traditional fluorescence imaging methods. This problem present in the traditional methods is countered by the presence of silver and gold nanoparticles, resulting in additional brightness. The brightness is also enhanced due to the likely role played by the ultrafast laser to generate third harmonics.
This imaging methodology is currently at the experimental stage. The National Institutes of Health and the National Science Foundation are funding this ongoing research. The Bindley Bioscience Center and the Birck Nanotechnology Center, both located inside the Discovery Park area of Purdue, are also associated with this research. Findings of the experiment were published in an online research paper in the international edition of the journal Angewandte Chemie. The research paper has been authored by Ling Tong, Purdue’s chemistry doctoral student; Claire M. Cobley, Washington University’s graduate student and others.
The near-infrared (IR) laser pulses are made to pass through the skin to identify solid nanoparticles and hollow nanocages, which have been earlier injected in the bloodstream. This methodology also does create a background auto fluorescent glow for the tissues that surround the imaged tissue and this glow causes interference to the imaging process, resulting in lower brightness and contrast.