Assignment Example | Topics and Well Written Essays - 250 words - 98

Assignment Example This scenario may, however, fail to materialize. One of the factors that may lead to the failure of this mechanism is loss of fluorescence. The exact origin of signal loss has not been established, but tentative explanations have been given. A mechanism that could explain this is the slow degradation of surface ligands and coatings, when they are in body fluids (Gao, Cui and Levenson). This issue may be resolved by continuous laser excitation which corrects the surface defects. The process of imaging using CdSe quantum dots capped with ZnS may also fail due to the light type used during imaging. The orange/red emitting QDs used are not optimized for tissue penetration. The QDs are also not optimized for imaging sensitivity. The mechanism associated with failure in this manner is the lack of capability of deep tissue imaging by this kind of light. To prevent failure in this manner, it is advisable to use far-red and near-infrared light. This light should be in the spectral range of 650-900 nm. This wavelength is separated from the absorbing peaks of water and blood. For this reason, the tumor imaging sensitivity will be improved y at least tenfold (Gao, Cui and Levenson). Another factor that may cause the failure of this process is the toxic nature of CdSe QDs under extended periods of illumination by UV radiation. Radiation by UV dissolves the semiconductor particles causing the release of cadmium ions into the medium. Cadmium ions are toxic in nature. This may be avoided by the use of QDs with a stable polymer protection layer (Gao, Cui and Levenson). The stably protected QDs are non-toxic to cells; they affect neither cell division, nor ATP production. Certain issues have to be addressed for the CdSe quantum dot-based cancer imaging to be successful. The researcher has to ask questions that include: Is the mode of imaging economically viable basing on the