Investigations on linear and non linear optical properties of hemicyanine laser dye for biophotonics applications in the context of technology development

Abstract

Biophotonics has become an emerging area of research in the field of basic newlinescience, which utilizes light-based technologies for studying biological objects. newlineIt links numerous new technologies such as photonics, biotechnology, lasers, newlinenanotechnology, etc for the development of new powerful tools for medical newlinediagnostic and therapy. The diverse applications of biophotonics techniques are newlinein biomedical research, drug development, healthcare, clinical diagnostics, etc. newlineTo maintain good health, the role of biophotonics will possibly grow even more newlinein the coming decades. newlineFluorescence based techniques have been utilized from the early days of newlinebiophotonics, and the field is developing dynamically. Organic dye molecules are newlineused as fluorescent molecules for clinical detection and diagnosis. Most of these newlineorganic dye molecules are excited with UV and Vis lights. The UV induced newlinephotobleaching of these molecules restricts their temporal use. Moreover, newlineautofluorescence of the biological tissue on UV excitation will reduce the contrast newlineof the image. Also, UV and VIS light exhibits a limited penetration depth into the newlinebiological samples thus not allowing deep-tissue imaging. The near infrared newlinefluorescence probes, which are chemically stable and possess good specificity newlineand selectivity on the target can reduce autofluorescence, and allows deep tissue newlineimaging within the biological window. The thesis discusses the biophotonics newlineapplications of hemicyanine dye for the development of new technologies for newlineclinical diagnostic applications. newlineThe thesis presents the linear and nonlinear optical properties of commercially newlineavailable laser grade hemicyanine dye LDS 821 in different biological medium. newlineSome of the challenges faced by organic dye molecules for bioimaging newlineapplications are autofluorescence by endogenous fluorophores, scattering of light newlineby biomolecules, limitation of depth in invivo imaging, and photobleaching