This lecture presents fundamentals and advances of tissue optics and tissue optical clearing. Controlling of tissue optical properties is based on using immersion technique via application of exogenous optical clearing agents (OCAs). Impact of OCA and water transport in a tissue caused by an action of a hyperosmotic OCA and leading to tissue reversible shrinkage and dehydration on temporal tissue optical properties is discussed. The specific features of optical clearing of fibrous and cell-structured tissues are investigated using different linear and nonlinear optical modalities in the visible, NIR and terahertz ranges. In vitro, ex vivo, and in vivo studies of a variety of human and animal tissues, including skin, fat, eye sclera, muscle, cerebral membrane, cartilage, blood vessels, and blood are presented. The technologies of delivery of OCAs and nanoparticles are also under discussion, including hidden free diffusion, enforced tissue permeability, and via blood and lymph vessel networking.
Nanoparticle/laser diagnosis and therapy of diseases is a novel modality realizing principles of theranostics which were recently formulated. To provide cancer and inflammatory diseases treatment, and cell optoporation/transfection, technologies based on gold nanoparticles (nanoshells, nanorods, nanocages, and nanostars), and nanoparticle/PDT dye composites will be discussed. Nanoparticle delivery in tissues and applications of gold nanoagents for optical imaging and therapy, and upconversion nanoluminophores for deep-tissue imaging will be analyzed.
Results of transcutaneous delivery of upconversion particles (UPs) and CaCO3-particles doped with the different contrast agents will be presented. Effective delivery of the particles was provided by fractional laser microablation of skin. For monitoring of particle localization, optical coherence tomography, reflectance spectroscopy, fluorescence spectroscopy, and luminescence of UPs in skin in combination with tissue optical clearing was used.