Abstract
Optical clearing (OC) is a promising method to overcome limitations in biomedical depth-resolved optical studies. Mechanisms of OC in purified bovine Achilles tendon, chicken skin, and chicken tendon were studied using time-lapsed, three-dimensional second harmonic generation (SHG) and two-photon fluorescence microscopic imaging. Quantified nonlinear optical measurements allowed temporal separation of two processes in collagen OC with glycerol. The first one is a fast process of tissue dehydration accompanied with collagen shrinkage and the second relatively slow process is glycerol penetration into the interfibrillar space of collagen alongside with CF swelling. The use of 50% glycerol induced less-expressed OC via partial substitution of water molecules with glycerol molecules. We also found that phosphate-buffered saline- and glycerol-treatments were reversible, and fiber morphology and SHG signal intensity were recovered after the removal of immersion agents. It was shown that tissue OC was a dynamic process and elucidation of its physical mechanisms may help choose optimal diagnostic, treatment, and modification regimes for collagen-based as well as other types of biomaterials.
Highlights
Reduction of light scattering in biological tissues can essentially enhance the efficacy of laser-based applications in biomedicine
The second harmonic generation (SHG) signal from the upper section of collagen fiber (CF) above dashed line in Fig. 2(a)–2(g) is more than three times stronger than that from the rest of CF and can be considered as forward SHG (FSHG) signal because the aluminum foil placed behind the CF reflects the forwardly directed SHG signal back to the focusing objective for collection and registration
The SHG image below dash line represents SHG signal backscattered within the specimen, which can be considered as backward SHG (BSHG) signal
Summary
Reduction of light scattering in biological tissues can essentially enhance the efficacy of laser-based applications in biomedicine. Optical clearing (OC) is an effective method to overcome the limitations of multiphoton microscopy caused by turbidity of biological materials.[1,2] The application of an optical clearing agent (OCA) to blood,[3] skin,[4,5,6,7] brain,[8] muscle,[9,10] bone,[11] and other turbid biological tissues[12,13,14,15,16] temporarily reduces optical scattering and increases light transparency. The induced optical transparency was preserved during a 4-week autogenic transplantation of the tissue into the rabbit corneal stromal pocket
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
