No abstract

We performed in vivo THz transmission imaging study on a subcutaneous xenograft mouse model for early human breast cancer detection. With a THz-fiber-scanning transmission imaging system, we continuously monitored the growth of human breast cancer in mice. Our in vivo study not only indicates that THz transmission imaging can distinguish cancer from the surrounding fatty tissue, but also with a high sensitivity. Our in vivo study on the subcutaneous xenograft mouse model will encourage broad and further investigations for future early cancer screening by using THz imaging system.

We used the combined imaging modality of multiphoton autofluorescence and second-harmonic generation microscopy to investigate the chondrogenic process of human mesenchymal stem cells cultured in chitosan scaffold. Isolated human mesenchymal stem cells seeded onto chitosan scaffold were induced to undergo chondrogenesis by addition of the transforming growth factor-β3. After continuous culturing, the engineered tissues at the same scaffold location were imaged at different time points for up to 49 days. Using the acquired images of the chondrogenic process, we quantify tissue morphogenesis by monitoring the changes in multiphoton autofluorescence and second-harmonic generation signals from the engineered tissues. We found that the extracellular matrix generation can be modeled by an exponential function during the initial growth stage and that saturation occurs between days 11 and 14. Further, the growth rate of the extracellular matrix was found to increase toward the surface of the chitosan scaffold. Our work demonstrates the use of multiphoton microscopy for performing long-term monitoring and quantification of the tissue engineering process.

Understanding and controlling the interactions between nanoscale objects and living cells is of great importance for diagnostic imaging and therapeutic applications. Quantum dots (QDs) have remarkable optical characteristics, such as uniquely feature bright, photostable, tunable and narrow fluorescence emissions, as well as broad absorption spectra. Here we report a platform of using quantum dots to investigate the cell uptake and the interactions between nanoscale objects and cells. QDs are uptaken by BHK cells easily through endocytosis. We could clearly differentiate the QDs outside the cell or inside the cell by quenching the QDs with similar sized gold nanoparticles and reduce the noise of fluorescent image. Microscopic images show that QDs are homogeneously distributed within the whole cell except the nucleus. However, unmodified QDs could not penetrate the nuclear membrane and move into the nucleus. Coupling QDs with Nuclear Localization Signal (NLS, CGGGPKKKRKVGG) can significantly enhance the translocation amount of QDs into the cell and cell nucleus. This method combined with microscopy imaging system can visualize the particle delivery routes and provide valuable information in the drug/gene delivery and tumor diagnosis.

No abstract