Two-photon excitation fluorescence imaging (TPEFI) is widely used in biomedicine because it has advantages of low cytotoxicity, high resolution and deep imaging depth. In this experiment, OVCAR-3 ovarian cancer cells were labelled with the squaraine dye and detected by confocal laser scanning microscope ( Leica TCS SP8 )for single-photon and two-photon imaging. The results showed that the squaraine dye can be used well to two-photon imaging.
In this work, gold nanoparticles coated with CTAB were used as probes for studying the interactions between nanoparticles and cells. The dark field scattering spectra from cells were obtained at different time points after they were treated with gold nanoparticles. By analyzing the results, we find that the dark field scattering spectrum changes at different time points, which is of certain significance in studying the interactions between cells and gold nanoparticles.
In this paper, we proposed a photoacoustic (PA) method for detecting liquid viscosity based on frequency-resolved measurement. A negative correlation was investigated theoretically between the liquid viscosity and the full width at half maximum (FWHM) of the PA frequency spectrum. To test the feasibility of this method, water mixed with different concentrations of ink and glycerol was measured. The results indicate that liquids with higher viscosity will lead to a higher FWHM reduction in the PA frequency spectrum and the frequency spectrum was independent from the absorption coefficient of the liquid, which demonstrate that this technique has future potential clinical applications for monitoring the viscosity changes in subcutaneous microvasculature.
As a near-infrared photosensitizer, IR780 is a promising agent for photodynamic therapy. However, its clinical application was limited by its poor aqueous solubility and chemical stability. Therefore, the purpose of this study was to prepare IR780 encapsulated nanoemulsion (IR780-NE) to enhance the solubility and chemical stability of IR780, using a low-energy emulsion inversion point (EIP) method, which could avoid complex procedure and IR780 degradation during preparation process. The IR780-NE presented a homogeneous and clear appearance, as well as a mean droplet diameter of 38.17 ± 3.59 nm, as determined by dynamic light scattering. The IR780-NE greatly enhanced the chemical stability of IR780, with more than 80% IR780 retained after storage at 25 °C for 4 days. The IR780-NE also showed satisfactory physical stability, with no alteration of mean droplet diameter during storage at 25 °C for 4 days or 4 °C for 30 days. The zeta potential of the IR780-NE was nearly zero (-0.27 ± 2.06 mV), and the ultraviolet-visible light absorption spectrum showed that the near-infrared light absorbing ability of IR780 was not influenced. In conclusion, the IR780-NE is a potential delivery system for the application of IR780 in biological systems.
We present our recent work on the applications of fluorescence lifetime imaging microscopy(FLIM), including the monitoring of macromolecule dynamic changes in the nucleolar compartments and the auxiliary diagnosis of H and E-stained sections. We demonstrated the capability of FLIM to measure protein concentration in the specific cellular compartments in live cells. We proposed to use FLIM to monitor changes in intracellular protein concentration caused by various factors e.g. cell cycle progression, drug treatment etc. In the future, FLIM technology is expected to be combined with super-resolution optical imaging. FLIM with molecular resolution will have the potential to serve as a powerful tool for discovering new phenomena and revealing new mechanisms in biomedical research, which will effectively promote the development of life science.
We report the observation of a supercontinuum (SC) in aqueous CdTe/ZnSe quantum dots (QDs) pumped by 800-nm femtosecond laser pulses based on simulations and experiments. For an average nanocrystal of 5.5 nm in size and a weight concentration of 5 mg/mL, the SC generated with a low-input energy range exhibits high optical to optical conversion efficiency. The measured SC spectrum exhibits spectral broadening that is significantly influenced by the nonlinear coefficient of the QDs. This nanoparticles-based SC effect may have special applications for optical coherence imaging and ultrashort pulse compression.