In this paper, HMME-TiO2 nanocomposites was synthesized and characterized through TEM， Uv-vis spectra, Zeta potential, FTIR spectra. The characterization results show that HMME was successfully conjugated onto the surface of TiO2. It can be seen from the TEM images the average size of HMME-TiO2 conjugation is nearly spherical and the particle size range from 20 to 28 nm. Compared with HMME, the B bands of HMME-TiO2 were much broader and lower while in the region of Q bands the absorption peaks of HMME-TiO2 are higher than that of HMME. Encapsulation efficiency of HMME-loaded TiO2 was assessed and calculated as 45.46%. FTIR spectra show the bonding between TiO2 and HMME was through the hydrogen-bonding between COOH and OH bonds. Fluorescence microscope results demonstrated HMME-TiO2 mainly distributed in the membrane and cytoplasm of SCC cells and its best incubation time is six hours. After treated with HMME-TiO2 plus light irradiation (1.8J/cm2 , 632nm), the viability of SCC cells turned to 32.96% is much lower than that treated with HMME plus light irradiation. It can be concluded that the combination of HMME and TiO2 will enhance the PDT efficiency of HMME. In the process of HMME-TiO2 mediated PDT, as a kind of photosensitizer HMME can induce the death of SCC cells, meanwhile it can transform electron to the conductive band of TiO2 stimulating the photocatalytic activity of TiO2 under visible light. The photocatalytic of TiO2 can also induce the death of SCC cells. The combination of these two effects lead to more SCC cells died.
Due to their unique optical properties, optical probes, including metal nanoparticles (NPs) and fluorescent dyes, are increasingly used as labeling tools in biological imaging. Using multiphoton microscopy and fluorescence lifetime imaging (FLIM) at 750-nm excitation, we recorded intensity and FLIM images from gold NPs (30 nm) and the fluorescent dye Alexa 488 (A488) conjugated with monoclonal ACT-1 antibodies as well as Hoechst 33258 (H258) after incubation with the lymphoma cell line (Karpas-299). From the FLIM images, we can easily discriminate the imaging difference between cells and optical probes according to their distinct fluorescence lifetimes (cellular autofluorescence: 1 to 2 ns; gold NPs: <0.02 ns; A488: 3.5 ns; H258: 2.5 ns). The NP-ACT-1 and A488-ACT-1 conjugates were bound homogeneously on the surface of cells, whereas H258 stained the cell nucleus. We demonstrate that the emission intensity of gold NPs is about ten times stronger than that of the autofluorescence of Karpas-299 cells at the same excitation power. Compared with fluorescent dyes, stronger emission is also observed from gold NPs. Together with their high photostability, these observations suggest that gold NPs are a viable alternative to fluorescent dyes for cellular imaging and cancer diagnosis.
Due to the unique optical properties, gold nanoparticles (NPs) can play a useful role in biological cellular imaging as
biological probes. Using multiphoton microscopy and fluorescence lifetime imaging (FLIM) system, we recorded the
images of Karpas 299 cells incubated without, or with gold NPs, and ACT1 antibodies conjugated with gold NPs. From
the FLIM, we can easily discriminate the difference among different experiment conditions due to the distinct lifetime
between cells and gold NPs. Our results present that nonconjugated gold NPs are accumulated inside cells, but
conjugated gold NPs bind homogeneously and specifically to the surface of cancer cells. For single Karpas 299 cells, the
signal is very week when the excitation power is about 10mw; while the power is approximately 28 mw, a very sharp cell
imaging can be obtained. For the Karpas 299 incubated with ACT1 conjugated gold NPs, while the excitation power is
10mw, gold NPs have clear fluorescence signal so that the profile of cells can be detected; Signal of gold NPs is very
strong when the power arrived in 20mw. These results suggest that the multiphoton lifetime imaging of antibody
conjugated gold NPs can support a useful method in diagnosis of cancer.
We describe a new method for delivering macromolecules into the target cells based on light-absorbing cationic colloidal
gold nanoparticles that are irradiated by focused femtosecond laser pulses. Cationic colloidal 15nm gold particles which
were made by conjugation with poly-L-Lysine, were attached on the anionic sites, especially on the membrane, of CHO-K1
cells because of their strong positive charge at physiological pH. Target cells labeled with cationic gold nanoparticles
were imaged under two-photon fluorescence microscopy, and lifetime images of the same targets were taken by TCSPC
technique in order to verify the fluorescence of the marker and the luminescence of the gold particles.
A macromolecular 10k Dalton fluorescein isothiocyanate dextran (FITC-D), was added into the sample and the focused
femtosecond laser of two-photon fluorescence microscopy was employed to scan the target cells layer by layer. Typical
laser power level used in biological imaging is about 3-5 mW. Here the laser power of scanning was below 5 mW in
order to prevent photochemical damage of the fs-pulses alone and to localize effects to the nanoparticles on a nano-scale.
After scanning the target cells under stack mode, macromolecular fluoresceins surrounding the cells was observed to
cross the membrane and to diffuse in the cytoplasma. Comparing with the images before scanning, the two-photon
fluorescence and fluorescence lifetime images revealed the delivery of FITC-D into target cells.
Multi-Sensor system has been proposed to measure electric current in a non-contact way. According to the Ampere's
Law, the value of the current flowing in a conductor can be obtained through processing the outputs of the magnetic
sensors around the conductor. As the discrete form of the Ampere's Law is applied, measurement noises are introduced
when there exists the interference magnetic field induced by nearby current flowing conductors. In this paper, the
measurement noises of the multi-sensor system measuring DC current are examined to reveal the impact of the
interference magnetic field and the number of the magnetic sensors on the measurement accuracy. A noise reduction
method based on Kalman filtering is presented. Computer simulation and experiment results show that the method
greatly improves the accuracy without seriously increasing the computation load in comparison with other approaches.
High-resolution optical mapping based on voltage-sensitive dyes is a relatively new technology that is used to “image” electrical activity in a wide range, from the level of cellular to the whole heart. By using optical recording it is possible to overcome several limitations of other conventional mapping techniques and to depict complex propagation patterns of cardiac transmembrane potentials while it has been proven to be very useful for illuminating basic electrophysiological development. Strategies for maximizing signal-to-noise ratios and removing motion artifacts are the research emphases. Currently, two types of devices dominate in this field, Charge Coupled Devices (CCD) and Photo Diode Arrays (PDA), and some algorithms correcting motion artifacts are used in data processing. In this article, we have attempted to conduct and present a comprehensive review and a perspective of this rapidly developing novel field.