Gold nanorods have unique optical properties as their two photon absorption cross sections are very high and their
spectral positions of extinction bands can be controlled by their aspect ratio only, so that gold nanorods have been
considered as agents for cell imaging. Two-photon photoluminescence imaging could be used to detect the cellular gold
nanorods with the high power femto-second (fs) infrared laser, but may cause the photothermal effect melting the rods.
The 3-D distribution of gold nanorods in living cells also can be measured by confocal reflectance microscopy with a
very low laser power, and thus the cell damaging can be avoided. In this work, these two methods were comparatively
studied in living rat basophilic leukemia (RBL-2H3) cells.
KEYWORDS: Heart, Digital image correlation, Imaging systems, Temperature metrology, Temporal resolution, Cadmium, Charge-coupled devices, Microscopes, Imaging devices, Green fluorescent protein
To develop an accurate and convenient method for measuring the heart rate of zebra fish in vivo, a system combining fast differential interference contrast (DIC) imaging with an autocorrelation technique is established. The imaging correlation coefficient corr(i,j) between frame i, selected from the obtained time-lapse imaging series as the reference image, and any other frame j, is calculated as the time-dependent cycle course. Heat rate is determined by the cycle period of the corr with a high temporal resolution of 4 ms, achieved by fast charge-coupled device (CCD) imaging of 250 frames per second. With this high-resolution system, we find that 1-mg/L cadmium not only induces the slowing of the heart rate, but also caused signs of arrhythmia in treated fish.
Photodynamic therapy (PDT) involves a combination of a lesion-localizing photosensitizer with light and has been established as a new modality for some medical indications. Much evidence has shown the correlation between subcellular localization of a photosensitizer with its photodynamic efficiency. However, the fluorescence of most photosensitizers in cells is weak and easily photobleached. We compare the effect of single-photon excitation (SPE) with that of two-photon excitation (TPE) on fluorescence detection of protoporphyrin IX (PpIX), a potent photosensitizer, in the PLC hepatoma cells in vitro. By using laser scanning confocal fluorescence microscopy, both fluorescence images and spectra of intracellular PpIX are studied with SPE of 405- and 488-nm lasers, and TPE of 800-nm femtosecond laser. The 405-nm laser is more efficient at exciting PpIX fluorescence than the 488-nm laser, but causes a considerable photobleaching of the PpIX fluorescence and induces weak autofluorescence signals of native flavins in the cells as well. The 800-nm TPE is found to significantly improve the quality of PpIX fluorescence images with negligible PpIX photobleaching and minimized endogenous autofluorescence, indicating the potential of 800-nm TPE for studying cellular localization of porphyrin photosensitizers for PDT.
The intravenous low power laser irradiation has been applied clinically in china. However the mechanism is still not fully understood. In this work, the stretching force on the surface of erythrocyte under low power laser irradiation was explored. With the total internal reflection apparatus, the refractive indexes of hemoglobin cytoplasm in erythrocyte and the serum outside erythrocyte were determined as 1.380 and 1.351 respectively. Taking the sphere model for erythrocyte, the force on the surface of the erythrocyte due to the hitting of laser beam was calculated with the way of ray optics. It is found that the acting forces of laser on front and back surfaces are just in opposite direction, but with the similar magnitude of 10-2 PN. This couple forces act as the stretching forces to deform the erythrocyte, which may help erythrocytes to improve their deformability.
The surface stress on the real shape (biconcave disklike) of an erythrocyte under laser irradiation is theoretically studied according to the finite-difference time-domain (FDTD) method. The distribution of the surface stresses depends on the orientation of erythrocytes in the laser beam. Typically when the erythrocyte was irradiated from the side direction (the laser beam was perpendicular to the normal of the erythrocyte plane), the surface stresses were so asymmetrical and nonuniform that the magnitude of the surface stress on the back surface was three times higher than that on the front surface, and the highest-to-lowest ratio of the stress reached 16 times. For comparison, the surface stress was also calculated according to the ray optics (RO) method. The tendency of the stress distribution from the RO calculation was roughly similar to that of the FDTD method. However the RO calculation produced some unphysical results, such as the infinite stress on some surface region and the zero stress on the most parts of the erythrocyte surface, which is due to the neglecting of light diffraction. The results obtained from the FDTD calculation are believed quantitatively reliable, because the FDTD method automatically takes into account of the diffraction and interference effects of the light wave. Thus, the FDTD method is more suitable than the RO method for the stress study of erythrocytes.
In view of explaining the results that AlSPC-PDT was more effective than HPD-PDT in destroying S180 fibrosarcoma (diameter: 0.5 - 0.8 cm; thickness: 0.4 - 0.7 cm) transplanted in white mice, the depth of necrosis of S180 sarcoma in mice in AlSPC-PDT was studied, compared with it in HPD-PDT. Two kinds of HPD were chosen as the control photosensitizers of AlSPC: Photofrin I (PI), and Photosensitizing drug-007 (PSD-007). The experimental tumors in mice were chosen with longitudinal diameters in the range of 0.8 - 1.0 cm and thickness in the range of 0.7 - 1.0 cm. A photosensitizer dose of 10 mg/kg was given (iv) for PI-PDT, PSD-007-PDT, and AlSPC-PDT. The dose of exposure light (600 - 750 nm) was 180 J/cm2. The experimental mice were killed 48 h after PDT to get the tumor necrotic depth. The depth was 0.55 +/- 0.14 cm (0.30 - 0.85 cm) in the AlSPC-PDT group, 0.35 +/- 0.12 cm (0.20 - 0.55 cm) in the PI-PDT group, and 0.36 +/- 0.11 cm (0.20 - 0.50 cm) in the PSD-007-PDT group. These differences may be due to the differences of the dyes' light absorbance spectra. AlSPC's main absorbance peak is at 675 nm and HPD's is around 400 nm with a smaller peak at 630 nm. The penetration of 675 nm light through biologic tissue is deeper than that of 400 nm light and 630 nm light.
Photodynamic therapy (PDT) with sulfonated aluminum phthalocyanine (AlSPC), i.e., AlSPC-PDT, in two murine tumor models is reported here. The encouraging therapy results were observed in S180 fibrosarcoma transplanted in white mice of the Kunming line and in human hepatocellular carcinoma transplanted in balb/c nu/nu nude mice. The experimental tumors in the mice were chosen of those 0.5 - 0.8 cm in diameter and 0.4 - 0.7 cm in thickness. Photofrin II (PII) and Photosensitizing drug-007 (PSD-007), two kinds of porphyrin derivative dyes, were chosen as the contrast photosensitizers of AlSPC. A dose of 10 mg/kg AlSPC or PII or PSD-007 was given (iv). The dose of light (600 - 750 nm) was 180 J/cm2. `Cure (short-term)' was defined as regression of neoplastic tissue to a non-palpable tumor within 14 days after PDT. `Cure (long-term)' was defined as absence of local tumor tissue and tumor metastasis on gross and microscopic examinations within 107 days after PDT. The curative results suggest that AlSPC may be a more effective sensitizer than both PII and PSD-007.
Pathologic changes were observed in S180 fibrosarcoma transplanted in white mice of Kunming line and in human hepatocellular carcinoma transplanted in balb/c nu/nu nude mice after photodynamic therapy (PDT) with sulfonated aluminum phthalocyanine (AlSPC). The experimental tumors in mice were chosen with diameters in the range of 0.5 - 0.8 cm. A dose of 10 mg/kg AlSPC was given (iv). The dose of light (600 - 750 nm) was 180 J/cm2. Degeneration of tumor cells, microvascular hyperemia, stroma edema, and hemorrhage were found soon after PDT under the microscope and the hyperemia and hemorrhage in hepatocellular carcinoma seems more obvious than in S180 sarcoma. Heave hyperemia and hemorrhage can not always be seen in the degenerative and necrotic area in S180 sarcoma. With transmission electron microscopic technique, the most significant early changes are apparent degeneration of the mitochondria, slight dilation of rough endoplasmic reticula, a little increase of lysosmes (both in tumor cells and in endathelia), collagen fiber degeneration in the subendothelial zone of the capillary wall and in other connective collagen fibers, and slight edema in intercellular space and in the interstitial tissue surrounding capillaries immediately after completion of 30 min PDT. Additionally, the results were discussed in combination with our other study of histochemistry on seven kinds of tissue enzymes in hepatocellular carcinoma which shows the activities of these enzymes reduced to be inconsiderable from within 30 min to within 6 h after AlSPC-PDT, in which the activity of SDHase reduced most quickly. The pathologic study suggested the cellular membrane system, especially the mitochondria, was probably one of the main reaction targets of AlSPC-PDT though what is the most important primary target (the tumor cell's and endothelium's mitochondria or subendothelial zone, or some other structure) further study is required to answer.
Sulfonated chloroaluminum phthalocyanine (AlClPCS) has been considered in recent years as a new photosensitizer with promising use in photodynamic therapy (PDT) of cancer. In this work, its biological effects were studied in mice bearing S180 tumors. It was found in tissue distribution measurements that AlClPCS can be selectively accumulated in the tumor, the peak tumor concentration of AlClPCS occurs 36 h after administration, with a tumor:skin ratio of 3:1. The spectral transmittance measurement in the tumor, carried out in vivo at 48 h after administration of AlClPCS at 10 mg/kg, showed that AlClPCS accumulation in the tumor affects the light penetration to some extent at its 675 nm main absorption peak, but the transmittance at 675 nm is still comparable to that at 630 nm, the absorption peak of HPD. The temperature measurement in the tumor showed that the temperature increase is minimal under 100 mw/cm2 irradiation. The tumor response to AlClPCS photodynamic therapy was encouraging. The cure rate of tumors (20 mice) reached 60% under conditions where the irradiation dose of red light was 180 J/cm2 and the dose of AlClPCS administration was 10 mg/kg, showing AlClPCS has the potential to become a candidate for clinical photodynamic therapy.
The mechanism of photodynamic therapy (PDT) with sulfonated aluminum phthalocyanine (AlSPC) studied with the human hepatocellular carcinoma cell line in culture is reported herein. Photofrin II (PII) was chosen as the control photosensitizer of AlSPC. Deuterium oxide (D2O), an enhancer of singlet oxygen (1O2); 1,3-diphenylisobenzofuran (DPBF), a quencher of 1O2: glycerol, a quencher of OH radical (OH(DOT)); superoxide dismutase (SOD), a quencher of O2- radical (O2-(DOT)); diethyldithiocarbamate (DDC), an inhibitor of SOD and glutathione peroxidase; were introduced into both the processes of photodynamic inactivation of human liver cancer cells in culture with AlSPC (AlSPC-PDT) and with PII (PII-PDT). The results suggest that: 1O2 is dominantly involved in both PII-PDT and AlSPC-PDT; O2-(DOT) is involved in AlSPC-PDT in a lower degree than 1O2, while almost not involved in PII-PDT; OH(DOT) is involved in PII-PDT in a lower degree than 1O2, while almost not involved in AlSPC-PDT.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.