The emission spectrum of the PCP complexes shown by a dotted line in Figure 1b features a single band at 670 nm [5], which is due to recombination in chlorophyll
molecules. We note that the emission of the PCP complexes overlaps with the extinction spectra of the silica nanoparticles. Figure 1 Scanning electron microscopy image and optical spectra of the silica nanoparticles. (a) Scanning electron microscopy image of the silica nanoparticles with a diameter of 1,100 nm. (b) Optical spectra of silica nanoparticles with diameters of 600 nm (dash-dot) and 1,100 nm (dash) compared to absorption spectrum of the PCP complex solution (solid) as well as its fluorescence (dot). The method used for sample preparation results with the PCP complexes being either very close to the nanoparticles or completely away. In this way, Temsirolimus datasheet we can determine the fluorescence intensity for both sets of PCP complexes in the same sample. Typical fluorescence image of the PCP complexes coupled to the silica nanoparticles with a diameter of 1.1 μm is shown in Figure 2. The 90 × 90 μm image Z-IETD-FMK chemical structure obtained by click here wide-field microscopy technique features many almost identical ring-shaped structures, with only a few exceptions. Such a high uniformity indicates – in accord with the structural data – high homogeneity of the silica nanoparticles used for preparing the hybrid nanostructure. Many of the nanoparticles are
connected together; however, uniform intensities suggest that the nanoparticles form a sub-monolayer on the cover slip surface. The observed rings are due to the PCP complexes that are close to the silica nanoparticles. The Nitroxoline emissions from such complexes exhibit considerably higher intensity as compared to those from the PCP complexes that are far away from the nanoparticles. The difference is visualized in Figure 2b, where we plot a histogram of intensities obtained for a fluorescence image
similar to the one shown in Figure 2a. The distribution is of a quasi-bimodal character. The subset around 104 counts per second corresponds predominantly to the PCP complexes that are away from the silica nanoparticles; on the other hand, the distribution around 2.2 × 104 counts per second is attributable to the PCP complexes that are in the vicinity of the silica nanoparticles and whose fluorescence is more efficiently collected by the resulting optical system. It is also instructive to determine the intensity profile for the PCP complexes coupled to silica nanoparticles that are in touch with each other, similarly to what is shown in Figure 2a (drawn by a white line). In this case we find three nanoparticles in line, and all of them feature enhancement of the emission of the PCP complexes. The intensity cross section of the fluorescence intensity obtained for these three nanoparticles is shown in Figure 2c.