The results suggest that the enhancement factor depends upon the size of nanoparticles. Citarinostat purchase The spectral shape as well as dynamic behavior of the emission remains unchanged upon coupling with the nanospheres; therefore, we attribute the observed enhancement as being due to enhanced efficiency of light collection from molecules in the vicinity of the silica nanoparticles. Methods Peridinin-chlorophyll-protein (PCP) photosynthetic molecules were obtained according to the protocol by Miller et al. [17]. Briefly, PCP apoprotein in 50 mM Tris-HCl (pH 8.0) solution was added to 25 mM tricine and 10 mM KCl (pH 7.6), mixed with a stoichiometric amount of PCP pigments dissolved in ethanol. The sample

was held in 4°C for 72 h. Reconstituted samples were equilibrated to 5 mM tricine with 2 mM KCl (pH 7.6) by passage through a PD-10 column and bound to a column of DEAE Trisacryl (Sigma-Aldrich, St. Louis, MO, USA). Reconstituted

PCP was then removed with 5 mM tricine with 2 mM KCl (pH 7.6) containing 0.06 M NaCl. The protein solution was characterized www.selleckchem.com/products/fosbretabulin-disodium-combretastatin-a-4-phosphate-disodium-ca4p-disodium.html by absorption and fluorescence spectroscopy. All reagents for silica nanoparticle synthesis were purchased and used as received from the indicated suppliers: nitric acid, hydrochloric acid, ammonium hydroxide (25%), and glucose from Chempur (Karlsruhe, Germany); potassium hydroxide and ethanol from POCh (Gliwice, Poland); tetraethylorthosilicate from Sigma-Aldrich (St. Louis, MO, USA); and silver nitrate from Lach-ner (Neratovice, Czech Republic). Deionized water was purified to a resistance of 18.2 MΩ (HLP 5UV System, Hydrolab, Hach Company,

Loveland, CO, USA) and filtered using a 0.2-μm membrane filter to remove any impurities. All glassware and equipment were first cleaned in an aqua regia Staurosporine purchase solution (3:1, HCl/HNO3) and rinsed with ultrapure water prior to use. All solutions were prepared under stirring and/or sonication, using 18.2 MΩ cm of ultrapure water. Silica particles with diameters of 250 nm to 1.1 μm and low dispersities were prepared using a variation of the method developed by Stöber et al. [18]. The obtained nanoparticles were characterized by scanning electron microscopy and absorption spectroscopy. The samples for fluorescence measurements were prepared by spin-coating the solution of silica nanoparticles onto a clean microscope cover slip. For that purpose, equal volumes of nanoparticle solution were mixed with PCP solution at a concentration of 2 μg/mL. After that, a solution of the PCP complexes was deposited on the nanoparticles. Alternative approach of mixing both samples prior to spin-coating was used, and the results were qualitatively identical. Absorption spectra were recorded on a Varian-Cary 50 UV-visible spectrophotometer (Palo Alto, CA, USA). Steady-state fluorescence measurements were performed using a FluoroLog 3 ABT-263 nmr spectrofluorometer (Jobin Yvon) equipped with a double grating monochromator.