We describe novel composite nanoparticles consisting of a gold-silver nanocage core and a mesoporous silica shell functionalized with the photodynamic sensitizer Yb-2,4-dimethoxyhematoporphyrin (Yb-HP). In addition to the long-wavelength plasmon resonance near 750-800 nm, the composite particles exhibited a 400-nm absorbance peak and two fluorescence peaks, near 580 and 630 nm, corresponding to bound Yb-HP. The fabricated nanocomposites generated singlet oxygen under 630-nm excitation and produced heat under laser irradiation at the plasmon resonance wavelength (750-800 nm). In particular, we observed enhanced killing of HeLa cells incubated with nanocomposites and irradiated by 630-nm light. Furthermore, an additional advantage of fabricated conjugates was an IR-luminescence band (900-1060 nm), originating from Yb(3+) ions of bound Yb-HP and located in the long-wavelength part of the tissue transparency window. This modality was used to control the accumulation and biodistribution of composite particles in mice bearing Ehrlich carcinoma tumors in a comparative study with intravenously injected free Yb-HP molecules. Thus, these multifunctional nanocomposites seem an attractive theranostic platform for simultaneous IR-luminescence diagnostic and photodynamic therapy owing to Yb-HP and for plasmonic photothermal therapy owing to Au-Ag nanocages.
Работа посвящена исследованию кинетики фотолюминесценции коллоидных растворов молекулярных нанокристаллов фталоцианина алюминия при различных pH и при взаимодействии с иммунокомпетентными клетками (макрофагами). Изучение кинетики проводилось при помощи системы регистрации, основанной на стрик-камере с пикосекундным разрешением (до 15 пс) C10627-13 Hamamatsu Photonics, сопряженной с волоконно-оптическим спектрометром, при пикосекундном лазерном возбуждении. В ходе эксперимента было зафиксировано изменение кинетики затухания флуоресценции, выраженное в появлении дополнительных компонент времен жизни флуоресценции. Количество компонент и длительность времени жизни изменялись при взаимодействии с клетками и в зависимости от pH. Так, при pH 2 было зафиксировано наличие двух времён жизни флуоресценции: 5 нс, что соответствует молекулярной форме в растворе, и 1,5 нс, что соответствует связанному состоянию молекулы фталоцианина. Так как кроме наночастиц в растворе других возможных объектов связывания нет, то, с большой степенью достоверности, можно предположить, что связывание происходит именно с наночастицами. Исследование времени жизни флуоресценции наночастиц фталоцианина алюминия в макрофагах показало наличие двух компонент порядка 9 нс и 4,5 нс. Была предложена модель перехода поверхностных молекул фталоцианина алюминия из пара-в орто-положение относительно поверхности кристаллической наночастицы.
Early diagnosis of caries and tooth enamel microcracks is of great importance for preventing the destruction of healthy tooth enamel. Inorder to detect microcracks in the enamel and pathogenic microflora foci that can cause caries, nanoform of aluminum phthalocyanine (AlPc) can be used as a marker. In a colloidal solution, the nanoparticles do not fluoresce, unlike their molecular form. To convert the particle into its molecular form, it is necessary to have a solvent or specific environment (bacteria, macrophages, etc.). That is why the hydrophobic nanoparticles of aluminum phthalocyanine (nAlPc) can act as markers for detecting hidden pathogenic microflora during fluorescent diagnostics. Further reduction of the diagnosis time and increase the efficiency can be achieved by using biologically compatible surfactants as additional activators of nAlPc.In order to carry out local fluorescence spectroscopy of enamel microcracks and pathogenic microflora foci on the enamel surface, a model compound containing surfactants, auxiliary components and nAlPc colloid at a concentration of 10 mg/l was prepared.Studies on the interaction of the model compound with nAlPc and Protelan MST-35 with tooth enamel ex vivo have shown this surfactant to be a promising auxiliary activator of the nanoparticles, allowing conducting local fluorescence spectroscopy of the tooth enamel surface 3 min after application. In addition, statistical processing of the results showed the effectiveness of using the model compound for local fluorescence spectroscopy of the enamel surface in order to detect the enamel microcracks and the pathogenic microflora accumulation foci that can lead to the development of a cariogenic process.
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