Functionalized Mesoporous SBA-15 with CeF3: Eu3+ Nanoparticle by Three Different Methods: Synthesis, Characterization, and Photoluminescence

Luminescence functionalization of the ordered mesoporous SBA-15 silica is realized by depositing a CeF3: Eu3+ phosphor layer on its surface (denoted as CeF3: Eu3+/SBA-15/IS, CeF3: Eu3+/SBA-15/SI and CeF3: Eu3+/SBA-15/SS) using three different methods, which are reaction in situ (I-S), solution impregnation (S-I) and solid phase grinding synthesis (S-S), respectively. The structure, morphology, porosity, and optical properties of the materials are well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption, and photoluminescence spectra. These materials all have high surface area, uniformity in the mesostructure and crystallinity. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the CeF3: Eu3+ nanophosphors. Furthermore, the efficient energy transfer in mesoporous material mainly occurs between the Ce3+ and the central Eu3+ ion. They show the characteristic emission of Ce3+ 5d → 4f (200–320 nm) and Eu3+5D0 → 7FJ(J = 1–4, with 5D0 → 7F1 orange emission at 588 nm as the strongest one) transitions, respectively. In addition, for comparison, the mesoporous material CeF3: Eu3+/SBA-15/SS exhibits the characteristic emission of Eu3+ ion under UV irradiation with higher luminescence intensity than the other materials

The sedimentation of colloidal nanoparticles in solution and its study using quantitative digital photography

Sedimentation and diffusion are important aspects of the behavior of colloidal nanoparticles in solution, and merit attention during the synthesis, characterization, and application of nanoparticles. Here, the sedimentation of nanoparticles is studied quantitatively using digital photography and a simple model based on the Mason–Weaver equation. Good agreement between experimental time‐lapse photography and numerical solutions of the model is found for a series of gold nanoparticles. The new method is extended to study for the first time the gravitational sedimentation of DNA‐linked gold nanoparticle dimers as a model system of a higher complexity structure. Additionally, simple formulas are derived for estimating suitable parameters for the preparative centrifugation of nanoparticle solutions

The sedimentation of colloidal nanoparticles in solution and its study using quantitative digital photography

Sedimentation and diffusion are important aspects of the behavior of colloidal nanoparticles in solution, and merit attention during the synthesis, characterization, and application of nanoparticles. Here, the sedimentation of nanoparticles is studied quantitatively using digital photography and a simple model based on the Mason–Weaver equation. Good agreement between experimental time‐lapse photography and numerical solutions of the model is found for a series of gold nanoparticles. The new method is extended to study for the first time the gravitational sedimentation of DNA‐linked gold nanoparticle dimers as a model system of a higher complexity structure. Additionally, simple formulas are derived for estimating suitable parameters for the preparative centrifugation of nanoparticle solutions

Spectroscopic and hydrodynamic characterisation of DNA‐linked gold nanoparticle dimers in solution using two‐photon photoluminescence

Two‐photon photoluminescence (TPPL) emission spectra of DNA–gold nanoparticle (AuNP) monoconjugates and the corresponding DNA‐linked AuNP dimers are obtained by photon time‐of‐flight spectroscopy. This technique is combined with two‐photon photoluminescence fluctuation correlation spectroscopy (TPPL–FCS) to simultaneously monitor the optical and hydrodynamic behaviour of these nano‐assemblies in solution, with single‐particle sensitivity and microsecond temporal resolution. In this study, the AuNPs have an average core diameter of 12 nm, which renders their dark‐field plasmonic light scattering too weak for single‐particle imaging. Moreover, as a result of the lack of plasmonic coupling in the dimers, the optical extinction, scattering and photoluminescence spectra of the DNA–AuNP complexes are not sufficiently different to distinguish between monomers and dimers. The use of TPPL–FCS successfully addresses these bottlenecks and enables the distinction between AuNP monomers and AuNP dimers in solution by measurement of their hydrodynamic rotational and translational diffusion

Spectroscopic and hydrodynamic characterisation of DNA‐linked gold nanoparticle dimers in solution using two‐photon photoluminescence

Two‐photon photoluminescence (TPPL) emission spectra of DNA–gold nanoparticle (AuNP) monoconjugates and the corresponding DNA‐linked AuNP dimers are obtained by photon time‐of‐flight spectroscopy. This technique is combined with two‐photon photoluminescence fluctuation correlation spectroscopy (TPPL–FCS) to simultaneously monitor the optical and hydrodynamic behaviour of these nano‐assemblies in solution, with single‐particle sensitivity and microsecond temporal resolution. In this study, the AuNPs have an average core diameter of 12 nm, which renders their dark‐field plasmonic light scattering too weak for single‐particle imaging. Moreover, as a result of the lack of plasmonic coupling in the dimers, the optical extinction, scattering and photoluminescence spectra of the DNA–AuNP complexes are not sufficiently different to distinguish between monomers and dimers. The use of TPPL–FCS successfully addresses these bottlenecks and enables the distinction between AuNP monomers and AuNP dimers in solution by measurement of their hydrodynamic rotational and translational diffusion