Mesoporous silica nanoparticles (MSNPs) are gaining a large interest in the field of medical and biomedical applications due to their biodegradability and high loading capacity as a carrier. In this work, a simple synthesis and functionalization procedure is reported, which allows tuning the nanoparticle properties, functionalization, and biodegradability. Variations in the synthesis procedure are introduced, including temperature, concentration of catalyst, and surface functionalization. These samples are characterized and afterwards degraded in phosphate buffered saline (PBS) to determine their degradation kinetics. The amount of degraded material is colorimetrically determined, using an optimized protocol based on molybdenum blue chemistry. It is shown that the degradability of the nanoparticles increased with decreasing synthesis temperatures, lower amounts of catalyst, and higher concentrations of nanoparticles. Surface functionalization alters the degradation kinetics as well, rendering amino-functionalized nanoparticles the fastest degradation behavior, followed by carboxylated and nonfunctionalized nanoparticles. From these results, it can be concluded that the degradation rate of MSNPs can be varied from a few hours to several days by small changes in the synthesis procedure. Moreover, the degradation behavior is strongly dependent on the nanoparticle growth rate.

The preparation of gold nanoparticles through reduction of chloroauric acid by trisodium citrate, also known as the Turkevich synthesis, was analyzed both ex situ and in situ. In situ experiments consist of dynamically tracking second and third harmonic light scattering and multiphoton luminescence. By complementing in situ data with ex situ quenching experiments, which enabled further UV−vis−NIR spectroscopy, as well as transmission electron microscopy (TEM) and dynamic light scattering (DLS) characterization, we obtained new insight into the mechanistic process of gold nanoparticle growth. Our results reveal that the growth proceeds through a metastable state of aggregation and offer additional evidence for a sharp transition from metallic molecular cluster to plasmonic nanoparticle behavior in the initial stage of the process. While multiphoton luminescence can be used as a marker for this transition, second and third harmonic scatterings reveal surface and bulk information such as size, shape, and the presence of aggregates.

Gold nanoparticles (AuNPs) are regarded as promising building blocks in functional nanomaterials for sensing, drug delivery and catalysis. One remarkable property of these particles is the localized surface plasmon resonance (LSPR), which gives rise to augmented optical properties through local field enhancement. LSPR also influences the nonlinear optical properties of metal NPs (MNPs) making them potentially interesting candidates for fast, high resolution nonlinear optical imaging. In this work we characterize and discuss the wavelength dependence of the hyper‐Rayleigh scattering (HRS) behavior of spherical gold nanoparticles (GNP) and gold nanorods (GNR) in solution, from 850 nm up to 1300 nm, covering the near‐infrared (NIR) window relevant for deep tissue imaging. The high‐resolution spectral data allows discriminating between HRS and two photon photoluminescence contributions. Upon particle aggregation, we measured very large enhancements (ca. 104) of the HRS intensity in the NIR, which is explained by considering aggregation‐induced plasmon coupling effects and local field enhancement. These results indicate that purposely designed coupled nanostructures could prove advantageous for nonlinear optical imaging and biosensing applications.

In this work, the use of a newly developed direct liquid injection low pressure chemical vapor deposition (DLI-LPCVD) system is described, which allows for the deposition of thin films in a controlled and reproducible manner. The capabilities of this system are described via silica thin films deposited using the precursor tetraethyl orthosilicate (TEOS). The deposition of thin films is controlled by parameters, such as deposition temperature, partial pressure of the gases, and flow rate of the precursor solution. The thickness of the deposited layer is varied simply by changing deposition temperature and time. X-ray reflectivity and spectroscopic ellipsometry of the deposited samples show that the thickness of the layers is well controlled by deposition temperature and time. Auger electron spectroscopy, in addition, motivates our choice to use cyclohexane as a solvent. A growth rate of 12.2 Åmin À1 is obtained. Atomic force microscopy, Rutherford backscattering spectroscopy, Fourier transform infrared spectroscopy, and drop shape analysis are used to measure roughness, composition, and hydrophobicity. Thin films of silicon dioxide are successfully grown by the newly developed DLI-LPCVD system. This system can be used for a wide range of films by varying the precursors.

In this work, an unusual silicon chemical vapor deposition precursor is used, which allows the safe deposition of thin silica films in a controlled and reproducible manner at a lower thermal budget with a newly developed direct liquid injection À low pressure chemical vapor deposition system. The deposition is controlled by parameters such as deposition temperature, partial pressure of the gases, and flow rate of the precursor solution. X-ray reflectivity and spectroscopic ellipsometry of the deposited samples show that the thickness of the layers is well controlled by deposition temperature, time, and oxygen flow. A growth rate of 4.5 Am in À1 is obtained without the addition of oxygen, which can be increased to 10.2 Åmin À1 by the addition of oxygen. Atomic force microscopy, Rutherford backscattering spectroscopy, Fourier transform infrared spectroscopy, and drop shape analysis are used to measure roughness, composition, and hydrophobicity. Thin films of silicon dioxide are successfully grown. In addition, this newly developed system can be used for a wide range of films by varying the precursors or by co-injecting nanoparticles suspension mixed with the chemical vapor deposition precursor in the direct liquid injection vaporizer.