Laserbasierte Generierung matrixbinderfreier Nanopartikel-Polymerkomposite für bioaktive Medizinprodukte

Laser Synthesis and Processing of Colloids: Fundamentals and Applications

Driven by functionality and purity demand for applications of inorganic nanoparticle colloids in optics, biology, and energy, their surface chemistry has become a topic of intensive research interest. Consequently, ligand-free colloids are ideal reference materials for evaluating the effects of surface adsorbates from the initial state for application-oriented nanointegration purposes. After two decades of development, laser synthesis and processing of colloids (LSPC) has emerged as a convenient and scalable technique for the synthesis of ligand-free nanomaterials in sealed environments. In addition to the high-purity surface of LSPC-generated nanoparticles, other strengths of LSPC include its high throughput, convenience for preparing alloys or series of doped nanomaterials, and its continuous operation mode, suitable for downstream processing. Unscreened surface charge of LSPC-synthesized colloids is the key to achieving colloidal stability and high affinity to biomolecules as well as support materials, thereby enabling the fabrication of bioconjugates and heterogeneous catalysts. Accurate size control of LSPC-synthesized materials ranging from quantum dots to submicrometer spheres and recent upscaling advancement toward the multiple-gram scale are helpful for extending the applicability of LSPC-synthesized nanomaterials to various fields. By discussing key reports on both the fundamentals and the applications related to laser ablation, fragmentation, and melting in liquids, this Article presents a timely and critical review of this emerging topic.

Adsorption of colloidal platinum nanoparticles to supports: charge transfer and effects of electrostatic and steric interactions

Adsorption of colloidal nanoparticles to surfaces and supports is a convenient approach to heterogeneous catalysts, polymer additives, or wastewater treatment. We investigated the adsorption efficiency of laser-generated and initially ligand-free platinum nanoparticles to TiO2 supports as a function of pH, ionic strength, and ligand surface coverage. The nanoparticle adsorption is dominantly controlled by electrostatic interactions: if the pH of the suspension is between the isoelectric point of the nanoparticles and the support, nanoparticles are adsorbed and transfer a net charge to the support. This charge-driven adsorption is not affected by steric repulsion due to various ligands attached to the nanoparticle surface. In addition to electrostatic interactions, colloidal stability given by moderate ionic strengths and pH values above the isoelectric point of nanoparticles are prerequisites for colloidal deposition.