Studies on the structure of coumarin-modified dextran nanoparticles by fluorescence spectroscopy

Exploring the Photophysical and Mechanical Behavior of Fluorescent Metal-Organic Framework Monoliths

Luminescent metal-organic frameworks exhibit great potential as materials for nanophotonic applications because of their programmable properties and tunable structures. In particular, luminescent guests (LG) can be hosted by metal-organic frameworks due to their porosity and guest confinement capacity, forming LG@MOF composite systems. However, such guest-host systems are mainly produced as loose powders, preventing their widespread use in practical devices and technological applications that require implementation of a stable continuum solid. In this regard, using monolithic MOF hosts might be a workable option to solve this challenge. Herein, we reported the facile synthesis and fabrication of novel prototypical sol-gel monolithic systems, designated as LG@monoMOF. Red (rhodamine B), blue (7-methoxycoumarin), and yellow (fluorescein) emitting dyes were encapsulated in a robust UiO-66 monolithic host, resulting in the red, blue, and yellow light-emitting luminescent monoliths. The mechanical and photophysical characterization of the three LG@monoMOF systems was systematically carried out in order to unravel the role of guest-host interactions in the mechanical and optical response of the bespoke LG@monoMOF composites.

Dual Photo- and pH-Responsive Spirooxazine-Functionalized Dextran Nanoparticles

A dual photo- and pH-responsive spirooxazine-functionalized polymer was synthesized by functionalization of dextran with a spirooxazine derivative (SO-COOH). The functionalized dextran derivatives can form nanoparticles in aqueous medium. Under UV light irradiation, the spirooxazine-functionalized dextran (Dex-SO) nanoparticles isomerize to zwitterionic merocyanine-functionalized dextran (Dex-MC), which leads to aggregation. However, the process is reversible upon irradiation with visible light. Under acidic conditions, the hydrophobic spirooxazine is protonated, and the nanoparticles aggregate or swell at pH values of 5 or 3, respectively. The encapsulation of the hydrophobic fluorescent dye Nile Red as model drug allowed us to gain more information about the structural changes under stimulation of UV light and acid treatment.

Nanoparticles Based on Hydrophobic Polysaccharide Derivatives-Formation Principles, Characterization Techniques, and Biomedical Applications

Polysaccharide (PS) nanoparticles (NP) are fascinating materials that combine huge application potential with the unique beneficial features of natural biopolymers. Different types of PS-NP can be distinguished depending on the basic preparation principles (top-down vs bottom-up vs coating of nanomaterials) and the material from which they are obtained (native PS vs chemically modified PS derivatives vs nanocomposites). This review provides a comprehensive overview of an approach towards PS-NP that has gained rapidly increasing interest within the last decade; the nanoself-assembling of hydrophobic PS derivatives. This facile process is easy to perform and offers a broad structural diversity in terms of the PS backbone and the additional functionalities that can be introduced. Fundamental principles of different NP preparation techniques along with useful characterization methods are presented in this work. A comprehensive summary of PS-NP prepared by different techniques and with various PS backbones and types/amounts of hydrophobic substituents is given. The intention is to demonstrate how different parameters determine the size, size distribution, and zeta-potential of the particles. Moreover, application trends in biomedical areas are highlighted in which tailored functional PS-NP are evaluated and constantly developed further.