Lanthanide-activated SrF nanoparticles with a multishell architecture were investigated as optical thermometers in the biological windows. A ratiometric approach based on the relative changes in the intensities of different lanthanide (Nd and Yb) NIR emissions was applied to investigate the thermometric properties of the nanoparticles. It was found that an appropriate doping with Er ions can increase the thermometric properties of the Nd-Yb coupled systems. In addition, a core containing Yb and Tm can generate light in the visible and UV regions upon near-infrared (NIR) laser excitation at 980 nm. The multishell structure combined with the rational choice of dopants proves to be particularly important to control and enhance the performance of nanoparticles as NIR nanothermometers.

Supramolecular interactions allow fine tuning of the charge of coordination complexes, with concomitant control over size and stability of cyclodextrin-based complex coacervate core micelles.

No abstract

Coacervate-core micelles are considered promising materials for several applications, from catalysis to drug delivery. However, oxidant-responsive coacervate-core micelles, able to undergo structural changes upon specific oxidation stimuli, are not well reported. Here, we present a novel ferrocene-dipicolinic acid derivative as redox-responsive subcomponent to be incorporated in cyclodextrin-based coacervate core micelles, C4Ms, with tuneable core structure and responsiveness towards H 2 O 2 treatment. The Fc-C4Ms are formed combining three orthogonal supramolecular interactions, namely (i) metal-to-ligand coordination between europium(III) ions and dipicolinic acid molecules, (ii) host-guest interaction between beta cyclodextrins and ferrocenes and (iii) electrostatic coacervation interaction. The micelle stability against oxidation can be controlled by varying three main parameters: (a) the core-unit structure, from monomeric metal complexes to supramolecular oligomers, (b) the H 2 O 2 equivalents and c) the ratio between redoxresponsive and non-redox-responsive bislinker. The H 2 O 2 -responsive ferrocene-based systems might have an interesting application, e.g. reactive oxygen species-mediated drug delivery.

Polymer-based micellar assemblies are gaining increasing attention in the smart materials field, yet the design of micelles that show redox-responsive disassembly and, e. g., cargo release is still a challenge. To form redox-responsive micelles, we developed cyclodextrin-based coacervate core micelles that form under interplay of four orthogonal interactions: multivalent electrostatic coacervation, metal-to-ligand coordination chemistry, supramolecular host-guest interactions, and a reversible covalent disulfide metal-complex crosslinker. The cleavage of this crosslinker by dithiotreithol results in the breaking of oligomeric europium(III) structures in the core and results in the disassembly of the 70 nm size micelles. Over hours, due to the oxidation of thiolates to disulfides, monomeric units can recrosslink into oligomeric core-units, favoring micellar reassembly. The time required to reassemble can be controlled by varying the reducing agent concentration or the ratio between redox-responsive and non-redox-responsive crosslinkers. Controlled Methyl Red encapsulation and release indicate the potential of these micelles, for, e. g., controlled drug uptake and delivery.

1.1. Nanotechnology towards nanomedicine 1.2. Polymeric micelles 1.3. Complex Coacervate Core Micelles 1.4. Metal-to-ligand-based Complex Coacervate Core Micelles 1.5. Dendrimicelles 1.6. Cyclodextrin-based Complex Coacervate Core Micelles 1.7. Stimuli-responsive Complex Coacervate Core Micelles 1.8. Motivation, aim and outline of this research Chapter 2 Cyclodextrin-based Complex Coacervate Core Micelles 39 Abstract 2.1. Introduction 2.2. Experimental section 2.3. Results and discussion 2.4. Conclusion 2.5. Supporting information 2.6. References Chapter 3 Assembly, Disassembly and Reassembly of Cyclodextrin-based Complex Coacervate Core Micelles with Redox-Responsive Supramolecular Cross Linkers 73 Abstract 3.1. Introduction 3.2. Experimental section 3.3. Results and discussion 3.4. Conclusion 3.5. Supporting information 3.6. References Chapter 4 Oxidant-responsive of Ferrocene-based Cyclodextrin Complex Coacervate Core Micelles 117 Abstract 4.1. Introduction 4.2. Experimental section 4.3. Results and discussion 4.4. Conclusion 4.5. Supporting information 4.6. References Chapter 5 Light-responsive Cyclodextrin-based Complex coacervate Core Micelles 149