Metal-Loaded Synthetic Melanin via Oxidative Polymerization of Neurotransmitter Norepinephrine Exhibiting High Photothermal Conversion.

Polydopamine (PDA)-derived melanin-like materials exhibit significant photothermal conversion owing to their broad-spectrum light absorption. However, their low near-infrared (NIR) absorption and inadequate hydrophilicity compromise their utilization of solar energy. Herein, we developed metal-loaded poly(norepinephrine) nanoparticles (PNE NPs) by predoping metal ions (Fe3+, Mn3+, Co2+, Ca2+, Ga3+, and Mg2+) with norepinephrine, a neuron-derived biomimetic molecule, to address the limitations of PDA. The chelation between catechol and metal ions induces a ligand-to-metal charge transfer (LMCT) through the formation of donor-acceptor pairs, modulating the light absorption behavior and reducing the band gap. Under 1 sun illumination, the Fe-loaded PNE coated wood evaporator achieved a high seawater evaporation rate and efficiency of 1.75 kg m-2 h-1 and 92.4%, respectively, owing to the superior hydrophilicity and photothermal performance of PNE. Therefore, this study offers a comprehensive exploration of the role of metal ions in enhancing the photothermal properties of synthetic melanins.

Enzymatic mineralization generates ultrastiff and tough hydrogels with tunable mechanics.

The cartilage and skin of animals, which are made up of more than fifty per cent water, are rather stiff (having elastic moduli of up to 100 megapascals) as well as tough and hard to break (with fracture energies of up to 9,000 joules per square metre). Such features make these biological materials mechanically superior to existing synthetic hydrogels. Lately, progress has been made in synthesizing tough hydrogels, with double-network hydrogels achieving the toughness of skin and inorganic-organic composites showing even better performance. However, these materials owe their toughness to high stretchability; in terms of stiffness, synthetic hydrogels cannot compete with their natural counterparts, with the best examples having elastic moduli of just 10 megapascals or less. Previously, we described the enzyme-induced precipitation and crystallization of hydrogels containing calcium carbonate, but the resulting materials were brittle. Here we report the enzyme-induced formation of amorphous calcium phosphate nanostructures that are homogenously distributed within polymer hydrogels. Our best materials have fracture energies of 1,300 joules per square metre even in their fully water-swollen state-a value superior to that of most known water-swollen synthetic materials. We are also able to modulate their stiffness up to 440 megapascals, well beyond that of cartilage and skin. Furthermore, the highly filled composite materials can be designed to be optically transparent and to retain most of their stretchability even when notched. We show that percolation drives the mechanical properties, particularly the high stiffness, of our uniformly mineralized hydrogels.

Spatiotemporal Control of Supramolecular Polymerization and Gelation of Metal-Organic Polyhedra.

In coordination-based supramolecular materials such as metallogels, simultaneous temporal and spatial control of their assembly remains challenging. Here, we demonstrate that the combination of light with acids as stimuli allows for the spatiotemporal control over the architectures, mechanical properties, and shape of porous soft materials based on metal-organic polyhedra (MOPs). First, we show that the formation of a colloidal gel network from a preformed kinetically trapped MOP solution can be triggered upon addition of trifluoroacetic acid (TFA) and that acid concentration determines the reaction kinetics. As determined by time-resolved dynamic light scattering, UV-vis absorption, and 1H NMR spectroscopies and rheology measurements, the consequences of the increase in acid concentration are (i) an increase in the cross-linking between MOPs; (ii) a growth in the size of the colloidal particles forming the gel network; (iii) an increase in the density of the colloidal network; and (iv) a decrease in the ductility and stiffness of the resulting gel. We then demonstrate that irradiation of a dispersed photoacid generator, pyranine, allows the spatiotemporal control of the gel formation by locally triggering the self-assembly process. Using this methodology, we show that the gel can be patterned into a desired shape. Such precise positioning of the assembled structures, combined with the stable and permanent porosity of MOPs, could allow their integration into devices for applications such as sensing, separation, catalysis, or drug release.

Radiation-induced graft polymerization of elastin onto polyvinylpyrrolidone as a possible wound dressing.

The purpose of our study was to obtain new wound dressings in the form of hydrogels that promote wound healing taking advantage of the broad activities of elastin (ELT) in physiological processes. The hydrogel of ELT and polyvinylpyrrolidone (PVP; ELT-PVP) was obtained by cross-linking induced by gamma irradiation at a dose of 25 kGy. The physicochemical changes attributed to cross-linking were analyzed through scanning electron microscopy (SEM), infrared spectroscopy analysis with Fourier transform (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Furthermore, we performed a rheological study to determine the possible changes in the fluidic macroscopic properties produced by the cross-linking method. Finally, we accomplished viability and proliferation analyses of human dermal fibroblasts in the presence of the hydrogel to evaluate its biological characteristics. The hydrogel exhibited a porous morphology, showing interconnected porous with an average pore size of 16 ± 8.42 µm. The analysis of FTIR, DSC, and TGA revealed changes in the chemical structure of the ELT-PVP hydrogel after the irradiation process. Also, the hydrogel exhibited a rheological behavior of a pseudoplastic and thixotropic fluid. The hydrogel was biocompatible, demonstrating high cell viability, whereas ELT presented low biocompatibility at high concentrations. In summary, the hydrogel obtained by gamma irradiation revealed the appropriate morphology to be applied as a wound dressing. Interestingly, the hydrogel exhibited a higher percentage of cell viability compared with ELT, suggesting that the cross-linking of ELT with PVP is a suitable strategy for biological applications of ELT without generating cellular damage.

Photo-Polymerization Damage Protection by Hydrogen Sulfide Donors for 3D-Cell Culture Systems Optimization.

Photo-polymerized hydrogels are ideally suited for stem-cell based tissue regeneration and three dimensional (3D) bioprinting because they can be highly biocompatible, injectable, easy to use, and their mechanical and physical properties can be controlled. However, photo-polymerization involves the use of potentially toxic photo-initiators, exposure to ultraviolet light radiation, formation of free radicals that trigger the cross-linking reaction, and other events whose effects on cells are not yet fully understood. The purpose of this study was to examine the effects of hydrogen sulfide (H2S) in mitigating cellular toxicity of photo-polymerization caused to resident cells during the process of hydrogel formation. H2S, which is the latest discovered member of the gasotransmitter family of gaseous signalling molecules, has a number of established beneficial properties, including cell protection from oxidative damage both directly (by acting as a scavenger molecule) and indirectly (by inducing the expression of anti-oxidant proteins in the cell). Cells were exposed to slow release H2S treatment using pre-conditioning with glutathione-conjugated-garlic extract in order to mitigate toxicity during the photo-polymerization process of hydrogel formation. The protective effects of the H2S treatment were evaluated in both an enzymatic model and a 3D cell culture system using cell viability as a quantitative indicator. The protective effect of H2S treatment of cells is a promising approach to enhance cell survival in tissue engineering applications requiring photo-polymerized hydrogel scaffolds.

Simultaneous Grafting Polymerization of Acrylic Acid and Silver Aggregates Formation by Direct Reduction Using γ Radiation onto Silicone Surface and Their Antimicrobial Activity and Biocompatibility.

The modification of medical devices is an area that has attracted a lot of attention in recent years; particularly, those developments which search to modify existing devices to render them antimicrobial. Most of these modifications involve at least two stages (modification of the base material with a polymer graft and immobilization of an antimicrobial agent) which are both time-consuming and complicate synthetic procedures; therefore, as an improvement, this project sought to produce antimicrobial silicone (PDMS) in a single step. Using gamma radiation as both an energy source for polymerization initiation and as a source of reducing agents in solution, PDMS was simultaneously grafted with acrylic acid and ethylene glycol dimethacrylate (AAc:EGDMA) while producing antimicrobial silver nanoparticles (AgNPs) onto the surface of the material. To obtain reproducible materials, experimental variables such as the effect of the dose, the intensity of radiation, and the concentration of the silver salt were evaluated, finding the optimal reaction conditions to obtain materials with valuable properties. The characterization of the material was performed using electronic microscopy and spectroscopic techniques such as 13C-CPMAS-SS-NMR and FTIR. Finally, these materials demonstrated good antimicrobial activity against S. aureus while retaining good cell viabilities (above 90%) for fibroblasts BALB/3T3.

Lossless immunocytochemistry using photo-polymerized hydrogel thin-films.

Immunocytochemistry (ICC), or immunofluorescence microscopy, is an essential biological technique for phenotyping cells in both research and diagnostic applications. Standard ICC methods often do not work well when the cell sample contains a small number of cells (<10 000) because of the significant cell loss that occurs during washing, staining, and centrifugation steps. Cell loss is particularly relevant when working with rare cells, such as circulating tumor cells, where such losses could significantly bias experimental outcomes. In order to eliminate cell loss in ICC protocols, we present a method to encapsulate the cell sample in a photo-polymerized hydrogel thin-film. The hydrogel thin-film is permeable to antibodies and other ICC reagents, thereby allowing the use of standard ICC protocols without modification. The cell sample is physically constrained by the hydrogel at the bottom surface of a standard (unmodified) imaging microtiter plate, thereby enabling the acquisition of high-quality micrographs regardless of the properties of the cell sample or staining reagents. Furthermore, while standard ICC requires several centrifugation steps during staining and washing, our hydrogel encapsulation method requires only a single centrifugation step. This property greatly reduces the time required to perform ICC protocols and is more compatible with robotic platforms. In this study, we show that standard ICC and Cytospin protocols are extremely lossy (>70% loss) when the sample contains less than 10 000 cells, while encapsulating the cells using a permeable hydrogel thin-film results in a lossless ICC process.

Metal-Organic Frameworks in Polymer Science: Polymerization Catalysis, Polymerization Environment, and Hybrid Materials.

The development of metal-organic frameworks (MOFs) has had a significant impact on various fields of chemistry and materials science. Naturally, polymer science also exploited this novel type of material for various purposes, which is due to the defined porosity, high surface area, and catalytic activity of MOFs. The present review covers various topics of MOF/polymer research beginning with MOF-based polymerization catalysis. Furthermore, polymerization inside MOF pores as well as polymerization of MOF ligands is described, which have a significant effect on polymer structures. Finally, MOF/polymer hybrid and composite materials are highlighted, encompassing a range of material classes, like bulk materials, membranes, and dispersed materials. In the course of the review, various applications of MOF/polymer combinations are discussed (e.g., adsorption, gas separation, drug delivery, catalysis, organic electronics, and stimuli-responsive materials). Finally, past research is concluded and an outlook toward future development is provided.

High-Molecular-Weight Polyampholytes Synthesized via Daylight-Induced, Initiator-Free Radical Polymerization of Renewable Itaconic Acid.

Herein, it is reported for the first time that when mixed with choline chloride, itaconic acid (IA), normally a low-reactive vinyl monomer, undergoes initiator-free radical polymerization under normal daylight. Furthermore, the process results in the formation of abnormally high-molecular-weight poly(itaconic acid) derivatives with Mw greater than ≈800 000 g mol-1 . Detailed 1D/2D NMR studies indicate that the polymers have two types of ionizable moieties, that is, anionic carboxylic and cationic choline ester groups in an average molar ratio of 12:1. Potentiometric titration shows polyampholyte behavior of the polymers. Tentative mechanistic studies reveal that the daylight-induced polymerization is initiated by species generated via interactions of near UV light with IA. However, EPR findings show that choline also participates in secondary radical reactions. The obtained polyampholytes are useful bio-based materials for fast and straightforward fabrication of polymer-clay nanocomposite hydrogels with excellent mechanical properties.

NIR Sensitizer Operating under Long Wavelength (1064 nm) for Free Radical Photopolymerization Processes.

Free radical polymerization upon near-infrared (NIR) light is still the subject of intense research efforts and remains a huge challenge particularly for long wavelengths (>1000 nm). In this study, a NIR sensitizer operating upon long wavelength (1064 nm) is proposed for an efficient polymerization of acrylate monomers. A new three-component photoinitiating system is developed comprising the NIR sensitizer in combination with an Iodonium salt (Iod) and an amine. Remarkably, the NIR sensitizer (IR 1064) absorbing strongly in all the near infrared region (700-1200 nm) offers the possibility to use a broad range of irradiation wavelengths, i.e., examples are provided at 785 and 1064 nm. Such long wavelengths are characterized by many advantages such as a deeper penetration of light and therefore a better curing of the monomer but it is also much safer than UV light. Excellent performance is observed for the three-component IR 1064/Iod/Amine system under air: high conversion of acrylate functions associated with a fast polymerization time. The use of IR 1064 as NIR sensitizer with a broad NIR absorption is-to the best of current knowledge-never proposed in the literature. The photoinitiating performances are studied using real-time Fourier transform infrared spectroscopy.

Polymeric Iodonium Salts to Trigger Free Radical Photopolymerization.

In a significant breakthrough from classical molecular (i.e., nonpolymeric) iodonium salts in light-induced photochemistry, the synthesis and use of new safer polymeric iodonium salts are reported here. They are shown to be involved in charge transfer complexes (CTCs) while in interaction with a safe amino acid derivative (N-phenylglycine). Also, this study demonstrates i) the formation of CTCs between the iodonium (acceptor) and an aryl/alkyl amine (donor) through UV-vis measurements of the monomer, ii) the formation of radicals in electron spin resonance spin trapping experiments when the CTCs are irradiated by visible light (405 nm), and iii) their efficiency as a photoinitiator to polymerize three different acrylic monomers under LED irradiation at 405 nm under air and their application to 3D resolved laser writing of thick samples (3 mm). High reactivity for polymeric iodonium salts comparable with molecular ones is exhibited with the advantage of potential lower migration. To the best of the authors' knowledge, this is the first reported instance of polymeric iodonium salts acting as polymerization initiators.

Fabrication of 3D-Printed Fish-Gelatin-Based Polymer Hydrogel Patches for Local Delivery of PEGylated Liposomal Doxorubicin.

3D printing technology has been applied to various fields and its medical applications are expanding. Here, we fabricated implantable 3D bio-printed hydrogel patches containing a nanomedicine as a future tailored cancer treatment. The patches were prepared using a semi-solid extrusion-type 3D bioprinter, a hydrogel-based printer ink, and UV-LED exposure. We focused on the composition of the printer ink and semi-synthesized fish gelatin methacryloyl (F-GelMA), derived from cold fish gelatin, as the main component. The low viscosity of F-GelMA due to its low melting point was remarkably improved by the addition of carboxymethyl cellulose sodium (CMC), a pharmaceutical excipient. PEGylated liposomal doxorubicin (DOX), as a model nanomedicine, was incorporated into the hydrogel and liposome stability after photo-polymerization was evaluated. The addition of CMC inhibited particle size increase. Three types of 3D-designed patches (cylinder, torus, gridlines) were produced using a 3D bioprinter. Drug release was dependent on the shape of the 3D-printed patches and UV-LED exposure time. The current study provides useful information for the preparation of 3D printed nanomedicine-based objects.

Evaluation of degree of conversion, rate of cure, microhardness, depth of cure, and contraction stress of new nanohybrid composites containing pre-polymerized spherical filler.

The aim of the present study was to characterize nanohybrid and nanofilled composites in terms of degree of conversion (DC), rate of cure (RC), microhardness (Vickers hardness number; VHN), depth of cure, and contraction stress (CS). Ceram.X® universal- A3, duo enamel E2, and duo dentin D3 composites were compared to Tetric EvoCeram® and FiltekTMSupreme XTE composites of equivalent dentin and enamel shades under a 40 s photopolymerization protocol. DC was measured by infrared spectroscopy, calculating RC from the kinetic curve. Top and bottom VHN were determined using a Vickers indenter, and bottom/top surface ratio (Vickers hardness ratio; VHR) calculated. CS vs. time was assessed by a universal testing machine and normalized for the specimen bonding area. All materials showed DC < 60%, Ceram.X® composites reaching higher values than the other composites of corresponding shades. RC at 5 s of photopolymerization was always higher than that at 10 s. All the Ceram.X® composites and the lighter-shaded Tetric EvoCeram® and FiltekTMSupreme XTE composites reached the RC plateau after 25 s, the remaining materials showed a slower kinetic trend. Tetric EvoCeram® and FiltekTMSupreme XTE composites displayed the softest and the hardest surfaces, respectively. Differently from darker-shaded materials, the universal and the three enamel-shaded composites resulted optimally cured (VHR > 80%). The tested composites differed in CS both during and after light cure, Tetric EvoCeram® and FiltekTMSupreme XTE composites displaying the highest and the lowest CS, respectively. Only the Ceram.X® universal-A3 reached a CS plateau value. The tested composites exhibited material-dependent chemo-mechanical properties. Increasing the curing time and/or reducing the composite layer thickness for dentin-shaded composites appears advisable.

Visible-Light-Controlled Ruthenium-Catalyzed Olefin Metathesis.

Olefin metathesis is now one of the most efficient ways to create new carbon-carbon bonds. While most efforts focused on the development of ever-more efficient catalysts, a particular attention has recently been devoted to developing latent metathesis catalysts, inactive species that need an external stimulus to become active. This furnishes an increased control over the reaction which is crucial for applications in materials science. Here, we report our work on the development of a new system to achieve visible-light-controlled metathesis by merging olefin metathesis and photoredox catalysis. The combination of a ruthenium metathesis catalyst bearing two N-heterocyclic carbenes with an oxidizing pyrylium photocatalyst affords excellent temporal and spatial resolution using only visible light as stimulus. Applications of this system in synthesis, as well as in polymer patterning and photolithography with spatially resolved ring-opening metathesis polymerization, are described.

Antifouling Photograftable Zwitterionic Coatings on PDMS Substrates.

The foreign body response (FBR) to implantable materials can negatively impact performance of medical devices such as the cochlear implant. Engineering surfaces that resist the FBR could lead to enhanced functionality including potentially improving outcomes for cochlear implant recipients through reduction in fibrosis. In this work, we coat poly(dimethylsiloxane) (PDMS) surfaces with two zwitterionic polymers, poly(sulfobetaine methacrylate) (pSBMA) and poly(carboxybetaine methacrylate) (pCBMA), using a simultaneous photografting/photo-cross-linking process to produce a robust grafted zwitterionic hydrogel. reduce nonspecific protein adsorption, the first step of the FBR. The coating process uses benzophenone, a photografting agent and type II photoinitiator, to covalently link the cross-linked zwitterionic thin film to the PDMS surface. As the concentration of benzophenone on the surface increases, the adhesive strength of the zwitterionic thin films to PDMS surfaces increases as determined by shear adhesion. Additionally, with increased concentration of the adsorbed benzophenone, failure of the system changes from adhesive delamination to cohesive failure within the hydrogel, demonstrating that durable adhesive bonds are formed from the photografting process. Interestingly, antifouling properties of the zwitterionic polymers are preserved with significantly lower levels of nonspecific protein adsorption on zwitterion hydrogel-coated samples compared to uncoated controls. Fibroblast adhesion is also dramatically reduced on coated substrates. These results show that cross-linked pSBMA and pCBMA hydrogels can be readily photografted to PDMS substrates and show promise in potentially changing the fibrotic response to implanted biomaterials.

Synthesis, characterization, and application of chemically interconnected carbon nanotube monolithic sorbents by photopolymerization in polypropylene caps.

A facile and convenient approach for the preparation of interconnected multiwalled carbon nanotube (MWCNT) monolithic sorbents in recycled plastic caps has been developed. The method, which was based on the photopolymerization of the individual MWCNTs via the formation of a W/O medium internal phase emulsion (40/60 w/w%), provides control over the size of pores, rigidity, and the mechanical stability of the final solid. Pluronic L121 was used as a surfactant containing the water phase inside it and, consequently, the organic and non-polar phase, in which the MWCNTs and the cross-linker were trapped, remained on the outside of the droplets. Optical microscopy and scanning electron microscopy (SEM) were employed to characterize the morphology of both the emulsions and the final solids, respectively. In addition, nitrogen intrusion porosimetry was performed in order to study how the specific surface area of the final monolithic solid changed (from 19.6 to 372.2 m2 g-1) with the variables involved in the polymerization step. To exemplify the great sorbent potential of the synthesized material, a colorimetric assay based on the retention of methylene blue within the interconnected MWCNT monolithic structure was carried out. Finally, following the positive results, the carbon nanotube-monolithic stirred caps were applied for the determination of chlorophenols in a biological matrix such as human urine, obtaining excellent recovery values (91-98%) and good precision (5.4-9.1%) under optimized extraction conditions. Graphical abstract.

Reversible Destabilization of UV-Responsive Polymer Particles (Latex) using a Photoresponsive Surfactant.

Production of aqueous dispersions of polymeric nanoparticles via heterogeneous radical polymerization in emulsion-type systems is of enormous commercial importance. The ability to reversibly destabilize such a latex is highly desirable, for example, to save transportation costs. Herein, a method for synthesis of photo-responsive polymer latexes that can be destabilized (leading to sedimentation) by only using UV irradiation (no addition of chemicals or change in the experimental conditions) and subsequently redispersed by stirring under visible light irradiation is described. The destabilization/redispersion mechanism relies on photoinduced trans-cis isomerization of the cationic diazene surfactant 2-(4-(4-butylphenyl)diazenylphenoxy)ethyltrimethylammonium bromide (C4AzoTAB) used in conjunction with the anionic surfactant sodium dodecyl sulfate. It is demonstrated that reversible destabilization can be achieved very rapidly (90 s residence time) employing continuous flow technology.

Photo-Controlled Polymerization-Induced Self-Assembly (Photo-PISA): A Novel Strategy Using In Situ Bromine-Iodine Transformation Living Radical Polymerization.

A series of hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) macroinitiators and stabilizers are synthesized in methanol through in situ photo-controlled bromine-iodine transformation living radical polymerization, where ethyl α-bromophenylacetate (EBPA) is the initial initiator and is converted to an iodo-type initiator in the presence of NaI. The subsequent photo-controlled polymerization-induced self-assembly (photo-PISA) process is achieved by adding a second monomer, hydrophobic benzyl methacrylate (BnMA), under irradiation with blue light emitting diode (LED) light at room temperature. The effect of the target degree of polymerization (DP) of PPEGMA, PBnMA, as well as the solids content on the self-assembly behavior of block copolymer PPEGMA-b-PBnMA is evaluated by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) spectroscopy, transmission electron microscopy (TEM), and dynamic light scattering (DLS) characterization. Resulting uniform spherical micelles and vesicle aggregates are observed.

Ketone-Functionalized Polymer Nano-Objects Prepared via Photoinitiated Polymerization-Induced Self-Assembly (Photo-PISA) Using a Poly(diacetone acrylamide)-Based Macro-RAFT Agent.

Herein, ketone-functionalized diblock copolymer nano-objects are prepared by photoinitiated reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of tert-butyl acrylate (tBA) using a poly(diacetone acrylamide) (PDAAM)-based macromolecular RAFT (macro-RAFT) agent in ethanol/water (60/40, w/w) at room temperature. A high polymerization rate is observed via the exposure of visible light (λmax = 405 nm, 0.45 mW cm-2 ) with near quantitative monomer conversion being achieved within 60 min. A morphological phase diagram is constructed by changing the degree of polymerization (DP) of PtBA and the monomer concentration. The morphologies of polymer nano-objects are further tuned by incorporating isobornyl acrylate (IBOA) into the core-forming block. The ketone-functionalized diblock copolymer nano-objects can be shell-cross-linked by reacting with a diamine. Finally, the shell-cross-linked polymer nano-objects are further hydrolyzed and employed as a template for the synthesis of silver composites.

Synthesis of Light-Responsive Pyrene-Based Polymer Nanoparticles via Polymerization-Induced Self-Assembly.

The use of an in situ, one-pot polymerization-induced self-assembly method to synthesize light-responsive pyrene-containing nanoparticles is reported. The strategy is based on the chain extension of a hydrophilic macromolecular chain transfer agent, poly(oligo(ethylene glycol) methyl ether methacrylate), using a light-responsive monomer, 1-pyrenemethyl methacrylate (PyMA), via a reversible addition-fragmentation chain transfer dispersion polymerization; yielding nanoparticles of various morphologies (spherical micelles and worm-like micelles). In this process, addition of comonomers, such as butyl methacrylate (BuMA) or methyl methacrylate (MMA), are required to obtain high PyMA monomer conversion (>80% in 24 h). The addition of comonomers reduces the π-π stacking of the pyrene moieties, which facilitates the diffusion of monomers in the nanoparticle core. The addition of BuMA (as a comonomer) offers P(PyMA-co-BuMA) core-forming chains with high mobility that enables the reorganization of chains and then the evolution of morphology to form vesicles. In contrast, when MMA comonomer is used, kinetically trapped spheres are obtained; this is due to the low mobility of the core-forming chains inhibiting in situ morphological evolution. Finally, the UV-light-induced dissociation of these light-responsive nanoparticles due to the gradual cleavage of the pyrene moieties and the subsequent hydrophobic-to-hydrophilic transitions of the core-forming blocks is demonstrated.