Conjugated polymer nanoparticles exhibit strong fluorescence and have been applied for biological fluorescence imaging in cell culture and in small animals. However, conjugated polymer particles are hydrophobic and often chemically inert materials with diameters ranging from below 50 nm to several microns. As such, conjugated polymer nanoparticles cannot be excreted through the renal system. This drawback has prevented their application for clinical bio-medical imaging. Here, we present fully conjugated polymer nanoparticles based on imidazole units. These nanoparticles can be bio-degraded by activated macrophages. Reactive oxygen species induce scission of the conjugated polymer backbone at the imidazole unit, leading to complete decomposition of the particles into soluble low molecular weight fragments. Furthermore, the nanoparticles can be surface functionalized for directed targeting. The approach opens a wide range of opportunities for conjugated polymer particles in the fields of medical imaging, drug-delivery, and theranostics.

There exists a critical need in biomedical molecular imaging and diagnostics for molecular sensors that report on slight changes to their local microenvironment with high spatial fidelity. Herein, a modular fluorescent probe, termed StyPy, is rationally designed which features i) an enormous and tunable Stokes shift based on twisted intramolecular charge transfer (TICT) processes with no overlap, a broad emission in the far‐red/near‐infrared (NIR) region of light and extraordinary quantum yields of fluorescence, ii) a modular applicability via facile para‐fluoro‐thiol reaction (PFTR), and iii) a polarity‐ and viscosity‐dependent emission. This renders StyPy as a particularly promising molecular sensor. Based on the thorough characterization on the molecular level, StyPy reports on the viscosity change in all‐DNA microspheres and indicates the hydrophilic and hydrophobic compartments of hybrid DNA‐based mesostructures consisting of latex beads embedded in DNA microspheres. Moreover, the enormous Stokes shift of StyPy enables one to detect multiple fluorophores, while using only a single laser line for excitation in DNA protocells. The authors anticipate that the presented results for multiplexing information are of direct importance for advanced imaging in complex soft matter and biological systems.

Arylazopyrazoles are an emerging class of photoswitches with redshifted switching wavelength, high photostationary states, long thermalh alf-lives and facile synthetic access. Understanding pathways for as imple modulation of the thermalh alf-lives,w hile keepingo ther parameters of interest constant,i sa ni mportanta spectf or out-of-equilibrium systems design anda pplications. Here, it is demonstrated that the thermalh alf-life of aw ater-solubleP EG-tethered arylazo-bis(o-methylated)pyrazole (AAP) can be tuned by more than five orderso fm agnitude using simple pH adjustment, which is beyond the tunability of azobenzenes. The mechanism of thermalr elaxation is investigated by thorough spec-troscopic analyses and density functional theory (DFT) calculations.F inally,t he concepts of at unable half-life are transferred from the molecular scale to the materials cale. Based on the photochromic characteristics of E-a nd Z-AAP,t ransient information storage is showcased in form of light-written patterns inside films cast from different pH, which in turn leads to different times of storage. With respect to prospective precisely tunable materials and time-programmed outof-equilibrium systems, an externally tunable half-life is likely advantageous over changing the entire system by the replacementoft he photoswitch.

Responsive materials, such as switchable hydrogels, have been largely engineered for maximum changes between two states. In contrast, adaptive systems target distinct functional plateaus between these maxima. Here, we demonstrate how the photostationary state (PSS) of an E/Z‐arylazopyrazole photoswitch can be tuned by the incident wavelength across a wide color spectrum, and how this behavior can be exploited to engineer the photo‐dynamic mechanical properties of hydrogels based on multivalent photoswitchable interactions. We show that these hydrogels adapt to the wavelength‐dependent PSS and the number of arylazopyrazole units by programmable relationships. Hence, our material design enables the facile adjustment of the mechanical properties without laborious synthetic efforts. The concept goes beyond the classical switching from state A to B, and demonstrates pathways for a truly wavelength‐gated adaptation of hydrogel properties potentially useful to engineer cell fate or in soft robotics.

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We introduce a modular photodynamic covalent crosslinker, named qStyPy, with an increased water-solubility that undergoes [2+2] cycloadditions upon irradiation with 470 nm and directly self-reports on its cycloadduct formation.

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Responsive Materialien, wie z. B. schaltbare Hydrogele, wurden in den meisten Fällen dahingehend entworfen, eine maximale Änderung zwischen zwei Zuständen zu generieren. Im Gegensatz dazu zielen adaptive Systeme auf unterschiedliche funktionelle Plateaus zwischen diesen Maxima ab. In diesem Forschungsartikel zeigen wir daher, wie der photostationäre Zustand (PSS) eines E/Z‐Arylazopyrazol‐Photoschalters mit Hilfe der eingestrahlten Wellenlänge über ein breites Farbspektrum eingestellt werden kann, um die photodynamischen Eigenschaften von Hydrogelen auf der Grundlage von multivalenten, photoschaltbaren Wechselwirkungen zu beeinflussen. Wir präsentieren, dass sich diese Hydrogele an den wellenlängenabhängigen PSS und an die Anzahl der Arylazopyrazol‐Einheiten durch programmierbare Beziehungen anpassen. Unser Materialdesign ermöglicht daher die einfache Einstellung der mechanischen Eigenschaften ohne eine zeitaufwändige Synthese. Das Konzept geht über das klassische Schalten zwischen Zustand A und B hinaus und zeigt Wege für eine wellenlängenabhängige Adaption der Hydrogeleigenschaften auf, die für Weiterentwicklungen in der Zellkultivierung oder in der Soft‐Robotik nützlich sein werden.