Single-chain nanoparticles (SCNPs) are highly versatile structures resembling proteins,a ble to function as catalysts or biomedical delivery systems.B ased on their synthesis by single-chain collapse into nanoparticular systems, their internal structure is complex, resulting in nanosized domains preformed during the crosslinking process.I nt his study we present proof of such nanocompartments within SCNPs via acombination of electron paramagnetic resonance (EPR) and fluorescence spectroscopy. An ovel strategy to encapsulate labels within these water dispersible SCNPs with hydrodynamic radii of % 5nmi sp resented, based on amphiphilic polymers with additional covalently bound labels, attached via the copper catalyzedazide/alkyne "click" reaction (CuAAC). Adetailed profile of the interior of the SCNPs and the labels microenvironment was obtained via electron paramagnetic resonance (EPR) experiments,f ollowed by an assessment of their photophysical properties.

Careful balance of hydrophilicity of precisely engineered polymers alters aggregation of the amyloidogenic protein Aβ1–40.

Deep eutectic solvents (DES) are a novel class of ionic liquid-based solvents, combining an organic salt and a hydrogen bond acceptor (HBA) at specific molar ratios.

Controlling the internal structures of single‐chain nanoparticles (SCNPs) is an important factor for their targeted chemical design and synthesis, especially in view of nanosized compartments presenting different local environments as a main feature to control functionality. We here design SCNPs bearing near‐infrared fluorescent dyes embedded in hydrophobic compartments for use as contrast agents in pump–probe photoacoustic (PA) imaging, displaying improved properties by the location of the dye in the hydrophobic particle core. Compartment formation is controlled via single‐chain collapse and subsequent crosslinking of an amphiphilic polymer using external crosslinkers in reaction media of adjustable polarity. Different SCNPs with hydrodynamic diameters of 6‐12 nm bearing adjustable label densities are synthesized. It is found that the specific conditions for single‐chain collapse have a major impact on the formation of the desired core–shell structure, in turn adjusting the internal nanocompartments together with the formation of excitonic dye couples, which in turn increase their fluorescence lifetime and PA signal generation. SCNPs with the dye molecules accumulate at the core also show a nonlinear PA response as a function of pulse energy—a property that can be exploited as a contrast mechanism in molecular PA tomography.

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