  By means of extensive simulations, we investigate concentrated solutions of
globular single-chain nanoparticles (SCNPs), an emergent class of synthetic
soft nano-objects. By increasing the concentration, the SCNPs show a reentrant
behaviour in their structural and dynamical correlations, as well as a soft
caging regime and weak dynamic heterogeneity. The latter is confirmed by
validation of the Stokes-Einstein relation up to concentrations far beyond the
overlap density. Therefore SCNPs arise as a new class of soft colloids,
exhibiting slow dynamics and actualizing in a real system structural and
dynamical anomalies proposed by models of ultrasoft particles. Quantitative
differences in the dynamical behaviour depend on the SCNP deformability, which
can be tuned through the degree of internal cross-linking.
