Incorporation of branched structures
is a major pathway to build
macromolecules with desired three-dimensional (3D) structures, which
are of high importance in the rational design of functional polymeric
scaffolds. Dendrimers and hyperbranched polymers have been extensively
studied for this purpose, but proper gain-of-function for these structures
usually requires large enough molecular weights and a highly branched
interior so that a spherical 3D core–shell architecture can
be obtained, yet it is generally challenging to achieve precise control
over the structure, high molecular weight, and high degree of branching
(DoB) simultaneously. In this article, we present a set of snowflake-shaped
star polymers with functional cores and dendronized arms, which ensure
a high DoB and an overall globular conformation, thus facilitating
the introduction of functional moieties onto the easily achieved scaffold
without the need for high-generation dendrons. Using a polyglycerol
dendron (PGD) as a proof of concept, we propose that this dendronized
arm snowflake polymer (DASP) structure can serve as a better performing
alternative to high-generation PGDs. DASPs with molecular weights
of 750, 1220, 2120, and 3740 kDa were prepared with >85% yields
in
all cases, and we show that these DASPs have high encapsulating efficiency
of Nile Red due to their high DoB and high biocompatibility due to
their hydroxyl-rich nature after ketal removal, as well as high cell
permeability that is molecular-weight-dependent. Introduced fluorophores
such as fluorescein and difluoroboron 1,3-diphenylaminophenyl β-diketonate
with suitable excitation wavelengths may turn the DASPs into stable,
endosome-staining fluorophores with ultra-large Stokes shifts, narrowed
emission bands, and suitability for long-term cellular tracing. Moreover,
the scaffold can encapsulate antibiotic molecules and deliver them
into phagolysosomes for efficient elimination of intracellular Staphylococcus aureus, which is insensitive toward
many antibiotics but is a key target for the clinical success of methicillin-resistant Staphylococcus aureus infection treatment. Elimination
of Staphylococcus aureus could be improved
to >99.9% for chloramphenicol at 32 μg/mL with 450 μg/mL
DASP.