The shape of nanoparticles is a key factor for efficient delivery of a cargo to cells. We prepared nanogels of
controllable shape suitable for boron delivery from cationic triblock terpolymers poly(ethylene oxide)-bpoly(
2-(N, N, N’, N’-tetramethyl guanidium) ethyl acrylate)-b-poly(2-(dimethylamino)ethyl acrylate),
PEO-b-PGEA-b-PDMAEA, and closo-dodecaborate nano-ions. The physical crosslinking based on ion pairing
of closo-dodecaborate with PGEA blocks led to preassembled nanogels of spherical and wormlike
shape. PDMAEA blocks were later chemically crosslinked with 1,2-bis(2-iodoethoxy)ethane, BIEE, to
maximize the boron loadings and the nanogels stability. Depending on the blocks lengths, a shape transition
was observed after the chemical crosslinking. As confirmed by flow cytometry and confocal microscopy
in cervical carcinoma cell lines in vitro, the wormlike chemically crosslinked nanogels were
internalized the most efficiently.