Compositions and methods for intracellular delivery and release of cargo

A nanoparticle is fabricated from a reaction of a polymer, a crosslinker, a nucleic acid, and between about 2 wt% and about 75 wt% of a charged monomer within a cavity of a mold resulting in a particle having a substantially predetermined three dimensional shape and a largest cross-sectional dimension of less than about 5 micron. The mold can include perfluoropoly ether and the nucleic acid can include less than about 30 nucleotides and the polymer can be poly( vinyl pyrrolidinone). The particles can be washed after being molded and the mold can include less than about 1 wt% initiator, less than about 0.5 wt% initiator, or less than about 0.1 wt% initiator.