We present the results of discontinuous
molecular dynamics (DMD)
simulations aimed at understanding the formation of DNA-mediated hydrogels
and assessing their drug loading ability. Poly(ethylene glycol) (PEG)
precursors of four and six arms that are covalently functionalized
on all ends with oligonucleotides are cross-linked by a single oligonucleotide
whose sequence is complementary to the oligonucleotide conjugated
to the precursor. We show that the precursors with large molecular
weight and many arms are advantageous in forming a three-dimensional
percolated network. Analysis of the percolated networks shows that
the pore diameter distribution becomes narrower as the precursor concentration,
the number of arms, and the molecular weight increase. The pore throat
diameter, the size of the largest molecule that can travel through
the hydrogel networks without being trapped, is determined. The percolated
network slows the movement of molecules inside the pores. Molecules
larger than the pore throat diameter have more restrictions on their
movement in the percolated network than those with smaller sizes.