Multi-orthogonal folding of single polymer chains into soft nanoparticles.

Efficient folding of single polymer chains is a topic of great interest due, mainly, to the challenging possibility of mimicking and controlling the structure and functionality of natural biomacromolecules (e.g., enzymes, drug delivery vehicles, and catalysts) by means of artificial single chain nano-objects. By performing extensive molecular dynamics simulations we investigate the formation of soft nanoparticles by irreversible intramolecular cross-linking of polymer precursors of different lengths. In order to optimize the folding process and to obtain more compact structures we vary the number of chemical species among the linker groups (orthogonal chemistry) which selectively form the bonds. The use of orthogonal chemistry protocols, by increasing the number of different chemical species of the linkers, leads to nanoparticles that are systematically smaller and more spherical than their homofunctional counterparts. We characterize the conformational properties of the resulting nanoparticles. These are intrinsically polydisperse in size, with a significant fraction of sparse topologies. We discuss the relevance of our results for synthesis protocols in real systems.