Building Stimuli-Responsive Nanoparticle Assemblies In Polymer Matrix and Solutions*

Nanoparticle assemblies had drawn tremendous interest because of their potential applications in the fields of biomedicine, drug delivery, therapeutics, and cancer cell imaging. Building nanoparticle assemblies that are responsive to external stimuli offers great potential to tune a wide array of morphological transitions. Self-assembly of polymer grafted nanoparticles is responsive to external stimuli including polymer chain length, polymer concentration, salt concentration, pH, ionic strength of salt, and so on. In the present work, we used electrostatics to tune these stimuli-responsive transitions in solutions. Molecular dynamics simulations have been performed in the framework of the coarse grain model to study and understand the transitions in self-assembly. Transitions in self-assembly at different graft lengths and graft densities are reported. By varying the parameters including polymer and salt concentration, matrix length, and polymer weight, we are able to tune the transitions of self-assembled morphologies from rings to dispersed state, ordered crystal structures to smaller disordered aggregates. We believe that this model will act as a template in building stimuli-responsive systems which offer diverse applications in bio-imaging, targeting drug delivery, and sensing applications.