Abstract: In one aspect, the invention relates to functionalized solid lipid nanoparticles comprising a neutral lipid and a first functionalized polymer comprising at least one ionic or ionizable moiety and methods for providing same. In a further aspect, the invention relates to tumor targeting therapeutic systems, multimodal diagnostic therapeutic systems, thermoresponsive payload delivery systems, magnetic-driven targeting systems, therapeutic diagnostic systems, stabilized ink compositions, and cosmetic formulations comprising the solid lipid nanoparticles of the invention. In a further aspect, the invention relates to methods of delivering at least one biologically active agent, pharmaceutically active agent, magnetically active agent, or imaging agent across the blood-brain barrier, across a cellular lipid bilayer and into a cell, and to a subcellualr structure. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.