Encapsulation of nanoparticles in block copolymer micelles and applications in biotechnology

This thesis describes the co-assembly of amphiphilic block copolymers and nanoparticles and their practical applications in biotechnology. Amphiphilic block copolymers can be spontaneously assembled and cross-linked around inorganic nanoparticles to form permanent core-shell type nanostructures without the need for specific interaction between the polymer and the nanoparticles.

Magnetic iron oxide nanoparticles and semiconducting quantum dots were encapsulated within micelles made from amphiphilic polystyrene-block -poly(acrylic acid) block copolymers. Encapsulation was accomplished by simultaneously desolvating the hydrophobic nanoparticles and the hydrophobic polymer block to localize the nanoparticles within the micelle core. The hydrophilic, outer shells of these micelles were then chemically cross-linked, resulting core-shell architectures, which were extensively characterized by transmission electron microscopy. We have found that the structure and physical properties of these nanomaterials were precisely programmable by the characteristics of the self-assembled components. We have also demonstrated that we could attach desired molecules on the surface of the assembled nanostructure through the covalent chemistry of the polymeric shell surrounding the nanostructure. With these integrated nanostructures, we have explored their potential uses as recyclable enzyme supports, biological labels for extreme physiological conditions, and triggered drug delivery vehicles.

Because the cross-linked micelle shells are topologically linked to nanoparticles rather than chemically bound, we anticipate that the encapsulation approach to core-shell nanostructures might open a new avenue for nanomaterials that lack effective surface chemistries and functionalities.