Nature has evolved exquisite synthetic strategies over the past 3-4 billion years for controlling biological nanostructures as a function of size, shape and regio placement of chemical groups.1-2 Critical constructs such as globular proteins and their various self-assemblies, not only define essential life processes and architectures, but also demonstrate the importance of controlling these three synthetic parameters.
Dendrimers have exhibited remarkable globular protein-like properties as evidenced by their precise masses, comparable dimensions/ shapes and electrophoretic properties.2-4 They have been used as protein mimics in many applications such as gene transfection, diagnostics, enzyme mimics and as anti-prion agents. As such, these nanostructures are widely referred to as "artificial proteins."4-6 In an effort to more closely mimic the "higher complexity" of many differentiated shapes and chemical surfaces found in biological proteins, several synthesis strategies have been investigated in our laboratory. The first approach provides a systematic strategy for differentiating dendron generations and surface chemistry within a single dendrimer structure. This is accomplished by hybridizing (oxidizing) various combinations of mercapto-core functionalized dendrons.5 A second strategy allows the systematic synthesis of chemically differentiated nano-cusps/clefts found in "partial shell filled," core-shell tecto(dendrimer) architectures.6-7 Covalent attachment of additional dendrimer shells to these architectures has allowed the systematic "bottom-up" synthesis of higher [n-shell]:core-shell structures possessing virtually any combination of nano-dimension (i.e., 5-100 nm) and surface chemistry desired. This lecture will overview these methodologies, their implications and other unique dendritic effects related to nanoscale spheroidal packing and symmetry.8