Freestanding microscale 3D polymeric structures with biologically-derived shapes and nanoscale features

Microscale polymeric structures with intricate three-dimensional (3D) shapes and nanoscale features were synthesized by using silica-based microshells of diatoms (unicellular algae) as transient scaffolds. Diatom microshells were immersed in dilute solutions of polymer precursors in volatile solvents. After extraction and solvent evaporation, the resulting thin films on the microshells were cross-linked to form rigid polymer coatings. Selective silica dissolution then yielded freestanding polymeric structures that retained the microshell shapes and fine features. By utilizing bioscaffolds capable of genetically precise and massively parallel replication, enormous numbers of polymeric micro/nanostructures with identical 3D shapes may be generated for various applications.