The ability to manipulate nanocrystals into robust integrated structures will be essential to their application in future nanoelectronics and nanobiotechnlogies. We developed a new nano-scale assembly and patterning methods by combining nature's nanometer-scale self-assembly capabilities with modern technologies in genetic engineering, peptide/protein synthesis, and nanoparticle chemistry. Purple membrane (PM), a protein crystal patch from halobacterial cell membrane, was genetically engineered to display cysteine or histidine groups on the membrane surface with nanoscale symmetry (16). The engineered PM formed stable 2-D crystals in the cell membrane and, when used as a template, exhibited designed reactivity for inorganic NPs while promoting the formation of nanoscale 2-D particle assembly (16, O-12). PM is a durable membrane that can be produced in large scale, fabricated into thin films, or embedded into a polymer matrix. By exploiting the catalytic or luminescent properties of NPs in conjunction with further engineering, NP conjugated PM may be used in the development of biosensors or polymer films of high catalytic activity.

 We have been also working with NPs capable of controlled self-assembly. In particular, we developed CMP passivated gold NPs that are extremely stable in aqueous condition and can withstand wide range of PH and salt concentration without aggregation (14). The thickness of the organic layer of this NP can be controlled precisely by the length of the CMP that forms a stable poly(proline)-II helix on the NP surface (Fig 6).  Many infectious bacteria and viruses have dense layer of collagen-like proteins on their outer most cell surfaces with unknown function. Recognizing the resemblance of such surface layers with our CMP conjugated NPs, we are studying the colloidal stability, collagen binding, and CMP-CMP adhesion properties by various analytical tools (e.g. AFM) (5). This new research direction is expected to provide ground-breaking insights into the roles of the collagen-like surface layers play in infectious capacity of pathogenic micro-organisms.

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