title: Supramolecular photochemical self-assemblies for fluorescence "turn on" and "turn off" assays for chem-bio-helices.
abstract: We describe the development of an optical sensing system for the high-throughput screening (HTS) of a broad range of biological molecules, whole cells, organisms and pathogens, and illustrate the technology applications by a hyaluronidase enzyme activity assay as a specific example. At the core of the technology described in this paper, is the exciton concept that is relevant to molecular aggregation. J-aggregates of cyanine dyes have a narrower, red-shifted absorption band compared to monomer. We demonstrate that self-assembly may be driven by the helicogenic nature of the cyanine dye, converting the linear polymers of hyaluronic acid or carboxymethyl cellulose into supramolecular helical assemblies. This self-assembly is accompanied by an intense, sharp, red-shifted J-aggregate fluorescence. We utilized this property to develop an assay for the enzyme hyaluronidase, based upon the concept of "scaffold destruction," whereby the disruption/destruction of the hyaluronic acid polymer by hyaluronidase is accompanied by an attenuation of light emission from the J-aggregate. The extent of light attenuation provides an index of hyaluronidase activity. Other polymers of carbohydrates, proteins, nucleic acids and chemical polymers (such as the carbon nanotube) might provide a similar scaffold for helicogenic dyes upon which molecular aggregation can occur. A key feature of these assays is that they are label-free.
authors.affiliation: Biosensors and Nanomaterials Department, Sandia National Laboratories, P.O. Box 5800, MS 1425, Albuquerque, New Mexico 87185-1425, USA. kachyut@sandia.gov
authors.forename: Komandoor E
authors.initials: KE
authors.lastname: Achyuthan
authors.forename: Liangde
authors.initials: L
authors.lastname: Lu
authors.forename: Gabriel P
authors.initials: GP
authors.lastname: Lopez
authors.forename: David G
authors.initials: DG
authors.lastname: Whitten
mesh_terms: D005453:Fluorescence; D006821:Hyaluronoglucosaminidase / Q000378:metabolism; D010777:Photochemistry; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D006821:Hyaluronoglucosaminidase