Chemistry

From Pathogen to Polymer?

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Science  09 Nov 2007:
Vol. 318, Issue 5852, pp. 888
DOI: 10.1126/science.318.5852.888c

Diagnosing diseases would ideally entail simple, rapid, inexpensive tests with both high sensitivity and high specificity. One widely applied approach at the molecular level has been the enzyme-linked immunosorbent assay (ELISA), in which an antigen associated with the disease is induced to bind with an antibody attached to an enzyme. A substrate is then added that the enzyme can modify to elicit a visible response, such as fluorescence, for quantification. In some cases, however, ELISAs can be complicated to implement and may not offer the requisite sensitivity. Sikes et al. present a promising preliminary exploration of an alternative approach, in which the enzyme is replaced by a synthetic photoinitiator of free-radical polymerization. Specifically, the authors appended ∼140 initiators and one or two avidin derivatives to each chain in a sample of acrylic acid/acrylamide copolymer. They then exposed a surface functionalized with biotin to this sensing polymer and detected avidin-biotin binding by adding aqueous acrylate monomers and irradiating the samples with ultraviolet light to induce polymerization where the initiators were bound. A 10-min irradiation time was sufficient to produce visible white polymer spots on samples containing as few as 1000 biotin sites: a response several orders of magnitude more sensitive than an enzyme-based assay applied to the same system. — JSY

Nat. Mater. 10.1038/nmat2042 (2007).

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