Guanine-specific modification of both single- and double-stranded oligodeoxynucleotides via the autoxidation of sulfite is shown to be catalyzed by [NiCR]2+ (where CR = 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),2,11,13,15-pentaene) and [NiKGH-nh 2]+ (where KGH = lysylglycylhistidine). In the latter case, the nickel complex is proposed to act as a catalyst in three separate steps of sulfur oxide chemistry. Oxidative damage of guanines led to strand scission after piperidine treatment. The observed reactivity represents the first demonstration of DNA damage by sulfite and nickel(II) complexes. Importantly, these reactions were conducted using sulfite concentrations relevant to levels known to be cytotoxic. Mechanistic studies suggest the importance of both monoperoxysulfate and sulfate radical anion in the observed DNA damage. Evidence for formation of guanine radical cation as the initial product of DNA oxidation was found by comparison of the sequence dependence of guanine reactivity in a duplex restriction fragment. These studies underscore a role for sulfite in nickel toxicity and suggest a new method of site-specific oxidation with bioconjugates using sulfite rather than highly reactive oxidants such as monoperoxysulfate.

Evaluation of the sequence selectivity, noncovalent association, and orientation of the DNA cross-linking agent azinomycin B on its duplex DNA receptor is described. A strong correlation between sequence nucleophilicity and cross-linking yield was observed, and steric effects due to the thymine C5-methyl group were identified. Detailed studies on the role of the azinomycin naphthoate using viscometry, fluorescence contact energy transfer, and DNA unwinding assays point to a nonintercalative binding mode for this group. A kinetic assay for agent regioselectivity was used to determine the orientation of binding and covalent cross-link formation.

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A prototype rapid antigen test for the on-site detection of respiratory syncytial virus (RSV) infection was developed and evaluated. The platform uses instrumented assay analysis, eliminating potential operator bias in the interpretation of the test result that may occur with visually interpreted rapid antigen assays. The device was tested as the first point-of-care (POC) infectious disease application of novel reporter up-converting phosphor technology (UPT) using a specifically designed portable UPT reader (UPlink). Assays were performed by mixing nasopharyngeal specimen with RSV-specific UPT reporter particles and addition of the mixture to a disposable cassette containing a lateral flow (LF) strip with RSV capture antibodies. UPT reporters bound on the specific capture zone were analyzed with the UPlink reader. Reproducibility testing of the UPlink-RSV (UPR) test by naïve users confirmed the potential of UPlink for POC applications where testing is not always performed by highly trained medical staff. The performance of UPR was further evaluated with clinical nasopharyngeal specimens. A prospective study at an independent test site demonstrated clinical parameters of 90% sensitivity and 98.3% specificity with an overall correlation of 96.2% as compared to viral culture with RT-PCR verification. These results are in agreement with in-house retrospective studies and results obtained with other available commercial rapid antigen assays.

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