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distribute matrixes on MALDI targets,
Single-molecule SNOM
eliminating the need to manually position
It may soon be possible to view objects at the single-molecule level under visible light thanks to recent developments in scanning near-field optical microscopy (SNOM). Until now, it has not been possible to achieve resolution of 0.1 mM). In this paper, an on-line SPR system was shown to detect carbohydrates separated by HPLC, including those from a mixture in calf serum. The monoclonal antibodies used for the SPR detection, designated 39.4, were isolated by the researchers from hybridomas and have a dissociation constant of 0.26 mM for maltose. In effect, they are “dynamic” antibodies, holding onto analytes as long as the sample concentration is high enough. Tests with single injections of carbohydrates typically showed square-shaped pulses, in which the steady-state detector response corresponded to the sample concentration in the flow. A mixture of mouse IgG antibodies at the same concentration as 39.4 were the basis of a reference flow cell, which helped maintain specificity. The SPR detector successfully analyzed oligosaccharide mixtures in 1% and 10% serum. HowAnalysis of a mixture in 1% serum. Dotted line is UV detection, solid line represents the SPR response, and pnp ever, the signal intensities is p-nitrophenyl. (Adapted with permission. Copyright are quite low, typically 2000 Academic Press.)
