Bead-based spontaneous Raman codes for multiplex immunoassay.

In the immunoassay process, for fulfilling the need to identify multiple analytes in a small amount of complex sample matrix, it is desirable to develop highly efficient and specific multiplex suspension array technology. Raman coding strategy offers an attractive solution to code the suspension arrays by simply combing narrow spectral bands with stable signal intensities through solid-phase synthesis on the resin beads. Based on this strategy, we report the bead-based spontaneous Raman codes for multiplex immunoassay. The study resulted in superior selectivity of the Raman-encoded beads for binding with single and multiple analytes, respectively. With the use of mixed types of Raman-encoded immunoassay beads, multiple targets in small amounts of samples were identified rapidly and accurately. By confirming the feasibility of bead-based spontaneous Raman codes for multiplex immunoassay, we anticipate this novel technology to be widely applied in the near future.

Conjugation of (E)-5-[2-(Methoxycarbonyl)ethenyl]cytidine to hydrophilic microspheres: development of a mobile microscale UV light actinometer.

( E)-5-[2-(Methoxycarbonyl)ethenyl]cytidine was biotinylated through a diisopropylsilylacetal linkage and attached to the surface of hydrophilic streptavidin-coated microspheres through the high-affinity noncovalent interaction between biotin and streptavidin. The functionalized microspheres form a stable suspension in water. Upon UV irradiation, the nonfluorescent ( E)-5-[2-(methoxycarbonyl)ethenyl]cytidine on the microspheres undergoes photocyclization to produce highly fluorescent 3-beta-D-ribofuranosyl-2,7-dioxopyrido[2,3-d]pyrimidine. The fluorescence intensity of the microspheres can be correlated to the particle-specific UV doses applied at different suspension concentrations. The microspheres allow one to measure the UV dose (fluence) distribution in high-throughput water disinfection systems.

(E)-5-[2-(methoxycarbonyl)ethenyl]cytidine as a chemical actinometer for germicidal UV radiation.

(E)-5-[2-(Methoxycarbonyl)ethenyl]cytidine (S) was examined for use as a chemical actinometer for germicidal UV radiation. Its photoproduct, 3-beta-D-ribofuranosyl-2,7-dioxopyrido[2,3-d]pyrimidine (P), is strongly fluorescent with excitation and emission maxima at 330 and 385 nm, respectively. Experiments were conducted to characterize the dynamic behavior of aqueous solutions of S and P when subjected to UV radiation. UV sources used for these experiments included a low-pressure mercury lamp, a XeBr excimer lamp, and a KrCI excimer lamp; all three sources were mounted in collimating devices to provide incident beams that could be easily and accurately characterized by radiometry. These three sources each yielded essentially monochromatic outputwith characteristic wavelengths of 254, 282, and 222 nm, respectively. At practical concentrations, it was found that the absorbance of the actinometer solution was neither high enough to make the actinometer solutions optically opaque nor low enough to be optically transparent to UV. In addition, the photoproduct displayed a molar absorption coefficient that was similar in magnitude to that of the parent compound, thereby resulting in competitive absorption of UV energy between Sand Pduring irradiation. For purposes of evaluation of the results of irradiation, a mathematical model was developed to accountforthe nonideal optical characteristics of the system. The model is based on a description of local photochemical kinetics; predictions of overall reactor performance were developed by spatial and temporal integration of model results. The model was used to analyze the dynamic behavior of actinometer solutions during UV irradiation and to estimate the quantum yield for photoproduction of Pfrom S. This modeling approach is potentially applicable to other photochemical processes in which multiple compounds are present that absorb photoactive radiation; however, general application of this modeling approach to photochemical reactor systems will require inclusion of othertermsto describe relevanttransport behavior within the system.