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Two approaches based on magnetic nanoparticles (MNPs) have been compared to analyze C-reactive protein (CRP). Both the non-eluted and eluted MNP-1°Ab-CRP-2°Ab/FITC bioconjugates were measured by a microplate reader with fluorescence detection. The linear ranges for the non-elution and elution methods were 10-200 and 0.1-2.0 µg/mL, respectively. The concentration limits of detection for the nonelution and elution methods were 2.91 and 0.04 µg/mL, respectively. The non-elution method gave better precision and recovery than the elution method, and also showed comparable results to that of ELISA assay. The non-elution method is simple and only needs minute volumes of sample and buffer. There is no need to dissociate the fluorescence probes from the bioconjugates, and the fluorescence signals can be directly measured on the MNP-1°Ab-CRP-2°Ab/FITC bioconjugates. Meanwhile, samples with high CRP concentrations are not necessarily to be diluted before analysis.

Liquid-phase and solid-phase extractions (SPE) in combination with a simple micellar electrokinetic chromatography (MEKC) method were used to investigate human very low-density lipoprotein (VLDL) lipids for two healthy donors. At absorbance 200 nm, the effective mobilities and peak areas of the MEKC profiles showed good reproducibility and precisions. A major peak and several minor peaks appeared for the total lipids of native VLDL, but both the peak numbers and areas reduced for the in vitro oxidized VLDL. Two chloroform and two methanol fractions were obtained from SPE of VLDL total lipids. Significant differences were observed for the first methanol fraction between native and in vitro oxidized VLDL lipids. The first methanol fraction showed a major peak and several minor peaks for native VLDL, but both the peak numbers and areas reduced for oxidized VLDL. Oxidation of VLDL caused decomposition of lipids, and thus the reduction of peak numbers and areas.