Preparation of highly fluorescent magnetic nanoparticles for analytes-enrichment and subsequent biodetection

Bifunctional nanoparticles with highly fluorescence and decent magnetic properties have been widely used in biomedical application. In this study, highly fluorescent magnetic nanoparticles (FMNPs) with uniform size of ca. 40 nm are prepared by encapsulation of both magnetic nanoparticles (MNPs) and shell/core quantum dots (QDs) with well-designed shell structure/compositions into silica matrix via a one-pot reverse microemulsion approach. The spectral analysis shows that the FMNPs hold high fluorescent quantum yield (QY). The QYs and saturation magnetization of the FMNPs can be regulated by varying the ratio of the encapsulated QDs to MNPs. Moreover, the surface of the FMNPs can be modified to offer chemical groups for antibody conjugation for following use in target-enrichment and subsequent fluorescent detection. The in vitro immunofluorescence assay and flow cytometric analysis indicate that the bifunctional FMNPs-antibody bioconjugates are capable of target-enrichment, magnetic separation and can also be used as alternative fluorescent probes on flow cytometry for biodetection.

Graphical abstractHighly fluorescent magnetic nanoparticles were prepared based on the selection of proper type of quantum dots as the fluorescent moiety for the target-enrichment, magnetic separation and subsequent flow cytometric analysis.Figure optionsDownload full-size imageDownload high-quality image (76 K)Download as PowerPoint slideResearch highlights► Highly fluorescent magnetic nanoparticles (FMNPs) are prepared by encapsulation of both MNPs and proper type of QDs into silica. ► FMNPs contained well-designed seven layered shell/core QDs hold high and stable QY. ► Both target-enrichment process and fluorescent detection step can be accomplished by the same single bifunctional FMNPs.