Fluorescent labeling of cellular targets and multicolor imaging with gold nanorods

• Synthesis of a novel immunofluorescent nanoprobe by conjugation with folic acid on cystamine-modified gold nanorods.
• Characterizations of fluorescent properties of folic-acid conjugated gold nanorods.
• Gold nanorods had brighter and more photostable than comparable organic dye, rhodamine B.
• Cellular fluorescence imaging showed that gold nanorods was effective in multicolor fluorescent target labeling.

Gold nanorods (AuNRs) are among the promising emerging fluorescent labels for cellular imaging. However, it is unclear whether AuNRs can specifically label molecular target and fluorescent imaging at a subcellular level. Here we have used AuNRs linked to cystine and folic acid (FA) to label live cancer cells, and to detect the distributions of FA receptors on cell membrane. The labeling signals are specific for intended targets and more photostable than comparable organic dyes, rhodamine B. Using AuNRs with different excitation wavelength, we simultaneously detect one cellular target with different labeling colors. Furthermore, AuNRs-labeled red and AuNRs-labeled green came from the same cellular targets are observed with different filter sets. This result indicates that AuNRs-based fluorescent nanoprobes can be very effective in cellular imaging and offer substantial advantage over organic dyes in multicolor target detection.

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