We report the first demonstration of flow cytometry using upconverting phosphor microsphere reporters. These unique materials are excited by near infrared light from a diode laser and emit visible light in narrow emission bands in the 500 to 700 nm spectral region. Advantages of upconverting phosphors over conventional fluorescent reporters include greater multiplexing, no autofluorescence background, no photobleaching, and excitation by a compact laser source. We modified and optimized a commercial flow cytometer for upconversion detection, and we evaluated system performance in a sandwich assay format, using magnetic bead capture surfaces for small antigen detection. Preliminary results using mouse IgG targets show sensitivities at the ng/mL level using a 25 (mu) L sample volume and a total analysis time of several minutes. Efforts to improve the sensitivity to a variety of small antigen targets and to demonstrate multiplexing with different phosphor compositions will be discussed along with efforts to develop a compact upconverting flow cytometer for field applications.

Date Published: 29 April 1998
PDF: 10 pages
Proc. SPIE 3260, Optical Investigations of Cells In Vitro and In Vivo, (29 April 1998); doi: 10.1117/12.307099

Published in SPIE Proceedings Vol. 3260:
Optical Investigations of Cells In Vitro and In Vivo
Robert C. Leif; Daniel L. Farkas; Robert C. Leif; Bruce J. Tromberg, Editor(s)