Protein G-liposomal nanovesicles as universal reagents for immunoassays

Chien-Sheng Chen, Antje J. Baeumner, Richard A. Durst

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


To improve the antigen-binding activity of liposome-coupled antibodies and to develop universal liposomal nanovesicles for immunoassays, protein G was conjugated to dye-loaded liposomal nanovesicles for the preparation of immunoliposomes. Sulfosuccinimidyl-4-(N-maleimidomethyl) cyclohexane-1- carboxylate (sulfo-SMCC), a heterobifunctional cross-linker, was used to modify protein G for conjugation to the liposomal nanovesicles. Liposome immunosorbent assays were used to evaluate the binding ability of protein G after sulfo-SMCC modification, to optimize the protein G density on the liposome surface and to determine the amount of IgG binding to the protein G-liposomal nanovesicles. Test strips coated with a narrow zone of antibodies were used to show the successful conjugation. Immunomagnetic beads were used to demonstrate the feasibility of protein G-tagged universal liposomal nanovesicles for immunoassays. Results indicate that the Fc-binding capacity of protein G decreased by only 5.3% after sulfo-SMCC modification. Antibodies were easily conjugated to universal protein G-liposomal nanovesicles in 30 min. The conjugates (protein G-immunoliposomes) were successfully used in immunomagnetic bead assays for the detection of Escherichia coli O157:H7 with a detection limit of approximately 100 CFU/ml. This work demonstrated that protein G-liposomal nanovesicles are a successful universal reagent for easily coupling antibodies in an active orientation on the liposome surface for use in immunoassays.

Original languageEnglish
Pages (from-to)205-211
Number of pages7
Issue number1
Publication statusPublished - 2005 Jul 15

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry


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