Abstract: A method for rapidly lysing liposomes having transition temperatures in the range of 35.degree. to 65.degree. C. is provided. Such liposomes are treated with a surfactant including ##STR1## wherein x represents an average of 9 or 12. The method is applicable to fluorescence immunoassay procedures.

Abstract: A liposome reagent encapsulating a molecule to be targeted to a body site or used as an assay reporter has a ligand and a sulfonate-containing group on the liposome surface. Preferred ligands are antibodies or antibody fragments and preferred encapsulants are enzymes or dyes. In the most preferred reagents, the antibody and sulfonate-containing group are covalently bonded to the liposome surface through a connecting group which includes a succinimidyl group resulting from addition of the ligand or sulfonate-containing group to a maleimidyl group. The invention includes a kit of materials for performing an assay using the reagent of the invention as the tracer.

Abstract: A method for rapidly lysing liposomes having transition temperatures in the range of 35.degree. C. to 65.degree. C. is provided. Such liposomes are treated with a surfactant including polyethyleneglycol mono-n-alkyl ethers such as C.sub.12 H.sub.25 O(CH.sub.2 CH.sub.2 O).sub.n H where n=9-10, a nine mole ethylene oxide adduct of a blend of n-dodecanol, n-tetradecanol and n-hexadecanol, or other appropriate polyethyleneglycol mono-n-alkyl ether capable of causing rapid lysis. The method is applicable to fluorescence immunoassay procedures.