This　work　designed　a　signal-on　competitive-type　colorimetric　immunoassay　of　streptomycin　(STR)　using　glucose-loaded　liposome　(GLL)　and　unique　iron(II)-phenanthroline　[Fe(II)-Phen]　system.　The　assay　was　executed　based　on　the　change　in　the　color　and　absorbance　of　Fe(II)-Phen　system,　followed　by　enzyme-triggered　Fe(II)　oxidization　into　Fe(III)　in　the　presence　of　glucose　oxidase　(GOx).　To　construct　such　an　assay,　STR-bovine　serum　albumin　(STR-BSA)　conjugates　were　covalently　linked　with　glucose-loaded　liposome,　whereas　anti-STR　antibodies　were　coated　onto　a　microplate.　In　the　presence　of　STR,　a　competitive　immunoreaction　was　executed　between　the　analyte　and　STR-BSA-GLL　for　the　immobilized　anti-STR.　Upon　addition　of　Triton　X-100,　the　carried　liposome　was　dissociated　to　release　the　loaded　glucose,　which　was　oxidized　by　GOx　into　gluconic　acid　and　hydrogen　peroxide　(H2O2).　The　as-generated　H2O2　oxidized　iron(II)　into　iron(III),　and　decreased　the　complexation　of　iron(II)　with　Phen,　thereby　resulting　in　the　color　change　and　the　decreasing　absorbance.　Under　optimal　conditions,　the　colorimetric　immunoassay　with　the　Fe(II)-Phen　system　exhibited　a　low　detection　limit　(LOD)　of　0.4　pg　mL−1　with　a　wide　dynamic　working　range　from　1.0　pg　mL−1　to　20　ng　mL−1　STR,　accompanying　good　reproducibility　and　high　specificity.　©　2018　Elsevier　B.V.