A　nanoparticle-based　potentiometric　immunoassay　was　designed　for　the　sensitive　detection　of　squamous　cell　carcinoma　antigen　(SCCA;　cervical　carcinoma　marker)　on　a　portable　pH　meter　coupling　enzyme-labeled　hybridization　chain　reaction　(HCR)　with　two　alternating　hairpin　DNA　probes　for　the　signal　amplification.　Initially,　a　sandwich-type　immunoreaction　was　carried　out　between　anti-SCCA　capture　antibody-conjugated　magnetic　bead　and　detection　antibody/initiator　strand-coated　gold　nanoparticle　(AuNP).　Then,　the　HCR　reaction　was　readily　executed　between　two　glucose　oxidase　(GOx)-labeled　hairpins　through　the　initiator　strand　to　form　numerous　GOx　concatamers　on　the　AuNP　via　the　long　nicked　double-helix.　The　concatenated　GOx　oxidized　glucose　into　gluconic　acid　and　hydrogen　peroxide,　thus　resulting　in　the　pH　change　of　the　detection　solution　on　a　handheld　pH　meter.　Several　labeling　protocols　including　GOx-antibody,　GOx-AuNP-antibody　and　GOx-HCR-AuNP-antibody　were　investigated　for　detection　of　target　SCCA,　and　improved　analytical　features　were　obtained　with　the　immune-HCR　assay.　Under　optimum　conditions,　the　immune-HCR　assay　exhibited　good　pH　responses　for　the　determination　of　SCCA　at　a　concentration　as　low　as　5.7　pg/mL.　Additionally,　the　immune-HCR　assay　had　good　precision　and　reproducibility,　high　specificity,　and　acceptable　accuracy　for　analyzing　human　serum　specimens.　©　2019　The　Author