An　interdigitated　capacitance　immunosensing　system　based　enzymatic　biocatalytic　precipitation　on　micro-comb　electrode　was　designed　for　the　sensitive　detection　of　prostate-specific　antigen　(PSA)　by　coupling　Ti3C2　MXenes　with　tyramine　signal　amplification　strategy.　The　immunosensor　was　prepared　by　immobilizing　anti-PSA　capture　antibody　on　MXenes-coated　interdigitated　electrode,　whereas　gold　nanoparticles　heavily　functionalized　with　horseradish　peroxidase　(HRP)　and　detection　antibody　were　utilized　as　the　signal-transducer　tags.　Introduction　of　interdigitated　electrode　was　expected　to　enhance　the　sensitivity　of　capacitance　immunosensor.　This　system　mainly　consisted　of　the　sandwich-type　immunoreaction,　formation　of　tyramine-HRP　repeats　on　gold　nanoparticle　and　enzymatic　biocatalytic　precipitation.　The　concatenated　HRP　through　the　tyramine　oxidized　numerous　4-chloro-1-naphthol　molecules　into　insoluble　benzo-4-chlorohexadienone　with　the　help　of　H2O2,　and　coated　the　modified　immunosensor　to　keep　free　ions　away　from　the　electrode,　thus　causing　the　local　alteration　in　the　capacitance.　Under　optimum　conditions,　the　change　of　the　immunosensor　in　the　capacitance　increased　with　the　increasing　target　PSA　concentrations　from　0.1　ng　mL−1　to　50　ng　mL−1　at　a　detection　limit　of　0.031　ng　mL−1.　Moreover,　the　interdigitated　capacitance　immunosensor　showed　good　reproducibility,　high　specificity　and　acceptable　accuracy　for　the　analysis　of　human　serum　specimens　in　comparison　with　those　obtained　from　commercial　human　PSA　ELISA　kit.　Importantly,　Ti3C2　MXenes-based　interdigitated　capacitance　transducer　open　new　opportunities　for　protein　diagnostics　and　biosecurity.　©　2019　Elsevier　Ltd