A　convenient　photothermal　biosensor　was　constructed　for　p53　DNA　sequence　detection　based　on　the　high　discrimination　capability　of　locked　nucleic　acid　and　high　efficiency　of　signal　amplification　strategy　of　DNA　walkers　and　difference　photothermal　effect　between　aggregated　and　dispersed　gold　nanoparticles　(AuNPs).　The　presence　of　target　activated　the　DNA　walkers　via　the　high　affinity　between　target　and　complementary　locked　nucleic　acid　in　the　probe　strand,　resulting　in　the　hybridization　of　the　walker　strand　and　substrate　strand　to　form　a　specific　enzyme　recognition　site.　Under　the　cleavage　of　the　endonuclease,　single-stranded　DNA　(ssDNA)　was　released　to　the　solution.　Then　the　walker　strand　bound　to　a　new　substrate　strand,　and　the　next　round　of　cleavage　was　triggered.　The　released　ssDNA　enhanced　the　stability　of　AuNPs　against　salt-induced　aggregation.　Given　difference　photothermal　effects　of　the　aggregated　AuNPs　and　dispersed　AuNPs　under　the　near-infrared　laser,　the　change　of　the　temperature　was　detected　by　a　common　thermometer　easily,　which　had　a　linear　relationship　with　the　target　concentration　in　the　range　of　2.0–120.0　pM,　the　detection　limit　was　1.4　pM　(S/N　=　3).　The　proposed　photothermal　assay　has　been　applied　to　detect　p53　DNA　sequence　spiked　complex　samples　with　satisfying　results.　©　2020　Elsevier　B.V.