To　meet　the　requirements　of　point-of-care　testing　(POCT),　the　development　of　miniaturized　and　user-friendly　readout　strategies　has　become　increasingly　valuable　and　significant.　Gold　nanostars　(AuNSs)　have　a　stronger　photothermal　effect　than　spherical　gold　nanoparticles　due　to　the　multiple　pointed　protrusions　on　their　surface.　In　this　study,　a　simple　POCT　biosensor　for　uric　acid　(UA,　chosen　as　a　model　target)　was　developed　based　on　the　photothermal　effect　of　AuNSs　using　a　simple　thermometer　as　a　readout　device.　In　the　presence　of　urate　oxidase　(UAO),　different　amounts　of　UA　react　with　dissolved　oxygen　to　generate　different　amounts　of　H2O2.　The　generated　H2O2　molecules　etch　the　surface　of　AuNSs　with　the　help　of　Fe2+,　leading　to　the　gradual　weakening　of　the　spiky　features　of　the　star-shaped　nanoparticles　until　their　morphology　stabilizes　to　an　approximately　spherical　shape.　The　change　in　the　morphology　and　particle　size　of　AuNSs　causes　a　blue　shift　of　the　localized　surface　plasmon　resonance　(LSPR)　peak,　leading　to　a　decrease　in　the　system　temperature　under　laser　irradiation.　The　change　in　temperature　exhibits　a　linear　relationship　with　the　UA　concentrations　in　the　range　of　5.0-500.0　μM,　with　a　limit　of　detection　(LOD)　of　1.6　μM.　Through　this　simple　strategy,　the　detection　of　UA　can　be　completed　within　14　minutes　using　only　a　regular　thermometer.　This　method　was　successfully　validated　for　the　detection　of　UA　in　serum　and　urine　samples.　Since　various　enzymatic　reactions　can　produce　H2O2,　this　proposed　method　can　be　adapted　to　detect　different　analytes　by　simply　replacing　the　enzyme　used.　©　2025　The　Royal　Society　of　Chemistry.