Point of care biosensor for uric acid based on the target induce changing of photothermal effect of gold nanostars using thermometer as readout

Abstract

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) has a stronger photothermal effect than that of 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 model target) had been developed based on the photothermal effect of AuNSs using a simple thermometer as the readout device. At present 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 morphologies stabilize to approximately spherical shapes. The change in the morphologies and particle size of AuNSs brings forth a blue shift of the localized surface plasmon resonance (LSPR) peak, causing a decrease in the system temperature under laser radiation. The change of 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 used enzyme.