Temperature modulating the peroxidase-mimic activity of poly(N-isopropyl acrylamide) protected gold nanoparticles for colorimetric detection of

More recently, loading polymer-ligand onto the surface of gold nanoparticles (AuNPs) as nanozymes has gained considerable attention. However, the efficient modulation of the nanozymes catalytic capability depending on external stimuli remains challenging. Herein, utilizing the thermo-responsive poly(N-isopropyl acrylamide) (PNIPAM) as a stabilizer and a reducing agent to make PNIPAM@AuNPs, we reported a straightforward and efficient protocol for modulating the peroxidase-mimic catalytic capability of PNIPAM@AuNPs in oxidation of 3,3 ',5,5 '-tetramethyl benzidine (TMB)-H2O2 system by change of environmental temperature. More hydroxyl radicals yielded and surface confinement effect induced by the coiled PNIPAM chains at high temperature could further significantly boost the nanozymes catalytic capability. In the presence of glutathione, the generation of oxidized TMB was inhibited and the absorption intensity of the reaction system decreased at 650 nm. The color-fading property provided a highly selective assay for visualized and quantitative test of glutathione ranging 1.0 ~ 17.0 mu M (R2 = 0.993), the limit of detection was 0.8 mu M. Moreover, the proposed method exhibited a promising application in analysis of rat serum glutathione following an intravenous injection. The strategy supplies a facile guideline for preparation of stimuli-responsive polymer@AuNPs with improved peroxidase-mimic catalytic activity toward application in real living bio-systems.

Automated summary

Recently, the loading of polymer-ligand onto the surface of gold nanoparticles as nanozymes has attracted attention. A study reported a method to modulate the peroxidase-mimic catalytic capability of PNIPAM@AuNPs by changing temperature. The presence of glutathione inhibits the generation of oxidized TMB, and the method could be used for the analysis of serum glutathione.