Xian Liu,Like Chen,Yang Yang,Liping Xu,Junyong Sun,Tian Gan
Rational tailoring of hollow and porous bimetallic structures with excellent electrocatalytic performance is appealing yet challenging. Further, combining independent bimetallic nanoparticles with flexible two-dimensional substrate by forming stable heterocomplex is still highly desired for electrocatalysis. Herein, hierarchical PtCu alloy octahedrons with hollow interiors and nanosheet-assembled nanoshells were synthesized by a facile and efficient chemical transformation strategy using Cu 2 O as sacrificial templates. Such octahedral PtCu nanocages displayed significantly enhanced electrocatalytic activity owing to their unique hollow and porous architectures which provided easy access for analytes to the catalyst surface. Thereafter, introduction of Ti 3 C 2 T x MXene was realized via simple incubation of Ti 3 C 2 T x in solution containing the 3-aminopropyltriethoxysilane-capped PtCu, and their electrostatic interaction guaranteed the firm adsorption of PtCu nanocages on Ti 3 C 2 T x nanosheets. It turned out that the sensitivity of the hybrid sensor was remarkably improved for electrochemical monitoring of endocrine disrupting pollutants in water, exhibiting ultrawide linear ranges and sub-nanomole detection limits. The eminent electrode performance is attributed to the high specific area, fast electrochemical kinetics, decent electrical catalytic ability, and the synergistic effect between Pt, Cu, and MXene.
Nanozymes are a type of artificial enzymes that can replace traditional natural enzymes for biotechnology to biosensing, biocatalysis , and biological imaging. Nevertheless, it is still a huge challenge in the pursuit of new mimic enzymes or multiple enzyme-like activities mimics. In this work, PtCu nanocages (PtCu NCs) with hollow interior and rough exterior was prepared. PtCu NCs displayed superior tetra-enzyme mimetic activities including peroxidase (POD)-, superoxide dismutase (SOD)-, catalase (CAT)- and ascorbic acid oxidase (AAO)-like activities. Meaningfully, attributed to the POD mimic activity, sensitive and convenient colorimetric biosensors for L -Cysteine ( L -Cys), homocysteine (Hcy) and glutathione (GSH) were developed with wide linear range (LR) and low limit of detection (LOD) of 0.28 μM, 1.48 μM and 0.75 μM (S/N = 3), respectively. Moreover, based on the AAO mimic activity, the cascade reaction was proposed including the oxidation of ascorbic acid (AA) to dehydroascorbic acid (DHAA) by PtCu NCs and the formation of the fluorescent quinoxaline (DFQ) coming from the reaction between DHAA and o-phenylenediamine (OPD). A novel fluorescent biosensor for dehydroepiandrosterone (DHEA) was successfully constructed based on the immunoassay method combined with the cascade reaction for AA, with the LR of 0.6–464.9 ng·mL −1 and LOD of 0.5 ng·mL −1 . These colorimetric and fluorescent biosensors displayed outstanding performance in terms of sensitivity, specificity, and accuracy for real samples, suggesting that PtCu NCs was a promising candidate for biosensing.
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