Facile preparation of Fe ₃ O ₄ @Pt nanoparticles as peroxidase mimics for sensitive glucose detection by a paper-based colorimetric assay

Abstract

A simple strategy to rapidly detect glucose was developed by utilizing core (Fe 3 O 4 )–shell (Pt) magnetic nanoparticles (Fe 3 O 4 @Pt NPs) as a nanoenzyme and a paper-based colorimetric sensor. In the presence of H 2 O 2 , Fe 3 O 4 @Pt NPs catalyze the redox reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) and generate a colour change from colourless to blue. On this basis, a colorimetric glucose sensing method assisted by glucose oxidase (GOx) was developed. Under the optimal conditions, the detection limits of the proposed assay for H 2 O 2 and glucose were 0.36 µM and 1.27 µM, respectively. Furthermore, the fabricated colorimetric method was successfully applied to analyze glucose concentrations by using a paper device as a measuring platform without a spectrometer. In addition, this method exhibited satisfactory recovery for glucose detection in human serum samples and urine samples, which satisfied the requirements for normal detection of real samples. This study provides a good candidate for health monitoring of glucose and also expands the applications of nanoenzymes and paper-based colorimetric assays in point-of-care testing.

Facile green synthesis of wasted hop-based zinc oxide nanozymes as peroxidase-like catalysts for colorimetric analysis

“…When compared with other previously reported nanozymes in the literature (see Table 1), WHE-ZnO NZs exhibit remarkable POD-like properties. For instance, compared with Fe 3 O 4 @Pt NPs, 30 WHE-ZnO NZs have 36.6 times higher affinity to H 2 O 2 . Furthermore, when compared with P–Co 3 O 4 NPs, 24 the WHE-ZnO NZs demonstrate enhanced POD-like activity toward H 2 O 2 , therefore proving to be a more efficient candidate for H 2 O 2 colorimetric detection.…”

Dual-aptamer-based colorimetric assay for the accurate identification of circulating tumor cells via Fe3O4@Pt NP nanozymes and G-quadruplex/hemin for signal amplification

“…The Fe 3 O 4 @Pt NPs were prepared according to the method we reported previously. 45 Then, 100 μL of 100 μg mL −1 Fe 3 O 4 @Pt NPs dissolved in TES buffer and 2.5 μL of 20 μg mL −1 streptavidin were mixed together and incubated at 37 °C and 300 rpm for 4 h in the dark. After washing with 100 μL of TEST buffer 3 times, 100 μL of 0.08 μM AS1411 aptamer (Apt AS1411 , dissolved in TES buffer) and 100 μL of 0.1 μM signal probe (S p , dissolved in TES buffer) were added and incubated at 37 °C and 300 rpm for 0.5 h in the dark to immobilize Apt AS1411 and S p on the surface of Fe 3 O 4 @Pt NPs via the streptavidin–biotin interaction.The obtained Fe 3 O 4 @Pt NPs–Apt AS1411 /S p conjugates were further treated with 100 μL of 5% BSA (dissolved in TES buffer) for 30 min at 37 °C to reduce nonspecific adsorption.…”