Development of an Ultrasmall and Biocompatible Platinum Nanozyme Encapsulated by Zwitterionic Dendrimer for Highly Sensitive Detection of Glucose

Abstract

Many kinds of noble metal nanoparticles can mimic the peroxidase-like function of horseradish peroxidase, which results in their wide applications in bio-related detection and drug delivery. However, those metal nanoparticles usually have low stability and reduced catalytic activity in biological complex medium. Herein, a zwitterionic peroxidase-like enzyme has been developed, which has high stability in fibrinogen solutions and high sensitivity for glucose detection. Maleic anhydride, cysteamine, and zwitterionic peptide EKEKC (EK-5) were used to modify generation 5 poly(amido amine) dendrimers (G5 PAMAM) to prepare zwitterionic dendrimer G5MEKnC with nonfouling properties. Finally, the G5MEKnC-encapsulated platinum nanoparticles (Pt n -G5MEK50C) were prepared by entrapping the platinum nanoparticles (1.40 nm) in the catalytic centers in the interior of G5MEK50C. Pt 55 -G5MEK50C showed high stability in the buffer solution and the fibrinogen solution within 4 days. They also displayed high biocompatibility toward HeLa cells based on cytotoxicity results and morphological observations. Furthermore, the catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine with H 2 O 2 by Pt 55 -G5MEK50C followed the Michaelis−Menten equation, which confirmed their peroxidase-like properties. The catalytic mechanism was due to the generation of • OH from H 2 O 2 . More importantly, the peroxidase-like ability of Pt 55 -G5MEK50C was successfully used to establish a method for the determination of glucose concentration with a broad linear range of 1−2000 μM and a low detection limit of 0.1 μM. This method was highly accurate for the determination of glucose concentration in plasma. The zwitterionic dendrimer template enhanced the properties of Pt 55 -G5MEK50C. Taken together, a new kind of biocompatible nanozyme has been developed and successfully used for the sensitive detection of glucose in bio-related medium.

Galvanic Bipolar Electrode Arrays with Self-Driven Optical Readouts

“…As illustrated in Figure 2a, we used the oxidation of colorless 4-chloro-1-naphthol (4-CN) to insoluble blue-purple benzo-4-chlorohexadienone (4-CD) in the presence of H 2 O 2 , which is known to be catalyzed by peroxidases such as horseradish peroxidase (HRP). 29,30 Based on previous studies reporting that Pt nanoparticles encapsulated inside dendrimers exhibited peroxidase-mimetic activity, 15,31 we expected the facile oxidation of 4-CN to blue-purple 4-CD precipitate as well as the reduction of H 2 O 2 on the BPE poles modified with Pt nanoparticles. Figure 2b shows the UV−vis absorption spectra obtained from a region of the anodic BPE pole modified with Pt 200 in an anodic reservoir containing a 4-CN solution before and after the addition of a H 2 O 2 solution to the cathodic reservoir.…”

“…The unique absorption band with a maximum of 532 nm resulted from the catalytic deposition of insoluble blue-purple precipitates (i.e., 4-CD) on the anodic pole of BPE (see inset in Figure 2b). 18,30 This demonstrates the self-driven colorimetric readout capability of the galvanic BPE system for signal transduction of the faradaic reduction process of H 2 O 2 on the cathodic pole of BPE. Figure 2c shows a colorimetric intensity profile in grayscale obtained along the dashed black line shown in the inset displaying the anodic poles for an array of three BPEs with H 2 O 2 added at different concentrations in the cathodic reservoir.…”

Colloidal Polymer‐Templated Formation of Inorganic Nanocrystals and their Emerging Applications

“…Dendrimer-encapsulated Pt [71,79,84] and Au [73,83] nanocrystals have been used for the detection of glucose. To develop efficient field-effect transistor-based sensing of glutamate, dendrimerencapsulated Pt nanocrystals were attached to single-walled carbon nanotubes (Figure 10A) via electro-oxidative grafting.…”

Dual-Active Au@PNIPAm Nanozymes for Glucose Detection and Intracellular H2O2 Modulation

“…Since the first preparation of peroxidase-like Fe 3 O 4 nanoparticles had been compounded by Yan and her colleagues in 2007, more than 40 nanozymes, which have covered mimic peroxidase, mimic glucose oxidase (GOx), and mimic superoxide dismutase (SOD), have been successfully discovered and obtained. − Under physiological conditions, both enzymatic mechanisms and kinetics of them are similar to natural enzymes. , Gold nanoparticles (AuNPs), as a typical nanozyme, have been subjected to in-depth research because of the simple preparation process and excellent biocompatibility. − However, when the AuNPs are exposed to normal saline or special pH environment, they are easy to aggregate rapidly and lose catalytic performance due to their special dimension. In order to better guarantee the biomimetic catalytic activity of AuNPs, it is urgent to develop a simple method to maintain the monodisperse morphology of them.…”