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Turn-on type fluorescence sensing of O 2 is considered a promising approach to developing ways to measure O 2 in microenvironments with spatially distributed O 2 levels. As a class of nanomaterials with a high degree of control over composition and structure, dendrimer-encapsulated nanoparticles (DENs) are promising candidates to mimic biological enzymes. Here, we report a strategy to monitor spatially distributed O 2 across a three-dimensional (3D) human intestinal epithelial layer in a gut-on-a-chip in a turn-on fluorescence sensing manner. The strategy is based on the oxidase-mimetic activity of Pt DENs for catalytic oxidation of nonfluorescent Amplex Red to highly fluorescent resorufin in the presence of O 2 . We synthesized Pt DENs using two different types of dendrimers (i.e., amine-terminated or hydroxyl-terminated generation 6 polyamidoamine (PAMAM) dendrimers) with six different Pt 2+ /dendrimer ratios (i.e., 55, 200, 220, 550, 880, and 1320). After clarifying the intrinsic oxidase-mimetic activity of Pt DENs, we determined tunable oxidase-mimetic activity of Pt DENs, especially with fine-tuning the ratios of the Pt precursor ions and dendrimers. Particularly, the optimal Pt DENs having a Pt 2+ /dendrimer ratio of 1320 exhibited an ∼117-fold increase in the oxidase-mimetic activity for catalyzing the aerobic oxidation of Amplex Red to resorufin compared to one having a Pt 2+ /dendrimer ratio of 200. This study exemplified a simple yet effective approach for spatially resolved imaging of O 2 using metal nanoparticle-based oxidase mimics in microphysiological environments like a human gut-on-a-chip.

Nanozymes are nanostructure-based materials which mimic the enzymatic characteristics of natural enzymes. Biological applications of nanozymes have been highlighted in basic research, industry, and translational medicine as a new cutting-edge tool. In this work, and for the first time, we disclose a tumor alleviation property of a nanozyme that is made up of amine-terminated sixth-generation polyamidoamine dendrimers with encapsulated tiny platinum nanoparticles. We systematically conducted the synthesis and characterization of the dendrimer-encapsulated Pt nanoparticles (denoted Pt-dendrimer) and confirmed their enzymatic function (hydrogen peroxide (H2O2) decomposition) within various cell lines (normal, cancerous), including glioblastoma (GBM) cells. By understanding the effects of the Pt-dendrimer at the gene level, especially related to cancer cell metastasis, we have thoroughly demonstrated its ability for tumor alleviation and suppressing GBM migration, invasion, and adhesion. The present findings show great promise for the application of the nanozyme for use in GBM-related basic research as well as at clinical sites.

We demonstrate the feasible use of Pt nanoparticles encapsulated inside amine-terminated fourth-generation polyamidoamine dendrimers as peroxidase-mimetic labels for sensitive colorimetric assays. This was performed by utilizing intrinsic dual functionalities of the dendrimer-encapsulated Pt nanoparticles, i.e. peroxidase-like activity and multiple conjugation sites.

We demonstrate a method for constructing bifunctional nanostructures, which conjugate biochemical and electrocatalytic activities, on glassy carbon surfaces by decorating the carbon surfaces with both biologically active glucose oxidases and size-monodisperse Pt nanoparticles (less than 2 nm in diameter) utilizing only a single dendrimer layer.

We synthesized Pt nanoparticles using amine‐terminated poly(amidoamine) dendrimers to hybridize the nanoparticles encapsulated inside dendrimers with graphene oxide (GO) sheets. The resulting Pt–GO hybrid composites revealed improved electrocatalytic activity in oxygen reduction reaction compared with GO sheets. [ABSTRACT FROM AUTHOR]

We reported the electrochemically induced deposition of hydroxyl‐terminated poly(amidoamine) dendrimers encapsulating Pt nanoparticles on the surface of indium tin oxide (ITO). The electrochemical deposition led to significantly high surface coverage of Pt nanoparticles encapsulated inside the dendrimers on ITO surfaces, which allowed enhanced (i.e., ca. 212‐fold) electrochemiluminescence of Ru(bpy)32+/tripropylamine on the modified ITOs compared to unmodified ITO. [ABSTRACT FROM AUTHOR]

Intense electrochemiluminescence (ECL) of water-soluble dendritic conjugates, which are poly(amidoamine) (PAMAM) dendrimers conjugated with multiple Ru(II) tris(bipyridine) ([Ru(bpy)3]2+, where bpy=2,2'-bipyridine) units on the periphery, is demonstrated in the absence of any additional co-reactant. The ECL results were investigated by taking into account the co-reactant effect of PAMAM dendrimers. The water-soluble dendritic conjugates were synthesized by derivatizing amine-terminated 4th-generation PAMAM dendrimers (G4-NH2) through covalent linkages with [Ru(bpy)3]2+- N-hydroxysuccinimide esters. Interestingly, the synthesized dendritic conjugates alone exhibit significantly enhanced oxidative-reduction ECL, that is, an approximate nine-fold increase compared to conventional ECL obtained from corresponding aqueous mixtures of free G4-NH2 dendrimers and [Ru(bpy)3]2+ complexes. [ABSTRACT FROM AUTHOR]

The article discusses that Fluorescence Quenching of Dendrimer-Encapsulated cadmium sulfide (CdS) Quantum Dots (QDs) can be used for detection of Hydrogen peroxide. It mentions that hydrogen peroxide is present at micromolar range in rainwater, and is a an important byproduct in many chemical reactions. It reflects on the use of dendrimers for synthesis of cadmium sulfide (CdS) Quantum Dots, and discusses the hydrogen peroxide sensitive fluorescence of CdS QDs.

Enhanced electrochemiluminescence (ECL) of luminol was reported with the use of dendrimer-encapsulated Au nanoparticle (Au DEN)-modified ITOs in the presence of hydrogen peroxide, which was applied for sensitive ECL-based electroanalysis of hydrogen peroxide. The enhanced ECL of luminol in the presence of hydrogen peroxide was attributed to facile electrochemical oxidation of luminol/hydrogen peroxide on the Au DEN-modified ITOs at potentials as low as ∼0.4 V (vs. Ag/AgCl). Spooling ECL spectroscopy measurements indicated that the enhanced ECL emission of luminol/hydrogen peroxide system on the Au DEN-modified ITOs originated from excited 3-aminophthalate as same as that obtained on bare ITOs. Stability of Au DENs on ITO surfaces was also addressed and found to be closely related with the presence of chloride ions in electrolyte solutions. [ABSTRACT FROM AUTHOR]

The article discusses a study which reported the photoluminescence of gold nanoclusters encapsulated in hydroxyl-terminated fourth generation polyamidoamine dendrimers (G4-OH). Topics include an investigation of the possible existence of different types of gold nanoclusters in G4-OH(Au), a description of the ultraviolet (UV) emission intensity of the dendrimer, and details of the preparation and optical measurements.

We report the electrochemical grafting of amine-terminated dendrimers encapsulating nanoparticles onto indium tin oxide (ITO) surfaces. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Electrochemical functionalization of swCNTs was achieved via electrografting of amine-terminated dendrimers encapsulating nanoparticles. • Functionalized swCNTs improved the water wettability of CNT-based FET channels on hydrophobic FET substrates. • Spatially-controlled surface functionalization of swCNTs with dendrimers was demonstrated. • The functionalized CNT-based FET can be modified further with enzymes by crosslinking to the terminal amine groups of the grafted dendrimers. • The functionalized CNT-based FET provides a powerful platform for the development of high-performance integrated FET sensors. Abstract We present a method for functionalization of single-walled carbon nanotubes (CNTs) with amine-terminated dendrimers encapsulating catalytic nanoparticles, and demonstrate the feasibility of functionalized CNTs as efficient field-effect transistor (FET)-sensing platforms. As a model system, we synthesized Pt dendrimer-encapsulated nanoparticles (DENs) using amine-terminated sixth-generation poly(amidoamine) dendrimers, and functionalized CNT-based FET channels with Pt DENs via electro-oxidative grafting of the terminal amines of dendrimers onto the surface of CNTs. We also demonstrated spatially-controlled surface functionalization of CNTs and subsequent modification of the functionalized CNT-based FET channels with glutamate oxidases for efficient FET-based sensing of glutamates. Our approach could facilitate the functionalization of CNTs with a variety of catalytic nanoparticles and biologically active materials, enabling the development of sensitive and selective FET-based sensor devices. [ABSTRACT FROM AUTHOR]

The article discusses that Fluorescence Quenching of Dendrimer-Encapsulated cadmium sulfide (CdS) Quantum Dots (QDs) can be used for detection of Hydrogen peroxide. It mentions that hydrogen peroxide is present at micromolar range in rainwater, and is a an important byproduct in many chemical reactions. It reflects on the use of dendrimers for synthesis of cadmium sulfide (CdS) Quantum Dots, and discusses the hydrogen peroxide sensitive fluorescence of CdS QDs.

[Display omitted] • Both poles of a closed bipolar electrode (BPE) were modified with catalytic Pt nanoparticles. • The dual-modified BPE showed amplified electrochemiluminescence (ECL) of Ru(bpy) 3 2+. • The amplified ECL was ascribed to simultaneous catalysis on the both BPE poles. • The dual-modified BPE was utilized for bipolar ECL imaging analysis of H 2 O 2. Here, we report highly enhanced electrochemiluminescence (ECL) from a closed bipolar electrode (BPE) system consisting of an indium tin oxide (ITO) microband BPE whose both poles were modified with catalytic Pt nanoparticles encapsulated inside dendrimers. The closed BPE-based ECL sensing system generated sensitive and stable ECL emission under a mild driving voltage owing to simultaneous catalysis of both anodic ECL and cathodic sensing reactions on the reporting pole and the detecting pole of the dual-modified ITO microband BPE, respectively. We demonstrated much amplified ECL of Ru(bpy) 3 2+/tripropylamine with the closed BPE-based ECL systems having the dual-modified ITO BPEs; specifically, ∼4 times higher sensitivity than that of the ECL systems having unmodified ITO BPEs for bipolar ECL imaging analysis of H 2 O 2 as a model marker of metabolism. In addition, the closed BPE-based ECL systems exhibited stable and steady ECL emission even upon 50 consecutive applications of a driving voltage of 2.3 V for robust and extended bipolar ECL imaging analysis of H 2 O 2. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • ITOs modified with Pt DENs were investigated as p -AP redox cycling platforms. • p -AP redox cycling on Pt DEN-modified ITOs were compared with conventional ITOs. • Pt DEN-modified ITOs showed increased oxidation current of p -AP during redox cycling. • Pt DEN-modified ITOs showed higher sensitivity than that of conventional ITOs. • Pt DEN-modified ITOs allowed immobilization of ssDNA with high surface density. Abstract In this work, we studied indium tin oxides (ITOs) modified with dendrimer-encapsulated Pt nanoparticles (Pt DENs) to develop efficient p -aminophenol (p -AP) redox cycling platforms. The ITO surfaces were modified via electro-oxidative grafting of the terminal amine groups of the dendrimers encapsulating catalytic Pt nanoparticles (i.e. , Pt DENs). Compared to conventional ITO surfaces, the Pt DEN-modified ITOs showed highly enhanced electrochemical oxidation current of p -AP even at low potentials with no significant background oxidation current due to the catalytic activity of Pt nanoparticles, leading to high signal-to-background ratio for sensitive p -AP redox cycling. The enhanced p -AP redox cycling on the Pt DEN-modified ITOs led to ∼17.8 times higher sensitivity of the p -AP redox cycling than that obtained with conventional ITOs. In addition, the Pt DEN-modified ITOs were found to be suitable as platforms for the immobilization of oligonucleotides due to the globular structure of dendrimers, which have a high surface-to-volume ratio and multiple terminal functional groups, grafted on ITO surfaces. The DEN-modified ITOs could be further functionalized by the immobilization of single-strand DNA oligonucleotides with high surface density (i.e. , (2.2 ± 0.4) × 1012 molecules/cm2), which is ∼4.4-fold higher than that on the surface of conventional ITOs. [ABSTRACT FROM AUTHOR]

Abstract: Amine-terminated polyamidoamine (PAMAM) dendrimers were immobilized on glassy carbon electrodes (GCEs) via electrochemical oxidation of the terminal amine groups of dendrimers. The electrochemical immobilization of dendrimers was confirmed by cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The immobilized dendrimer films were robust and behaved as charge-selective electrochemical gates for oppositely charged redox molecules. The immobilization approach was applied to assemble Au dendrimer-encapsulated nanoparticles (Au DENs, dia. 1.5±0.3nm) on GCEs, and the resulting Au DEN films showed electrocatalytic activity to hydrazine oxidation. [Copyright &y& Elsevier]