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Indium tin oxide modified with dendrimer-encapsulated Pt nanoparticles as efficient p-aminophenol redox cycling platforms
摘要： 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.
关键词： Indium tin oxide (ITO),Amine-terminated dendrimer,p-aminophenol (p-AP) redox cycling,Dendrimer-encapsulated nanoparticle (DEN)
更新于2025-09-23 15:22:29
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In-situ synthesis of gold nanocrystals anchored graphene oxide and its application in biosensor and chemical sensor
摘要： This research demonstrated the development of graphene oxide (GO)-gold nanocrystals (AuNCs) composite-modified glassy carbon electrode (GCE) for the sensitive detection of dopamine (DA), uric acid (UA), and 4-aminophenol (4-AP). The GO was synthesized by modified Hummer’s method, which was utilized to prepare GO-AuNCs composites by in situ synthesis method using sodium L(-) malate as a reducing agent. Morphological, X-ray diffraction, and spectral analysis revealed the homogeneous formation of AuNCs with high crystallinity and purity on the GO surface and the sizes of the NCs were decreased with increasing the concentrations of sodium L(-) malate. The optimal GCE/GO-AuNCs sensor exhibited excellent electrocatalytic activity towards the oxidation of DA, UA, and 4-AP. The sensor showed interference-free and selective detection of DA and UA with sensitivities of ca. 30.3 and 17.28 μA/cm2/μM, respectively, and detection limits of ca. 28 and 50 nM, respectively, with wider dynamic ranges, measured by differential pulse voltammetry (DPV) technique. Whereas, it displayed a sensitivity and detection limit of ca. 5.70 μA/cm2/mM and 0.017 nM, respectively, for the detection of 4-AP, using current density (J)-voltage (V) measurement method. The sensor also revealed excellent stability, reproducibility, and recoveries of DA, UA, and 4-AP in real samples.
关键词： dopamine,4-aminophenol,Graphene Oxide-Au nanocrystals,uric acid,electrochemical detection
更新于2025-09-23 15:22:29
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Insight into the electron density distribution in an O,N-heterocyclic stannylene by means of high resolution x-ray diffraction analysis
摘要： In this paper we present the synthesis and results of a high-resolution single crystal X-ray diffraction experiment on the O,N-heterocyclic stannylene (t-BuAPSn) (1) containing the chelate 4,6-di-tert-butyl-N-tert-butyl-o-aminophenolate ligand. The experimental work is accompanied by a charge density study based on a topological analysis according to quantum theory of atoms in molecules (QTAIM) together with a NBO calculation of the crystal packing fragment containing a Sn-Sn bond. According to QTAIM, the Sn-Sn interaction is covalent (?2ρ(r)<0, he(r)<0). In the view of NBO analysis, there are two donor-acceptor bonding interactions between the tin atoms of adjacent molecules. The Sn-Sn bond energy evaluated by the Espinosa-Molins-Lecomte correlation is equal to ?9.1 kcal/mol. We carried out the investigation of source function not only in CP(3,-1) on the Sn-Sn bond but also on NCI-defined isosurface (λ2<0). The source function shows that the electron density from the Sn basins extensively contributes to the formation of this Sn–Sn bond in 1.
关键词： aminophenol,QTAIM theory,electron density distribution,stannylene,nature and energy of Sn-Sn interaction
更新于2025-09-23 15:19:57
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Silicon-grafted Ag/AgX/rGO nanomaterials (X = Cl or Br) as dip-photocatalysts for highly efficient p-nitrophenol reduction and paracetamol production
摘要： In this work, plasmonic Ag/AgX/rGO (X = Cl or Br) nano‐photocatalysts were grafted with silicon by adding trimethylsilyl chloride as silicon precursor. The synthesized Ag/AgX/rGO‐Si hybrids showed a large improvement of photocatalytic activity towards the synthesis of p‐aminophenol (PAP) as well as paracetamol (acetaminophen; APAP) through the photoreduction of p‐nitrophenol (PNP). The prepared catalysts Ag/AgX/rGO were characterized using SEM, XRD, FTIR and the reduction reaction of p‐nitrophenol was monitored by UV–Vis measurements, GC/MS and 1HNMR data. From the results, it was demonstrated that the rate order of reduction process of the PNP to PAP and to APAP under visible light irradiation of the samples was as follows; Ag/AgBr/rGO‐Si > Ag/AgCl/rGO‐Si > Ag/AgBr/rGO > Ag/AgCl/rGO. The reaction mechanism had been postulated that was supported with the spectroscopic data. In addition, the catalysts were recovered from the reaction medium and re‐used in three cycles that indicated the reusability and stability of the catalysts. This study was featured by the following; i) fast reaction, ii) the reduction of p‐nitrophenol to paracetamol was performed in a facile one‐pot reaction compared to previous approaches that tends to reduce the production cost, and iii) investigations on the catalytic properties of Ag/AgX/rGO in organic transformations open the door to find a benefice of these catalysts in other organic reactions and in the development in the synthesis of pharmaceutical products.
关键词： reduced graphene oxide,Ag/AgX nanocomposites,P‐aminophenol,photocatalysis,paracetamol
更新于2025-09-04 15:30:14