A visual application of gold nanoparticles: Simple, reliable and sensitive detection of kanamycin based on hydrogen-bonding recognition
TL;DR: In this article, a visual detection strategy employing 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazole (AHMT) functionalized gold nanoparticles (AuNPs) to detect kanamycin (KA) in various samples.
Abstract: The authors here described a visual detection strategy employing 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazole (AHMT) functionalized gold nanoparticles (AuNPs) to detect kanamycin (KA) in various samples. The AHMT with mercapto group was self-assembled onto the surface of AuNPs and the AHMT functionalized AuNPs (AHMT-AuNPs) aggregated when KA existed owing to the hydrogen-bonding interaction between KA and AHMT. As a result, the color of the AHMT-AuNPs solution changed from wine red-to-deep purple with the increasing concentration of KA. Taking advantage of the hydrogen-bonding interaction, KA could be quantitatively detected by the proposed sensor in the range of 0.005–0.1 μM and 0.1–20 μM, with the detection limit as low as 0.004 μM which is much lower than the maximum contamination level for KA in milk defined by the European Union. Furthermore, the proposed sensor was not affected by the interference chemicals including common amine acid, antibiotics, and metal ions. The sensor was also used to detect KA from various real samples, and the results were excellent in accord with the values measured by the high performance liquid chromatography (HPLC). This sensor exhibited a promising potential for simple and real-time detection of KA in various real samples.
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TL;DR: This critical review briefly describes the synthesis routes for COF powders and thin films and the most fascinating and significant applications of COFs in sensing fields including explosive sensing, humidity sensing, pH detection, biosensing, gas sensing, metal ion sensing, and other substance sensing.
Abstract: As a newly emerging kind of porous material, covalent organic frameworks (COFs) have drawn much attention because of their fascinating structural features (e.g., divinable structure, adjustable porosity and total organic backbone). Since the seminal work of Yaghi and co-workers reported in 2005, the COF materials have shown superior potential in diverse applications, such as gas storage, adsorption, optoelectronics, catalysis, etc. Recently, COF materials have shown a new trend in sensing fields. This critical review briefly describes the synthesis routes for COF powders and thin films. What's more, the most fascinating and significant applications of COFs in sensing fields including explosive sensing, humidity sensing, pH detection, biosensing, gas sensing, metal ion sensing, and other substance sensing are summarized and highlighted. Finally, the major challenges and future trends of COFs with respect to their preparation and sensing applications are discussed.
510 citations
TL;DR: In this paper, a metal-free carbon doping-carbon nitride (BCM-C 3 N 4 ) nanocomposite was synthesized by introducing barbituric acid and cyanuric acids during the polymerization of melamine.
Abstract: Many organic and inorganic compounds have been developed as visible light driven photocatalysts for environment and energy application. In this work, a metal-free carbon doping–carbon nitride (BCM-C 3 N 4 ) nanocomposite was synthesized by introducing barbituric acid and cyanuric acid during the polymerization of melamine. The BCM-C 3 N 4 was characterized by structure, porosity, optical performance, and photoelectrochemical properties. Results demonstrated that BCM-C 3 N 4 sample exhibited higher surface area, lower fluorescence intensity, better photocurrent signals and more efficient charge transfer in comparison to pure C 3 N 4 . The BCM-C 3 N 4 exhibits excellent photocatalytic degradation ability of sulfamethazine (SMZ) under visible light irradiation. Much superior photocatalytic activity and high pollutant mineralization rate was achieved by BCM-C 3 N 4 , where it was 5 times than that of pristine C 3 N 4 . The effect of initial SMZ concentrations on photocatalyst was also investigated. Additionally, the trapping experiments and electron spin resonance tests demonstrated that the main active species, such as O 2 − and h + , could be produced under light irradiation. This work might provide an effective approach to the design of low-cost and highly efficient photocatalysis degradation systems for water treatment.
458 citations
TL;DR: In this article, an interfacial Schottky junction composed of Ti3C2 and porous g-C3N4 nanosheets (TC/pCN) is constructed by a facile electrostatic self-assembly route to significantly boost the spatial charge separation to promote the activation of molecular oxygen for H2O2 production.
Abstract: The development of efficient photocatalysts for the production of hydrogen peroxide (H2O2) is a promising strategy to realize solar-to-chemical energy conversion. Graphitic carbon nitride (g-C3N4) presents giant potential for photocatalytic H2O2 production, but the sluggish charge separation depresses its photocatalytic performance. Herein, an interfacial Schottky junction composed of Ti3C2 nanosheets and porous g-C3N4 nanosheets (TC/pCN) is constructed by a facile electrostatic self-assembly route to significantly boost the spatial charge separation to promote the activation of molecular oxygen for H2O2 production. As the optimal sample, TC/pCN-2 possesses the highest H2O2 production rate (2.20 μmol L−1 min−1) under visible light irradiation (λ > 420 nm), which is about 2.1 times than that of the porous g-C3N4. The results of superoxide radical detection and rotating disk electrode measurement suggest that the two-step single-electron reduction of oxygen is the predominant reaction step during this photocatalytic H2O2 production process. The enhanced photocatalytic performance is ascribed to the formation of Schottky junction and subsequent built-in electric field at their interface, which accelerate the spatial charge separation and restrain the charge recombination. This work provides an in-depth understanding of the mechanism of photocatalytic H2O2 production, and gives ideas for the design of highly active materials for photocatalytic H2O2 production.
427 citations
TL;DR: In this article, the photocatalytic activity of CuS/BiVO4 composites for Ciprofloxacin (CIP) removal was examined under visible light irradiation.
389 citations
TL;DR: In this article, a review of carbon nanomaterials (CNMs)-modified photocatalysts is presented, which provides a wide view of recent preparation methods, applications, prospects and challenges.
Abstract: Highly-efficient materials and technologies for environmental pollutant treatment and hydrogen production are urgently needed in "green" 21st century. Notably, photocatalytic process over carbon nanomaterials (CNMs)-modified photocatalysts is an effective solution for these crises. CNMs (e.g., fullerenes, carbon nanotubes, graphene, carbon nanofibers, and carbon quantum dots) reveal remarkable morphological, mechanical, electrical and optical properties, which have been of significantly scientific and technological interest in photocatalysis. Until now, many efforts have been made to take advantage of these unique size- and surface-dependent properties of CNMs for photocatalytic process. In this review, we firstly summarize selective preparation of CNMs that has a great impact on their photocatalytic performance. Then we provide an updated outline of advanced photocatalytic application of CNMs in addressing both environmental pollution and hydrogen energy crisis. The difference in the role of various CNMs play in the enhancement of photocatalytic performance is also discussed. Lastly, we discuss the limitations of CNMs applied in photocatalysis or even wider fields. We hope this review will project a fast developmental path with providing a wide view of recent preparation methods, applications, prospects and challenges.
361 citations
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TL;DR: A highly selective, colorimetric polynucleotide detection method based on mercaptoalkyloligonucleotide-modified gold nanoparticle probes is reported, which can detect about 10 femtomoles of an oligonucleotide.
Abstract: A highly selective, colorimetric polynucleotide detection method based on mercaptoalkyloligonucleotide-modified gold nanoparticle probes is reported. Introduction of a single-stranded target oligonucleotide (30 bases) into a solution containing the appropriate probes resulted in the formation of a polymeric network of nanoparticles with a concomitant red-to-pinkish/purple color change. Hybridization was facilitated by freezing and thawing of the solutions, and the denaturation of these hybrid materials showed transition temperatures over a narrow range that allowed differentiation of a variety of imperfect targets. Transfer of the hybridization mixture to a reverse-phase silica plate resulted in a blue color upon drying that could be detected visually. The unoptimized system can detect about 10 femtomoles of an oligonucleotide.
4,334 citations
TL;DR: The advent of AuNP as a sensory element provided a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.
Abstract: Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13
In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28
Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37
Figure 1
Physical properties of AuNPs and schematic illustration of an AuNP-based detection system.
In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.
3,879 citations
TL;DR: The observations suggest that catalytic activity arises from the altered electronic structure intrinsic to small gold nanoparticles, and that the use of 55-atom gold clusters may prove a viable route to the synthesis of robust gold catalysts suited to practical application.
Abstract: Supported gold nanoparticles have excited much interest owing to their unusual and somewhat unexpected catalytic properties1,2,3,4,5,6,7, but the origin of the catalytic activity is still not fully understood. Experimental work4 on gold particles supported on a titanium dioxide (110) single-crystal surface has established a striking size threshold effect associated with a metal-to-insulator transition, with gold particles catalytically active only if their diameters fall below ∼3.5 nm. However, the remarkable catalytic behaviour might also in part arise from strong electronic interaction between the gold and the titanium dioxide support2,3,5. In the case of industrially important selective oxidation reactions, explanation of the effectiveness of gold nanoparticle catalysts is complicated by the need for additives to drive the reaction5,7,8, and/or the presence of strong support interactions and incomplete understanding of their possible catalytic role1,2,3,5. Here we show that very small gold entities (∼1.4 nm) derived from 55-atom gold clusters and supported on inert materials are efficient and robust catalysts for the selective oxidation of styrene by dioxygen. We find a sharp size threshold in catalytic activity, in that particles with diameters of ∼2 nm and above are completely inactive. Our observations suggest that catalytic activity arises from the altered electronic structure intrinsic to small gold nanoparticles, and that the use of 55-atom gold clusters may prove a viable route to the synthesis of robust gold catalysts suited to practical application.
1,224 citations
TL;DR: In this paper, a new definition of the hydrogen bond is proposed, which emphasizes the need for evidence, and a list of criteria has been provided, and these can be used as evidence for hydrogen bond formation.
Abstract: The term "hydrogen bond" has been used in the literature for nearly a century now. While its importance has been realized by physicists, chemists, biologists, and material sci- entists, there has been a continual debate about what this term means. This debate has inten- sified following some important experimental results, especially in the last decade, which questioned the basis of the traditional view on hydrogen bonding. Most important among them are the direct experimental evidence for a partial covalent nature and the observation of a blue-shift in stretching frequency following X-HY hydrogen bond formation (XH being the hydrogen bond donor and Y being the hydrogen bond acceptor). Considering the recent experimental and theoretical advances, we have proposed a new definition of the hydrogen bond, which emphasizes the need for evidence. A list of criteria has been provided, and these can be used as evidence for the hydrogen bond formation. This list is followed by some char- acteristics that are observed in typical hydrogen-bonding environments.
809 citations
TL;DR: This paper is written to clear up the confusion over the validation requirements that are presented by each of the three sources, the International Conference on Harmonization (ICH), and the US Food and Drug Administration and United States Pharmacopeia.
765 citations