Aqueous Phase Synthesis Research Articles

Aqueous phase synthesis of 2-D copper nanosheets stabilized by organic moieties with enhanced photocatalytic and biological activity.

Copper nanosheets supported by organic ligands are significant for biological, electrical, and catalytic applications. The discovery that the coronavirus has a significantly reduced maximum survival period on copper surfaces has elevated the utility of copper nanomaterials. Here, we report a non-hazardous and inexpensive biological technique for forming copper nanosheets (Cu Nsts); synthesis of Cu Nsts has always been a challenge for researchers due to the significant problem of oxidation; in this research, we have successfully synthesized stable Cu Nsts by using Saussurea lappa root extract for the first time, the obtained Cu Nsts has a shiny black color with self-standing ability, the crystal structure of Cu nanosheets was determined using Powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM) revealed that copper nanoparticles grow and aggregates to form Cu Nsts. The surface morphology of Cu Nsts is clear evidence of their synthesis. These nanosheets were very proficient in the deduction of harmful dye (methylene blue); within 105 minutes, the degradation capacity of Cu nanosheets for methylene blue reached 93.493%. This remarkable property of Cu Nsts as a photocatalyst gives potential application for removing dyes from industrial wastewater. Cu Nsts showed excellent antioxidant and antibacterial activity. The Cu Nsts demonstrated potent inhibitory zones against E. coli, with inhibition zones measuring 39 mm. This research lays the foundations for purifying wastewater from harmful dyes and bacteria.

One-pot aqueous-phase synthesis of polyimides from typical monomers

One-pot aqueous-phase synthesis of polyimides (PIs) offers great economic and environmental benefits and improves the hydrolytic stability of the precursor (polyamic acid) obviously. However, this method is only suitable for the polymerization of very limited dianhydride and diamine monomers up to now. In this study, the most commonly used dianhydrides and diamines for the preparation of commercially available PI products were selected for one-pot aqueous-phase synthesis of various polyamic acid salts (PAAS). The effects of the structure of monomers, the reaction temperature and the adding process of the organic base on the polymerization reaction were explored by rotational rheology, nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. The polymerization products obtained via the aqueous-phase route show high molecular weight when the reaction conditions have been optimized. Various PI films prepared by the thermal imidization of corresponding PAAS demonstrate good optical transparency, excellent thermal stability, and outstanding mechanical and electrical properties. This work proposes the reaction mechanism of PAAS via one-pot aqueous-phase route and utilizes this novel polymerization strategy to synthesize high-molecular-weight PIs from typical aromatic dianhydride and diamine monomers.

In vivo tumor imaging and therapy based on near-infrared cadmium-free quantum dots

Near-infrared fluorescence imaging technology, which possesses superior advantages including real-time and fast imaging, high spatial and temporal resolution, and deep tissue penetration, shows great potential for tumor imaging in vivo and therapy. Ⅰ-Ⅲ-Ⅵ quantum dots exhibit high brightness, broad excitation, easily tunable emission wavelength and superior stability, and do not contain highly toxic heavy metal elements such as cadmium or lead. These advantages make Ⅰ-Ⅲ-Ⅵ quantum dots attract widespread attention in biomedical field. This review summarizes the recent advances in the controlled synthesis of Ⅰ-Ⅲ-Ⅵ quantum dots and their applications in tumor imaging in vivo and therapy. Firstly, the organic-phase and aqueous-phase synthesis of Ⅰ-Ⅲ-Ⅵ quantum dots as well as the strategies for regulating the near-infrared photoluminescence are briefly introduced; secondly, representative biomedical applications of near-infrared-emitting cadmium-free quantum dots including early diagnosis of tumor, lymphatic imaging, drug delivery, photothermal and photodynamic therapy are emphatically discussed; lastly, perspectives on the future directions of developing quantum dots for biomedical application and the faced challenges are discussed. This paper may provide guidance and reference for further research and clinical translation of cadmium-free quantum dots in tumor diagnosis and treatment.

Aqueous and Solid Phase Synthesis of [Ni(Me3en)(acac)]BPh4 and its Solvatochromic Properties: A Laboratory Experiment for First-Year Undergraduates

Aqueous and Solid Phase Synthesis of [Ni(Me₃en)(acac)]BPh₄ and its Solvatochromic Properties: A Laboratory Experiment for First-Year Undergraduates

A Novel Enhanced-Fluorescent Probe Based on DHLA-Stabilized Red-Emitting Copper Nanoclusters for Methimazole Detection Via Aggregation-Induced Emission Effect.

Herein, an aqueous phase synthesis approach was presented for the fabrication of copper nanoclusters (Cu NCs) with aggregation-induced emission (AIE) property, utilizing lipoic acid and NaBH4 as ligands and reducing agent, respectively. The as-synthesized Cu NCs exhibit an average size of 3.0 ± 0.2nm and demonstrate strong solid-state fluorescence upon excitation with UV light. However, when dissolved in water, no observable fluorescent emission is detected in the aqueous solution of Cu NCs. Remarkably, the addition of Methimazole induced a significant red fluorescence from the aqueous solution of Cu NCs. This unexpected phenomenon can be ascribed to the aggregation of negatively charged Cu NCs caused by electrostatic interaction with positively charged imidazole groups in Methimazole, resulting in enhanced fluorescence through AIE mechanism. Therefore, there exists an excellent linear correlation between the fluorescent intensities of Cu NCs aqueous solution and the concentration of Methimazole within a range of 0.1-1.5 mM with a low limit of detection of 82.2 µM. Importantly, the designed enhanced-fluorescent nanoprobe based on Cu NCs exhibits satisfactory performance in assaying commercially available Methimazole tablets, demonstrating its exceptional sensitivity, reliability, and accuracy.

Lipase in-situ immobilized in covalent organic framework: Enzymatic properties and application in the preparation of 1, 3-dioleoyl-2-palmitoylglycerol

In this study, the critical importance of designing an appropriate immobilized carrier and method for free lipase to ensure exceptional biological catalytic activity and stability was emphasized. Covalent organic frameworks (COF-1) were synthesized as a novel porous carrier with an azine structure (-CN-NC-) through the condensation of hydrazine hydrate and benzene-1,3,5-tricarbaldehyde at room temperature. Simultaneously, Rhizomucor miehei lipase (RML) was immobilized within the COF-1 carrier using an in-situ aqueous phase method. Characterization of the carrier and RML@COF-1 and evaluation of the lipase properties of RML and RML@COF-1 through p-Nitrophenyl palmitate hydrolysis were conducted. Additionally, application in the synthesis of 1, 3-dioleoyl-2-palmitoylglycerol (OPO) was explored. The results showed that RML@COF-1 exhibited a high enzymatic loading of 285.4 mg/g. Under 60℃ conditions, the activity of RML@COF-1 was 2.31 times higher than that of free RML, and RML@COF-1 retained 77.25% of its original activity after 10 cycles of repeated use, indicating its excellent thermal stability and repeatability. Under the optimal conditions (10%, 1:8 PPP/OA, 45℃, 5 h), the yield of OPO reached 47.35%, showcasing the promising application prospects of the novel immobilized enzyme synthesized via in-situ aqueous phase synthesis for OPO preparation.

Ionic Liquid-Mediated Dynamic Polymerization for Facile Aqueous-Phase Synthesis of Enzyme-Covalent Organic Framework Biocatalysts.

Utilizing covalent organic framework (COF) as a hypotoxic and porous scaffold to encapsulate enzyme (enzyme@COF) has inspired numerous interests at the intersection of chemistry, materials, and biological science. In this study, we report a convenient scheme for one-step, aqueous-phase synthesis of highly crystalline enzyme@COF biocatalysts. This facile approach relies on an ionic liquid (2 μL of imidazolium ionic liquid)-mediated dynamic polymerization mechanism, which can facilitate the in situ assembly of enzyme@COF under mild conditions. This green strategy is adaptive to synthesize different biocatalysts with highly crystalline COF "exoskeleton", as well evidenced by the low-dose cryo-EM and other characterizations. Attributing to the rigorous sieving effect of crystalline COF pore, the hosted lipase shows non-native selectivity for aliphatic acid hydrolysis. In addition, the highly crystalline linkage affords COF "exoskeleton" with higher photocatalytic activity for in situ production of H2 O2 , enabling us to construct a self-cascading photo-enzyme coupled reactor for pollutants degradation, with a 2.63-fold degradation rate as the poorly crystalline photo-enzyme reactor. This work showcases the great potentials of employing green and trace amounts of ionic liquid for one-step synthesis of crystalline enzyme@COF biocatalysts, and emphasizes the feasibility of diversifying enzyme functions by integrating the reticular chemistry of a COF.

Enhancing orange-red emission by doping/codoping CsPb2Br5 with cations through a room-temperature aqueous-phase synthesis

The facile room-temperature aqueous phase approach for synthesis of orange-red emissive cation-doped and codoped CsPb2Br5 with enhanced photoluminescence performance and stability.

Water-dispersible fluorescent COFs disturb lysosomal autophagy to boost cascading enzymatic chemodynamic-starvation therapy.

Cascading enzymatic therapy is a promising approach in cancer treatment. However, its effectiveness is often hindered by enzyme inactivation, limited exposure of active sites, cancer cell self-protection mechanisms such as autophagy, and non-specific toxicity, which can lead to treatment failure. To address these challenges, we used a low-temperature aqueous-phase synthesis method to create semi-crystalline, water-dispersible fluorescent COF nanospheres. These nanospheres can stably load glucose oxidase (GOx) and ultrafine Fe2O3 nanozymes, allowing for convenient coating with tumor cell membranes to form a uniform tumor-targeted cascading enzymatic nanosystem (CFGM). This system promotes a cycle of tumor glucose depletion, reactive oxygen species (ROS) generation, and oxygen production, facilitating tumor-targeted starvation therapy (ST) and chemodynamic therapy (CDT). Notably, the semi-crystalline COF carrier within this system can degrade slowly under mildly acidic conditions, forming large aggregates that damage lysosomes and disrupt lysosomal autophagy, thereby eliminating the autophagy protection of cancer cells activated by the combined ST. This synergistic approach enhances the catalytic inhibition of tumors. Our research thus provides an alternative COF-based platform and strategy for effective cancer treatment.

Physically Exfoliating 2D Materials: A Versatile Combination of Different Materials into a Layered Structure.

Improving the properties of the existing two-dimensional (2D) materials is a major concern for many researchers today. Synergistic coupling of single-phase 2D material species with secondary functional materials has resulted in 2D nanohybrids with significantly enhanced properties beyond the sum of their individual components. In particular, nanohybrids created by alternatingly integrating different material species in the confined 2D nanometer regime have the potential to meet the needs of a wide variety of applications, particularly the many important energy-related applications that are of interest. However, scaling up production of 2D nanohybrids is still challenging, which is a major barrier to their practical application. Delamination and exfoliation by physical means separate the weakly bound 2D nanosheets into kinetically stable single- or few-layers. Herein, we provide a concise overview of recent achievements in the physical exfoliation-based fabrication of 2D nanohybrids featuring controlled heterolayered structures. Several strategies to efficiently produce heterolayered 2D nanohybrids in large quantities are described, such as (i) coexfoliation of different 2D species, (ii) aqueous-phase synthesis, and (iii) gas-phase synthesis. The versatility of the 2D nanohybrids was also illustrated by remarkable research examples, especially in energy-related applications.

Synergistic effect of silanols in mesopores leading to unexpected catalysis of dendritic mesoporous silica particles in the aqueous-phase synthesis of 5-hydroxymethylfurfural from fructose

Synthesis of 5-hydroxymethylfurfural (5-HMF) from fructose in water over acids catalysts usually produces unsatisfactorily low yield and selectivity due to inevitable side reactions, i.e., rehydration and condensation. Unprecedentedly, these complications in the aqueous phase synthesis of 5-HMF could be overcome by dendritic mesoporous silica particles (DMSNs). In the hydrothermal reactions of fructose, it was discovered that the synergy of silanols and mesopores transformed seemingly inert DMSNs into active catalysts, leading to a fructose conversion and 5-HMF yield of over 90%. The silanols on DMSNs offered weak Brønsted acid sites for catalyzing the dehydration of fructose to 5-HMF, while undesired reactions were substantially prohibited. The presence of glucose in the reaction suggests that fructose converts to 5-HMF via the acyclic route, and the competing reaction is indeed the isomerization. As revealed experimentally, mesopores full of silanols promoted the conversion of fructose to 5-HMF, but mesopores with a few silanols were relatively hydrophobic, offering a preferential partitioning of 5-HMF in mesopores of DMSNs. DFT analysis theoretically supported that in the presence of silanols, transforming fructose to 5-HMF is thermodynamically more favorable than the isomerization of fructose to glucose.

Green reduction and uniform assembly of silver nanoparticles on polydopamine functionalized sulfur-doped graphitic carbon nitride nanosheets for highly sensitive H2O2 detection via nonenzymatic approach

In this study, we demonstrate a new strategy to fabricate an enzyme-free hydrogen peroxide (H2O2) sensor electrode based on silver nanoparticles (AgNPs) decorated polydopamine/sulfur-doped graphitic carbon nanocomposite (denoted as AgNPs@PDA/S-g-C3N4). The S-g-C3N4 nanosheets are derived from the pyrolysis of trithiocyanouric acid, followed by thermal exfoliation. A mussel-inspired PDA nanolayer enhances the solubility and high dispersion of S-g-C3N4 nanosheets and AgNPs in aqueous phase synthesis. The amine and catecholic functional groups of PDA are the major nucleation sites for Ag+ ions adsorption and ascorbic acid was further used as a green reducing agent for the growth of AgNPs. PDA adhesion layer can effectively connect the AgNPs and S-g-C3N4 nanosheets via electrostatic interaction to increase the stability and biocompatibility of the ternary composite structure. Various spectroscopy and microscopy techniques confirmed the formation of AgNPs@PDA/S-g-C3N4 nanocomposite. Our AgNPs@PDA/S-g-C3N4 nanocomposite fabricated disposable sensor exhibited outstanding sensing ability to H2O2 reduction at −0.65 V (vs. Ag/AgCl), which is confirmed through an amperometric detection method. The sensor exhibits rapid response (2 s) to H2O2 sensing with high sensitivity (1020 μA mM−1 cm−2), wide detection range (0.002–23 mM) and low limit of detection of 0.086 μM. The practicality of the H2O2 sensor was evaluated with commercial milk and mouthwash samples, which retained satisfactory recoveries. Thus, our results indicate that the PDA functionalization not only enhances the S-g-C3N4 solubility but also increases the interfacial charge transport in AgNPs@PDA/S-g-C3N4 nanocomposite material which develops a potential sensing method for nonenzymatic H2O2 sensor. Due to the effective surface modification strategies, such as PDA nanocoating and AgNPs deposition, the exfoliated S-g-C3N4 nanosheets gained excellent electrochemical properties, facilitating potential candidates in electrochemical applications.

Unraveling ultrasonic assisted aqueous-phase one-step synthesis of porous PtPdCu nanodendrites for methanol oxidation with a CO-poisoning tolerance

The tailored design of tri-metallic Pt-based porous nanodendrites (PNDs) is crucial for green energy production technologies, ascribed to their fancy features, great surface areas, accessible active sites, and stability against aggregation. However, their aqueous-phase one-step synthesis at room temperature remains a daunting challenge. Herein, we present a facile, green, and template-free approach for the one-step synthesis of PtPdCu PNDs by ultrasonication of an aqueous solution of metal salts and Pluronic F127 at 25 ℃, based on natural isolation among nucleation and growth step driven by the disparate reduction kinetics of the metals and acoustic cavitation mechanism of ultrasonic waves. The resultant PtPdCu PNDs formed in a spatial nanodendritic shape with a dense array of branches, open corners, interconnected pores, high surface area (46.9 m2/g), and high Cu content (21 %). The methanol oxidation reaction (MOR) mass activity of PtPdCu PNDs (3.66 mA/µgPt) is 1.45, 2.73, and 2.83 times higher than those of PtPd PNDs, PtCu PNDs, and commercial Pt/C, respectively based on equivalent Pt mass, which is superior to previous PtPdCu catalysts reported elsewhere, besides a superior durability and CO-poisoning tolerance. This study may pave the way for the controlled fabrication of ternary Pt-based PNDs for various electrocatalytic applications.

Engineering of Thermoelectric Composites Based on Silver Selenide in Aqueous Solution and Ambient Temperature.

The direct, solid state, and reversible conversion between heat and electricity using thermoelectric devices finds numerous potential uses, especially around room temperature. However, the relatively high material processing cost limits their real applications. Silver selenide (Ag2Se) is one of the very few n-type thermoelectric (TE) materials for room-temperature applications. Herein, we report a room temperature, fast, and aqueous-phase synthesis approach to produce Ag2Se, which can be extended to other metal chalcogenides. These materials reach TE figures of merit (zT) of up to 0.76 at 380 K. To improve these values, bismuth sulfide (Bi2S3) particles also prepared in an aqueous solution are incorporated into the Ag2Se matrix. In this way, a series of Ag2Se/Bi2S3 composites with Bi2S3 wt % of 0.5, 1.0, and 1.5 are prepared by solution blending and hot-press sintering. The presence of Bi2S3 significantly improves the Seebeck coefficient and power factor while at the same time decreasing the thermal conductivity with no apparent drop in electrical conductivity. Thus, a maximum zT value of 0.96 is achieved in the composites with 1.0 wt % Bi2S3 at 370 K. Furthermore, a high average zT value (zTave) of 0.93 in the 300-390 K range is demonstrated.

A Robust Metal-Organic Framework with Scalable Synthesis and Optimal Adsorption and Desorption for Energy-Efficient Ethylene Purification.

Adsorptive separation is an energy-efficient alternative, but its advancement has been hindered by the challenge of industrially potential adsorbents development. Herein, a novel ultra-microporous metal-organic framework ZU-901 is designed that satisfies the basic criteria raised by ethylene/ethane (C2 H4 /C2 H6 ) pressure swing adsorption (PSA). ZU-901 exhibits an "S" shaped C2 H4 curve with high sorbent selection parameter (65) and could be mildly regenerated. Through green aqueous-phase synthesis, ZU-901 is easily scalable with 99 % yield, and it is stable in water, acid, basic solutions and cycling breakthrough experiments. Polymer-grade C2 H4 (99.51 %) could be obtained via a simulating two-bed PSA process, and the corresponding energy consumption is only 1/10 of that of simulating cryogenic distillation. Our work has demonstrated the great potential of pore engineering in designing porous materials with desired adsorption and desorption behavior to implement an efficient PSA process.

A facile aqueous-phase synthesis of Co-based nanostructures composed of cobalt hydroxide and cobalt oxide for enhanced photocatalytic activity of dye-sensitized H2 production

Transition metal catalysts are more cost competitive than noble metal catalysts, but there is a drawback in that catalyst activity must be greatly increased for industrial use. In this research, we report the formation of cobalt-based mixture nanostructures composed of cobalt hydroxide having high photoelectron attracting force, electron transfer ability, and easy access and cobalt oxide having facile charge transfer based on the interchangeability to significantly increase the activity of transition metal-based catalysts. Furthermore, the Co-based nanostructures (CNS) were easily synthesized via an aqueous-phase synthesis, and the molar ratio of α-Co(OH)2/Co3O4 was controlled by simply varying the reaction time. Due to the well-mixed structure of α-Co(OH)2 and Co3O4, which could have a beneficial effect on each other in a photocatalytic reaction, the CNS exhibited 11 times superior hydrogen production than the commercial α-Co(OH)2 in a photocatalytic hydrogen production reaction.

Highly Sensitive Fiber-Optic SPR Urea Sensor Based on ZIF-8/Urease

A highly-sensitive fiber-optic urea sensor was designed and experimentally demonstrated based on surface plasmon resonance (SPR) effect and metal-organic zeolite framework (ZIF-8)/urease modification. The SPR effect was excited by plating gold film on the thin core fiber in multimode-thin core-multimode fiber structure, which behaved high refractive index sensitivity. The ZIF-8/urease composite film was grown on the gold film by rapid aqueous phase synthesis method, in which the ZIF-8 could immobilize more urease and made urease and urea fully contact. Since the urease catalyzed urea hydrolysis would change the refractive index, the measurement of urea concentration was realized with high sensitivity and good selectivity. Experimental results showed that the urea measurement sensitivity of the proposed sensor could reach 6 nm/mM within the concentration range of 1-7 mM, which has great application potential in the field of human health monitoring.

A simple microplasma reactor paired with indirect ultrasonication for aqueous phase synthesis of cobalt oxide nanoparticles.

Cobalt oxide nanoparticles are widely used owing to their distinct properties such as their larger surface area, enhanced reactivity, and their superior optical, electronic, and magnetic properties when compared to their bulk counterpart. The nanoparticles are preferably synthesized using a bottom-up approach in liquid as it allows the particle size to be more precisely controlled. In this study, we employed microplasma to synthesize Co3O4 nanoparticles because it eliminates harmful reducing agents and is efficient and cost-effective. Microplasma reactors are equipped with copper wire electrodes to generate plasma and are simple to configure. The product was characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The experimental parameters that were varied for the synthesis were: with or without stirring, with or without indirect ultrasonication, and with or without capping agents (urea and sucrose). The results showed that the microplasma enabled Co3O4 nanoparticles to be successfully synthesized, with particle sizes of 10.9-17.7 nm, depending on the synthesis conditions.

Aqueous phase synthesis of ion-imprinted cryogel for paper-based colorimetric detection of As(V) with high selectivity.

A novel hydrophilic As(V) ion-imprinted cryogel (IIC) was green prepared by cryogelation in aqueous environment which was coincident with the adsorption condition and can improve the specific recognition performance. The methacrylamido propyl trimethyl ammonium chloride (MPTAC) was selected as the functional monomer and the saturated adsorption capacity of the prepared IIC and NIC were 55.0mg/g and 29.4mg/g, and with high imprinting factor of 1.87. Additionally, the prepared IIC showed admirable reusability and highselectivity, and the recovery was in the range 81.2-97.9% with RSD range of 1.9-4.3%, which was similar to the value obtained by hydride generationatomic absorption spectrometry. IIC can be used as solid material for colorimetric detection at the ultraviolet wavelength of 858nm without color interference of material matrix, in the range 5-200μg/L (R2 = 0.990)with a detection limit of 0.970 µg/L. Obviously, this synthetic strategy provides a simple, efficient, and green method for the preparation of water-compatible ion-imprinted polymers providingselectiveseparation and detection of trace As(V) in real complex samples.

An effective one-step aqueous-phase synthesis of finely controllable Ag nanorods with tunable short aspect ratios and electronic dynamics properties

Ag nanorods with finely controllable aspect ratios (especially 1–5) were synthesized in high yield via an effective one-step aqueous-phase method, in which the longitudinal plasmon modes in visible and infrared regions of short Ag nanorods were well adjustable. Meanwhile, excitation wavelength- and excitation fluence-dependent electronic dynamics of short Ag nanorods were acquired and were found to be regular. This suggested that short Ag nanorods would have great potential in plasmonic and photoelectronic fields.