Deep eutectic solvent-assisted facile synthesis of copper hydroxide nitrate nanosheets as recyclable enzyme-mimicking colorimetric sensor of biothiols.

In the quest for alternative products that would conquer natural enzyme drawbacks, enzyme-like nanomaterials with controllable morphology, high catalytic activity, excellent stability, and reusability have gained extensive attention in recent years. Herein, a simple and versatile strategy based on basic deep eutectic solvents was used to create layered copper hydroxide nitrate (Cu2(OH)3NO3) with a well-structured nanosheet-like morphology. The present nanosheets exhibited extraordinary oxidase and peroxidase-like activity. More importantly, these nanosheets have shown the ability to operate at low and high temperatures with appreciable stability and multiple reusabilities. Based on inhibiting the oxidase-like activity of the prepared Cu2(OH)3NO3, we designed a colorimetric sensing technique with a high-efficiency detection of biothiols in serum samples. Because of the simplicity and low-cost fabrication approach, our findings would be beneficial to the artificial enzyme research community as another facile and green tactics to fabricate heterogeneous artificial enzymes. Graphical abstract.

Cadmium cobaltite nanosheets synthesized in basic deep eutectic solvents with oxidase-like, peroxidase-like, and catalase-like activities and application in the colorimetric assay of glucose.

Cadmium cobaltite (CdCo2O4) nanosheets were ultra-fast synthesized based on a new basic deep eutectic solvent (DES) which served simultaneously as reactant, solvents, and template. Interestingly, the nanosheets were found to exhibit triple-enzyme mimetic activities including oxidase-like activity, peroxidase-like activity, and catalase-like activity. Their catalytic activity followed the typical Michaelis-Menten kinetics, and high affinity for H2O2 and TMB was observed. Based on the superior peroxidase-like catalytic activity of CdCo2O4 nanosheets, a highly sensitive and selective colorimetric strategy for the determination of glucose was established. Under optimized conditions, the absorbance at 652 nm increases linearly in the 0.5 to 100 µM concentration range, and the limit of detection is 0.13 µM (S/N = 3). Finally, the method was successfully used for determination of glucose in serum samples. Graphical abstract The CdCo2O4 nanosheets were ultra-fast synthesized with a basic deep eutectic solvent, and this nanomaterial exhibited triple-enzyme mimetic activities: oxidase-like activity, peroxidase-like activity, and catalase-like activity. Based on the peroxidase-like activity, a highly sensitive and selective glucose colorimetric sensor was established.

Effective extraction of flavonoids from Lycium barbarum L. fruits by deep eutectic solvents-based ultrasound-assisted extraction.

The efficient extraction of natural products from biomass is deemed an essential area of interest using green technology in the pharmaceutical and biochemical industries. In recent years, deep eutectic solvents (DESs) have been paying broad interest as compatible, safe, and inexpensive solvents. In this study, we addressed, for the first time, to give a fruitful illustration to extract bioactive compounds from favourite Lycium barbarum L. fruits using DESs as green designer solvents, and displaying the tuneability of DESs to extract bioactive compounds from biomass efficiently. Among the studied DESs, the 1 : 2 M mixture of choline chloride and p-toluene sulfonic acid (DESs-6) with an ultra-sound assisted extraction (UAE) method was more efficient to get high extraction yields of flavonoids including myricetin (57.2 mg/g), morin (12.7 mg/g), and rutin (9.1 mg/g) in net DESs. The resulting extraction method in which 50 mg of sample powder was extracted by UAE for 1.5 h using DESs-6 was found to be a more efficient process than conventional extraction methods such as heating plus stirring. Operational conditions including the extractant to sample solid ratio, the effect of water content, the effect of temperature, recycling of DESs, and the effect of ultra-sound irradiation time were investigated. The proposed DESs based extraction procedure attained recovery for flavonoids were in the range 75.6%-96.9%. Therefore, p-toluenesulfonic acid-based DESs may have strong potential as promising materials for the green and efficient extraction of pharmaceutical compounds from other plants or fruits.

Label-free fluorescence imaging of cytochrome c in living systems and anti-cancer drug screening with nitrogen doped carbon quantum dots.

As an important biomarker for the early stage of apoptosis, cytochrome c (Cyt c) has been recognized as a key component of the intrinsic apoptotic pathway. Fluorescence imaging tools enabling detection of Cyt c in apoptotic signaling have been rarely explored, though they are critical for cell biology and clinical theranostics. Here, we designed a novel label-free N-doped carbon dot (N-doped CD)-based nanosensor that enables fluorescence activation imaging of Cyt c release in cell apoptosis. The inner filter effect of Cyt c towards N-doped CDs enabled quantitative Cyt c measurement. The nanosensor exhibited high sensitivity and selectivity, rapid response, good cell-membrane permeability and low cytotoxicity. All these features are favorable for in situ visualization of Cyt c for apoptosis research. Notably, the developed nanosensor was successfully applied to monitor intracellular release of Cyt c, and to visualize Cyt c in living zebrafish for the first time. Moreover, it also provided a viable platform for cell-based screening of apoptosis-inducing compounds. In virtue of these advantages and potential, the developed assay not only holds great significance for the better understanding of certain diseases at the cellular level, but also provides an invaluable platform for apoptotic studies and screening of anti-cancer drugs toward drug development.

Hybrid Deep Eutectic Solvents with Flexible Hydrogen-Bonded Supramolecular Networks for Highly Efficient Uptake of NH3.

Serious environmental concerns have led to a great demand for efficient uptake of NH3 by solvents. However, traditional aqueous absorbents have many shortcomings and efforts to use ionic liquids have met with limited success. A hybrid deep eutectic solvents (DESs) designed with a flexible hydrogen-bonded supramolecular network exhibits both exceptional NH3 uptake capacity and superior desorption-regeneration performance, along with superb NH3 /CO2 selectivity and environmental merit. Elucidated by molecular dynamic simulations and spectroscopic analysis, the abundant hydrogen-bonding sites in the hybrid DESs bind every atom of the NH3 molecule and enable strong physical reversible solvation, whereas the multiple interactions among the hybrid components create a flexible hydrogen-bonded supramolecular network and allow for solvent-unbreaking absorption to ensure the full participation of the solvent and process stability. A mass solubility of NH3 up to 0.13 g g-1 was achieved at 313 K and 101 kPa by the hybrid DES choline chloride/resorcinol/glycerol (1:3:5), which is higher than all reported ionic liquids and ordinary DESs. Moreover, the performance remained the same after ten absorption-desorption cycles and the DESs could be easily regenerated.

Graphene Oxide/Ag Nanoparticles Cooperated with Simvastatin as a High Sensitive X-Ray Computed Tomography Imaging Agent for Diagnosis of Renal Dysfunctions.

Graphene oxides (GO) are attracting much attention in the diagnosis and therapy of the subcutaneous tumor as a novel biomaterial, but its diagnosis to tissue dysfunction is yet to be found. Here, a novel application of GO for diagnosis of renal dysfunction via contrast-enhanced computed tomography (CT) is proposed. In order to serve as contrast-enhanced agent, Ag nanoparticles (AgNPs) are composited on the surface of GO to promote its X-ray absorption, and then simvastatin is coinjected for eliminating in vivo toxicity induced by AgNPs. It is found that GO/AgNPs can enhance the imaging of CT into the lung, liver, and kidney of mice for a long circulation time (≈24 h) and a safety profile in vivo in the presence of simvastatin. Interestingly, the lower dose of GO/AgNPs (≈0.5 mg per kg bw) shows an excellent performance for CT imaging of renal perfusion, and visually exhibits the right renal dysfunction in model mice. Hence, this work suggests that graphene nanoparticles will play a vital role for the future medical translational development including drug carrier, biosensing, and disease therapy.