Molecular Dynamics Study on Au/Fe3O4 Nanocomposites and Their Surface Function toward Amino Acids

Development of highly efficient magnetically recyclable Cu2+/Cu0 nano-photocatalyst and its enhanced catalytic performance for the degradation of organic contaminations

This work reports the successful functionalization of l-proline on the surface of superparamagnetic iron oxide nanoparticles (SPION) synthesized via a simple, cost-effective hydrothermal method. Moreover, the chemical attachment of Cu²⁺/Cu⁰ nanoparticles on the surface of SPION@l-proline was done by an in-situ deposition method. The developed nano-photocatalyst was characterized in detail by XRD, FT-IR, XPS, FE-SEM, TEM, EDX, BET, TGA, and VSM. XRD of SPION@l-proline-Cu reveals peaks of both SPION and copper nanoparticles which confirms the formation of nanophotocatalyst. TGA demonstrates a major weight loss between 250 and 310 °C due to l-proline which ensures the successful immobilization of SPION on the surface of l-proline. The band energy at 932 eV suggests a complete reduction of Cu²⁺ ion to Cu⁰ metal on the surface of SPION@l-proline nanocomposite as confirmed by the XPS technique. Under UV light irradiation, the photocatalytic reduction performance of the developed Cu²⁺ metal ion-based and Cu⁰ nanoparticle-based magnetic nano-photocatalysts was demonstrated and compared for the first time for the photocatalytic reduction of 4-NP, 4-NA, NB, MO, MB, and CR. The results show that Cu⁰-based magnetic nanophotocatalyst has slightly enhanced catalytic activity. Furthermore, solar-driven photocatalytic degradation of CR azo dye by synthesized nano-photocatalyst was also investigated, with a 95 % degradation efficiency in just 40 min. The developed magnetic nano-photocatalyst can easily be separated by using an external magnet due to the superparamagnetic nature of core material (SPION) at room temperature as confirmed from VSM and can be reused for multiple cycles without losing considerable catalytic activity. Because of its high photocatalytic efficiency, cost-effectiveness, good magnetic separation performance, non-toxicity, and strong thermal and chemical stabilities, Cu²⁺/Cu⁰-based magnetic nano-photocatalyst has potential application in wastewater treatment.

Noble-Nanoparticle-Decorated Ti3C2T x MXenes for Highly Sensitive Volatile Organic Compound Detection

Two-dimensional transition-metal carbides and nitrides (MXenes) have been regarded as promising sensing materials because of their high surface-to-volume ratios and outstanding electronic, optical, and mechanical properties with versatile transition-metal and surface chemistries. However, weak gas-molecule adsorption of MXenes poses a serious limitation to their sensitivity and selectivity, particularly for trace amounts of volatile organic compounds (VOCs) at room temperature. To deal with these issues, Au-decorated MXenes are synthesized by a facile solution mixing method for room-temperature sensing of a wide variety of oxygen-based and hydrocarbon-based VOCs. Dynamic sensing experiments reveal that optimal decoration of Au nanoparticles (NPs) on Ti₃C₂T _x MXene significantly elevates the response and selectivity of the flexible sensors, especially in detecting formaldehyde. Au-Ti₃C₂T _x gas sensors exhibited an extremely low limit of detection of 92 ppb for formaldehyde at room temperature. Au-Ti₃C₂T _x provides reliable gas response, low noise level, ultrahigh signal-to-noise ratio, high selectivity, as well as parts per billion level of formaldehyde detection. The prominent mechanism for Au-Ti₃C₂T _x in sensing formaldehyde is elucidated theoretically from density functional theory simulations. The results presented here strongly suggest that decorating noble-metal NPs on MXenes is a feasible strategy for the development of next-generation ultrasensitive sensors for Internet of Things.

Surface Functionalization of Layered Molybdenum Disulfide for the Selective Detection of Volatile Organic Compounds at Room Temperature

Semiconducting two-dimensional (2D) transition-metal dichalcogenides (TMDCs) are considered promising sensing materials due to the high surface-to-volume ratio and active sensing sites. However, the reported strategies for 2D TMDCs toward sensing of volatile organic compounds (VOCs) present with some drawbacks. These include high operation temperatures, low gas response, and complex fabrication, limiting the development of room-temperature gas sensors. In this study, 2D MoS₂ nanoflakes were prepared by liquid-phase exfoliation, and their surface was functionalized with Au nanoparticles (NPs) through a facile solution mixing method. MoS₂ decorated with Au NPs with an average size of 10 nm was used as a material platform for an electrochemical sensor to detect a wide variety of VOCs at room temperature. Through dynamic sensing tests, the enhancement of gas-sensing performance in terms of response and selectivity, especially in detecting oxygen-based VOCs (acetone, ethanol, and 2-propanol), was demonstrated. After Au functionalization, the response of the gas sensor to acetone improved by 131% (changing from 13.7% for pristine MoS₂ to 31.6% for MoS₂-Au(0.5)). Sensing tests under various relative humidity values (10-80%), bending or long-term conditions, indicated the sound robustness and flexibility of the sensor. Density functional theory simulations suggested that the adsorption energy of VOC molecules on MoS₂-Au is significantly higher than that on pristine MoS₂, contributing to the gas-sensing enhancement; a VOC-sensing mechanism for Au-decorated MoS₂ nanoflakes was proposed for the first time for the highly sensitive and selective detection of oxygen-based VOCs.

Preferential adsorption of flavonoids from peanut shell by amino-modified Fe3 O4 nanoparticles (MNP-NH2 )

BACKGROUND

The highly selective capture of individual components of complex systems such as Chinese medicine extracts is a great challenge. With the rapid development of nanoscience, magnetic materials have attracted increased attention as suitable candidates for use in drug transport vehicles.

RESULTS

In this work, amino-modified Fe₃ O₄ nanoparticles (MNP-NH₂ ) have been synthesized and successfully used to selectively isolate luteolin, a type of flavonoid, from peanut shell, coupled with high-performance liquid chromatography. MNP-NH₂ were characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometer analysis, which showed that the amino functional groups were successfully bound to the surface of the magnetic particles. Adsorption of six different flavonoids by MNP-NH₂ showed that the mechanism of adsorption was related to the number of ortho-phenolic hydroxyl groups. The optimized adsorption conditions were extraction for 40 min at 30 °C by single-factor experiments and the final elution conditions were determined to be 5 mL of 20% glacial acetic acid (methanol:water = 60:40) and ultrasonication for 40 min by L9 (3⁴ ) orthogonal test.

CONCLUSION

Based on these findings, we first created a method for separating luteolin from peanut shell extract by MNP-NH₂ . This newly developed magnetic method of extracting chemical compounds from herbal foodstuffs and medicines provides new ideas for the utilization of a cash crop. © 2018 Society of Chemical Industry.

Iron oxide nanoparticles - In vivo/in vitro biomedical applications and in silico studies

The review presents a broad overview of the biomedical applications of surface functionalized iron oxide nanoparticles (IONPs) as magnetic resonance imaging (MRI) agents for sensitive and precise diagnosis tool and synergistic combination with other imaging modalities. Then, the recent progress in therapeutic applications, such as hyperthermia is discussed and the available toxicity data of magnetic nanoparticles concerning in vitro and in vivo biomedical applications are addressed. This review also presents the available computer models using molecular dynamics (MD), Monte Carlo (MC) and density functional theory (DFT), as a basis for a complete understanding of the behaviour and morphology of functionalized IONPs, for improving NPs surface design and expanding the potential applications in nanomedicine.

Synthesis of hierarchical nanosheet-assembled V2O5 microflowers with high sensing properties towards amines

Hierarchical three-dimensional nanosheet-assembled vanadium pentoxide (V₂O₅) microflowers are successfully synthesized by a hydrothermal method, followed by a high-temperature sintering treatment.

Theoretical simulations of structure and X-ray photoelectron spectra of glycine and diglycine adsorbed on Cu(110)

The study of adsorption of glycine and glycylglycine (or diglycine) on a copper surface is an important step for the comprehension of mechanisms that determine the stability of biological functionalizers on metal substrates. These two molecules can be considered as prototypes and essential models to investigate, theoretically and experimentally, the adaptability of flexible short peptide chains to a definite interface. In this work, we have improved and updated earlier molecular dynamics simulations by including reactivity of the various species and the comparison of ab initio calculated C, N, and O core photoelectron chemical shifts with the ones found in previous studies. New diglycine-copper bonding is predicted, and the results of the chemical shift analysis are, in all cases, fully compatible with structural information obtained through experimental measurements. Moreover, we have found that the process of proton transfer, which is fundamental in the dynamics of amino acids and peptides, occurs mainly by intermolecular interaction between the first and second layer of the adsorbate.