Host-guest supramolecular assembly directing beta-cyclodextrin based nanocrystals towards their robust performances

Cyclodextrin modified green synthesized graphene oxide@iron nanoparticle composites for enhanced removal of oxytetracycline

The presence of residual antibiotics will lead to potential environmental risks. Here cyclodextrins (CDs) were successfully used to modify graphene-based iron nanoparticles (GO@Fe NPs) to enhance the absorption of oxytetracycline hydrochloride (OTC). The removal of OTC decreased in the order: γCD-GO@Fe NPs > βCD-GO@Fe NPs > αCD-GO@Fe NPs > GO@Fe NPs, with better performance than that of bare GO and Fe NPs. Characterization techniques were applied to better understand how CDs impact the structure of GO@Fe NPs and improve removal performance. Raman and X-ray diffraction analysis showed that GO acted as a carrier to support Fe NPs within the grafted cyclodextrin, where GO also participated in the removal process. Cyclodextrin modified GO@Fe NPs had relatively small particle sizes (15 nm), with a high surface area (61.7 m² · g^-1). X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy suggested that cyclodextrin acted as both a stabilizing and capping agent during green synthesis, which could protect the reactivity of Fe NPs and simultaneously reduce aggregation. A potential synthesis mechanism of cyclodextrins modified composites was also proposed, and subsequent wastewater testing indicated that γCD-GO@Fe NPs had high potential for practical applications.

Caffeine-Cyclodextrin Complexes as Solids: Synthesis, Biological and Physicochemical Characterization

Mechanochemical and in-solution synthesis of caffeine complexes with α-, β-, and γ-cyclodextrins was optimized. It was found that short-duration, low-energy cogrinding, and evaporation (instead of freeze-drying) are effective methods for the formation and isolation of these complexes. The products obtained, their pure components, and their mixtures were examined by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), FT-IR and Raman spectroscopy. Moreover, molecular modeling provided an improved understanding of the association process between the guest and host molecules in these complexes. The complexes were found to exhibit high toxicity in zebrafish (Danio rerio) embryos, in contrast to pure caffeine and cyclodextrins at the same molar concentrations. HPLC measurements of the caffeine levels in zebrafish embryos showed that the observed cytotoxicity is not caused by an increased caffeine concentration in the body of the organism, as the concentrations are similar regardless of the administered caffeine form. Therefore, the observed high toxicity could be the result of the synergistic effect of caffeine and cyclodextrins.

Intermolecular interactions between β-cyclodextrin and water

This study focused on demonstrating the intermolecular interactions between β-cyclodextrin and water, with the aim to better understand the transfer of small molecules to β-cyclodextrin. The intermolecular interaction strength between β-cyclodextrin and water was analyzed using different methods such as the dynamic adsorption of water, the TG-DSC of β-cyclodextrin and molecular modeling employing MM2 force field calculations. The experiments for the adsorption of water on β-cyclodextrin was aimed to systematically investigate the adsorption characteristics, such as adsorption capacity, adsorption rate, adsorption heat and activation energy, influenced by the adsorption temperature and vapor pressure of water. The results indicated that the water adsorption on β-cyclodextrin is an exothermic process. The hysteresis loop type in the adsorption isotherms at multiple temperatures indicated that water adsorption is not purely a traditional physical adsorption due to the existence of structure effects such as the cavity effect and hydrogen bonding. The activation energy during water adsorption was 7.4 kJ mol⁻¹. However, the activation energy during water desorption was in the range of 35–45 kJ mol⁻¹, which decreased with an increase in the amount of water adsorbed. This indicated that water adsorption is much easier than water desorption from β-cyclodextrin and that water desorption is more difficult with a small amount of adsorbed water compared with a large amount of adsorbed water. Subsequently, the obtained average intermolecular interaction strength between β-cyclodextrin and water under the experimental conditions was 67.5 kJ mol⁻¹ (water), which was verified by DSC.

This study focused on demonstrating the intermolecular interactions between β-cyclodextrin and water, with the aim to better understand the transfer of small molecules to β-cyclodextrin.

Construction of a sustainable/controlled-release nano-container of non-toxic corrosion inhibitors for the water-based siliconized film: Estimating the host-guest interactions/desorption of inclusion complexes of cerium acetylacetonate (CeA) with beta-cyclodextrin (β-CD) via detailed electronic/atomic-scale computer modeling and experimental methods

Utilization of the coatings with self-healing anti-corrosion activities is one of the most promising routes for the development of advanced anti-corrosion coatings. In the present work, the green/sustainable corrosion inhibitive compounds based on the cerium acetylacetonate (CeA) was loaded into a beta-cyclodextrin (β-CD) nano-container (with negligible hazardous impacts) and through combined computer modeling and experimental approaches, the host-guest interactions/desorptions of the inclusion complexes of CeA with beta-cyclodextrin (β-CD) were assessed. The inhibition performance of the β-CD-CeA inclusion complex was investigated by electrochemical and surface experiments in a saline solution (NaCl, 3.5 wt.%). The particles were analyzed by Raman, XRD, FT-IR, and UV-vis spectroscopies. Additionally, the thermal properties in the 30-600 °C temperature range were examined by employing TGA/DTG test, and via the ICP analysis, the concentration of the released inorganic compounds in the electrolyte was studied. Achievements demonstrated 24 ppm Ce element existence after introducing β-CD-CeA inclusion complexes (during 24 h) in NaCl 3.5 wt.% solution. The analysis of Tafel curves proved that the prepared β-CD-CeA inclusion complex could inhibit the metallic substrate corrosion following the mixed cathodic and anodic mechanisms. The EIS investigation disclosed about 82 % inhibition degree after 48 h of metal immersion in the solution containing β-CD-CeA extract. The EIS analysis clarified that the silane coating (SC) resistance was enhanced noticeably by introducing the β-CD-CeA particles into the SC matrix. Using detailed-level (i.e., electronic and atomic) computer modeling techniques applying density functional theory (DFT), Mote Carlo (MC) and molecular dynamics (MD), the active sites, and the adsorption propensity of CeA complexes over the steel-based metallic adsorbents were explored. These modelings evidenced the CeA complexes interfacial adsorption on the steel.

Accelerated photoelectron transmission by carboxymethyl β-cyclodextrin for organic contaminants removal: An alternative to noble metal catalyst

Applications of noble metal decorated photocatalytic nanomaterials are restricted by its high cost. In this study, carboxymethyl β-cyclodextrin (CM-β-CD), as an alternative to gold nanoparticle, was used to modified titanium dioxide (CM-β-CD-P25) to accelerate photoelectron transmission and enhance the organic contaminants removal from water. Several of emerging organic contaminants, such as bisphenol A (BPA), phenol and sulphanilamide (SA), were used to evaluate their photocatalytic activities. Carboxymethyl-β-cyclodextrin not only provide hydrophobic sites to entrap organic contaminants but also provide a "bridge" for accelerated transmission of photogenerated charges without introducing the recombination interface. Consequently, 91.6 % of BPA, 71.9 % of phenol and 97.1 % of SA could be removed by CM-β-CD-P25(2:1) under 1 h UV light irradiation. The photooxidation rate constant of BPA, phenol and SA by CM-β-CD-P25(2:1) were 0.039 min^-1, 0.021 min^-1 and 0.062 min^-1, respectively, which are much higher than that of pristine P25 and Au-P25. Moreover, the photocatalytic activity of CM-β-CD-P25(2:1) remains almost unchanged in repeated cycle test owing to its high stability. The reasonable mechanism of CM-β-CD-P25 were investigated. CM-β-CD-P25 hybrid nanoparticles completely surpasses Au-P25 in organic contaminants removal, and shows great potential to replace noble metal as mediator.

Determination of pathogenic bacteria-Bacillus anthrax spores in environmental samples by ratiometric fluorescence and test paper based on dual-emission fluorescent silicon nanoparticles

Many lanthanide ions-based probes have been widely used for detecting anthrax spores biomarker-dipicolinic acid (DPA). However, little work has realized detection of bacillus anthrax spores in real environmental samples. In this work, a novel ratiometric fluorescent nanoprobe based on europium (Eu)-doped silicon nanoparticles (Eu@SiNPs) was fabricated for the first time by one-pot method without post-modification for determination of the DPA in bacillus subtilis spores (simulant bacillus anthrax spores). Based on Eu(III) in the Eu@SiNPs could be sensitized by DPA to emit intrinsic fluorescence and the fluorescence intensity of SiNPs in the Eu@SiNPs almost remained stable, a new ratiometric fluorescent method for determination of micro DPA in bacillus subtilis spores and bacillus subtilis spores in real environmental samples, such as Yellow river water, tap water and soil was established. Under the optimum conditions, the limit of detection (LOD) of the method toward bacillus subtilis spores was as low as 2.38×10⁴ spore/mL. Simple, fast and visual DPA and bacillus subtilis spores determination was also achieved by the Eu@SiNPs-based test paper. Therefore, the newly established method was expected to be a powerful tool for efficiently determination of bacillus anthrax spores to avoid anthrax threats.

Multifunctional Micro/Nanoscale Fibers Based on Microfluidic Spinning Technology

Superfine multifunctional micro/nanoscale fibrous materials with high surface area and ordered structure have attracted intensive attention for widespread applications in recent years. Microfluidic spinning technology (MST) has emerged as a powerful and versatile platform because of its various advantages such as high surface-area-to-volume ratio, effective heat transfer, and enhanced reaction rate. The resultant well-defined micro/nanoscale fibers exhibit controllable compositions, advanced structures, and new physical/chemical properties. The latest developments and achievements in microfluidic spun fiber materials are summarized in terms of the underlying preparation principles, geometric configurations, and functionalization. Variously architected structures and shapes by MST, including cylindrical, grooved, flat, anisotropic, hollow, core-shell, Janus, heterogeneous, helical, and knotted fibers, are emphasized. In particular, fiber-spinning chemistry in MST for achieving functionalization of fiber materials by in situ chemical reactions inside fibers is introduced. Additionally, the applications of the fabricated functional fibers are highlighted in sensors, microactuators, photoelectric devices, flexible electronics, tissue engineering, drug delivery, and water collection. Finally, recent progress, challenges, and future perspectives are discussed.

A beta-cyclodextrin-functionalized magnetic metal organic framework for efficient extraction and determination of prochloraz and triazole fungicides in vegetables samples

A β-cyclodextrin-functionalized magnetic zinc-metal organic framework (M-MOF/β-CD) was synthesized via a facile one-pot reaction. M-MOF/β-CD was used as a magnetic porous absorbent for the extraction and determination of prochloraz and three triazole fungicides in vegetable samples. M-MOF/β-CD was prepared by creating MOF layers on the surface of a Fe₃O₄-graphene oxide (GO) nanocomposite and bonding them with β-CD molecules. Characterization suggested that a 3D porous structure was formed, with M-MOF/β-CD exhibiting high superparamagnetism and a large surface area. As a new strategy, integrating MOFs with Fe₃O₄-GO could improve their water-resistance and mechanical strength by providing a rigid nanosupport interface. Combining M-MOF and β-CD resulted in excellent selective adsorption capacities for prochloraz and three triazole fungicides. The static adsorption process was evaluated and the results were in good agreement with the Freundlich model. Subsequently, M-MOF/β-CD was applied to extracting prochloraz and triazole fungicides from tomato and lettuce vegetables, followed by HPLC-MS/MS determination. The limits of detection for the above fungicides were found to be 0.25-1.0 μg/L at a signal-to-noise ratio of 3, with spiked recoveries of 74.13%-119.83%, indicating that M-MOF/β-CD was promising for application to the extraction and determination of fungicides in complex matrices.