Organic Shell Research Articles

Fluorescent Single-Core and Multi-Core Nanoprobes as Cell Trackers and Magnetic Nanoheaters

Iron oxide magnetic nanoparticles (MNPs) have been widely studied due to their versatility for diagnosis, tracking (magnetic resonance imaging (MRI)) and therapeutic (magnetic hyperthermia and drug delivery) applications. In this work, iron oxide MNPs with different single-core (8–40 nm) and multi-core (140–200 nm) structures were synthesized and functionalized by organic and inorganic coating materials, highlighting their ability as magnetic nanotools to boost cell biotechnological procedures. Single core Fe3O4@PDA, Fe3O4@SiO2-FITC-SiO2 and Fe3O4@SiO2-RITC-SiO2 MNPs were functionalized with fluorescent components with emission at different wavelengths, 424 nm (polydopamine), 515 (fluorescein) and 583 nm (rhodamine), and their ability as transfection and imaging agents was explored with HeLa cells. Moreover, different multi-core iron oxide MNPs (Fe3O4@CS, Fe3O4@SiO2 and Fe3O4@Citrate) coated with organic (citrate and chitosan, CS) and inorganic (silica, SiO2) shells were tested as efficient nanoheaters for magnetic hyperthermia applications for mild thermal heating procedures as an alternative to simple structures based on single-core MNPs. This work highlights the multiple abilities offered by the synergy of the use of external magnetic fields applied on MNPs and their application in different biomedical approaches.

Synthesis of bimetallic covalent organic framework nanocomposite for enhanced electrochemical detection of gallic acid

Here, a novel core-shell structured FeNi/covalent organic framework (TAPB-DMTP-COF) nanocomposite was synthesized by the formation of covalent organic framework shell on the surface of FeNi alloy core. The structural and electrochemical characteristics of the material were analyzed using powder X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray photoluminescence spectroscopy, and cyclic voltammetry. Due to the synergistic effects of high catalytivity of FeNi and large surface area of TAPB-DMTP-COF, FeNi@TAPB-DMTP-COF core-shell nanocomposite demonstrated excellent electrochemical oxidation response toward gallic acid. The parameters affecting the analytical procedure, such as buffer solution pH, scan rate, accumulation potential and time, were optimized. Under the optimal conditions, the electrochemical sensor exhibited two linear relationships with the wide gallic acid concentration in the range of 0.005–7.0 and 7.0–400 μmol/L, and the detection limit was calculated to be 1.3 nmol/mL (S/N = 3). The feasibility of the established method was successfully assessed by analyzing the content of gallic acid in real samples, and good recoveries were achieved. Our work thus paves a way to exploit bimetallic COF with high conductivities and electrocatalytic performances in electrochemical biosensors.

Encapsulation of inorganic phase change thermal storage materials and its effect on thermophysical properties: A review

Latent heat energy storage has received lots of concern on account of its high energy storage density and almost constant operating temperature. Phase change materials (PCM) possess unavoidable defects, like flammability, low thermal conductivity, subcooling, phase separation, etc. Encapsulation techniques have been adopted to address these challenges. Many efforts have been devoted to this by researchers, but the bulk of the work is based on organic PCMs, and particularly, reviews on encapsulating organic PCMs are frequent. In contrast, there are only a handful of comprehensive reviews on encapsulating inorganic PCMs, which hardly deliver complete information. Therefore, this review aims to provide a comprehensive look at the recent research advances for encapsulated inorganic PCMs. Two broadly adopted encapsulation methods are observed: core-shell encapsulated PCM and shape-stabilized PCM. Three main preparation processes for core-shell encapsulation (in situ polymerization, solvent evaporation and sol-gel methods) are described. The two former techniques are mostly adopted for the microencapsulated hydrated salt PCMs and forming organic shells. The latter is suitable for inorganic shells. The porous skeleton materials widely adopted for shape-stabilized PCMs are presented. The advantages and disadvantages of porous carbon, porous clay minerals, porous silica, and other materials were evaluated. In addition, thermophysical properties, such as supercooling, phase separation, phase change temperature, tent heat, thermal conductivity and thermal cycling reliability are discussed. It was found that encapsulation technology can have positive effects on thermophysical properties. It is hoped that this work will assist readers in gaining a comprehensive insight into the development of inorganic PCMs.

Achieving surface-sealing of hematite nanoarray photoanode with controllable metal–organic frameworks shell for enhanced photoelectrochemical water oxidation

Surface engineering of hematite (α-Fe2O3) photoanode by coupling electrocatalytically active metal–organic frameworks (MOFs) is an efficient way of boosting surface charge transfer for photoelectrochemical (PEC) water oxidation. However, the precise and controllable coating of conformal MOFs overlayer through a facile approach on photoelectrode still faces a challenge. In this work, NiFe metal–organic frameworks (NiFe-MOFs) are conformally deposited on zirconium-doped hematite (Zr-Fe2O3) by a novel indirect ligand-assisted transformation method, in which the well-coupled NiFe-layered double hydroxides (NiFe-LDHs) on photoanode act as self-templates due to their special layered structure and suitable interlayer spacing to provide with large specific area for the in-situ etching and coordinating, thus achieving the in-situ transformation of NiFe-LDHs layer into conformal NiFe-MOFs shell. Then, detailed investigations reveal that this conformal NiFe-MOFs shell endows the photoanode with a larger electrochemical active area, higher stability, and longer charge carrier lifetime compared to that of crystalline NiFe-MOFs on Zr-Fe2O3 from traditional solvothermal, resulting in outstanding PEC water oxidation performance of the target core–shell Zr-Fe2O3@NiFe-MOFs photoanode.

Novel nanoparticle-modified multifunctional microcapsules with self-healing and antibacterial activities for dental applications

ObjectiveAlthough microcapsules (MCs) have been used for dental resins to achieve self-healing capabilities, the fragile organic shell and single healing event functions during the service period limit their use. Herein, a novel nanoparticle-modified MC with a nano-antibacterial inorganic filler (NIF) containing a quaternary ammonium salt was synthesized to address these issues. MethodsMCs with 0 %–30 % NIFs were prepared via an in situ polymerization method and characterized their morphology, chemical composition, thermal stability, roughness, mechanical properties, and antibacterial effect. Subsequently, M-10 MCs were mixed into the resin matrix at a mass fraction of 7.5 %. The self-healing capability and cytotoxicity were evaluated. ResultsThe introduction of nanomaterials enhances the shell of the MCs and endows them with an antibacterial effect. With the addition of NIFs, the roughness, modulus, and hardness values of MCs all increased (p < 0.05). The presence of M-10 MCs reduced the CFU by 2–3 orders of magnitude compared to the control group. The dental resin containing 7.5 % M-10 MCs obtained almost 69 % self-healing efficiency, without significantly compromising cell viability (p < 0.05). SignificanceSelf-healing MCs with NIFs were prepared for the first time with strong antibacterial properties, a substantial self-healing capability, and low toxicity. This multifunctional MC is a promising candidate for use in dental resins to extend the service life and resolve the problem of bulk fracture and secondary caries.

Bulky Thiolate-Protected Silver Nanocluster Ag 213 (Adm-S) 44 Cl 33 with Excellent Electrocatalytic Performance toward Oxygen Reduction

Bulky Thiolate-Protected Silver Nanocluster Ag ₂₁₃ (Adm-S) ₄₄ Cl ₃₃ with Excellent Electrocatalytic Performance toward Oxygen Reduction

Impacts of microplastics and carbamazepine on the shell formation of thick-shell mussels and the underlying mechanisms of action

Forming calcareous exoskeletons is crucial for the health and survival of calcifiers such as bivalves. However, the impacts of waterborne emergent pollutants on this important process remain largely unknown. In this study, the effects of two types of emergent pollutants, microplastics (MPs) and carbamazepine (CBZ), which are ubiquitously present in ocean environments, on shell formation were assessed in the thick-shell mussel (Mytilus coruscus) with a shell regeneration experiment. In addition, their impacts on the in vivo contents of ATP, Ca2+, carbonic anhydrase (CA), and bone morphogenetic protein receptor type-2 (BMPR2), the activity of phosphofructokinase (PFK) and Ca2+-ATPase, and the expression of shell-formation related genes were analyzed. The data collected demonstrated that shell regeneration after mechanical injury was significantly arrested by CBZ and/or MPs. Besides, all the physiological and molecular parameters investigated were markedly suppressed by these two pollutants. Furthermore, synergistic impacts on most of the parameters examined were observed between CBZ and MPs. Our results indicate that these two pollutants may disrupt shell formation by constraining the availability of raw materials and energy, inhibiting the formation of the organic shell matrix, and interfering with the regulation of crystallization, which may have far-reaching impacts on the health of marine calcifiers.

Facile microencapsulation of phase change material with organic silicon shell used for energy storage

A novel organic silicon microencapsulated phase change materials (OS-MPCMs) was successfully designed and prepared via single-step in-situ polymerization. OS-MPCMs with n-ocadecane as core material and silicone as shell material, has excellent latent heat storage and release performance (ΔHm = 103.3J/g, ΔHc = 104.5J/g), excellent thermal stability and cycle durability of at least 200 cycles, as well as remarkable mechanical properties. The effects of core/shell ratio on morphology, thermal properties, thermal stability and mechanical properties of OS-MPCMs were further investigated. The experimental scheme was optimized and adjusted to ensure that OS-MPCMs could adapt to a more complex environment. In this study, the single-step in-situ polymerization method was adopted to simplify the synthesis process, and the self-assembly of microcapsules could be completed through one feeding. At the same time, OS-MPCMs encapsulation efficiency is improved, up to 86.45%. The raw materials used in production are simple and easy to obtain, and the production process is green and environmentally friendly. The excellent performance and simple production mode makes OS-MPCMs have an unexceptionable application prospect in the energy storage fields of energy-efficient building, thermo-regulated fabrics and so on.

Observation of an Orientational Glass in a Superlattice of Elliptically-Faceted CdSe Nanocrystals.

Extensive prior work has shown that colloidal inorganic nanocrystals coated with organic ligand shells can behave as artificial atoms and, as such, form superlattices with different crystal structures and packing densities. Although ordered superlattices present a high degree of long-range positional order, the relative crystallographic orientation of the inorganic nanocrystals with respect to each other tends to be random. Recent works have shown that superlattices can achieve orientational alignment through combinations of nanocrystal faceting and ligand modification, as well as selective metal particle attachment to particular facets. These studies have focused on the assembly of high-symmetry nanocrystals, such as cubes and cuboctahedra. Here, we study the assembly of elliptically faceted CdSe/CdS core/shell nanocrystals with one distinctive crystallographic orientation along the major elliptical axis. We show that the nanocrystals form an unexpectedly well-ordered translational superlattice, with a degree of order comparable to that achieved with higher-symmetry nanocrystals. Additionally, we show that, due to the particles' faceted shape, the superlattice is characterized by an orientational glass phase in which only certain orientations are possible due to entropically frustrated crystallization. In this phase, the nanocrystals do not exhibit a local orientational ordering but rather have distinct orientations that emerge at different locations within the same domain. The distinct orientations are a result of a facet-to-facet lock-in mechanism that occurs during the self-assembly process. These facet-to-facet alignments force the nanocrystals to tilt on different lattice planes forming different projections that we termed apparent polydispersity. Our experimental realization of an orientational glass phase for multifaceted semiconducting nanocrystals can be used to investigate how this phase is formed and how it can be utilized for potential optical, electrical, and thermal transport applications.

ZnO‐Reinforced Thermal Regulating Microcapsules with Double‐Layer Shell via Atomic Layer Deposition

AbstractConventional plain organic or inorganic shell for microcapsules has their own drawbacks, the organic shell has defects in thermal conductivity and stability; while the compactness and coverage of inorganic shell are not satisfactory. Herein, a novel approach to synthesis of organic–inorganic composite double‐layer shell phase change microcapsule (DLSPCM) is proposed, which is achieved by forming inorganic outer shell on the surface of organic shell via atomic layer deposition (ALD). Taking the pristine microcapsule with paraffin core and melamine formaldehyde (MF) shell as an example, MF‐ZnO composite double‐layer shell (DLS) is formed in this paper. The melting enthalpy of DLSPCM obtained by 100 ALD cycles is 159.7 J g−1, which is only 12.1 J g−1 lower than that of paraffin @ MF microcapsules (control sample), while the thermal conductivity of DLSPCM surges by 77.8%, and the thermal energy storage ability and thermal regulation performance are basically maintained. After 900 thermal cycles, the heat storage capacity of DLSPCM obtained by 100 ALD cycles decreased by only 3%. Besides, the photocatalytic performance and antibacterial activity of ZnO‐reinforced DLSPCM are further confirmed. The successful design of DLSPCM via ALD is prospective for the encapsulation, modification, and reinforcement of phase change microcapsules.

PH Switchable Water Dispersed Photocatalytic Nanoparticles

Photogeneration of Reactive Oxygen Species (ROS) finds applications in fields as different as nanomedicine, art preservation, air and water depollution and surface decontamination. Here we present photocatalytic nanoparticles (NP) that are active only at acidic pH while they do not show relevant ROS photo‐generation at neutral pH. This dual responsivity (to light and pH) is achieved by stabilizing the surface of TiO2 NP with a specific organic shell during the synthesis and it is peculiar of the achieved core shell‐structure, as demonstrated by comparison with commercial photocatalytic TiO2 NP. For the investigation of the photocatalytic activity, we developed two methods that allow real time detection of the process preventing any kind of artifact arising from post‐treatments and delayed analysis. The reversibility of the pH response was also demonstrated as well as the selective photo‐killing of cancer cells at acidic pH.

Structural Isomerization in Cu(I) Clusters: Tracing the Cu Thermal Migration Paths and Unveiling the Structure-Dependent Photoluminescence

Structural Isomerization in Cu(I) Clusters: Tracing the Cu Thermal Migration Paths and Unveiling the Structure-Dependent Photoluminescence

Study of Cloud Condensation Nuclei Activities and Hygroscopic Properties Based on Core-Shell Model

Cloud condensation nuclei (CCN) activities and hygroscopic properties of aerosol particles were studied based on the core-shell model with extended Köhler equation. Three kinds of core-shell particles were mainly considered: (1) insoluble core and soluble inorganic shell; (2) insoluble core and organic shell with limited solubility; (3) organic core with limited solubility and soluble inorganic shell. Results of the model calculations showed that Köhler curves of aerosol particles were different from classical Köhler curves of inorganic particles. Particle size, chemical composition and mass fraction of components all influence the curve shape, and the curve might show one or more extreme points of supersaturation. Critical supersaturation decreased when the mass fraction of the shell increased. This implied that the heterogeneous chemical reaction that happened to suspended particles in air could increase shell mass fraction and make particles more CCN active and hygroscopic. When the three models were compared, particles in model 3 were most CCN active, while those in model 2 were least CCN active. If the shell mass fraction was 0.1–0.2 for model 3 and 0.3–0.4 for model 1, the calculated hygroscopic parameter κ was closer to historical measuring results of 0.2–0.3 in polluted areas in China while the hygroscopic parameter would never be close to measuring results in model 2 no matter how high the shell mass fraction was. Based on discussion of two component particles of the core-shell model, more components in core-shell model could be considered, and the calculations were discussed in this article.

Electron-Hole Binding Governs Carrier Transport in Halide Perovskite Nanocrystal Thin Films.

Two-dimensional halide perovskite nanoplatelets (NPLs) have exceptional light-emitting properties, including wide spectral tunability, ultrafast radiative decays, high quantum yields (QY), and oriented emission. Due to the high binding energies of electron-hole pairs, excitons are generally considered the dominant species responsible for carrier transfer in NPL films. To realize efficient devices, it is imperative to understand how exciton transport progresses therein. We employ spatially and temporally resolved optical microscopy to map exciton diffusion in perovskite nanocrystal (NC) thin films between 15 °C and 55 °C. At room temperature (RT), we find the diffusion length to be inversely correlated to the thickness of the nanocrystals (NCs). With increasing temperatures, exciton diffusion declines for all NC films, but at different rates. This leads to specific temperature turnover points, at which thinner NPLs exhibit higher diffusion lengths. We attribute this anomalous diffusion behavior to the coexistence of excitons and free electron hole-pairs inside the individual NCs within our temperature range. The organic ligand shell surrounding the NCs prevents charge transfer. Accordingly, any time an electron-hole pair spends in the unbound state reduces the FRET-mediated inter-NC transfer rates and, consequently, the overall diffusion. These results clarify how exciton diffusion progresses in strongly confined halide perovskite NC films, emphasizing critical considerations for optoelectronic devices.

Detoxified and antimicrobial-enhanced olive mill wastewater phenols capping ZnO nanoparticles incorporated with carboxymethyl cellulose for fresh strawberry preservation

The underutilized by-products of hydrophilicity olive mill wastewater phenols (OPs) have great antimicrobial potential. ZnO NPs is one of most wildly used nano material with anti-bacterial function as well. This study aimed to prepare the detoxified and antimicrobial-enhanced OPs capping ZnO nanoparticles (OPs-ZnO NPs) containing metal core of ZnO NPs and organic shell of OPs, respectively. The OPs-ZnO NPs was chemically coordinated/chelated driven by Lewis bases (NaOH) in aqueous solution. The results obtained by SEM and TEM showed that those irregular sphere OPs-ZnO NPs were ranged from 58 to 92 nm, with an OPs caption of 35.40% (w/w). Importantly, the in vitro results showed that the strategy of capping OPs in ZnO NPs decreased the toxicity of ZnO NPs (< 0.02 g/L). Moreover, OPs-ZnO NPs presented a higher stability in simulated gastrointestinal digestion (Zn2+ < 0.07 g/L after 12 h). The results also showed that the protective coating of OPs-ZnO NPs and OPs-ZnO NPs/CMC (carboxymethyl cellulose) enhanced the antimicrobial activity of Escherichia coli, Staphylococcus aureus and Aspergillus niger. Furthermore, the coating of OPs-ZnO NPs/CMC decreased the weight loss and the rotting ratio of fresh strawberry, and ultimately prolonged its shelf-life at least 4 days under 25 ºC. Therefore, this study provided a biosafety strategy for the preparation of detoxified and antimicrobial enhanced OPs-ZnO NPs and its CMC protective coating for fresh produce throughout storage.

Record Aluminum Molecular Rings for Optical Limiting and Nonlinear Optics

AbstractCrystalline cluster materials, a class of functional motif aggregations, provide a great opportunity for tuning the properties stemming from the flexible and accurate variation of inorganic and organic compositions. In this study, we demonstrate the effects of functional ligand and ring size regulation on the structures and third‐order nonlinear optical (NLO) properties. Revealed by the single‐crystal X‐ray analysis results, aluminum molecular ring expansion is achieved by 2×9 and 3×6 strategies. In terms of the given organic shells, we further tuned the aluminum molecular ring sizes from 3.0 nm to 1.7 nm. The picosecond Z‐scan measurements results revealed that the third‐order NLO performances do not only depend on the general conjugate interactions but are also related to hydrogen bonding, polarizability, and ring sizes. The large nonlinear absorption coefficient and onset prove that the observed samples are promising candidates for the field of nonlinear optics.

Record Aluminum Molecular Rings for Optical Limiting and Nonlinear Optics.

Crystalline cluster materials, a class of functional motif aggregations, provide a great opportunity for tuning the properties stemming from the flexible and accurate variation of inorganic and organic compositions. In this study, we demonstrate the effects of functional ligand and ring size regulation on the structures and third-order nonlinear optical (NLO) properties. Revealed by the single-crystal X-ray analysis results, aluminum molecular ring expansion is achieved by 2×9 and 3×6 strategies. In terms of the given organic shells, we further tuned the aluminum molecular ring sizes from 3.0 nm to 1.7 nm. The picosecond Z-scan measurements results revealed that the third-order NLO performances do not only depend on the general conjugate interactions but are also related to hydrogen bonding, polarizability, and ring sizes. The large nonlinear absorption coefficient and onset prove that the observed samples are promising candidates for the field of nonlinear optics.

Role of the surface effects and interparticle magnetic interactions in the temperature evolution of magnetic resonance spectra of ferrihydrite nanoparticle ensembles

Ferrihydrite is characterized by the antiferromagnetic ordering and, in ferrihydrite nanoparticles, as in nanoparticles of any antiferromagnetic material, an uncompensated magnetic moment is formed. We report on the investigations of ferrihydrite powder systems with an average particle size of ∼ 2.5 nm obtained (i) as a product of the vital activity of bacteria (sample FH-bact) and (ii) by a chemical method (sample FH-chem). In the first approximation, these samples can be considered to be identical. However, in sample FH-chem, particles contact directly, while in sample FH-bact, they have organic shells; therefore, the interparticle magnetic interactions in these samples have different degrees. The main goal of this work has been to establish the effects of the interparticle magnetic interactions and individual characteristics of ferrihydrite nanoparticles on ferromagnetic resonance (FMR) spectra. The FMR spectra have been measured at different (9.4–75 GHz) frequencies in a wide temperature range. It has been found that, at low temperatures, the field-frequency dependence ν(HR) of the investigated systems has a gap ν/γ = HR + HA, where HR is the resonance field and HA is the induced anisotropy, which decreases with increasing temperature. To estimate a degree of the effect of interparticle interactions on the results obtained and to correctly determine the temperature range of the superparamagnetic (or blocked) state, the static magnetic measurement and Mössbauer spectroscopy data have been obtained and analyzed. It has been shown that the most striking feature of the FMR spectra - a gap in the field-frequency dependences - is a manifestation of individual characteristics of ferrihydrite nanoparticles. The induced anisotropy is caused by freezing of a subsystem of surface spins and its coupling with the particle core, which is observed in both samples at a temperature of ∼80 K. The temperature range (below 80 K) in which the gap exists corresponds to the blocked state in the FMR technique. In sample FH-bact, the ratio between the FMR parameters HA and linewidth ΔH obeys the standard expression HA ∼ (ΔH)3. In sample FH-chem, however, the interparticle magnetic interactions dramatically affect the behavior of parameters of the FMR spectra, which change nonmonotonically upon temperature variation. This fact is attributed to the collective freezing of the magnetic moments of particles under the conditions of sufficiently strong interactions, which follows from the temperature dependence of the particle magnetic moment relaxation time determined from the Mössbauer spectroscopy and static magnetometry data obtained in weak magnetic fields.

The role of organic ligand shell structures in colloidal nanocrystal synthesis

Organic ligands are essential in the growth of monodisperse colloidal inorganic nanocrystals and can be leveraged to create a wide variety of shapes and sizes. Inorganic nanocrystals coated with surfactant-like organic molecules have a vast range of properties that arise from the combination of the individual components. In this Review, we discuss the role that the tails of the organic ligands play in the synthesis and properties of colloidal nanocrystals, particularly the collective effects of the organic ligands on the surface. Ligand–ligand interactions influence the thermodynamic and kinetic properties of the nanocrystals, as well as alter their colloidal stability. These interactions should inform the conceptualization of new nanocrystal syntheses as they influence the surface energy of the colloid, and these interactions should play a role in subsequent assembly strategies to prepare nanocrystal superlattices, which are driven by interparticle interactions.

Octopus tentacle-like molecular chains in magnetic flocculant enhances the removal of Cu(II) and malachite green in water

• A recyclable flocculant with strong adsorption configuration was prepared simply. • Flocculant can remove Cu(II) and malachite green efficiently and synchronously. • Adsorption by functional groups and sweep flocculation were the mechanism. • Flocculant was easily regenerated and separated. • Flocculant can remove multiple contaminants in single-stage water treatment. Conventional flocculants are difficult to effectively remove dissolved ions and organic matter from water. This work aims to develop an environmentally friendly and renewable core–shell type flocculant (MCHS-g-P(AM-IA)) with octopus tentacle-like strong adsorption structure. The organic shell hydrolyses into molecular chains like octopus tentacles and adsorb dissolved ions/organic macromolecules through suckers-like functional groups, while the magnetic core acts as the growth center of flocs. Configuration and physical/chemical properties of the flocculant were analyzed by a series of characterization methods. Set Cu(II) and malachite green (MG) as models of heavy metal and organic pollutants separately, the removal capacity of MCHS-g-P(AM-IA) for water contaminants was studied in single-contaminant system and binary-contaminant system. The flocculation behavior and mechanism of MCHS-g-P(AM-IA) were deeply investigated by analysis of pH-dependence, background cationic influence and flocculation kinetics and SEM-EDS/XPS analysis of flocs. Furthermore, the flocculation performance in actual water matrix and regeneration tests of MCHS-g-P(AM-IA) were carried out to evaluate the applicable feasibility of flocculants for purification of complex wastewater in single stage water treatment.