Morphology Of Nanoaggregates Research Articles

Detailed characterisation of TiO2 nano-aggregate morphology using TEM image analysis

A detailed morphological characterisation is performed on flame synthesised TiO2 nano-aggregates (number of primaries, N<10) using transmission electron microscopy (TEM) image analysis and mobility measurements. The size-dependent collection efficiency of the TEM sampling method is accounted for with a simple correction for particle deposition through impaction and diffusion. The TEM-derived sizes show excellent agreement with electrical mobility measurements. Primary particle size, aggregate size, and degree of aggregation distributions were obtained for two different flames and varying precursor loading rates. The analysis reveals some particle aggregation which is likely to occur only very late in the growth stage, leading to the similarity between the primary particle and spherical particle size distributions. The degree of aggregation is defined as the ratio of gyration to spherical equivalent sizes from the projected area analysis, allowing identification of particles with spherical and non-spherical morphologies. The size distributions are found to be strongly affected by precursor loading but not by flame mixture or maximum temperature. In all cases, approximately 60–70% particles are spherical while the rest form small aggregates. The detailed morphological information reported provides the much-needed experimental data for studying the early stage particle formation of TiO2 from titanium tetraisopropoxide (TTIP) in a well-defined burner configuration.

Pendant chain engineering to fine-tune the nanomorphologies and solid state luminescence of naphthalimide AIEEgens: application to phenolic nitro-explosive detection in water.

Strategically, a series of five angular "V" shaped naphthalimide AIEEgens with varying pendant chains (butyl, hexyl, octyl, cyclohexyl and methylcyclohexyl) have been synthesized to fine-tune their nanomorphological and photophysical properties. With similar aromatic cores and electronic states, unexpected tuning of the condensed state emission colors and nanomorphologies (reproducible on any kind of surface) of naphthalimides has been achieved for the first time simply by varying their side chains. Conclusive analysis by various spectroscopic techniques (SC-XRD, powder-XRD, DLS, FESEM) and DFT computational studies confirmed the full control of the pendant chain (in terms of bulkiness around the naphthalimide core, which restricts the ease of intermolecular π-π interactions) over the nanoaggregate morphology and solid state emissive properties of the AIEEgens; this can be rationalized to all aggregation-prone systems. These comprehensive studies establish a conceptually unique yet simple and effective method to precisely tune the nanomorphologies and the emission colors of aggregation-prone small organic molecules by judicious choice of the non-conjugated pendant chain. Thus, considering the prime role of the active layer nanomorphology in all organic optoelectronic devices, this methodology may emerge as a promising tool to improve device performance. Among all the congeners, the hexyl chain-containing congener (HNQ) forms well-defined nanoribbons with smaller diameters (as confirmed from DLS: 166 nm and FESEM: 150 nm) and provides a larger surface area. Consequently, the HNQ-nanoribbons were employed as a fluorescent sensor for the discriminative detection of trinitrophenol (TNP) in pure aqueous media. FE-SEM images revealed that, upon gradual addition of TNP (10 nM to 100 μM), these nanoribbons undergo an aggregation/disaggregation process, forming non-fluorescent co-aggregates with TNP, and provide highly enhanced sensitivity compared to existing state-of-the-art on aggregation-prone systems. Fluorescence titration studies confirmed that HNQ can detect the presence of TNP as low as 16.8 ppb and can serve as a cost-effective portable device incorporated with UV-light for on-site visual detection of TNP, even in the presence of potentially competing nitroaromatic compounds.

Na-ion storage performance of amorphous Sb2S3nanoparticles: anode for Na-ion batteries and seawater flow batteries

Amorphous (a-) Sb2S3 nanoparticle aggregates were synthesized using a facile polyol-mediated process at room temperature and their Na-ion storage capability was evaluated. Owing to the spherical nano-aggregate morphology and amorphous structure, the a-Sb2S3 anode exhibited superior rate capability and cycling stability compared to that of crystalline, microscale Sb2S3 particles. The a-Sb2S3 electrode was also examined as an anode for eco-friendly, Na metal-free seawater flow batteries.

Nano molar detection of Al3+in aqueous medium and acidic soil using chromone based fluorescent organic nanoparticles (FONPs)

Compounds 1 (1,2-bis[4-oxo-4H-1-benzopyran-3-ylmethylenamino]-ethanes) and 2 (3-((E)-(3-(dimethylamino) propylimino)methyl)-4H-chromen-4-one) were synthesized using a one pot condensation reaction between 3-formylchromone and ethylenediamine/N,N-dimethylpropylamine, respectively. Compounds 1 and 2 were purified and characterized using 1H and 13C NMR, IR, mass and CHN analysis. Fluorescent organic nanoparticles (FONPs) were developed from the compounds 1 and 2 using a reprecipitation technique. The size and morphology of nano-aggregates 1 and 2 was analysed using DLS and TEM analysis. Nanoaggregates of 1 and 2 were further exploited for chemosensory applications in an aqueous medium. An efficient nanoaggregate of compound 1 has shown an excellent detection limit of 100 nM for Al3+ in an aqueous medium. The stoichiometry of the complex formation of 1 with Al3+ was found to be 1:1 using Job's plot method. The sensor 1 was further checked for its practical applications, e.g., soil and water analysis (drinking, tap and river water). Results of Al3+ determination in soil and water were well coordinated with the existing methods. Finally, the mechanism of fluorescence recognition is supported with DFT calculations, which shows the effective binding of Al3+ with chromone leading to the lowering in the energy and thus stability. The present approach is the first report on the fabrication and chemosensory applications of chromone-based FONPs for the nanomolar detection of Al3+ in an aqueous medium.

High performance mesoporous zirconium phosphate for dehydration of xylose to furfural in aqueous-phase

The conversion of sugars to chemicals in aqueous-phase is especially important for the utilization of biomass. In current work, zirconium phosphate obtained by hydrothermal methods using organic amines as templates has been examined as a solid catalyst for the dehydration reaction of xylose to furfural in aqueous-phase. The use of dodecylamine and hexadecylamine in the synthesis process results in mesoporous zirconium phosphate with uniform pore width of ∼2 nm and in morphology of nanoaggregates, which is characterized by powder X-ray diffraction, N2 isothermal sorption, NH3 temperature-programmed desorption, FT-IR, and 31P MAS NMR spectroscopy. When used as a catalyst for xylose dehydration to furfural in aqueous-phase, the mesoporous zirconium phosphate presents excellent catalytic performance with high conversions up to 96% and high furfural yields up to 52% in a short time of reaction. Moreover, the catalyst is easily regenerated by thermal treatment in air and shows quite stable activity. The open structure with numerous active sites of the Brønsted/Lewis acid sites is responsible for the high catalytic efficiency of mesoporous zirconium phosphate.

卟啉有机纳米聚集体的研究 Research the Property of Organic Nano Gathered Based on Porphyrin

本文设计合成了两个以卟啉为核心尾端分别连有亲水基团和疏水基团的枝状化合物，并对其在水中的聚集行为进行研究及表征。通过紫外可见(UV-vis)吸收光谱和扫描电子显微镜(SEM)的分析，发现在连有疏水基团的卟啉化合物1是H型聚集的棒状结构，而连有亲水基团的卟啉化合物2则是J型聚集的空心球结构(直径大约340 nm)，与纳米粒度分析仪计算的结果基本一致。所以我们得出，通过改变卟啉外部的取代基可以调控其纳米聚集体的形貌。 We designed and synthesized dendritic porphyrin which brings hydrophilic groups and hydrophobic groups. Their different aggregation behaviors in aqueous solution were studied by using UV absorption spectroscopy, scanning electron microscopy (SEM) and Nanoparticle technology. Results indicated that porphyrin 1 bearing hydrophobic group can form rod-like structures introduced by H-aggregation. Porphyrin 2 containing hydrophilic moiety can form hollow spherical structures (diameter is about 340 nm) caused by J-aggregation. So we have come, by changing the the por- phyrins external substituents can be modulated by the morphology of nano-aggregates.

Aqueous re-dispersibility of spray-dried antibiotic-loaded polycaprolactone nanoparticle aggregates for inhaled anti-biofilm therapy

Antibiotic-loaded nanoparticles have emerged as one of the most promising inhaled antibiotic formulations for treating bacterial biofilm infections in the lung. To effectively deliver the nanoparticles by inhalation, the nanoparticles are transformed into micro-scale dry-powder structures in the form of nanoparticle aggregates that can be easily aerosolized off the inhaler. Moreover, the nano-aggregates must readily reconstitute into the primary nanoparticles to be therapeutically effective upon their deposition in the lung. In the present work, respirable dry-powder aggregates of antibiotic-loaded polycaprolactone nanoparticles are produced by the spray-drying technique. The effects of the excipient formulation and drying temperature on the aqueous re-dispersibility, morphology, production yield, and flowability of the nano-aggregates are investigated. Three excipients commonly used in inhaled dosage formulation (i.e. mannitol, lactose, and leucine) and their combinations are examined. The results indicate that the nano-aggregate morphology is not greatly influenced by the excipient formulation, where low-density spherical nano-aggregates are consistently produced. The inclusion of hydrophobic leucine is mandatory to produce free-flowing particles, which however leads to decreased production yields. The aqueous re-dispersibility is strongly dependent on the excipient formulation, where only lactose–leucine formulations at particular nanoparticle to excipient concentration ratios are capable of producing re-dispersible nano-aggregates.

Effects of excipient formulation on the morphology and aqueous re-dispersibility of dry-powder silica nano-aggregates

Dry-powder aggregates of biocompatible silica nanoparticles are manufactured by the spray-drying technique to be potentially developed as an inhaled drug delivery vehicle. The micron-scale nano-aggregates are specifically designed to exhibit large, hollow, and spherical morphologies in order to achieve high aerosolization efficiency and an effective deposition in the lung. In addition to the specific morphology, the dry-powder nano-aggregates must readily re-disperse into the primary nanoparticles in an aqueous medium to be therapeutically effective. The presence of water-soluble excipients that form “excipient bridges” interconnecting the silica nanoparticles is found to be critical in the nano-aggregate re-dispersion process. The effects of different excipient formulations on the nano-aggregate morphology and aqueous re-dispersibility are therefore examined. Three of the most widely used excipients in inhaled drug delivery formulations (i.e. leucine, mannitol, and lactose) are employed as the excipient candidates. The nano-aggregate morphology and the aqueous re-dispersibility are found to be highly influenced by the excipient type, in particular its hydrophilicity, and the nanoparticle to excipient concentration ratio. A multiple-excipient formulation of leucine and lactose at a 1:6 concentration ratio is found to produce nano-aggregates having both the desired morphology and excellent aqueous re-dispersibility.

Spray drying formulation of hollow spherical aggregates of silica nanoparticles by experimental design

The present work employs an experimental design methodology to optimize the spray-drying production of micron-size hollow aggregates of biocompatible silica nanoparticles that are aimed to serve as drug delivery vehicles in inhaled photodynamic therapy. To effectively deliver the nanoparticles to the lung, the aerodynamic size ( d A) of the nano-aggregates, which is a function of the geometric size ( d G) and the degree of hollowness, must fall within a narrow range between 2 and 4 μm. The results indicate that (1) the feed concentration, (2) the feed pH, and (3) the ratio of the gas atomizing flow rate to the feed rate are the three most significant parameters governing the nano-aggregate morphology. Spray drying at a low pH (<7) and at a low feed concentration (<1%, w/w) generally results in nano-aggregates having small geometric and aerodynamic sizes ( d A = d G ≈ 3 μm) with a relatively monodisperse size distribution. Spray drying at a higher feed concentration produces nano-aggregates having a larger d G but with a multimodal particle size distribution. A trade-off therefore exists between having large d G to improve the aerosolization efficiency and obtaining a uniform particle size distribution to improve the dose uniformity.

Microscopy and Quantitative Morphology of Aluminum Silicate Nanoparticles Grown on Organic Templates

Biomimetic synthesis of ceramic materials is increasing in popularity because it offers many advantages. In this work, aluminum silicate nanoparticles were obtained on a self-assembled organic multilayer at near room temperature (30 < or = T < or = 50 degrees C) and at atmospheric pressure. Morphological and microanalytical characterization was carried out by means of transmission electron microscopy and subsequent image analysis. The roles of some process parameters such as template type, reactant concentration, [Al]:[Si] molar ratio, number of initiation steps (IS) of mineralization, and reaction time (rt) were assessed by comparing images, diffraction patterns, and EDX spectra. Generally, the Si-rich phase exhibited higher crystallinity, whereas the Al-rich phase was mostly amorphous. Crystal structure resulted with rt > or = 4 days for template-grown materials. Images of materials obtained at T = 50 degrees C, rt = 3 days, and 1 < or = IS < or = 4 were further analyzed by "spectrum enhancement," an algorithm based on the Fourier transform. Morphological indicators were extracted from suitably processed power spectral densities, a correlation matrix was formed, and multivariate statistics was carried out. Visual differences in nanoaggregate morphology were quantitatively translated. Materials were ranked by the spatial uniformity of nanoparticle distribution: the most uniform aggregates were those grown on templates by IS > or = 2. Univariate statistics validated the conclusion: the particles of those same materials had a narrower size distribution and sharper edges. This last property has been ascribed to crystalline structure, independently demonstrated by diffraction patterns.