- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Discriminative Preparation of Stable H- or J-aggregates of Astaxanthin in Waterborne Chitosan/DNA Nanoparticles
摘要： Into colloidal particles formed from chitosan and DNA, microcrystallines of either H- or J-aggregates of astaxanthin have been selectively incorporated. Which form of the aggregate is produced in the nanoparticles is governed by the composition of ethanol-water solutions used for their preparations. These aqueous colloidal dispersions show large hypsochromic and bathochromic shifts, with respect to the monomeric dye, indicating strong potentials to medical and pharmaceutical applications.
关键词： astaxanthin,aggregates,nanoparticles
更新于2025-09-19 17:15:36
-
Aggregate dispersions to enhance the intrachain order in surfactant-stabilized aqueous colloids of poly(3-hexylthiophene)
摘要： Aqueous colloids of conjugated polymers (CP), such as poly(3-hexylthiophene) (P3HT), are an attractive alternative for processing CP-based materials because (1) the microstructure of the conjugated polymers can be optimized during the formation of the colloid and (2) this method can significantly reduce the amount of hazardous organic solvents used during manufacturing. This investigation addresses the optimization of the polymer structure by studying the intrachain order of P3HT aggregates pre-assembled in mixtures of chloroform (CF) with dichloromethane (DCM) and subsequently dispersed in aqueous solutions of the surfactant sodium dodecyl sulfate (SDS) using a mini-emulsion method. Compared to an amorphous solution of P3HT, the observed intrachain order of P3HT in the colloids is much higher when using aggregate dispersions pre-assembled in the CF:DCM mixtures. Similar results are observed for aggregate dispersions of a benchmark organic photovoltaic system composed of P3HT and the fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM), but in this case the intrachain order of P3HT in the P3HT:PCBM colloids is anomalously higher than the pure P3HT colloids. Atomic force microscopy (AFM) imaging reveals changes in the dominant structural motifs and morphology of the colloidal P3HT films, but not in a way that correlates with films processed from the aggregate dispersions.
关键词： Emulsion,Colloids,Poly(3-hexylthiophene),Aggregates,PCBM
更新于2025-09-19 17:15:36
-
Effects of near-field electromagnetic coupling in dimers of nanoparticles with a silver core and a J-aggregate dye shell
摘要： We report a theoretical study of the plasmon – exciton coupling effect on the absorption spectra of pairs of closely spaced double-layer hybrid nanoparticles consisting of a metallic core and a J-aggregate dye shell. The effect of frequency conversion of plasmonic lines due to the near-field interaction between plasmons and Frenkel excitons of the organic shell is demonstrated. The effect leads to the appearance of additional spectral lines in the long-wavelength part of the spectrum of the system of hybrid particles. The shapes and the relative intensities of the additional lines exactly reproduce the specific features of the original spectrum of plasmonic absorption bands in uncoated metallic nanoparticles. The discovered phenomenon can be used to design new types of high-sensitivity nanosensors, based on plasmon – exciton effects and principles of near-field optics.
关键词： near-field electromagnetic coupling,nanophotonics,Frenkel excitons,dimers of metalorganic nanoparticles,plasmon – exciton interaction,molecular J-aggregates,localised plasmons,absorption spectra
更新于2025-09-19 17:15:36
-
Time-dependent optimization of laser-produced molecular plasmas through high-order harmonic generation
摘要： Analysis and characterization of laser-produced plasmas (LPPs) require the advanced methods for determination of different multiparticle component formation and spreading. Time-resolved high-order harmonic generation (HHG) in spreading LPPs allows determining optimal conditions for this process. One of the most important parameters of HHG in LPP is the delay between the heating and driving pulses. We demonstrate that the optimization of delays allows achieving the maximal harmonic yields in LPP created on the surfaces of the solid targets possessing different molar masses (m). The optimal delays (t) for B4C, ZnO, GaP, GaAs, and Ag2S plasmas were determined to be approximately 200, 300, 350, 500, and 700 ns, respectively. These variations of delays correspond to the t1(m)0.5 dependence for different materials. We demonstrate the applicability of the proposed method for analysis of the resonance-enhanced harmonics in atomic and molecular plasmas (Mo and MoS2) and for studies of large perovskite aggregates as potential emitters of harmonics. This diagnostic technique can also be applied to the analysis of the presence of different nanostructures in LPPs through HHG with a high spatiotemporal resolution.
关键词： perovskite aggregates,laser-produced plasmas,molar masses,time-resolved,high-order harmonic generation,optimization,nanostructures,resonance-enhanced harmonics
更新于2025-09-19 17:13:59
-
Stereochemistry controlled supramolecular architectures of novel tetrahydroxy functionalized amphiphilic carbocyanine dye
摘要： The synthesis of novel amphiphilic 5,5',6,6'-tetrachlorobenzimidacarbocyanine (TBC) dye derivatives with amino-propanediol head groups differing in stereochemistry (chiral enantiomers, meso-form, and conformer) is reported. For the achiral meso-form, a new synthetic route towards asymmetric cyanine dyes was established. All compounds form J-aggregates in water whose optical properties were characterized by spectroscopic methods. The supramolecular structure of the aggregates was investigated by cryo-transmission electron microscopy (cryo-TEM), cryo-electron tomography (cryo-ET), and atomic force microscopy (AFM) revealing extended sheet-like aggregates for the chiral enantiomers and nanotubes for the mesomer, respectively, while the conformer forms predominately needle-like crystals. The experiments demonstrate that the aggregation behavior of compounds can be controlled solely by head group stereochemistry which in case of the enantiomers enables formation of extended hydrogen bond chains by the hydroxyl functionalities. In case of the achiral meso-form, however, such chains turned out to be sterically excluded.
关键词： Stereochemistry,cryo-TEM,supramolecular architectures,amphiphilic carbocyanine dye,cryo-ET,J-aggregates,AFM
更新于2025-09-19 17:13:59
-
Effects of Milling Time, Zirconia Addition, and Storage Environment on the Radiopacity Performance of Mechanically Milled Bi2O3/ZrO2 Composite Powders
摘要： Mineral trioxide aggregate (MTA) typically consists of Portland cement (75 wt.%), bismuth oxide (20 wt.%), and gypsum (5 wt.%) and is commonly used as endodontic cement. Bismuth oxide serving as the radiopacifying material reveals the canal filling effect after clinical treatment. In the present study, bismuth/zirconium oxide composite powder was prepared by high energy ball milling of (Bi2O3)100?x (ZrO2)x (x = 5, 10, 15, and 20 wt.%) powder mixture and used as the radiopacifiers within MTA. The crystalline phases of the as-milled powders were examined by the X-ray diffraction technique. The radiopacities of MTA-like cements prepared by using as-milled composite powders (at various milling stages or different amount of zirconia addition) were examined. In addition, the stability of the as-milled powders stored in an ambient environment, an electronic dry box, or a glove box was investigated. The experimental results show that the as-milled powder exhibited the starting powder phases of Bi2O3 and ZrO2 and the newly formed δ-Bi7.38Zr0.62O2.31 phase. The longer the milling time or the larger the amount of the zirconia addition, the higher the percentage of the δ-Bi7.38Zr0.62O2.31 phase in the composite powder. All the MTA-like cements prepared by the as-milled powder exhibited a radiopacity higher than 4 mmAl that is better than the 3 mmAl ISO standard requirement. The 30 min as-milled (Bi2O3)95(ZrO2)5 composite powder exhibited a radiopacity of 5.82 ± 0.33 mmAl and degraded significantly in the ambient environment. However, storing under an oxygen- and humidity-controlled glove box can prolong a high radiopacity performance. The radiopacity was 5.76 ± 0.08 mmAl after 28 days in a glove box that was statistically the same as the original composite powder.
关键词： mineral trioxide aggregates,radiopacity,bismuth oxide,mechanical milling,zirconia
更新于2025-09-19 17:13:59
-
Ultra-Stable Plasmonic Colloidal Aggregates for Accurate and Reproducible Quantitative SE(R)RS in Protein-Rich Biomedia
摘要： Au/Ag colloids aggregated with simple salts are amongst the most commonly used substrates in surface-enhanced (resonance) Raman spectroscopy (SE(R)RS). However, salt-induced aggregation is a dynamic process, which means that SE(R)RS enhancements vary with time and that measurements therefore need to be taken at a fixed time point, normally within a short time-window of a few minutes. Here, we present an emulsion templated method which allows formation of densely-packed quasi-spherical Au/Ag colloidal aggregates. Since the particles in the product aggregates retain their weakly adsorbed charged ligands and the ionic strength remains low these charged aggregates resist further aggregation while still providing intense SE(R)RS enhancement which remains stable for days. This eliminates a major source of irreproducibility in conventional colloidal SE(R)RS measurements and paves the way for SE(R)RS analysis in complex systems, such as protein-rich bio-solutions where conventional aggregated colloids fail.
关键词： self-assembly,interfaces,colloidosomes,SE(R)RS,aggregates
更新于2025-09-19 17:13:59
-
Green-light-induced melting of self-assembled azobenzene nano/microstructures
摘要： We report the formation of green-light-responsive fluorescent aggregates composed of trigonal molecules having three ortho-dialkylated azobenzene wings at the periphery (a green-light-responsive 3BuES and an aggregation-induced emission/aggregation-induced emission enhancement [AIE/AIEE]-active 3BuAz). Exposure of the respective (3BuES and 3BuAz) spheres to green light leads to color tuning and/or fluorescence switching. The results can be rationalized in terms of green-light-induced molecular conformational changes of the trigonal azobenzene molecules and the resulting phase transition of the self-assembled structures. For instance, irradiation of 3BuES with green light produces B35% of U-shaped cis forms (i.e., approximately one-third of the trans-azobenzene units isomerizes to the cis forms), which seems to be su?cient to weaken the degree of the molecular packing of the trigonal azobenzene frameworks and lower the melting temperatures. Moreover, to apply the excellent fluorescence switching functions of 3BuAz aggregates to create new fluorescent organic materials, we used a co-assembly of 3BuES–3BuAz binary mixtures. Our important approach for obtaining green-light-responsive fluorescent nano/microstructures from the binary mixtures is phase separation based on the structural difference between 3BuES (having a planar central core) and 3BuAz (having a distorted conformation), which helps retain the fluorescence functions of the AIE/AIEE-active 3BuAz chromophore. Scanning electron microscopy (SEM), optical microscopy (OM), and fluorescence optical microscopy (FOM) observations prove apparent green-light-induced melting, color tuning and fluorescence switching of the phase-separated structures (i.e., microspheres and nanoparticles).
关键词： green-light-responsive,AIE/AIEE,azobenzene,fluorescent aggregates,fluorescence switching,phase separation
更新于2025-09-16 10:30:52
-
Quantum Dots as Promising Theranostic Tools Against Amyloidosis: A Review
摘要： Amyloids are highly ordered beta sheet rich stable protein aggregates, which have been found to play a significant role in the onset of several degenerative diseases such as Alzheimer’s disease, Huntington’s disease, Parkinson’s disease, Type II diabetes mellitus and so on. Aggregation of proteins leading to amyloid fibril formation via intermediate(s), is thought to be a nucleated condensation polymerization process associated with many pathological conditions. There has been extensive research to identify inhibitors of these disease oriented aggregation processes. In recent times, quantum dots, with their unique physico-chemical properties have grabbed the attention of scientific community due to its applications in medical sciences. Quantum dots are nano-particles usually made of semiconductor materials which emit fluorescence upon radiation. The wavelength of fluorescence emission varies with changes in size of quantum dots. Several studies have reported significant inhibitory effects of these quantum dots towards amyloidogenesis, thereby presenting themselves as promising candidates against amyloidosis. Further, studies have also revealed amyloid detection capacity of quantum dots with sensitivity and specificity better than conventional probes. In the current review, we will discuss the various effects of quantum dots on protein aggregation pathways, their mechanism of actions and their potentials as effective therapeutics against amyloidosis.
关键词： quantum dots,Protein quality control,amyloid,degenerative disorders,small molecule inhibitors,aggregates
更新于2025-09-16 10:30:52
-
Liposome-Templated Indocyanine Green J- Aggregates for <i>In Vivo</i> Near Infrared Imaging and Stable Photothermal Heating
摘要： Indocyanine green (ICG) is an FDA-approved near-infrared fluorescent dye that has been used in optical imaging and photothermal therapy. Its rapid in vivo clearance and photo-degradation have limited its application. ICG pharmacokinetics and biodistribution have been improved via liposomal encapsulation, while its photothermal stability has been enhanced by ICG J-aggregate (IJA) formation. In the present work, we report a simple approach to engineer a nano-sized, highly stable IJA liposomal formulation. Our results showed that lipid film hydration and extrusion method led to efficient IJA formation in rigid DSPC liposomes, as supported by molecular dynamics modeling. The engineered DSPC-IJA formulation was nano-sized, and with spectroscopic and photothermal properties comparable to free IJA. Promisingly, DSPC-IJA exhibited high fluorescence, which enabled its in vivo tracking, showing prolonged blood circulation and significantly higher tumor fluorescence signals, compared to free ICG and IJA. Furthermore, DSPC-IJA demonstrated high photo-stability in vivo after multiple cycles of 808 nm laser irradiation. Finally, doxorubicin was loaded into liposomal IJA to utilize the co-delivery capabilities of liposomes. In conclusion, with both liposomes and ICG being clinically approved, our novel liposomal IJA could offer a clinically relevant theranostic platform enabling multimodal imaging and combinatory chemo- and photothermal cancer therapy.
关键词： liposomes,J-aggregates,indocyanine green,theranostics,photothermal therapy
更新于2025-09-16 10:30:52