Colloid and Polymer Science最新文献

The study investigates the heat and mass transfer of mixed peristaltic Casson fluid flow through a porous medium in the presence of electroosmosis. It uses the lubrication LWL-LRN analytical technique to transform flow-control equations into ordinary differential equations. The equation is simplified using a numerical solver, bvp4c, in MATLAB software. The study analyses the behaviour of momentum, thermal, solutal, and nanoparticle concentration using parameters such as the magnetic field parameter, porous, electroosmotic, Prandtl, thermal Grashof number, and solutal concentration. Comparing this work with the existing investigation reveals a high level of concordance regarding the impact of thermophoresis and Brownian variables on momentum fields. The study’s novelty is the double-diffusive effects of Casson fluid, which provides a more accurate characterisation of its flow behaviour with convective boundary conditions over an inclined surface. Such observations are useful in real-life applications to capture the shear and stress-thinning properties and flow of synovial fluid in joints, as well as to understand blood flow in several physiological conditions.

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The emergency of peptide-assembled nanomaterials motivates the efforts towards understanding the composition effects governing the assembly structure of peptides. Herein, we used time-lapse atomic force microscopy (AFM) to characterize the time-dependent structural transformation of phenylalanine (F)-rich self-assembled peptides and elucidated the impacts of composition heterogeneity on modulating peptide aggregation. Four binary peptides (F5Y5, F5A5, F5H5, and F5D5) were synthesized to arrange distinct types of amino acids, including aromatic tyrosine (Y), nonpolar alanine (A), cationic histidine (H), and anionic aspartic acid (D), in the proximity of an F-rich moiety. We compared the time-dependent structural transitions of these peptide assemblies using AFM. F5Y5 and F5A5 were observed to form fibril-like aggregates over time, whereas F5H5 and F5D5 assembled into globular particles during the time course examined. The impacts of neighboring amino acids on affecting F-rich peptide fibrillation are in line with the hydrophobicity scales of amino acid side chains. Specifically, Y and A facilitate the fibril aggregation, whereas H and D hinder the fibril formation of F-rich peptides. Our results manifest the hydrophobicity of amino acids proximal to the F residues is important for the fibril-like aggregation of peptides.

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We analyze the swelling behavior of N-isopropylacrylamide (NIPAM)-based microgels incorporating the non-thermoresponsive comonomer N-tert-butylacrylamide (NtBAM) using photon correlation spectroscopy (PCS) and atomic force microscopy (AFM). Previous thermodynamic analysis of PNIPAM-co-NtBAM microgel swelling relied on the classical Flory-Rehner theory. However, this approach struggled to accurately describe swelling curves at higher NtBAM content. Our present work combines the original expression for the Flory-Huggins interaction parameter (chi _{FH}) for NtBAM with a recently adapted Hill-like model for the interaction parameter (chi _{Hill}) that accounts for cooperative effects in the volume phase transition in poly(NIPAM) microgels. This approach outperforms other methods in fitting quality. The observed results are revealing an exponential decrease in hydrodynamic radius upon increasing NtBAM content for swollen microgels. In addition, an exponential decay of the number of water molecules leaving the polymer chain during the volume phase transition is found, which can be attributed to the steric influence of one NtBAM monomer on the hydration of neighboring NIPAM monomers. The molar interaction enthalpy (Delta H_{SP}= text {-49 kJ / mol}) and entropy (Delta S_{SP} = text {-177 J /( mol K)}) were obtained from the fits of the swelling curves.

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Diallyl thiosulfinate (DT), a major organosulfur chemical with several notable therapeutic characteristics, is highly unstable and easily degradable which restricts its extensive use in biopharmaceutical commodities. Therefore, utilizing the self-assembly nature of polyoxyethylene (Brij S20 and Brij 58), appropriate pH-responsive micelle carrier systems have been designed to entrap and improve DT’s stability at an ambient temperature (25 °C) while preserving its quantity and biological activity. Comparing with the Brij S20 with the Brij 58 micelle carrier system, the latter demonstrated superior stability and entrapment of DT. In addition, it was found that DT’s stability in micellized condition is significantly influenced by both pH and temperature (p < 0.05). The micelle system was capable enough to reduce degradation significantly. Additionally, the liberation of DT from micelle is greatly aided by acidic pH 1.5. Around 77% DT was released from Brij 58 system. Various biochemical analyses were done. The liberation of DT from the micelle in a controlled manner using lower pH as stimuli may facilitate its biological action at an individual’s gastrointestinal lumen or near cancer cell environment having lower pH. Additionally, it was made sure that the micellization method did not impair DT’s bioactivity or reduce appropriate biocompatibility. The current study increases the likelihood of creating a commercially available DT-loaded, micelle-based formulation for application in biopharma and food-related industries.

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As an antioxidative isoquinoline quaternary alkaloid, berberine (BR) is derived from certain types of plants, such as Berberis aristate, and despite its ability to inhibit cell proliferation, its poor aqueous solubility has limited its effectiveness in treatments. This study attempted to extract cellulose nanocrystals (CNCs) from ginger sticks to perform BR delivery and proceeded by characterizing the prepared CNCs and CNCs-BR by the results of DLS, TEM, FESEM, XRD, and FTIR. Moreover, various biophysical methods were used to investigate the interaction of BR-loaded CNCs with human serum holo-transferrin (HTF). The obtained outcomes confirmed the effectiveness of our spherical CNCs in reducing the size of the drug from 403.06 to 203.42 nm in CNCs-BR and consequently improving the solubility of BR. The XRD analysis approved the successful elimination of amorphous regions in cellulose, while the diminution of crystallinity index after the loading of BR indicated the occurrence of their interaction. The induced alterations in the functional groups and hydrophilicity enhancement of CNCs and CNCs-BR were displayed by FTIR. The fluorescence studies indicated the capability of CNCs-BR in interacting with HTF and quenching its fluorescence emission intensity through a static quenching process, which was revealed by the inverse correlation between Ksv values and temperature. In conformity to the results of synchronous fluorescence spectroscopy, CNCs-BR caused more changes in the vicinity of Trp residue in contrast to Tyr, while the FRET analysis determined the energy transfer between HTF and CNCs-BR to be 0.18, and their distance to be 2.41 nm. The drawn conclusion from these observations confirmed the suitability of CNCs as a carrier for BR along with their improved bioavailability caused by the effective interaction between HTF and BR-loaded CNCs. The results also showed that loading BR on CNCs not only improved its water solubility but also led to a sustained release behavior in a simulated gastrointestinal condition of the body.

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Hydrophilic mesoporous silica aerogel particles were synthesized via self-assembly of amphiphilic polymer (Ph8-PEG6-PEOS) and its instantaneous hydrolysis and condensation in the alkaline environment. Meanwhile, the capture and encapsulation of flame retardant (IPPP) and oil soluble dyes were successively completed during the two processes above. Observed by thermal field scanning electron microscopy (TFESEM), the average diameter of aerogel particles reached about 10 µm. BET surface area analysis displayed that the existence of oil-phase component (IPPP) can result in the expansion of pore diameter, and promote the evolution of mesopores into macropores. Then, IPPP@SiO₂ aerogel particles were utilized to improve the flame retardancy of polyvinyl alcohol (PVA) coatings implemented onto cotton yarns, by employing developed knife coating procedure in an aqueous suspension. The thermal stabilities and flammability behaviors of the samples were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), and vertical burning test, respectively. Both thermal decomposition temperature and LOI value of coating composites gradually increased with the increment of IPPP@SiO₂-n (n = 10, 30, 50, 70), attaching to the synchronous advancement in stretching property. Furthermore, coatings were thickened by degrees from 0.4 to 4 mm, based on knife coating in multi-stage layer-by-layer mode, to build an ordered porous structure with the assisted adhesion of PVA. The following sintering preserved the close packing of silica aerogel particles and facilitated the formation of a coherent porous monolithic material with excellent thermal insulation performance.

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This study presents the self-assembly of polyethylene oxide (PEO)-block-polypropylene oxide (PPO)-block-polyethylene oxide (PEO)-based block copolymer (BCP) commercially known as Pluronic^® P123 in water and in the presence of different copolymeric surfactants (L61, L62, L64, and F68) with varying degree of hydrophilicity, i.e., %EO content. The clouding behavior demonstrates the varied phase transition ranging from solution, blue point (BP), and cloud point (CP). The characteristics of the micelles in the single and mix system are characterized utilizing dynamic light scattering (DLS) and small-angle neutron scattering (SANS) techniques at different temperatures. These scattering approaches provide an insightful information on the micelle size and shape. The size variations in self-assembled micelles designated the micelles to undergo growth/transition in shape from spherical to elongated ellipsoidal as function of temperature. Additionally, the application of these nanoscale micellar aggregates as carriers for delivering the anticancer drug Quercetin (QCT) was undertaken by a thorough quantitative and qualitative analysis to gain valuable insights into the effectiveness of the mix-micellar system as an ideal platform for drug delivery. A comprehensive investigation of drug release kinetics is presented using various kinetic models. The MTT (cytotoxicity assay) assay is used to gauge the effectiveness of the QCT-loaded copolymeric micelles.

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Micellar transition of 5% w/v P123 in water and in the presence of copolymeric surfactants as additives at 0.2% weight fraction (fix) at different temperatures

Abstract

Colloidal particles play a pivotal role in numerous applications across various disciplines, many of which necessitate precise control over particle size and size distribution. Seeded growth reactions have been established as effective methods for reproducibly accessing tailor-made particles. However, conventional batch-wise syntheses only yield discrete particle sizes. With the increasing focus on complex structures in current research, there is a demand for innovative and adaptable techniques to produce colloidal particles with precise sizes and size distributions. The Controlled Emulsion Extraction Process (CrEEP) is capable of addressing this challenge. Here, we present in detail how this synthesis works and demonstrate its reliability and versatility. Our approach exploits the time-dependent particle growth and enables accessing dispersions of controlled particle size distributions. We highlight these possibilities through a variation of the monomer feed and feed composition, resulting in gradual changes in both size and glass transition temperature, respectively. Beyond its application to polymer particles, CrEEP can be seamlessly extended to other seeded-growth mechanisms, such as the silica Stöber synthesis. Consequently, the Controlled Extraction Stöber Process (CrESP) similarly yields a size gradient, showcasing the generality of this synthetic advancement.

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