Conformational Structure of Triblock Copolymers by FT-Raman and FTIR Spectroscopy

Novel Thermosensitive and Mucoadhesive Nasal Hydrogel Containing 5-MeO-DMT Optimized Using Box-Behnken Experimental Design

We present the development and characterization of a nasal drug delivery system comprised of a thermosensitive mucoadhesive hydrogel based on a mixture of the polymers Poloxamer 407, Poloxamer 188 and Hydroxypropyl-methylcellulose, and the psychedelic drug 5-methoxy-N,-N-dimethyltryptamine. The development relied on a 3 × 3 Box-Behnken experimental design, focusing on optimizing gelification temperature, viscosity and mucoadhesion. The primary objective of this work was to tailor the formulation for efficient nasal drug delivery. This would increase contact time between the hydrogel and the mucosa while preserving normal ciliary functioning. Following optimization, the final formulation underwent characterization through an examination of the in vitro drug release profile via dialysis under sink conditions. Additionally, homogeneity of its composition was assessed using Raman Confocal Spectroscopy. The results demonstrate complete mixing of drug and polymers within the hydrogel matrix. Furthermore, the formulation exhibits sustained release profile, with 73.76% of the drug being delivered after 5 h in vitro. This will enable future studies to assess the possibility of using this formulation to treat certain mental disorders. We have successfully developed a promising thermosensitive and mucoadhesive hydrogel with a gelling temperature of around 32 °C, a viscosity close to 100 mPas and a mucoadhesion of nearly 4.20 N·m.

Comparative Studies of the Uptake and Internalization Pathways of Different Lipid Nano-Systems Intended for Brain Delivery

Lipid nano-systems were prepared and characterized in a series of well-established in vitro tests that could assess their interactions with the hCMEC/D3 and SH-SY5Y cell lines as a model for the blood-brain barrier and neuronal function, accordingly. The prepared formulations of nanoliposomes and nanostructured lipid carriers were characterized by z-average diameters of ~120 nm and ~105 nm, respectively, following a unimodal particle size distribution (PDI < 0.3) and negative Z-potential (-24.30 mV to -31.20 mV). Stability studies implied that the nano-systems were stable in a physiologically relevant medium as well as human plasma, except nanoliposomes containing poloxamer on their surface, where there was an increase in particle size of ~26%. The presence of stealth polymer tends to decrease the amount of adsorbed proteins onto a particle's surface, according to protein adsorption studies. Both formulations of nanoliposomes were characterized by a low cytotoxicity, while their cell viability was reduced when incubated with the highest concentration (100 μg/mL) of nanostructured lipid formulations, which could have been associated with the consumption of cellular energy, thus resulting in a reduction in metabolic active cells. The uptake of all the nano-systems in the hCMEC/D3 and SH-SY5Y cell lines was successful, most likely following ATP-dependent internalization, as well as transport via passive diffusion.

Poloxamer-based nanogels as delivery systems: how structural requirements can drive their biological performance?

Poloxamers or Pluronics®-based nanogels are one of the most used matrices for developing delivery systems. Due to their thermoresponsive and flexible mechanical properties, they allowed the incorporation of several molecules including drugs, biomacromolecules, lipid-derivatives, polymers, and metallic, polymeric, or lipid nanocarriers. The thermogelling mechanism is driven by micelles formation and their self-assembly as phase organizations (lamellar, hexagonal, cubic) in response to microenvironmental conditions such as temperature, osmolarity, and additives incorporated. Then, different biophysical techniques have been used for investigating those structural transitions from the mechanisms to the preferential component's orientation and organization. Since the design of PL-based pharmaceutical formulations is driven by the choice of the polymer type, considering its physico-chemical properties, it is also relevant to highlight that factors inherent to the polymeric matrix can be strongly influenced by the presence of additives and how they are able to determine the nanogels biopharmaceuticals properties such as bioadhesion, drug loading, surface interaction behavior, dissolution, and release rate control. In this review, we discuss the general applicability of three of the main biophysical techniques used to characterize those systems, scattering techniques (small-angle X-ray and neutron scattering), rheology and Fourier transform infrared absorption spectroscopy (FTIR), connecting their supramolecular structure and insights for formulating effective therapeutic delivery systems.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12551-023-01093-2.

Structural Behavior of Amphiphilic Triblock Copolymer P104/Water System

A detailed study of the different structural transitions of the triblock copolymer PEO₂₇-PPO₆₁-PEO₂₇ (P104) in water, in the dilute and semi-dilute regions, is addressed here as a function of temperature and P104 concentration (C_P104) by mean of complimentary methods: viscosimetry, densimetry, dynamic light scattering, turbidimetry, polarized microscopy, and rheometry. The hydration profile was calculated through density and sound velocity measurements. It was possible to identify the regions where monomers exist, spherical micelle formation, elongated cylindrical micelles formation, clouding points, and liquid crystalline behavior. We report a partial phase diagram including information for P104 concentrations from 1 × 10^-4 to 90 wt.% and temperatures from 20 to 75 °C that will be helpful for further interaction studies with hydrophobic molecules or active principles for drug delivery.

Characterization of Hyaluronic Acid-Coated PLGA Nanoparticles by Surface-Enhanced Raman Spectroscopy

Nanoparticles (NPs) coated with hyaluronic acid (HA) seem to be increasingly promising for targeted therapy due to HA chemical versatility, which allows them to bind drugs of different natures, and their affinity with the transmembrane receptor CD-44, overexpressed in tumor cells. However, an essential aspect for clinical use of NPs is formulation stability over time. For these reasons, analytical techniques capable of characterizing their physico-chemical properties are needed. In this work, poly(lactide-co-glycolide) (PLGA) NPs with an average diameter of 100-150 nm, coated with a few 10 s of nm of HA, were synthesized. For stability characterization, two complementary investigative techniques were used: Dynamic Light Scattering (DLS) and Surface-Enhanced Raman Scattering (SERS) spectroscopy. The first technique provided information on size, polidispersity index, and zeta-potential, and the second provided a deeper insight on the NP surface chemicals, allowing distinguishing of HA-coated NPs from uncoated ones. Furthermore, in order to estimate formulation stability over time, NPs were measured and monitored for two weeks. SERS results showed a progressive decrease in the signal associated with HA, which, however, is not detectable by the DLS measurements.

How Kosmotropic and Chaotropic Osmolytes Perturb the Properties of an Aqueous Solution of a Pluronic Block Copolymer?

Poloxamer 407 (P-407) composed of a poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG) unit has two distinct microenvironments: the interior core formed by the PPG unit and the exterior shell formed by the PEG unit. In this work, we have used two fluorescent molecules coumarin-153 and 8-anilino-1-naphthalene sulfonic acid (ANS) of contrasting natures to characterize and probe the water dynamics in the core and corona regions of the copolymer by means of spectroscopic techniques, namely, absorption, fluorescence, and time-resolved fluorescence emission spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Changes in the surface morphologies were characterized by using microscopic techniques. Further, two classes of osmolytes kosmotropic (betaine and sarcosine) and chaotropic (urea) known to perturb the water structure were added to aqueous solutions of P-407. Our studies reveal that the addition of kosmotropes decreases the critical micelle temperature (CMT) of the copolymer, whereas the chaotropic osmolyte increases the CMT. Steady-state studies reveal that the addition of the osmolytes to the copolymer increases the polarity of the micelle formed and hence results in the red shift in the ANS absorbance maximum. FTIR spectroscopy reveals that kosmotropes interact with the PEG moiety of the copolymer, whereas the chaotrope interacts with both the PEG and PPG moieties of the copolymer. Solvent relaxation studies produced less changes upon the addition of the kosmotropes, whereas a greater change in the relaxation time was observed in the presence of the chaotrope.

Role of protein-copolymer assembly in controlling micellization process of amphiphilic triblock copolymer

HYPOTHESIS

Triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG) forms a well-known micellar assembly at a particular temperature. Apart from regular assembly within the copolymer, it is crucial to explore additional assembly behaviour via simple exposure of proteins which unveils biased interactions with blocks of copolymer. The current work focuses on the examination of Pluronic F108 i.e. PEG-PPG-PEG with two different proteins i.e. α-chymotrypsin (CT) and lysozyme (LSZ), aiming at probing the critical micellization temperature (CMT) and molecular level interactions.

EXPERIMENTS

Potential role of protein-copolymer assembly formation at a particular concentration of protein in modulating CMT was shown by a systematic experimental approach combined with a series of physicochemical methods. The sophisticated multiple techniques include fluorescence spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, dynamic light scattering (DLS), zeta potential measurements, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, molecular docking studies were also employed to correlate theoretical insights with experimental findings.

FINDINGS

CT and LSZ decrease CMT in regular concentration-dependent manner except for particular concentration (1.5 mg/mL) of LSZ which shows anomalous behaviour in steady-state fluorescence spectroscopy, temperature dependent fluorescence spectroscopy, Raman spectroscopy and DLS measurements. SEM and TEM results clearly reveal protein-copolymer assembly formation. The assembled structure has different biophysical properties. Docking studies elucidate several bio macromolecular interactions which can be involved in assembly formation. Based on obtained results from biophysical techniques mechanism of CMT variation was deduced. Obtained results can be useful in biosensors and targeted drug delivery systems.

Preparation and characterization of salicylic acid grafted chitosan electrospun fibers

Chitosan (chi) and its modified forms as electrospun nanofibers have potential applications in advanced water treatment and biomedicine. Polyethylene oxide (PEO) is an additive commonly used to facilitate the formation of chitosan electrospun fibers because PEO (Mw ≥ 400 kDa) affords chain entanglement that stabilize the electrospinning jet, leading to enhanced formation of chi-based electrospun fibers. Herein, we report on the preparation of chitosan grafted with salicylic acid and its utility to afford improved electrospun fibers with low molecular weight (LMw) PEO (Mw » 100 kDa). A comparison of the interactions between original and grafted chitosan with PEO reveals that stable supramolecular assemblies are established between grafted chitosan and PEO, which provides support that such supramolecular interactions favor formation of chitosan electrospun fibers. Moreover, a porous chitosan electrospun nanofiber was prepared through physical treatment that reveals notably higher (ca. 4-fold) dye uptake than the pristine (unmodified) chitosan electrospun nanofibers.

Confocal Raman Spectroscopic Imaging for Evaluation of Distribution of Nano-Formulated Hydrophobic Active Cosmetic Ingredients in Hydrophilic Films

Film-forming systems are highly relevant to the topical administration of active ingredients (AI) to the body. Enhanced contact with the skin can increase the efficacy of delivery and penetration during prolonged exposure. However, after the evaporation of volatile solvents to form a thin film, the distribution of the ingredient should remain homogenous in order to ensure the effectiveness of the formula. This is especially critical for the use of hydrophobic molecules that have poor solubility in hydrophilic films. In order to address this concern, hydroxyphenethyl esters (PHE) of Punica granatum seed oil were prepared as a nanosuspension stabilised by poloxamers (NanoPHE). NanoPHE was then added to a formulation containing polyvinyl alcohol (PVA) as a film forming agent, Glycerol as a plasticiser and an antimicrobial agent, SepicideTM HB. Despite their reliability, reference methods such as high-performance liquid chromatography are increasingly challenged due to the need for consumables and solvents, which is contrary to current concerns about green industry in the cosmetics field. Moreover, such methods fail to provide spatially resolved chemical information. In order to investigate the distribution of ingredients in the dried film, Confocal Raman imaging (CRI) coupled to Non-negatively Constrained Least Squares (NCLS) analysis was used. The reconstructed heat maps from a range of films containing systematically varying PHE concentrations highlighted the changes in spectral contribution from each of the ingredients. First, using NCLS scores it was demonstrated that the distributions of PVA, Glycerol, SepicideTM HB and PHE were homogenous, with respective relative standard deviations (RSD) of 3.33%, 2.48%, 2.72% and 6.27%. Second, the respective relationships between ingredient concentrations in the films and their Raman responses, and the spectral abundance were established. Finally, a model for absolute quantification for PHE was be constructed using the percentage of spectral abundance. The prepared %w/w concentrations regressed against predicted %w/w concentrations, displaying high correlation (R2 = 0.995), while the Root Mean Squared Error (0.0869% w/w PHE) confirmed the precision of the analysis. The mean percent relative error of 3.75% indicates the accuracy to which the concentration in dried films could be determined, further supporting the suitability of CRI for analysis of composite solid film matrix. Ultimately, it was demonstrated that nanoformulation of hydrophobic PHE provides homogenous distribution in PVA based film-forming systems independent of the concentration of NanoPHE used in the formula.

Anisotropic diffusion of Fe ions in Fricke-XO-Pluronic F-127 and Fricke-XO-gelatine 3D radiotherapy dosimeters

A new radiochromic dosimeter was examined with Raman spectroscopy and an optical approach for assessment of 3D dose distribution integrity. The acronym of the dosimeter is Fricke-XO-Pluronic F-127, where XO denotes xylenol orange; Pluronic F-127 is a copolymer matrix of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide), and the dosimeter contains the components of a Fricke dosimetric solution. Two dosimeter samples in cuvettes were partially irradiated such that a radiation dose was absorbed at the bottom of the cuvettes. After irradiation, one sample was stored upside down such that the irradiated part was at the top and another one was stored with the irradiated part at the bottom. Two diffusion coefficients of ferric ion complexes with XO ([XO-Fe]⁺³) were calculated. They were compared with those for similar dosimeter, however with gelatine matrix instead of Pluronic F-127. The results obtained indicate an impact of the gravitational force on the diffusion of [XO-Fe]⁺³ions over time after irradiation and thus a possibility of severely undermining the integrity of a dose distribution in irradiated dosimeter. The conclusions drawn suggest the necessity of examination of different 3D Fricke dosimeter compositions for anisotropic diffusion of ferric ions.

Folate-targeted Pluronic-chitosan nanocapsules loaded with IR780 for near-infrared fluorescence imaging and photothermal-photodynamic therapy of ovarian cancer

Herein, we report the fabrication of a nanotherapeutic platform integrating near-infrared (NIR) imaging with combined therapeutic potential through photodynamic (PDT) and photothermal therapies (PTT) and recognition functionality against ovarian cancer. Owing to its NIR fluorescence, singlet oxygen generation and heating capacity, IR780 iodide is exploited to construct a multifunctional nanosystem for single-wavelength NIR laser imaging-assisted dual-modal phototherapy. We opted for loading IR780 into polymeric Pluronic-F127-chitosan nanoformulation in order to overcome its hydrophobicity and toxicity and to allow functionalization with folic acid. The obtained nanocapsules show temperature-dependent swelling and spectroscopic behavior with favorable size distribution for cellular uptake at physiological temperatures, improved fluorescence properties and good stability. The fabricated nanocapsules can efficiently generate singlet oxygen in solution and are able to produce considerable temperature increase (46 °C) upon NIR laser irradiation. Viability assays on NIH-OVCAR-3 cells confirm the successful biocompatibilization of IR780 by encapsulating in Pluronic and chitosan polymers. NIR fluorescence imaging assays reveal the ability of folic-acid functionalized nanocapsules to serve as intracellular contrast agents and demonstrate their active targeting capacity against folate receptor expressing ovarian cancer cells (NIH-OVCAR-3). Consequently, the targeted nanocapsules show improved NIR laser induced phototherapeutic performance against NIH-OVCAR-3 cells compared to free IR780. We anticipate that this class of nanocapsules holds great promise as theranostic agents for application in image-guided dual PDT-PTT and imaging assisted surgery of ovarian cancer.

Probing the potential of ureasil-poly(ethylene oxide) as a glyphosate scavenger in aqueous milieu: force-field parameterization and MD simulations

The intensive use of glyphosate in conventional agriculture and its high solubility in water have led to contamination of aqueous systems worldwide.

Chemical Stability and Transformation of Molybdenum Disulfide Nanosheets in Environmental Media

Layered transition metal dichalcogenides, including molybdenum disulfide (MoS₂), have previously been considered stable in the ambient environment due to the absence of dangling bonds in the electron-filled shells of the end chalcogen atoms. Here, we evaluate the chemical stability of MoS₂ nanosheets fabricated by chemical exfoliation (ceMoS₂) and surfactant dispersion (sMoS₂). The results demonstrate that sMoS₂ exhibits greater long-term persistence. Contrarily, ceMoS₂ underwent progressive deterioration, in which preferential oxidation of the 1T of a mixture of 1T and 2H phases was observed. The oxidative degradation of ceMoS₂ was retarded in the presence of natural organic matter (NOM), including Suwannee River natural organic matter (SRNOM) and Aldrich humic acid (ALHA), in the dark ambient condition, while the aging process of MoS₂ with co-occurring ALHA was accelerated under sunlight exposure. The observed inhibition effect on the deterioration of ceMoS₂ by NOM was mainly attributed to slower dissolution kinetics with rapid initial oxidation (i.e., forming Mo-O bonding) or carbon grafting, rather than prevention of the formation of secondary small suspended Mo-containing particles. The compiled results highlight that the environmental fate of MoS₂ nanosheets will be regulated by the combined effects of exfoliating agents and environmentally relevant factors including organic macromolecules and sunlight exposure.

Quantitative analysis of the distribution and mixing of cellulose nanocrystals in thermoplastic composites using Raman chemical imaging

Raman chemical imaging is presented to both quantify the dispersion and the degree of mixing in a cellulose nanocrystal composite.

Nanopyroxene Grafting with β-Cyclodextrin Monomer for Wastewater Applications

Emerging nanoparticle technology provides opportunities for environmentally friendly wastewater treatment applications, including those in the large liquid tailings containments in the Alberta oil sands. In this study, we synthesize β-cyclodextrin grafted nanopyroxenes to offer an ecofriendly platform for the selective removal of organic compounds typically present in these types of applications. We carry out computational modeling at the micro level through molecular mechanics and molecular dynamics simulations and laboratory experiments at the macro level to understand the interactions between the synthesized nanomaterials and two-model naphthenic acid molecules (cyclopentanecarboxylic and trans-4-pentylcyclohexanecarboxylic acids) typically existing in tailing ponds. The proof-of-concept computational modeling and experiments demonstrate that monomer grafted nanopyroxene  or nano-AE of the sodium iron-silicate aegirine are found to be promising candidates for the removal of polar organic compounds from wastewater, among other applications. These nano-AE offer new possibilities for treating tailing ponds generated by the oil sands industry.

Effects of Liposomes Contained in Thermosensitive Hydrogels as Biomaterials Useful in Neural Tissue Engineering

Advances in the generation of suitable thermosensitive hydrogels for the delivery of cells in neural tissue engineering demonstrate a delicate relationship between physical properties and capabilities to promote cell proliferation and differentiation. To improve the properties of these materials, it is possible to add liposomes for the controlled release of bioactive elements, which in turn can affect the physical and biological properties of the hydrogels. In the present investigation, different hydrogels based on Pluronic F127 have been formulated with the incorporation of chitosan and two types of liposomes of two different sizes. The rheological and thermal properties and their relation with the neurite proliferation and growth of the PC12 cell line were evaluated. Our results show that the incorporation of liposomes modifies the properties of the hydrogels dependent on the concentration of chitosan and the lipid type in the liposomes, which directly affect the capabilities of the hydrogels to promote the viability and differentiation of PC12 cells.

Phospholipid Capped Mesoporous Nanoparticles for Targeted High Intensity Focused Ultrasound Ablation

The mechanical effects of cavitation can be effective for therapy but difficult to control, thus potentially leading to off-target side effects in patients. While administration of ultrasound active agents such as fluorocarbon microbubbles and nanodroplets can locally enhance the effects of high intensity focused ultrasound (HIFU), it has been challenging to prepare ultrasound active agents that are small and stable enough to accumulate in tumors and internalize into cancer cells. Here, this paper reports the synthesis of 100 nm nanoparticle ultrasound agents based on phospholipid-coated, mesoporous, hydrophobically functionalized silica nanoparticles that can internalize into cancer cells and remain acoustically active. The ultrasound agents produce bubbles when subjected to short HIFU pulses (≈6 µs) with peak negative pressure as low as ≈7 MPa and at particle concentrations down to 12.5 µg mL-1 (7 × 109 particles mL-1 ). Importantly, ultrasound agents are effectively uptaken by cancer cells without cytotoxic effects, but HIFU insonation causes destruction of the cells by the acoustically generated bubbles, as demonstrated by (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and lactate dehydrogenase assays and flow cytometry. Finally, it is showed that the HIFU dose required to effectively eliminate cancer cells in the presence of ultrasound agents causes only a small temperature increase of ≈3.5 °C.

Stable Encapsulation of Air in Mesoporous Silica Nanoparticles: Fluorocarbon-Free Nanoscale Ultrasound Contrast Agents

While gas-filled micrometer-sized ultrasound contrast agents vastly improve signal-to-noise ratios, microbubbles have short circulation lifetimes and poor extravasation from the blood. Previously reported fluorocarbon-based nanoscale contrast agents are more stable but their contrast is generally lower owing to their size and dispersity. The contrast agents reported here are composed of silica nanoparticles of ≈100 nm diameter that are filled with ≈3 nm columnar mesopores. Functionalization of the silica surface with octyl groups and resuspension with Pluronic F127 create particles with pores that remain filled with air but are stable in buffer and serum. Administration of high intensity focused ultrasound (HIFU) allows sensitive imaging of the silica nanoparticles down to 10(10) particles mL(-1) , with continuous imaging for at least 20 min. Control experiments with different silica particles supported the hypothesis that entrapped air could be pulled into bubble nuclei, which can then in turn act as acoustic scatterers. This process results in very little hemolysis in whole blood, indicating potential for nontoxic blood pool imaging. Finally, the particles are lyophilized and reconstituted or stored in PBS (phosphate-buffered saline, at least for four months) with no loss in contrast, indicating stability to storage and reformulation.

Functional double-shelled silicon nanocrystals for two-photon fluorescence cell imaging: spectral evolution and tuning

Functional near-IR (NIR) emitting nanoparticles (NPs) adapted for two-photon excitation fluorescence cell imaging were obtained starting from octadecyl-terminated silicon nanocrystals (ncSi-OD) of narrow photoluminescence (PL) spectra having no long emission tails, continuously tunable over the 700-1000 nm window, PL quantum yields exceeding 30%, and PL lifetimes of 300 μs or longer. These NPs, consisting of a Pluronic F127 shell and a core made up of assembled ncSi-OD kept apart by an octadecyl (OD) layer, were readily internalized into the cytosol, but not the nucleus, of NIH3T3 cells and were non-toxic. Asymmetrical field-flow fractionation (AF4) analysis was carried out to determine the size of the NPs in water. HiLyte Fluor 750 amine was linked via an amide link to NPs prepared with Pluronic-F127-COOH, as a first demonstration of functional NIR-emitting water dispersible ncSi-based nanoparticles.

A general and efficient method for decorating graphene sheets with metal nanoparticles based on the non-covalently functionalized graphene sheets with hyperbranched polymers

Multipyrene terminated hyperbranched polyglycidol (mPHP) has been synthesized and used to non-covalently functionalize pristine graphene sheets (GSs) through π-π stacking interactions. Mediated by the mPHP layer, a variety of metal nanoparticles (Au, Ag and Pt) were in situ generated and deposited onto the surface-modified GS, yielding versatile GS/mPHP/metal nanohybrids. As typical examples, by simply controlling the concentration of HAuCl(4) used, Au nanostructures ranging from isolated spheres to a continuous film were created and coated onto the surface-modified GS. The studies on the fluorescence properties of resulting GS/mPHP/Au hybrid nanostructures reveal that the GS and controllable content of Au components in the hybrids can effectively quench the fluorescence emission of mPHP in a controlled manner. Further investigation indicates that GS/mPHP/Au hybrids are promising surface enhanced Raman scattering (SERS) substrates. The SERS activities of these hybrids depend on the contents and form of the Au. The GS/mPHP/Au hybrid containing continuous Au films exhibits the strongest SERS activity. GS/mPHP/Au hybrids are also used as efficient heterogeneous catalysts for the reduction of 4-NP, and demonstrate excellent catalytic performance. The detailed reaction kinetics and the reusability of such catalysts have also been investigated.

Ultrasonochemically conjugated metalloid/triblock copolymer nanocomposite and subsequent thin solid laminate growth for surface and interface studies

Polymer and metalloid nanoparticles can be conjugated in a symphonized manner using ultrasonochemical force to obtain hybrid nanocomposites. The process is demonstrated using polymer poly(ethylene glycol) (PEG), metalloid SiO(2)@Ag, and triblock copolymer ABA. The acoustic microstreaming and cavitation force from the ultrasonics are crucial parameters that determine the harmonized PEG stabilization and ABA blending of the metalloid nanocomposites that are obtained. Surface plasmon resonance in the resulting hybrid systems are examined by UV-vis absorbance spectroscopy. The resulting PEG-stabilized SiO(2)-Ag conjugated with a triblock copolymer poly(p-dioxanone-co-caprolactone)-block-poly(ethylene oxide)-block-poly(p-dioxanone-co-caprolactone) (PPDO-co-PCL-b-PEG-b-PPDO-co-PCL/ABA) (PEG-SiO(2)@Ag/ABA) shows a red shift of 20 nm (410 nm) from its initial resonance at 390 nm (PEG-SiO(2)@Ag). Nanocomposite particles were then spin-coated on a glass substrate to obtain the growth of thin solid laminates (thickness 27 microm). Structural functionality was studied by FT-IR, (1)H NMR, and FT-Raman spectroscopy. Morphological properties were ensured from FE-SEM, HRTEM, AFM, and FIB-SEM. Identity and crystallinity of the prepared nanocomposite were confirmed by XRD analysis. A very low weight percentile loss of the fabricated nanocomposites ensures its high thermal stability. Fabricated nanocomposite laminate might have a role in coating, reinforcement, and resistance and as substrate additives for a variety of surface and interface studies. Further, the ultrasonochemical approach utilized here could also be a smart system to fabricate other heteronanostructures in a single platform.

Ultrafast infrared heating laser pulse-induced micellization kinetics of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) in water

The heating-induced micellization of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (Pluronic PE10300) triblock copolymer chains was studied by ultrasensitive differential scanning calorimetry, laser light scattering, and fluorescence spectrometry with a fluorescent probe, 8-anilino-1-naphthalenesulfonic acid ammonium salt. The critical micellization temperatures obtained from the three methods are similar. The micellization kinetics was studied in terms of changes in the fluorescence and Rayleigh scattering intensities after an ultrafast infrared heating laser pulse (approximately 10 ns)-induced temperature jump. The increases in the fluorescence and Rayleigh scattering intensities in the millisecond range can be well described by a single-exponential equation, corresponding to the incorporation of individual triblock copolymer chains (unimers) into large spherical micelles. The increase in copolymer concentration or the initial solution temperature decreases the characteristic transition time. In general, the fluorescence measurement has a better signal-to-noise ratio but leads to a transition time that is slightly shorter than that from the corresponding Rayleigh scattering measurement for a given copolymer solution.

Characterization and demulsification of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers

Four poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers with different molecular weights and PPO/PEO composition ratios were synthesized. The characterization of the PEO-PPO-PEO triblock copolymers was studied by surface tension measurement, UV-vis spectra, and surface pressure method. These results clearly showed that the CMC of PEO-PPO-PEO was not a certain value but a concentration range, in contrast to classical surfactant, and two breaks around CMC were reflected in both surface tension isotherm curves and UV-vis absorption spectra. The range of CMC became wider with increasing PPO/PEO composition ratio. Surface pressure Pi-A curves revealed that the amphiphilic triblock copolymer PEO-PPO-PEO molecule was flexible at the air/water interface. We found that the minimum area per molecule at the air/water interface increased with the proportion of PEO chains. The copolymers with the same mass fractions of PEO had similar slopes in the isotherm of the Pi-A curve. From the demulsification experiments a conclusion had been drawn that the dehydration speed increased with decreased content of PEO, but the final dehydration rate of four demulsifiers was approximate. We determined that the coalescence of water drops resulted in the breaking of crude oil emulsions from the micrograph.