Hydration of Sodium Alginate in Aqueous Solution

Stabilization Activity of Kelp Extract in Ethylene-Propylene Rubber as Safe Packaging Material

This paper presents the stabilization effects of the solid extract of kelp (Ascophyllum nodosum) on an engineering elastomer, ethylene-propylene copolymer (EPR), which may be used as packaging material. Progressive increase in additive loadings (0.5, 1, and 2 phr) increases the oxidation induction time for thermally aged rubber at 190 °C from 10 min to 30 min for pristine material and modified polymer by adding 2 phr protection powder. When the studied polymer is γ-irradiated at 50 and 100 kGy, the onset oxidation temperatures increase as a result of blocking the oxidation reactivity of free radicals. The stabilization effect occurs through the activity of alginic acid, which is one of the main active components associated with alginates. The accelerated degradation caused by γ-exposure advances more slowly when the kelp extract is present. The OOT value for the oxidation of EPR samples increases from 130 °C to 165 °C after the γ-irradiation of pristine and modified (2 phr of kelp powder) EPR, respectively. The altered oxidation state of EPR samples by the action of γ-rays in saline serum is faster in neat polymer than in stabilized material. When the probes are placed in physiological serum and irradiated at 25 kGy, the OOT value for neat EPR (145 °C) is much lower than the homologous value for the polymer samples protected by kelp extract (153 °C for the concentration of 0.5 phr, 166 °C for the concentration of 1 phr, and 185 °C for the concentration of 2 phr).

Elucidating Conformation and Hydrogen-Bonding Motifs of Reactive Thiourea Intermediates

Substituted diphenylthioureas (DPTUs) are efficient hydrogen-bonding organo-catalysts, and substitution of DPTUs has been shown to greatly affect catalytic activity. Yet, both the conformation of DPTUs in solution and the conformation and hydrogen-bonded motifs within catalytically active intermediates, pertinent to their mode of activation, have remained elusive. By combining linear and ultrafast vibrational spectroscopy with spectroscopic simulations and calculations, we show that different conformational states of thioureas give rise to distinctively different N-H stretching bands in the infrared spectra. In the absence of hydrogen-bond-accepting substrates, we show that vibrational structure and dynamics are highly sensitive to the substitution of DPTUs with CF3 groups and to the interaction with the solvent environment, allowing for disentangling the different conformational states. In contrast to bare diphenylthiourea (0CF-DPTU), we find the catalytically superior CF3-substituted DPTU (4CF-DPTU) to favor the trans-trans conformation in solution, allowing for donating two hydrogen bonds to the reactive substrate. In the presence of a prototypical substrate, DPTUs in trans-trans conformation hydrogen bond to the substrate's C=O group, as evidenced by a red-shift of the N-H vibration. Yet, our time-resolved infrared experiments indicate that only one N-H group forms a strong hydrogen bond to the carbonyl moiety, while thiourea's second N-H group only weakly interacts with the substrate. Our data indicate that hydrogen-bond exchange between these N-H groups occurs on the timescale of a few picoseconds for 0CF-DPTU and is significantly accelerated upon CF3 substitution. Our results highlight the subtle interplay between conformational equilibria, bonding states, and bonding lifetimes in reactive intermediates in thiourea catalysis, which help rationalize their catalytic activity.

Guar gum-sodium alginate nanocomposite film as a smart fluorescence-based humidity sensor: A smart packaging material

Perishable packed foods are easily damaged by the change in relative humidity. In this work, we demonstrate that guar gum- sodium alginate blending with glucose-glycerol carbon dots nanocomposite film can be used to detect relative humidity. The fabricated nanocomposite film was an excellent smart sensor based on the fluorescence 'on-off' mechanisms against humidity. The study demonstrates that at different relative humidity conditions, such as 11 %, 33 %, 75.30 %, 84 %, and 97 %, there is a change in the fluorescence of biocomposite films under UV light. The practical feasibility of the biocomposite developed film was tested in real conditions by placing a piece of bread with high humidity conditions wrapped with the developed nanocomposite film. It was observed that under such conditions, marked quenching of fluorescence was observed and hence detection of humidity was possible. Hence, the fabricated nanocomposite film can monitor the packed food freshness using just a UV light source. Such biopolymer nanocomposite is potential materials and may find application as smart packaging materials, especially as food packaging materials.

Chitosan-based composites reinforced with antibacterial flexible wood membrane for rapid hemostasis

Irregular hemorrhagic traumas always threaten the health of patients due to uncontrollable bleeding and wound infections. The traditional hemostatic materials show dissatisfactory hemostatic efficiency and antibacterial activity in solving these potential bleeding dangers. Herein, we proposed a kind of composites based on flexible wood membrane (FWM) loaded with chitosan/alginate derivative for accelerating rapid hemostasis and preventing infection. FWM was removed part of hemicellulose and lignin by using NaOH/Na₂SO₃ mixture to obtain excellent flexibility while retaining the original porous structure, followed by loading silver nanoparticles on the FWM surface to prepare AgNPs-FWM as an antibacterial bio-carrier. Then, AgNPs-FWM was coated with polyoxyethylene stearate-modified chitosan and multi-aldehyde sodium alginate to fabricate the composites of chitosan/alginate/AgNPs-FWM (CSA/AgNPs-FWM) using in-situ Schiff base reaction. Furthermore, in vitro and in vivo experiments showed that the CSA/AgNPs-FWM composites exhibited lower BCI value (2.6 ± 1.3 %), more rapid hemostasis (26 s) and lower blood loss (67.8 mg) than that of the traditional materials. The possible mechanism for the hemostasis process was not only the high blood absorption capacity, but also the synergistic interaction between hydrophobic alkane chains, amino groups, aldehydes, hydroxyl groups and blood cells. Moreover, CSA/AgNPs-FWM showed exceptional superiorities in mechanical properties and antibacterial activity, which endowed composites high potential in hemostasis application for irregular external wound.

Alginate-Based Hydrogel as Delivery System for Therapeutic Bacterial RNase

To deliver therapeutic proteins into a living body, it is important to maintain their target activity in the gastrointestinal tract after oral administration. Secreted ribonuclease from Bacillus pumilus (binase) has antitumor and antiviral activity, which makes it a promising therapeutic agent. This globular protein of small molecular weight (12.2 kDa) is considered as a potential agent that induces apoptosis of tumor cells expressing certain oncogenes, including colorectal and duodenum cancer. The most important problem of its usage is the preservation of its structure and target activity, which could be lost during oral administration. Here, we developed alginate microspheres reinforced with divalent cations and analyzed the enzyme release from them. Using methods of scanning electron microscopy, measurements of fluorescence, enzyme catalytic activity, and determination of viability of the duodenum adenocarcinoma tumor cell line, we characterized obtained microspheres and chose calcium as a biogenic ion-strengthening microsphere structure. Among such modified additivities as beta-casein, gelatin, and carbon nanotubes introduced into microspheres, only gelatin showed a pronounced increase in their stability and provided data on the prolonged action of enzyme release from microspheres into tumor cell culture medium during 48 h in an amount of about 70% of the loaded quantity.

Competing Effects of Hydration and Cation Complexation in Single-Chain Alginate

Alginic acid, a naturally occurring anionic polyelectrolyte, forms strong physically cross-linked hydrogels in the presence of metal cations. The latter engage in electrostatic interactions that compete with intra- and intermolecular hydrogen bonds, determining the gel structure and properties of the system in aqueous media. In this study, we use all-atom molecular dynamics simulations to systematically analyze the interactions between alginic acid chains and Na⁺ and Ca²⁺ counterions. The formed alginates originate from the competition of intramolecular hydrogen bonding and water coordination around the polyelectrolyte. In contrast to the established interpretation, we show that calcium cations strongly bind to alginate by disrupting hydrogen bonds within (1 → 4)-linked β-d-mannuronate (M) residues. On the other hand, Na⁺ cations enhance intramolecular hydrogen bonds that stabilize a left-hand, fourfold helical chain structure in poly-M alginate, resulting in stiffer chains. Hence, the traditionally accepted flexible flat-chain model for poly-M sequence is not valid in the presence of Na⁺. The two cations have a distinct effect on water coordination around alginate and therefore on its solubility. While Ca⁺ disrupts water coordination directly around the alginate chains, mobile Na⁺ cations significantly disrupt the second hydration layer.

Influence of Natural Polysaccharides on Properties of the Biomicroconcrete-Type Bioceramics

In this paper, novel hybrid biomicroconcrete-type composites were developed and investigated. The solid phase of materials consisted of a highly reactive α -tricalcium phosphate (α-TCP) powder, hybrid hydroxyapatite-chitosan (HAp-CTS) material in the form of powder and granules (as aggregates), and the polysaccharides sodium alginate (SA) or hydroxypropyl methylcellulose (HPMC). The liquid/gel phase in the studied materials constituted a citrus pectin gel. The influence of SA or HPMC on the setting reaction, microstructure, mechanical as well as biological properties of biomicroconcretes was investigated. Studies revealed that manufactured cement pastes were characterized by high plasticity and cohesion. The dual setting system of developed biomicroconcretes, achieved through α-TCP setting reaction and polymer crosslinking, resulted in a higher compressive strength. Material with the highest content of sodium alginate possessed the highest mechanical strength (~17 MPa), whereas the addition of hydroxypropyl methylcellulose led to a subtle compressive strength decrease. The obtained biomicroconcretes were chemically stable and characterized by a high bioactive potential. The novel biomaterials with favorable physicochemical and biological properties can be prosperous materials for filling bone tissue defects of any shape and size.

Quantifying Properties of Polysaccharide Solutions

We apply a scaling theory of semidilute polymer solutions to quantify solution properties of polysaccharides such as galactomannan, chitosan, sodium carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, xanthan, apple pectin, cellulose tris(phenyl carbamate), hydroxyethyl cellulose, hydroxypropyl cellulose, sodium hyaluronate, sodium alginate, and sodium κ-carrageenan. In particular, we obtain the molar mass of the chain segment inside a correlation blob M _g = B̂ ^3/(3ν-1) c ^1/(1-3ν) as a function of concentration c, interaction parameter B̂, and exponent ν. Parameter B̂ assumes values B̂ _g, B̂ _th and M ₀/N _A ^1/3 l for exponents v = 0.588, 0.5 and 1, respectively, where M ₀ is the molar mass of a repeat unit, l is the projection length of a repeat unit, and N _A is the Avogadro number. In the different solution regimes, the values of the B̂-parameters are extracted from the plateaus of the normalized specific viscosity η_sp (c)/M _w c ^1/(3ν-1), where M _w is the weight-average molecular weight of the polymer chain. The values of the B̂-parameters are used in calculations of the excluded volume v, Kuhn length b, and crossover concentrations c*, c _th, and c** into a semidilute polymer solution, a solution of overlapping thermal blobs and a concentrated polymer solution, respectively. This information is summarized as a diagram of states of different polysaccharide solution regimes by implementing a v/bl ² and c/c** representation. The scaling approach is extended to the entangled solution regime, allowing us to obtain the chain packing number, P̃ _e. This completes the set of parameters {B̂ _g, B̂ _th, P̃ _e} which uniquely describes the static and dynamic properties of a polysaccharide solution.

Revisiting Cation Complexation and Hydrogen Bonding of Single-Chain Polyguluronate Alginate

Modifying the properties of bio-based materials has garnered increasing interest in recent years. In related applications, the ability of alginates to complex with metal ions has been shown to be effective in liquid-to-gel transitions, useful in the development of foodstuff and pharma products as well as biomaterials, among others. However, despite its ubiquitous use, alginate behavior as far as interactions with cations is not fully understood. Hence, this study presents a detailed comparison of alginate's complexation with Na⁺ and Ca²⁺ and the involved intramolecular hydrogen bonding and biomolecular chain geometry. Using all-atom molecular dynamics simulations, we find that in contrast to accepted models, calcium cations strongly bind to alginate chains by disruption of hydrogen bonds between neighboring residues, stabilizing a left-hand, 3-fold helical chain structure that enhances chain stiffness. Hence, while present, the traditionally accepted egg-box binding mode was a minor subset of possible conformations. For a single chain, most of the cation binding occurred as single-cation interaction with a carboxyl group, without the coordination of other alginate oxygens. The monovalent Na⁺ ions were found to be mostly nonlocalized around alginate and therefore do not compete with intramolecular hydrogen bonding. The different binding modes observed for Na⁺ and Ca²⁺ contribute toward explaining the different solubility of sodium and calcium alginate.

Spatiotemporal Analysis of Hydration Mechanism in Sodium Alginate Matrix Tablets

Methods of spatiotemporal characterization of nonequilibrated polymer based matrices are still immature and imperfect. The purpose of the study was to develop the methodology for the spatiotemporal characterization of water transport and properties in alginate tablets under hydration. The regions of low water content were spatially and temporally sampled using Karl Fisher and Differential Scanning Callorimetry (spatial distribution of freezing/nonfreezing water) with spatial resolution of 1 mm. In the regions of high water content, where sampling was infeasible due to gel/sol consistency, magnetic resonance imaging (MRI) enabled characterization with an order of magnitude higher spatial resolution. The minimally hydrated layer (MHL), infiltration layer (IL) and fully hydrated layer (FHL) were identified in the unilaterally hydrated matrices. The MHL gained water from the first hour of incubation (5–10% w/w) and at 4 h total water content was 29–39% with nonfreezing pool of 28–29%. The water content in the IL was 45–47% and at 4 h it reached ~50% with the nonfreezing pool of 28% and T₂ relaxation time < 10 ms. The FHL consisted of gel and sol layer with water content of 85–86% with a nonfreezing pool of 11% at 4 h and T₂ in the range 20–200 ms. Hybrid destructive/nondestructive analysis of alginate matrices under hydration was proposed. It allowed assessing the temporal changes of water distribution, its mobility and interaction with matrices in identified layers.

Synergistic Effects of Alpha Olefin Sulfonate and Sodium Alginate on Inkjet Printing of Cotton/Polyamide Fabrics

Bicomponent or multicomponent fiber fabrics are important materials for manufacturing high-performance textiles. However, the printing and dyeing of these fabrics are very difficult because the dyeability of different fibers varies greatly. The present study investigated the inkjet printing performance of interwoven fabrics of cotton and polyamide 6. The surfactant alpha olefin sulfonate (AOS) was incorporated into the sodium alginate (SA) solution to pretreat the fabrics to improve the color effects of printed fabrics. The results indicate that fabric pretreatment using 5% alpha olefin sulfonate and 2% sodium alginate significantly enhanced the image colors through increasing the hydrophilicity of the film formed on polyamide fibers and changing the surface morphology of both the fibers. The molecules of AOS interacted with the macromolecules of SA to form the composite films, where the AOS concentration gradient increased outward and SA concentration gradient increased inward. The synergistic pretreatment of alpha olefin sulfonate and sodium alginate endowed the fabrics with high inkjet printing performance, satisfactory color fastnesses, and durability.

Microencapsulated soil conditioner with a water-soluble core: improving soil nutrition of crop root

Traditional level of fertilisers was used by most farmers in China with the risks about resources wasting, environmental pollution together with soil structure deterioration. It is practicable to tackle the challenges about over-fertilisation and low efficiency with microencapsulated soil conditioner (MSC), which clads the water soluble core with natural polymer. Fulvic acid (FA) can be used as core material, because it possesses the characteristics of water-soluble, fertiliser maintenance and expedient monitoring. The morphology, structure, and properties of MSC were studied and compared. The particle size of MSC was ranged from 1.58 to 2.14 mm with a similar shape which was obtained by conventional measuring method due to their soft features. This was mainly attributed to the concentration of liquid paraffin and the interaction between shell materials and calcium chloride_. FTIR spectra showed that a peak appeared at 1372 cm^-1, and this was ascribed to the microcapsules crosslinked and solidified by calcium ions. Sustained release experiment revealed that the microcapsules owned better fertiliser-retaining and water-retaining performances, and FA may be released as long as 750 h. Biodegradation experiments revealed that an obvious pore structure was found on the surface of microspheres after 30 d of degradation, and this was consistent with the sustained release experiment. Pot experiment illustrated that the plants cured with the microcapsules showed significant growth trend and grew up to 9.2 cm with a maximum rate, and this revealed that MSC owned better performance of promoting the growth of crop root.

Regulating association strength between quaternary ammonium chitosan and sodium alginate via hydration

Studies on interactions between oppositely charged polysaccharides have gathered great interest. We proposed that the association between oppositely charged polymers could be regulated via hydration. A comparison study was carried out by using quaternary chitosan with different counterions(Cl^-, Ac^-, OH^-) and sodium alginate. The results showed that the association between quaternary chitosan with less hydrated counter anion Cl^- and sodium alginate was weaker than that between quaternary chitosan with more hydrated counter anion Ac^- and sodium alginate. There was a pH transition point of thermal change of association between oppositely charged polymers, as the solution's pH had more effect on the hydration of polymers than counter ions. Further studies showed that a fraction of Cl^- was still attracted by polycation in the complex and competed with the interaction of polyanion after complexation. The competitive combination was critical for the property (such as self healing behavior) of the carbohydrate polymer complex.

Alginate-based composite microspheres coated by berberine simultaneously improve hemostatic and antibacterial efficacy

It is important to develop effective, biocompatible, easily stored and affordable hemostats for controlling bleeding and preventing infection in prehospital trauma. In this study, we synthesized a series of alginate-based composite microspheres coated by different amounts of berberine (SCC-1B, SCC-5B and SCC-10B), which were further characterized using scanning electron microscopy (SEM), viscometer, particle analyzer and Fourier transform infrared (FT-IR) spectroscopy. The in vitro and vivo results demonstrated that compared to control group (SCC, Composite polysaccharide microspheres without berberine, and CMPHP, Commercial hemostatic agent), SCC-10B with proper content berberine (7%), not only exhibited inherent excellent antibacterial activity, but also enhanced hemostatic effect by increasing adhesion and aggregation of blood cells, which could be considered as synergistic effects. More importantly, through inserting berberine into the cross-linked network, biodegradability and biocompatibility of SCC-10B were also improved. Taken together, SCC-10B could be a candidate for emergency hemostatic and antibacterial treatment in prehospital trauma.

Wound healing property of a gel prepared by the combination of Pseudomonas aeruginosa alginate and Alhagi maurorum aqueous extract in rats

Although alginate has been known to be a good wound dressing, it does not have antimicrobial properties, has low availability, and is expensive. To overcome these problems, the present study was conducted, where the extraction of this material from an available small factory Pseudomonas aeruginosa and the improvement of its wound healing property by its combination with herb extract, Alhagi maurorum, done. Nineteen P. aeruginosa strains were isolated and identified from burned skin, and the one isolated strain with the highest ability of alginate production was selected. A. maurorum aqueous extract was prepared, and the toxicity of each material was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide assay. A mixture of nontoxic doses of each substance was then prepared. Thirty-two Wistar rats were divided into four groups (n = 8). The control group and the rest three groups, which were treated by alginate, A. maurorum extract, and alginate- A. maurorum extract. Throughout the 21 days of treatment, the open wound sites were checked. Finally, the rats were sacrificed and the effect of each substance on their skin tissue was evaluated. The results showed that the high alginate production without any toxic effect was obtained from the P. aeruginosa strain K1. A. maurorum aqueous extract had dose-dependent toxicity. The aqueous solution of alginate- A. maurorum extract complex group showed the best wound healing activity in both macroscopic and microscopic examinations. Recent research has introduced a new type of wound dressing with high wound healing properties. This could decrease the time for re-epithelialization and increase wound contraction percentage.

Functionalized alginate with liquid-like behaviors and its application in wet-spinning

Alginate is a kind of marine-derived plant polysaccharide with useful properties including inherent flame-retardancy and biocompatibility, yet poor flowability and low processing efficiency induced by high viscosity impede its further industrial applications. In this study, PEG-substituted tertiary amines were adapted to functionalize alginate with different molecular weight via acid-base reaction to improve the flowability. Based on alginate with low molecular weight, alginate fluids exhibited excellent flowability at room temperature in the absence of solvent. For alginate with high molecular weight, gelatinous precipitated phase exhibited significant shear-thinning properties and higher solid content despite lack of solvent-free flowability, which was applied to wet-spinning. The alginate fibers exhibited increased tensile strength by 104% and elongation at break by 132% compared with conventional alginate fibers, and the spinning efficiency was significantly improved. The proposed strategy is expected to extend to highly efficient processing of other polysaccharides to obtain high-performance biomedical materials.

Preparation and properties of a thin membrane based on sodium alginate grafting acrylonitrile

Sodium alginate was modified for water resistance with acrylonitrile via by free radical graft copolymerization.

Effect of hydrocolloids on the energy consumption and quality of frozen noodles

Effects of hydrocolloids such as Sodium polyacrylate, xanthan gum and sodium alginate on the energy consumption and quality of frozen cooked noodles were investigated. Results showed that gelatinization temperature (GT) shortened significantly and texture properties (hardness, firmness, break strength) of frozen cooked noodle were significantly improved by adding different hydrocolloid additives (P < 0.05). Nevertheless, there were no significant differences of glass-transition temperature between hydrocolloid fortified and non fortified frozen cooked noodles. Moreover, the hydrocolloids improved quality of cooked noodle and increased energy consumption, however, xanthan gum showed the best results. The optimized constituents were: sodium polyacrylate 0.13 %, xanthan gum 0.86 %, sodium alginate 0.18 % with predicted sensory scores of 90.30. The study showed that hydrocolloids could be used as modifying agents in frozen cooked noodle process.

Ion exchange in alginate gels--dynamic behaviour revealed by electron paramagnetic resonance

The formation of alginate gel from low molecular weight alginate and very low molecular weight alginate in the presence of divalent cations was investigated using Electron Paramagnetic Resonance (EPR) spectroscopy. The transition from sol to gel in the presence of divalent cations was monitored by the changes in the dynamics of spin labelled alginate. The immobilisation of the spin labelled alginate in the gel reflects the strength of interaction between the cation and alginate chain. Diffusion experiments showed that both the cation and alginate polyanion in the gel fibres can exchange with molecules in solution. In particular, we showed that dissolved alginate polyanions can replace alginates in the gel fibres, which can hence diffuse through the bulk of the gel. This illustrates the surprisingly highly dynamic nature of these gels and opens up the possibility of preparing multicomponent alginate gels via polyanion exchange process.

Bulk and interfacial liquid water as a transient network

The special macroscopic properties of liquid water stem from its structure as a complex network of molecules connected by hydrogen bonds. While the dynamics of single molecules within this network has been extensively investigated, only little attention has been paid to the closed loops (meshes) of hydrogen-bonded molecules which determine the network topology. Using molecular dynamics simulations we analyze the size, shape, geometrical arrangement, and dynamical stability of loops containing up to 10 hydrogen bonds. We find that six-membered loops in liquid water even at room temperature retain a striking similarity with the well-known structure of ice. Analyzing the network dynamics we find that rings of more than five hydrogen bonds are stabilized compared to a random collection containing the same number of single bonds. We finally show that in the vicinity of hydrophobic and hydrophilic interfaces loops arrange in a preferred orientation.

Dielectric response of the water hydration layer around spherical solutes

We calculate the local dielectric function ɛ(r) inside the hydration layer around a spherical solute (i) from molecular dynamics simulations including explicit solutes and (ii) theoretically using the nonlocal dielectric function of bulk water which includes the radial electric field, but not the explicit solute. The observed agreement between the two concepts shows that while ɛ(r) is strongly different from bulk, this difference is not due to restructuring of the hydrogen bond network but is mostly a consequence of the field geometry. The dielectric response differs for anions and cations, yielding a natural explanation for the well-known charge asymmetry of ionic solvation in agreement with experimental data.

An insight into hydration structure of sodium glycinate from ab initio quantum chemical study

The hydration structure of sodium glycinate (Na(+)GL(-)) is probed by the Monte-Carlo multiple minimum (MCMM) method combined with quantum mechanical (QM) calculations at the MP2/6-311++G(d,p) level. In the gas phase, the energy of [Na(+)GL(-)]β is more than 30 kJ mol(-1) higher than [Na(+)GL(-)]α. With higher degrees of hydration, our results indicate that the most stable conformers of [Na(+)GL(-)]∙(H2O)8 were derived from [Na(+)GL(-)]β instead of [Na(+)GL(-)]α. The stable conformers determined by the conductor-like polarizable continuum model (CPCM) also show that [Na(+)GL(-)]β is more stable than [Na(+)GL(-)]α in the liquid phase. By analyzing the hydration process, water…water hydrogen bonding interaction will be more preferable than ion…water interaction as the number of water molecules increases. According to the electronic density at the bond critical point on the Na-X bonds (X = O1, O2, N) in the low-energy conformers, Na(+)GL(-) will be dissociated as Na(+) and GL(-) in the bulk water, which is not predicted by the CPCM model. The structure features and the charge redistribution of Na(+)GL(-) will provide a physical explanation for the weakening Na-O1 interaction.

Microfluidic production of perfluorocarbon-alginate core-shell microparticles for ultrasound therapeutic applications

The fabrication of micrometer-sized core-shell particles for ultrasound-triggered delivery offers a variety of applications in medical research. In this work, we report the design and development of a glass capillary microfluidic system containing three concentric glass capillary tubes for the development of core-shell particles. The setup enables the preparation of perfluorocarbon-alginate core-shell microspheres in a single process, avoiding the requirement for further extensive purification steps. Core-shell microspheres in the range of 110-130 μm are prepared and are demonstrated to be stable up to 21 days upon immersion in calcium chloride solution or water. The mechanical stability of the particles is tested by injecting them through a 23 gauge needle into a polyacrylamide gel to mimic the tissue matrix. The integrity of the particles is maintained after the injection process and is disrupted after ultrasound exposure for 15 min. The results suggest that the perfluorcarbon-alginate microparticles could be a promising system for the delivery of compounds, such as proteins, peptides, and small-molecule drugs in ultrasound-based therapies.