Gel Particles Research Articles

The hidden hierarchical nature of soft particulate gels

Soft particulate gels are composed of a small amount of particulate matter dispersed in a continuous fluid phase. The solid components assemble to form a porous matrix, providing rigidity and control of the mechanical response, despite being the minority constituent. The rheological response and gel elasticity are direct functions of the particle volume fraction. However, the diverse range of different functional dependencies reported experimentally has challenged efforts to identify general scaling laws. Here we reveal a hidden hierarchical organization of fractal elements that controls the viscoelastic spectrum, and which is associated with the spatial heterogeneity of the solid matrix topology. The fractal elements form the foundations of a viscoelastic master curve, constructed using large-scale three-dimensional (3D) microscopic simulations of model gels, which can be described by a recursive rheological ladder model over a range of particle volume fractions and gelation rates. The hierarchy of the fractal elements provides the missing general framework required to predict the gel elasticity and the linear viscoelastic response of these complex materials. Colloidal gels consist of particles embedded in a fluid. It is now found that a gel’s viscoelastic spectrum, relating mechanical properties and deformation frequencies, can be understood by modelling these gels as networks of fractal viscoelastic units, connected hierarchically.

Investigating the effect of preformed particle gel on conformance control of naturally fractured tight sandstone reservoirs: An experimental study using pressure transfer test method

The recovery of oil and gas resources is limited by the high water production from wells in unconventional reservoirs. While water intrusion prevention measures have been extensively investigated in highly permeable reservoirs, there has been limited research in tight unconventional reservoirs. In this study, a Pressure Transfer Test (PTT) method was used to evaluate the effect of preformed particle gel (PPG) on the conformance control of naturally fractured tight sandstone reservoirs. The study analyzed and compared four types of naturally fractured cores, and performed experiments on the PPG plugging effect under different natural fracture types, injection pressures, and salinities using a PTT device. The results showed that among the four fracture types, vertical and oblique penetrations had the highest plugging effect, with a 12% higher rate than fractures without effective channels. The injection pressure also had a significant impact on the plugging efficiency, with a 99.13% blocking rate at 12.5 MPa, which was almost completely plugged. Meanwhile, the salinity of the injected fluid had a decreasing effect on the PPG plugging efficiency, with the lower salinity of 1 wt% improving the plugging efficiency by 15% compared to high salinity. The experimental results and analysis were used to propose the plugging mechanism of PPG in different types of naturally fractured tight reservoirs. This study provides valuable experimental and theoretical references for the field application and further studies of PPG in naturally fractured tight reservoirs.

Comparative analysis of the residues of granular support bath materials on printed structures in embedded extrusion printing

Embedded extrusion printing facilitates the fabrication of complex biological structures using soft hydrogels that are challenging to construct using conventional manufacturing methods. While this targeting strategy is appealing, the residues of support materials on the printed objects have been overlooked. Here, we quantitatively compare the bath residues on fibrin gel fibers printed in granular gel baths that are conjugated with fluorescent probes for visualization, including physically crosslinked gellan gum (GG) and gelatin (GEL) baths and chemically crosslinked polyvinyl alcohol baths. Notably, all support materials can be detected on a microscopic scale, even on structures without any visible residues. Quantitative results indicate that baths with smaller size or lower shear viscosity show more and deeper diffusion into the extruded inks, and the removal efficiency of support materials depends mainly on the dissolving property of the granular gel baths. The residual amount of chemically cross-linked support materials on fibrin gel fibers is 28–70 μg mm−2, which is tens of times higher than physically cross-linked GG (7.5 μg mm−2) and GEL (0.3 μg mm−2) baths. Meanwhile, cross-sectional images suggest that most gel particles are distributed around the fiber surface, but a small amount is in the fiber center. Such bath residues or the blank pores created by the removal of gel particles induce changes in product surface morphology, physicochemical and mechanical properties, impeding cell adhesion. This study will draw attention to the effects of residual support materials on printed structures and encourage the development of new strategies to diminish these residues or to take advantage of the residual support baths to improve product performances.

Dynamic Sweep Experiments on a Heterogeneous Phase Composite System Based on Branched-Preformed Particle Gel in High Water-Cut Reservoirs after Polymer Flooding

Heterogeneous phase composite (HPC) flooding technology that is based on branched-preformed particle gel (B-PPG) is an important technology for enhancing oil recovery in high water-cut reservoirs. In this paper, we conducted a series of visualization experiments under the condition of developed high-permeability channels after polymer flooding, with respect to well pattern densification and adjustment, and HPC flooding and its synergistic regulation. The experiments show that for polymer-flooded reservoirs, HPC flooding can significantly reduce the water cut and increase oil recovery, but that the injected HPC system mainly advances along the high-permeability channel with limited sweep expansion. Furthermore, well pattern densification and adjustment can divert the original mainstream direction, which has a positive effect on HPC flooding, and can effectively expand the sweeping range under the synergistic effect of residual polymers. Due to the synergistic effect of multiple chemical agents in the HPC system, after well pattern densification and adjustment, the production time for HPC flooding with the water cut lower than 95% was significantly prolonged. In addition, conversion schemes, in which the original production well is converted into the injection well, are better than non-conversion schemes in terms of expanding sweep efficiency and enhancing oil recovery. Therefore, for well groups with obvious high-water-consuming channels after polymer flooding, the implementation of HPC flooding can be combined with well pattern conversion and intensification in order to further improve oil displacement.

Biodegradable Preformed Particle Gel (PPG) Made of Natural Chitosan Material for Water Shut-Off Application.

Oil and gas extraction frequently produces substantial volumes of produced water, leading to several mechanical and environmental issues. Several methods have been applied over decades, including chemical processes such as in-situ crosslinked polymer gel and preformed particle gel, which are the most effective nowadays. This study developed a green and biodegradable PPG made of PAM and chitosan as a blocking agent for water shutoff, which will contribute to combating the toxicity of several commercially used PPGs. The applicability of chitosan to act as a crosslinker has been confirmed by FTIR spectroscopy and observed by scanning electron microscopy. Extensive swelling capacity measurements and rheological experiments were performed to examine the optimal formulation of PAM/Cs based on several PAM and chitosan concentrations and the effects of typical reservoir conditions, such as salinity, temperature, and pH. The optimum concentrations of PAM with 0.5 wt% chitosan were between 5-9 wt%, while the optimum chitosan amount with 6.5 wt% PAM was in the 0.25-0.5 wt% range, as these concentrations can produce PPGs with high swellability and sufficient strength. The swelling capacity of PAM/Cs is lower in high saline water (HSW) with a TDS of 67.2976 g/L compared with fresh water, which is related to the osmotic pressure gradient between the swelling medium and the PPG. The swelling capacity in freshwater was up to 80.37 g/g, while it is 18.73 g/g in HSW. The storage moduli were higher in HSW than freshwater, with ranges of 1695-5000 Pa and 2053-5989 Pa, respectively. The storage modulus of PAM/Cs samples was higher in a neutral medium (pH = 6), where the fluctuation behavior in different pH conditions is related to electrostatic repulsions and hydrogen bond formation. The increase in swelling capacity caused by the progressive increment in temperature is associated with the amide group's hydrolysis to carboxylate groups. The sizes of the swollen particles are controllable since they are designed to be 0.63-1.62 mm in DIW and 0.86-1.00 mm in HSW. PAM/Cs showed promising swelling and rheological characteristics while demonstrating long-term thermal and hydrolytic stability in high-temperature and high-salinity conditions.

Effect of Poly(Vinyl Alcohol) Concentration and Chain Length on Polymer Nanogel Formation in Aqueous Dispersion Polymerization.

Nanotechnology has attracted increasing interest in various research fields for fabricating functional nanomaterials. In this study, we investigated the effect of poly(vinyl alcohol) (PVA) addition on the formation and thermoresponsive properties of poly(N-isopropyl acrylamide)-based nanogels in aqueous dispersion polymerizations. During dispersion polymerization, PVA appears to play three roles: (i) it bridges the generated polymer chains during polymerization, (ii) it stabilizes the formed polymer nanogels, and (iii) it regulates the thermoresponsive properties of the polymer nanogels. By regulating the bridging effect of PVA via changing the PVA concentration and chain length, the size of the obtained polymer gel particles was maintained in the nanometer range. Furthermore, we found that the clouding-point temperature increased when using low-molecular weight PVA. We believe that the knowledge gained in this study regarding the effect of PVA concentration and chain length on nanogel formation will aid in the future fabrication of functional polymer nanogels.

Encapsulation of SOD in chitosan-coated gel particles of alginate or mixture of alginate and shellac for targeted intestinal delivery

The chitosan-coated alginate gel particles (CS/SA) and chitosan-coated alginate-shellac gel particles (CS/SA/Lac) were constructed to serve as a potential oral delivery system to enhance the stability and activity of superoxide dismutase (SOD) in this study. The encapsulation efficiency (EE), enzyme activity retention ratio (ER), particle structure, and SOD release behavior, as well as the effect of shellac, were evaluated. The best formula is determined by the percentage of total effective activity (PTEA).The results showed that CS/SA prepared by 0.30‰ chitosan, 1.00% CaCl2, 2.00% sodium alginate (M/G = 1:1, Mw: 38,857 kDa), and gelation solution pH 5.50 had the best chitosan shell, the strongest gel structure and the maximum PTEA which was 10.75 ± 1.45%. Based on the optimal formula, addition of shellac that formed shellac-Ca2+ microspheres in the gel network was averse to SOD encapsulation, but it significantly improved the stability of SOD in gastric conditions. By adding 15.00% shellac, the PTEA reached 16.30 ± 1.64%. At optimal formulation, SOD encapsulated in CS/SA was completely released in the stimulated intestinal fluid and accumulative release enzyme activity (EA) was 966.62 ± 103.75 (U) after 6 h. However, the CS/SA/Lac with a low swelling ratio only released SOD in stimulated colonic fluid and the EA value reached 1692.28 ± 101.82 (U) after 1 h. These findings demonstrated that CS/SA and CS/SA/Lac were excellent candidates for SOD oral administration, which was useful in the food and biomedical industries for developing functional products containing SOD.

A systematic multi-scale experimental investigation of a newly developed halloysite nanotubes reinforced preformed particle gel for improving oil recovery from heterogeneous reservoir: Synthesis, characterization, optimization and performance assessment

Preformed particle gel (PPG), a recent gel treatment technique, is being utilized in reducing excessive water production to reduce its environmental impact and to improve the oil recovery in matured oilfields. In this research article a new class of PPG called Halloysite Nanotubes Reinforced Preformed Particle Gel (HNR-PPG) has been developed using acrylamide (monomer); n, n′- methylenebis (acrylamide) (crosslinker); halloysite nanotubes (reinforcement agent) and potassium persulphate (initiator) for water shut-off jobs. The results from chemical and morphological characterization viz. Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), Powder X-ray diffraction (PXRD), Field Emission Scanning Electron Microscopy (FESEM), and Energy dispersive X-ray spectroscopy (EDS) analyses suggest a successful synthesis of HNR-PPG. Swelling kinetics studies of HNR-PPG illustrate a faster rate of swelling in early phases and a relatively slow rate in later stages with an optimum swelling ratio of 24.56 (g/g). Rheological studies have demonstrated that reinforcement of halloysite nanotubes has increased its strength from 4611 Pa [i.e., for ‘PPG without reinforcement’ or ‘Conventional PPG’ (C-PPG)] to 6251 Pa [i.e., for ‘HNR-PPG’]. Thermogravimetric analysis (TGA) outcomes have deduced that the degradation temperature of the backbone of the main crosslinked chain has increased from 361 °C to 382 °C due to reinforcement, thus improving its thermal resistance. Single sandpack experiments elucidate good plugging ability in terms of permeability reduction (65–81%). To simulate a heterogenous non-cross flow reservoir, parallel sandpack experiments were conducted and the profile improvement rate is found to be around 81%, 87% and 90% for the permeability contrast of 2.25, 3.11 and 3.41 respectively after the HNR-PPG injection. Thus, the newly developed HNR-PPG can potentially improve water shut-off jobs and oil recovery in mature oil fields.

LCST-UCST Transition Property of a Novel Retarding Swelling and Thermosensitive Particle Gel

Super absorbent resin particles used as profile control and water plugging agent remains a deficiency that the particles swells with high speed when absorbing water, resulting in low strength and limited depth of migration. To address this issue, we proposed a thermosensitive particle gel possessing the upper critical solution temperature (UCST), which was synthesized from hydrophobically modified poly(vinyl alcohol)s (PVA) with glutaraldehyde (GA) as a cross-linker. The structure of the hydrogel was characterized by Fourier transform infrared spectrophotometer (FTIR) and nuclear magnetic resonance (NMR). The thermosensitive-transparency measurement and swelling experiment show that the hydrophobic-modified PVA solutions and corresponding hydrogels exhibited thermosensitive phase transition behaviors with lower critical solution temperature (LCST) and UCST. The results indicated that the temperature-induced phase transition behavior of CHPVA hydrogels leads to their retarding swelling property and great potential as an efficient water plugging agent with excellent temperature and salt resistance.

Isolation and Staining Reveal the Presence of Extracellular DNA in Marine Gel Particles.

Marine gel particles (MGP) are amorphous hydrogel exudates from bacteria and microalgae that are ubiquitous in the oceans, but their biochemical composition and function are poorly understood. While dynamic ecological interactions between marine microorganisms and MGPs may result in the secretion and mixing of bacterial extracellular polymeric substances (EPS) such as nucleic acids, compositional studies currently are limited to the identification of acidic polysaccharides and proteins in transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP). Previous studies targeted MGPs isolated by filtration. We developed a new way of isolating MGPs from seawater in liquid suspension and applied it to identify extracellular DNA (eDNA) in North Sea surface seawater. Seawater was filtered onto polycarbonate (PC) filters with gentle vacuum filtration, and then the filtered particles were gently resuspended in a smaller volume of sterile seawater. The resulting MGPs ranged in size from 0.4 to 100 µm in diameter. eDNA was detected by fluorescent microscopy using YOYO-1 (for eDNA), with Nile red (targeting cell membranes) as a counterstain. TOTO-3 was also used to stain eDNA, with ConA to localise glycoproteins and SYTO-9 for the live/dead staining of cells. Confocal laser scanning microscopy (CLSM) revealed the presence of proteins and polysaccharides. We found eDNA to be universally associated with MGPs. To further elucidate the role of eDNA, we established a model experimental MGP system using bacterial EPS from Pseudoalteromonas atlantica that also contained eDNA. Our results clearly demonstrate the occurrence of eDNA in MGPs, and should aid furthering our understanding of the micro-scale dynamics and fate of MGPs that underly the large-scale processes of carbon cycling and sedimentation in the ocean.

Preparation of plant-based meat analogs using emulsion gels: Lipid-filled RuBisCo protein hydrogels

RuBisCo from duckweed is a sustainable source of plant proteins with a high water-solubility and good gelling properties. In this study, we examined the impact of RuBisCo concentration (9–33 wt %) and oil droplet concentration (0 to 14 wt %) on the properties of emulsion gels designed to simulate the properties of chicken breast. The color (L*a*b*), water holding capacity (WHC), textural profile analysis, shear modulus, and microstructure of the emulsion gels were measured. The gel hardness and WHC increased significantly with increasing protein concentration, reaching values equivalent to chicken breast. The lightness of the emulsion gels was less than that of chicken breast, due to the presence of pigments (such as polyphenols) in the protein. Shear modulus versus temperature measurements showed that gelation began when the protein solutions were heated to around 40 °C and then the gels hardened appreciably when the temperature was further raised to 90 °C. The shear modulus of the gels then increased during cooling, which was attributed to the strengthening of hydrogen bonds at lower temperatures. The hardness of the gels increased slightly but then decreased when the oil droplet concentration was raised from 0 to 14 %. The lightness of the protein gels increased after adding the oil droplets, which was attributed to increased light scattering. Microstructure analysis showed that the RuBisCo proteins formed a particulate gel after heating, with the oil droplets being in the interstices between the particulates. In summary, RuBisCo proteins can be dissolved at high concentrations and can form strong emulsion gels. Consequently, they may be able to mimic the composition and textural attributes of real chicken.

Experimental Investigation on the Performance of Polymer-Coated Clay/Polyacrylamide Hydrogel for Water Shutoff Treatment

SummaryPolymer gel system has been identified as having the potential for blocking and diverting water flow. However, the current polymer reported an inability to maintain its mechanical strength, limited penetration depth, and instability in reservoir conditions of high temperature and high pressure. A distinctive bentonite nanomer clay (PGV)/acrylamide (AM)-co-2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) preformed particle gel with poly(ethylene glycol-b-tetramethylene oxide) (PEGTMO) coating to control the swelling kinetics is formulated. The in-house formulated gel’s ability to block and divert water flow in a porous medium is studied. The formation recipe of the gel was achieved by numerous swelling tests as induced by brine solution under reservoir conditions. Through the swelling tests, the long-term thermal stability of the gel solution was demonstrated. The incorporation of PGV clay particles improves the swelling and mechanical properties of the gel. Premature swelling can be avoided with PEGTMO coating as it slows the swelling rate over a 10-minute period, which gives the advantage of controlling the swelling before reaching the intended site of action during coreflood experiments. The rheological behavior of the hydrogel features rubber-like mechanical behavior with a viscosity value of 1.17 cp, which displayed water-like characteristics. Further, significant permeability reduction of large fractures is demonstrated by the coreflooding experiment with a calculated result of 96.2%. This formulated gel could offer the solution as a blocking agent in void space channels containing reservoirs that leads to a reduction of water cut due to thief zones.

Stress-stress correlations reveal force chains in gels.

We investigate the spatial correlations of microscopic stresses in soft particulate gels using 2D and 3D numerical simulations. We use a recently developed theoretical framework predicting the analytical form of stress-stress correlations in amorphous assemblies of athermal grains that acquire rigidity under an external load. These correlations exhibit a pinch-point singularity in Fourier space. This leads to long-range correlations and strong anisotropy in real space, which are at the origin of force-chains in granular solids. Our analysis of the model particulate gels at low particle volume fractions demonstrates that stress-stress correlations in these soft materials have characteristics very similar to those in granular solids and can be used to identify force chains. We show that the stress-stress correlations can distinguish floppy from rigid gel networks and that the intensity patterns reflect changes in shear moduli and network topology, due to the emergence of rigid structures during solidification.

Maximising olive oil by‐products

Maximising olive oil by‐products

Study of Varietal Differences in the Composition of Heteropolysaccharides of Oil Flax and Fiber Flax

Flaxseed mucilage and its derivatives have been extensively investigated over the last decade, mainly due to their inherent techno-functional (thickening, gelling, interface-stabilizing, and film-forming) properties that are relevant in the food industry. Hydrocolloids are used to modify food properties, such as for stabilization and emulsion, and are also used to control the microstructure of the food. Increasing research attention has been paid to the application of hydrocolloid materials in gel particles for encapsulation or texture control in food, pharmaceutical, cosmetic, and probiotic products. Thus, it is important to investigate the properties of hydrocolloids manufactured from various sources and explore their possible applications in the food industry. The applied nature of the study of plant mucus substances is associated with the ever-increasing demand for their use in the food, cosmetic, and pharmacological industries, determining the related research priorities, including the development of the most effective methods for the extraction of glycans and the search for highly productive raw materials for the production of polysaccharides. The aim of this work was to study varietal differences in the compositions of heteropolysaccharides in the mucus samples of oilseed and fiber flax varieties using a modern methodological approach for obtaining glycans based on the ultrasonic extraction of polysaccharides. The seeds of 10 flax varieties were studied, differing in their morphotype, place, and time of creation. The obtained results indicated significant differences in the quantitative and qualitative compositions of the heteropolysaccharides of flax seeds of various varieties. The contents of reducing sugars in the studied varieties ranged from 5.61 ± 0.01 to 18.81 ± 0.01 mg/g, indicating significant differences in the structural organization of glycans in different flax varieties. Additionally, the results obtained here allowed us to conclude that the range of reducing sugars for flax heteropolysaccharides is significantly less than this range for oilseed flax varieties. The obtained results of the study of the composition of flax seed heteropolysaccharides allowed us to consider them as selection trait and genetic markers.

Impact of different additives on low-temperature recrosslinkable preformed particle gel to mitigate fluid losses in fractured formations

During drilling through highly permeable or fractured formations, the entire drilling fluid or most of it might be lost into formations; this phenomenon is called lost circulation. Lost circulation can cause serious issues during drilling, such as challenging well control operations, and in some cases, complete loss of the well. In this paper, a Low-Temperature Recrosslinkable Preformed Particle Gel (LT-RPPG) was evaluated in the presence of various conventional additives to control drilling fluid loss in fractured formations. The additives tested in the study included mica, walnut shell and bentonite. Different factors were investigated, including mica concentrations, mica particle size, walnut shell concentrations and bentonite. Core flooding experiments were conducted to evaluate the LT-RPPG with the various additives plugging performance utilizing open fractured cores. The results showed that by mixing the LT-RPPG with the drilling fluid, a stronger material, reflected in a higher elastic modulus and sealing pressure, was obtained as compared by solely hydrating the LT-RPPG with brine. Also, the addition of mica and walnut shell further improved the LT-RPPG strength. While the mica particle size selection influenced the LT-RPPG rheological properties, the results from the core flooding experiments indicated the mica particle size had insignificant impact on the sealing pressure as compared with the mica concentration. Among the different tested addtivies, the optimum improvement on the LT-RPPG plugging performance was obtained by introducing 1.00% walnut shell. The mixture achieved a sealing pressure up to 5685.41 psi/ft for 3.0 mm fracture width. Furthermore, the core flooding results exhibited that the LT-RPPG combined with the additives effectivility reduced the fracture permeability to more than 108 times even after the gel rupture by subsequent drilling fluid circulation.

Dilution Driven Self-assembly and Re-entrant Phase Transition in Molecular Hydrogels

TX-100 molecular hydrogels exhibited re-entrant melt-gel-sol phase transition driven solely by dilution, which sequentially altered the self-assembly of the micellar formations and their population was investigated through the monitoring of the physical parameters namely, solution viscosity, particle size histogram, ergodicity, and gel rigidity modulus. This phenomenon was noticed at 20°C in the TX-100 concentration region of 0.2 to 1.2 M much above the critical micellar concentration of 0.22 mM. The particle size histograms revealed the presence of spherical micelles (size »3 nm) in the solution ([TX-100] < 0.5 M) which formed entangled wormlike cylindrical micelles (apparent hydrodynamic radius » 50 nm) when (0.5 M< [TX-100] < 0.9 M) giving rise to a gel-like structure. Further increase in the TX-100 concentration increased the propensity of these wormlike cylindrical micelles that got randomly distributed creating a dense melt phase. Interestingly, we observed transition solely driven by dilution which defined complete re-entrant behavior at room temperature. These molecular gels could be created by dilution of the melt or concentration of the sol unlike in the polymer gels. Remarkably, this hitherto little known unique phenomenon was exhibited by a simple system of non-ionic surfactant solution. Thus, we have a hydration reversible gel at our disposal which has a special place in soft matter arena.

Development of a composite hydrogel incorporating anti-inflammatory and osteoinductive nanoparticles for effective bone regeneration

BackgroundBone tissue regeneration is regulated by complex events, including inflammation, osteoinduction, and remodeling. Therefore, to induce the complete restoration of defective bone tissue, biomaterials with the ability to regulate the collective bone regenerative system are beneficial. Although some studies conclude that reducing reactive oxygen species created a favorable environment for bone regeneration by controlling inflammation, biomaterials that can simultaneously promote osteogenesis and regulate inflammation have not been developed. Herein, we describe the development of a multi-functional nanoparticle and its hydrogel composite with osteoinductive, anti-inflammatory, and osteoclast-maturation regulatory functions for enhanced bone regeneration.MethodsTannic acid–mineral nanoparticles (TMP) were prepared by self-assembly of tannic acid in an ion-rich simulated body fluid containing Ca2+ and PO43-. Particles with a diameter of 443 ± 91 nm were selected for their stable spherical morphology and minimal tendency to aggregate. The particles were homogeneously embedded within a gelatin-based cryogel (TMP/Gel) to be used in further experiments. The osteoinductive properties, anti-inflammatory and osteoclast-maturation regulatory functions in vitro were tested by culturing corresponding cells on either TMP/Gel or a gelatin-based cryogel without the particles (Gel). For in vivo analyses, a murine calvarial defect model was used. Statistical analyses were carried out using a Graphpad Prism 7 software (San Diego, CA, USA) to perform one-way analysis of variance ANOVA with Tukey’s honest significant difference test and a Student’s t-test (for two variables) (P < 0.05).ResultsExcellent biocompatibility and radical scavenging abilities were exhibited by the TMP/Gel. The expression of osteogenic mRNA is significantly increased in human adipose-derived stem cells seeded on the TMP/Gel compared to those without the particles. Furthermore, RAW264.7 cells seeded on the TMP/Gel displayed significantly lower-than-normal levels of pro-inflammatory and osteoclastogenic genes. Finally, the in vivo results indicated that, compared with the cryogel with no anti-inflammatory effect, the TMP/Gel significantly enhanced both the quality and quantity of newly formed bone, demonstrating the importance of combining anti-inflammation with osteoinduction.ConclusionCollectively, these findings suggest our nanoparticle-hydrogel composite could be an effective tool to regulate complex events within the bone healing process.Graphical

Effect of starch on the gel properties and protein conformation of egg white subjected to alkali‐heat treatment

SummaryThe colour, texture, water‐holding capacity (WHC) and particle properties of gels were examined to assess the impact of starch (cassava, corn and sweet potato starch) on the attributes of alkali‐heat‐induced gels. The results indicated that the whiteness, hardness and WHC of egg white gels were positively affected by starches. The microstructure of the mixed gel showed increasing reticulation and holes as the starch content increased, which contributed to the stiff structure of the gel. Although the gel made with corn starch had the lowest WHC, the gel made with sweet potato starch had the highest WHC. The average size of the gel particles decreased as a result of the inhibition of starch gelatinisation. Starch causes alterations in the protein secondary structure of egg white gels, primarily causing α‐helix and β‐sheet interconversion. The stiffness of the gels was improved by increasing the quantity of β‐sheet structures. According to the electrophoresis findings, a small amount of sweet potato starch can help prevent ovalbumin from degrading, while having no impact on the ability of the protein to cross‐link.

FUNDAMENTAL PRINCIPLES OF MICROGEL SYNTHESIS BY INVERSE EMULSION METHOD

Microgels represent a unique class of compounds that combine the properties of such classes of compounds as colloids, macromolecules and surfactants in a unique way. Microgels are widely used for wastewater treatment, as drug delivery systems, for drying biodiesel, in tissue regeneration and implantation, in chromatography, etc. At this point, such methods of microgel synthesis as the precipitation method, suspension polymerisation and the emulsion method have been developed, which have become traditional in the synthesis of microgels. This publication reviews the inverse emulsion method for microgel synthesis based on polyacrylamide and its derivatives. This method was chosen due to a number of advantages, such as a high degree of monomer conversion, the ability to control the granulometric composition of gel particles during synthesis, a simplified drying procedure for the finished product, etc. The article describes the synthesis features that affect the size and shape of microgels, describes the main factors to consider when planning an inverse emulsion synthesis; shows the difference between macroemulsion, nanoemulsion and microemulsion. The article also presents some aspects of the synthesis of microgel based on acrylamide and its derivatives: the main free-radical initiators are listed; monomers that affect microgel properties are described. This review may be of interest to specialists who are just starting research in this field. Based on this publication, the reader will be able to plan and conduct an experiment on the synthesis of polyacrylamide-based microgels by the inverse emulsion method. For citation: Burin D.A., Rozhkova Yu.A., Kazantsev A.L. Fundamental principles of microgel synthesis by inverse emulsion method. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 3. P. 6-17. DOI: 10.6060/ivkkt.20236603.6732.