Spherical Gel Research Articles

Preparation and adsorption performance of cellulose nanofibrils/polyvinyl alcohol composite gel spheres with millimeter size

Wastewater treatment is a huge problem facing human beings. The development of recyclable and efficient adsorption materials is of great benefit to solve the problem. Based on the biodegradable cellulose nanofibers (CNFs) derived from biomass resources, the large sized CNFs/PVA composite hydrogel spheres (CV-HSs, 1–3 mm) were successfully prepared by the inverse suspension pellet-forming technology using the polymers as raw materials, and another hydrophobic CNFs/PVA composite aerogel spheres (HCV-ASs) were also obtained by lyophilization and followed silylation of as-prepared CV-HSs. The CV-HSs showed excellent adsorption properties for simulated pollutants, including Cu2+, phenol and aniline in water. The maximum absorption capacity of CV-HSs was 17.22 mmol/g for Cu2+, 176.72 mg/g for phenol and 341.93 mg/g for aniline respectively. The HCV-ASs exhibited good absorption properties for weak polar organic solvents, such as petroleum ether, ethyl acetate and toluene. In summary, two kinds of large-sized CNFs/PVA composite gel spheres were successfully fabricated, and exhibited good adsorption properties for organic pollutants and heavy metal ions, indicating their potential for wastewater treatment.

Integrated Instillation Technology for the Synthesis of a pH-Responsive Sodium Alginate/Biomass Charcoal Soil Conditioner for Controlled Release of Humic Acid and Soil Remediation.

In this work, pH-responsive gel spheres for controlled release of humic acid (CSGCHs) were prepared by an integrated instillation technology using a composite material of sodium alginate (SA) and charcoal activated carbon (CAC) as a carrier, and their slow-release performance, pH-responsive performance, and soil amendment performance were investigated. The results showed that the prepared CSGCH was uniform in size with obvious base responsiveness. Soil remediation experiments revealed that CSGCH could play a good role in the remediation of different types of soils. After 50 days of remediation, the content of nutrients and organic matter in the soil increased significantly and the pH and salt content of saline soils decreased by 15.2 and 29.8%, respectively. The plant experiment showed that CSGCH could effectively promote the growth of crops. Therefore, the prepared soil conditioner has a great potential value for improving soil conditions and promoting crop growth in agricultural applications.

Trichloroethylene replacements for the cleaning of silicone oil used in the internal gelation process

Silicone oil continues to be used as a gelation medium for internal gelation process. Typically, the silicone oil has been removed from the gel spheres using trichloroethylene (TCE) washes. However, TCE is no longer a viable option for large-scale operations because of environmental issues, health concerns, and disposal costs. During the development of a large gelation system at the Y-12 National Security Complex, two new TCE wash replacements were identified. NuSolv SOR-C and FluoSolv WS were used in a number of uranium runs and found to effectively remove silicone oil. NuSolv SOR-C was determined to be the best option.

Deep photothermal effect induced by stereotactic laser beams in highly scattering media.

Plasmonic photothermal therapy (PPTT), as an increasingly studied treatment alternative, has been widely regarded mostly as a surface tissue treatment choice. Although some techniques have been implemented for interstitial tumors, these involve some grade of invasiveness, as the outer skin is usually broken to introduce light-delivering optical fibers or even catheters. In this work, we present a potential non-invasive strategy using the stereotactic approach, long employed in radiosurgery, by converging multiple near infrared laser beams for PPTT in tissue-equivalent optical phantoms that enclose small gel spheres and simulate interstitial tissue impregnated with plasmonic nanoparticles. The real-time in-depth monitoring of temperature increase is realized by an infrared camera face-on mounted over the phantom. Our results show that a significant reduction in the surface heating can be achieved with this configuration while remarkably increasing the interstitial reach of PPTT, assuring a ∼6∘C temperature increase for the simulated tumors at 10 mm depth and ∼4∘C at 15 mm depth and opening up new possibilities for future clinical applications.

Deep neural networks for large deformation of photo-thermo-pH responsive cationic gels

In this work, a model is developed to analyze homogeneous and inhomogeneous large deformation of photo-thermo-pH responsive cationic gels. Constitutive equations are achieved by considering the equilibrium thermodynamics of swelling gels through variational method. Employing this model, coupling effects of light intensity, temperature and pH variations on large deformation of gels are analyzed. The simulation results are compared with available experimental data. Then deep neural networks are developed to approximate solutions to equilibrium equations of inhomogeneous swelling of spherical shell structure gels. The volume phase transition temperature of the gels and their dependence on light intensity are also demonstrated.

Non-spherical abrasives with ordered mesoporous structures for chemical mechanical polishing

The chemical mechanical polishing (CMP) technology has been widely used for surface modification of critical materials and components with high quality and efficiency. In a typical CMP process, the mechanical properties of abrasives play a vital role in obtaining the ultra-precision and damage-free surface of wafers for improvement of their performances. In this work, a series of fine structured rod-shaped silica (RmSiO2)-based abrasives with controllable sizes and diverse ordered mesoporous structures were synthesized via a soft template approach, and successfully applied in the sustainable polishing slurry for improving the surface quality of cadmium zinc telluride (CZT) wafers. Compared with commercial silica gel, solid and mesoporous silica spheres, the RmSiO2 abrasives present superior elastic deformation capacity and surface precision machinability on account of their mesoporous structures and rod shapes. Especially, ultra-precision surface roughness and relatively effective material removal speed were achieved by the CMP process using the RmSiO2 abrasives with a length/diameter (L/d) ratio of 1. In addition, a potential CMP mechanism of the developed polishing slurry to CZT wafer was elucidated by analyzing X-ray photoelectron spectra and other characterizations. The proposed interfacial chemical and mechanical effects will provide a new strategy for improving abrasives’ machinability and precision manufacture of hard-to-machine materials.

Formulation, Development and Evaluation of Colloidosomes of Glipizide

Glipizide is a potent oral antidiabetic agent, a second generation sulphonyl urea used in lowering blood glucose in patients with type II diabetes mellitus. It has a short half life of 2-4 hours. The objective of the present study was development and evaluation of colloidosomes of glipizide for controlled/sustained drug release. An attempt was made to formulate and evaluate colloidosomes of glipizide as a model drug using water in oil emulsion based method by using CaCO3 with a view to deliver drug at controlled/sustained manner in GIT and consequently into systemic circulation. The prepared colloidosomes were evaluated for particle size, shape and surface morphology, FTIR study, % yield, zeta potential, SEM, % drug entrapment efficiency and in-vitro drug release studies. The obtained colloidosomes were found to be discrete and spherical in shape and found to possess mean particle size range of 2228 nm to 3551 nm. The drug entrapment efficiency was found to be 52.13±1.2% to 71.18±1.25%. Amongst the prepared batches, Glipizide colloidosomes of Batch C formulation were stable and exhibited good sustained release of the drug for a period of 12 hours.The release profile was compared with alginate gel spheres. This implied that the developed formulations have a potential to deliver the drug in a sustained manner. This outcome from the release profiling strongly recommends that the developed glipizide loaded colloidosomes may prove to be a useful delivery carrier to deliver the drug in controlled release manner which is a prime requirement for the treatment of type II diabetes mellitus.

Preparation and bacteriostatic research of porous polyvinyl alcohol / biochar / nanosilver polymer gel for drinking water treatment

Microbial contamination in drinking water has become an important threat to human health. There is thus an urgent need to develop antibacterial materials to treat drinking water. Here, porous silver-loaded biochar (C–Ag) was prepared using corn straw as the substrate and silver as the antibacterial agent. C–Ag was then uniformly distributed in polyvinyl alcohol gel beads of eluted calcium carbonate to prepare p-PVA/C–Ag antibacterial composite. The polymer composites were tested by FT-IR, XRD, SEM and TG-DSC. The results showed that C–Ag was more evenly distributed in the PVA gel spheres. Antibacterial experiments showed that p-PVA/C–Ag greatly inhibited Escherichia coli. Practical application tests revealed that p-PVA/C–Ag showed high and sustained bactericidal inhibition and reusability. Generally, p-PVA/C–Ag composite shows high potential to be applied to drinking water treatment.

Preparation and application of chiral silica gel spheres based on L-glutamic

无机介孔硅球因其具有足够的机械强度、热稳定性,以及适应多种流动相的优点,成为高效液相色谱(HPLC)柱填料中使用最广泛和最重要的材料。但在此研究领域中,并未见球形的全无机手性硅胶用作HPLC手性固定相。该文以无机球形介孔硅胶作为研究对象,通过堆砌硅珠法,以硅溶胶为原料,L-谷氨酸(L-Glu)为手性源,在手性环境中制造出脲醛树脂与胶体二氧化硅混合的小球,在550 ℃高温下煅烧除去树脂部分,制备基于L-Glu的无机介孔硅胶球。通过元素分析、红外光谱、扫描电镜、透射电镜和氮气吸附等表征证明这是一种具有规则球形的手性硅胶球,其手性来源于硅胶球自身的骨架和孔结构。将L-Glu手性硅胶球作为固定相制备了HPLC色谱柱,以正己烷-异丙醇(9∶1, v/v)作为流动相,流速为0.1 mL/min,考察了该手性柱对一系列外消旋化合物的拆分性能。实验表明,该手性柱拆分了15种外消旋化合物,其中特罗格尔碱、吡喹酮、3-苄氧基-1,2-丙二醇、1,2-环氧己烷、3-羟基-2-丁酮、2-甲基四氢呋喃-3-酮、异丙基缩水甘油醚达到基线分离;还分离了10种苯系位置异构体,o,m,p-氨基苯酚、o,p-氯苯酚、o,m,p-碘苯胺、o,m,p-甲苯胺、o,m,p-二硝基苯、o,m,p-氯苯胺、o,m,p-硝基苯酚、o,m,p-溴苯胺达到基线分离。实验表明,L-Glu手性硅胶球在手性分离方面具有良好的可行性,与普通硅胶相比不需要进一步修饰就可以有较好的手性分离效果,是一种低成本、制备便捷的手性无机硅胶固定相。

Single-Step Synthesis of Alginate Microgels Enveloped with a Covalent Polymeric Shell: A Simple Way to Protect Encapsulated Cells.

Microgels of biopolymers such as alginate are widely used to encapsulate cells and other biological payloads. Alginate is an attractive material for cell encapsulation because it is nontoxic and convenient: spherical alginate gels are easily created by contacting aqueous droplets of sodium alginate with divalent cations such as Ca2+. Alginate chains in the gel become cross-linked by Ca2+ cations into a 3-D network. When alginate gels are placed in a buffer, however, the Ca2+ cross-links are eliminated by exchange with Na+, thereby weakening and degrading the gels. With time, encapsulated cells are released into the external solution. Here, we describe a simple solution to the above problem, which involves forming alginate gels enveloped by a thin shell of a covalently cross-linked gel. The shell is formed via free-radical polymerization using conventional monomers such as acrylamide (AAm) or acrylate derivatives, including polyethylene glycol diacrylate (PEGDA). The entire process is performed in a single step at room temperature (or 37 °C) under mild, aqueous conditions. It involves combining the alginate solution with a radical initiator, which is then introduced as droplets into a reservoir containing Ca2+ and monomers. Within minutes of either simple incubation or exposure to ultraviolet (UV) light, the droplets are converted into alginate-polymer microcapsules with a core of alginate and a shell of the polymer (AAm or PEGDA). The microcapsules are mechanically more robust than conventional alginate/Ca2+ microgels, and while the latter swell and degrade when placed in buffers or in chelators like sodium citrate, the former remain stable under all conditions. We encapsulate both bacteria and mammalian cells in these microcapsules and find that the cells remain viable and functional over time. Lastly, a variation of the synthesis technique is shown to generate multilayered microcapsules with a liquid core surrounded by concentric layers of alginate and AAm gels. We anticipate that the approaches presented here will find application in a variety of areas including cell therapies, artificial cells, drug delivery, and tissue engineering.

DETERMINATION OF PROCESS RELATED GENOTOXIC IMPURITIES OF SALBUTAMOL SULPHATE BY LC METHOD

The main aim of this research work is to develop a suitable LC method for the quantitative determination of genotoxic impurities contains in Salbutamol Sulphate which is coming from the chemicals used during the manufacturing process. In manufacturing process many unwanted chemical materials are being used and out that many are following under Genotoxic category. After screening and doing the assessment on the genotoxic predication in salbutamol sulphate. The possible genotoxic impurities identified and likely to present in salbutamol Sulphate as Salicylic acid,[1][2][3] Acetyl methyl Salicylate (AMS),[4][5][6] Benzyl methyl salicylate (BMS),[7] Bromo-compound[8] and Dibromo-compound[8]. The main challenge is to separate all impurities from each other to get better resolution and response. As genotoxic[19][24] impurities estimation limit in final molecule is very minute and low it is not easy to quantify at ppm level present in Salbutamol sulphate in Active Pharmaceutical Ingredients. Hence the LC method was developed on Waters HPLC system (Water’s Ltd, USA) with 2995 UV detector at 273 nm as wavelength and 1.0 ml/min flow rate by using Spherical end-capped octylsilyl silica gel for chromatography (l = 0.15 m, Ø = 4.6 mm, 3µm) long with gradient system. The chromatographic and integrated data were recorded using Empower -3 data acquisition software. The limit of detection and the limit of quantitation for the impurity were established. Validation of the developed LC method was carried out as per ICH requirements and the data shows that the proposed method is specific, linear, accurate, precise and robust. This method has been tested in a number of Salbutamol Sulphate and used successfully for quantification of the reported impurities at ppm level. The developed LC method was found to be suitable to quantify the genotoxic impurities Salicylic acid, Acetyl methyl Salicylate (AMS), Benzyl methyl salicylate (BMS), Bromo-compound and Dibromo-compound at ppm level present Salbutamol Sulphate.

Pickering emulsion-embedded hierarchical solid-liquid hydrogel spheres for static and flow photocatalysis

Pickering emulsion-based photocatalysis is considered to be a promising system due to its large active surface area and water/oil spatial separation capability for enrichment of substrates and products. In this work, a novel hierarchical structure composed of calcium alginate gel sphere wrapped ionic liquid-in-water Pickering emulsion with TiO2 in the water phase, which are stabilized by graphene oxide, is prepared via a facile one-step emulsion gelation method. Such subtle combination of Pickering emulsion, hydrogel and TiO2 with a multi-stage solid-liquid assemblage structure shows enhanced degradation activity of 2-naphthol into small molecular alkanes under simulated solar irradiation. The photodegradation activity is attributed to the ionic liquid as adsorption medium for 2-naphthol, and the high-efficient charge separation at graphene oxide/TiO2 interface superior to that of pure TiO2. More importantly, the as-prepared millimeter-sized assembled gel spheres can be directly used as the column filler to construct continuous flow photocatalytic system, maintaining the promising performance in removing pollutants from water with ~100% remove ability of 2-naphthol on stream. A charge transfer mechanism of the photocatalyst is proposed, i.e. photogenerated charges are separated in TiO2/graphene oxide p-n heterostructure at the interface of Pickering emulsion droplets.

Separation of Colloidal Particle Using Elastic-Gel-Packed Column

Polymerized spherical gel (46 μm) was packed in a column to permeate silica particle suspension for the separation due to their differences of sizes. The elastic gel in the bottom domain of column deformed more because the pressure of the fluid flow suppressed the packed gel layer, that is, the formed gaps among the gels at the bottom domain had the smaller ‘pore’, resulting in filtering the smaller-size of the particles at the bottom of the column. The larger the size of silica particle, the upper the filtered domain in the column. To elute the filtered silica particle, the gel layer was compacted and restored by on-off of the fluid flow, to open the gaps in the gel layer repeatedly, demonstrating that the elution percentage of silica particle was gradually increased by the repeated on-off permeation of water.

Deformation Behavior of Spherical Gel under Quasi-static Compressive Loading Condition

Deformation Behavior of Spherical Gel under Quasi-static Compressive Loading Condition

Fabrication of Pill-Shaped Polyimide Aerogel Particles Using Microfluidic Flows

This work focuses on the fabrication and organic dye adsorption capacity of pill-shaped polyimide aerogel microparticles of diameter approximately 200 μm and length approximately 1000 μm. First, spherical polyimide sol droplets suspended in silicone oil are generated in a microfluidic droplet generator. Second, these droplets are guided into a contraction flow channel to deform them into pill-shaped droplets. Third, the pill-shaped droplets undergo sol–gel transition in a heated section of the flow channel and turn into particles. Finally, the pill-shaped aerogel microparticles are recovered via solvent exchange and supercritical drying and characterized. The data indicate that the flow rates of polyimide sol and silicone oil strongly influence the length of the microparticles while surfactants, although not necessary to obtain pill-shaped particles, exert strong influence on the aspect ratio of the particles. The aspect ratio of particles and the internal morphology are discussed using hydrodynamic and interfacial forces. The ionic dye adsorption capacity of these pill-shaped particles is determined and compared with that of spherical gel microparticles.

Filtration of Elastic Polymers and Spherical Gels through a Silica-Deposited Layer on a Porous Membrane

A 120-nm silica suspension was permeated through a porous polyethylene (PE) hollow-fiber membrane, as was a solution of deformable elastic particles of poly(N-isopropylacrylamide) (PNIPAM) gel and dextran. The amount adsorbed and flux of permeation were analyzed with ordinary differential equations to obtain adsorption coefficients, maximum amounts adsorbed, and pore-narrowing factors. The thickness of the “silica-deposited layer” on the membrane was 1 μm. In a batch adsorption mode, 5.0 mg of PNIPAM gel and 30 mg of dextran were adsorbed on the PE membrane, with no adsorption on the silica. The PE membrane pores were narrowed by a secondary layer of adsorbed PNIPAM gel. When filtered through the silica-deposited layer, PNIPAM gel occupies gaps, resulting in a reduced permeation flux. Dextran passed through the silica-deposited layer and was partially adsorbed on the PE membrane. The modified membrane can control adsorption, filtration, and flux permeation, which leads to dynamic membrane separations.

Production, Properties and Transit of Copper-Pectic Gel Particles through an Artificial Gastroenteric Environment

Spherical copper-pectic gel particles (CuPGPs) were obtained from aqueous solutions of commercial apple pectin (AP) AU701 (2%, 4%) in the presence of copper ions (CuCl2, 1%-10%), and their morphological (diameter) and structural-mechanical (density) characteristics were studied. It was found that with an increase in the concentration of AP from 2% to 4%, the diameter of dry gel particles at all tested concentrations of copper chloride (1-10%) increased from 0.64-0.76 mm (2% AP) to 0.87-0.94 mm (4% AP), and that the density of dry gel particles with an increase in the concentration of AP also increased from 1.27-1.48 mg/mm3 (2% AP) to 1.42-1.55 mg/mm3 (4% AP). The swelling and degradation of the obtained CuPGPs in an artificial gastroenteric environment was studied. It has been established that the CuPGPs based on 4% AP with 10% CuCl2 have the highest degree of swelling in the acidic environment of the intestinal gastric fluid (SGF). CuPGPs, depending on the concentration of AP and copper ions, are degraded in different parts of the intestine—in simulated intestinal fluid (SIF) or simulated colonic fluid (SCF).

Stiffness distribution of a spherical gel structure and bifurcation analysis with application to stem-cell differentiation

In biophysics, gel substrates have been used to do stem-cell differentiation by utilizing the stiffness distribution in the gel. However, in the currently available designs, the stiffness range may not be large enough and there also lacks a quantitative control. In this paper, we introduce a mechanical–chemical model for a spherical gel structure which generates an inhomogeneous deformation in the gel with a stiffness distribution when it is immersed in a solvent. The solution is quantitatively computed and the influences of adjustable geometric, material, loading parameters on the stiffness range are examined in detail. A bifurcation analysis is conducted to determine the threshold of the loading parameter. As a result, a guideline is provided on how to adjust the involved parameters to generate a desirable large stiffness range without the occurrence of bifurcation. Two examples are provided in which the proper parameters are selected, leading to the stiffness ranges suitable for stem-cell differentiation for skin and thyroid tissues.

Encapsulation of Activated Carbon into a Hollow-Type Spherical Bacterial Cellulose Gel and Its Indole-Adsorption Ability Aimed at Kidney Failure Treatment.

For reducing side effects and improvement of swallowing, we studied the encapsulation of activated carbon formulations with a hollow-type spherical bacterial cellulose (HSBC) gel using two kinds of encapsulating methods: Methods A and B. In Method A, the BC gelatinous membrane was biosynthesized using Komagataeibacter xylinus (K. xylinus) at the interface between the silicone oil and cell suspension containing activated carbon. In Method B, the bacterial cellulose (BC) gelatinous membrane was formed at the interface between the cell suspension attached to the alginate gel containing activated carbon and the silicone oil. After the BC gelatinous membrane was biosynthesized by K. xylnus, alginate gel was removed by soaking in a phosphate buffer. The activated carbon encapsulated these methods could neither pass through the BC gelatinous membrane of the HSBC gel nor leak from the interior cavity of the HSBC gel. The adsorption ability was evaluated using indole, which is a precursor of the uremic causative agent. From curve-fitting, the adsorption process followed the pseudo-first-order and intra-particle diffusion models, and the diffusion of the indole molecules at the surface of the encapsulated activated carbon within the HSBC gel was dominant at the initial stage of adsorption. It was observed that the adsorption of the encapsulated activated carbon by the intraparticle diffusion process became dominant with longer adsorption times.

Embedding Ordered Mesoporous Carbons into Thermosensitive Hydrogels: A Cutting-Edge Strategy to Vehiculate a Cargo and Control Its Release Profile.

The high drug loading capacity, cytocompatibility and easy functionalization of ordered mesoporous carbons (OMCs) make them attractive nanocarriers to treat several pathologies. OMCs’ efficiency could be further increased by embedding them into a hydrogel phase for an in loco prolonged drug release. In this work, OMCs were embedded into injectable thermosensitive hydrogels. In detail, rod-like (diameter ca. 250 nm, length ca. 700 nm) and spherical (diameter approximately 120 nm) OMCs were synthesized by nanocasting selected templates and loaded with ibuprofen through a melt infiltration method to achieve complete filling of their pores (100% loading yield). In parallel, an amphiphilic Poloxamer® 407-based poly(ether urethane) was synthesized ( 72 kDa) and solubilized at 15 and 20% w/v concentration in saline solution to design thermosensitive hydrogels. OMC incorporation into the hydrogels (10 mg/mL concentration) did not negatively affect their gelation potential. Hybrid systems successfully released ibuprofen at a slower rate compared to control gels (gels embedding ibuprofen as such), but with no significant differences between rod-like and spherical OMC-loaded gels. OMCs can thus work as effective drug reservoirs that progressively release their payload over time and also upon encapsulation in a hydrogel phase, thus opening the way to their application to treat many different pathological states (e.g., as topical medications).