Synthesis of phosphate-embedded calcium alginate beads for Pb(Ⅱ) and Cd(Ⅱ) sorption and immobilization in aqueous solutions

The phosphate-embedded calcium alginate beads were successfully synthesized based on sodium alginate, calcium dihydrogen phosphate and sodium hydrogen carbonate. Scanning electron microscopy, Fourier transformed infrared (FTIR) spectroscopy and X-ray diffraction (XRD) were conducted to characterize the morphology and structure of the phosphate-embedded calcium alginate beads. The effects of pH and the initial concentration of the metal ions on Pb(II) and Cd(II) sorption by the beads were investigated. The optimal pH values for Pb(II) and Cd(II) sorption are 4.0 and 5.5, respectively. The optimal initial concentrations of Pb(II) and Cd(II) are 200 mg/L and 25 mg/L, correspondingly, and the removal efficiencies are 94.2% and 80%,respectively. The sorption mechanism is that the heavy metal ions accessed the beads firstly due to the large surface area, combinedwith OH?, and then precipitated with phosphate radical, which was proven by FTIR and XRD. The sorption of Pb(II) and Cd(II) isfitted to Langmuir isotherm model with R2 values of 0.9957 and 0.988, respectively. The sorption capacities of Pb(II) and Cd(II) are263.16 mg/g and 82.64 mg/g, respectively. The results indicate that the phosphate-embedded calcium alginate beads could be appliedto treating Pb(II)/Cd(II)-containing wastewater and it could be implied that the synthesized beads also could be used as a kind of soil ameliorant for remediation of the heavy metal contaminated paddy soil.

Release Profile of Lansoprazole Encapsulated in Sodium Alginate Beads

Symptomatic gastroesophageal reflux disease (GERD) affects 11% of the population worldwide. Lansoprazole was the second commercially available proton pump inhibitor, recommended for healing and symptomatic relief of reflux esophagitis. This work presents the encapsulation of lansoprazole in sodium alginate beads, generating a controlled release system of the encapsulated drug. The quantification of lansoprazole contents from the encapsulated raw material was carried out, using the methodology prescribed in the Brazilian Pharmacopoeia 5th edition, with adjustments, the encapsulation efficiency and the release profile. Experimental tests were performed using scanning UV-Vis spectrophotometry. Encapsulation efficiency was 100%, obtained from the measurement of the absorbance of the filtrate. Release profile shows the concentration of lansoprazole in the external environment was 4 μg/mL (16%) immediately after 10 min. Concentration of lansoprazole released by the beads follows a linear dynamic as a function of time, with a maximum release equivalent to 25 μg/mL after 210 min (100%). The rate of release is influenced by pH, being higher by 7.4. Beads subjected to heat treatment have a higher release rate at a temperature of 30 °C when compared to a temperature of 60 °C. Increase in temperature decreases the diameter of the beads. The presence of lansoprazole affects the release curve. The absorption rate of the microbeads with lansoprazole is 0.83, and the absorption rate of the microbeads without lansoprazole is 0.58. Sodium alginate beads have a good controlled release effect on lansoprazole.

Electro-spray of high viscous liquids for producing mono-sized spherical alginate beads

Alginate beads, often used for controlled release of enzymes and drugs, are usually produced by spraying sodium alginate liquid into a gelling agent using mechanical vibration nozzle or air jet. In this work an alternative method of electro-spray was employed to form droplets with desired size from a highly viscous sodium alginate solution using constant DC voltage. The droplets were then cured in a calcium chloride solution. The main objective was to produce mono-sized beads from such a highly viscous and non-Newtonian liquid (1000–5000 mPa s). The effects of nozzle diameter, flow rate and concentration of liquid on the size of the beads were investigated. Among the parameters studied, voltage had a pronounced effect on the size of beads as compared to flow rate, nozzle diameter and concentration of alginate liquid. The size of beads was reduced to a minimum value with increasing the voltage in the range of 0–10 kV. At the early stages of voltage increase (i.e. up to about 4 kV), the rate of size reduction was relatively low, while the dripping mode dominated. However, in the middle part of the range of applied voltage, where the rate of size reduction was high (i.e. about 4–7 kV), an unstable transition occurred between dripping and jetting. At the end part of the range (i.e. 7–10 kV) jet mode of spray was observed. Increasing the height of fall of the droplets was found to improve the sphericity of the beads, because of the increased time of flight for the droplets. This was especially identifiable at higher concentrations of the alginate liquid (i.e. 3 w/v%).

Swelling Studies and in vitro Release of Acemetacin and BSA from Alginate Gel Beads Crosslinked with Ca^(2+) or Ba^(2+)

The aim of the present work was to investigate the swelling behavior and the in vitro release of acemetacin and bovine serum albumin from alginate gel beads crosslinked with Ca2＋ or Ba2＋. The release profiles suggested that the extent of swelling of the alginate beads played an important role in the release of drug. Small drugs are mainly released via diffusion through the alginate gel matrix. Compared with small drugs, large molecule drugs are difficult to diffuse through the pores of the matrix bead until the beads swell to a certain extent to provide enough large pores. The Ba2＋ crosslinked alginate beads showed slower release rate compared with the Ca2＋ crosslinked alginate beads, whether loaded the large molecules or small drugs. In conclusion, the Ba2＋ crosslinked alginate beads are considered more suitable than Ca2＋ crosslinked alginate beads for using as a sustained release vehicle especially for large molecule drugs.

CHEMICAL MODIFICATION OF THE SURFACE OF CALCIUM ALGINATE GEL BEADS

The chemical modification of the surface of calcium alginate gel beads (CAGB) via grafting copolymerization with vinyl acetate (VAc) was studied. The optimum reaction conditions with activation and graft copolymerization two steps were explored. First, 5 grams CAGB with 2.5 mm initial diameter was initiated with 0.0493 mol/L K2S2O8 at 51 °C for 30 min in 15 mL 1 % PVA/H2O. Then 4.34 moi/L VAc was added dropwise and the reaction was allowed to proce at 48 °C for 3 h. The grafting efficiency could come up to 30%. It was found the stability of modified CAGB in the air and in electrolyte solutions was greatly improved.

Preparation and Characterization of AlginateHyaluronic Acid-chitosan based Composite Gel Beads

The aim of this study was to fabricate composite gel beads based on natural polysaccharides. Hyaluronic acid（HA） and Chitosan（CS） were successfully admixed with Ca^2＋/alginate（SA） gel system to produce SA/HA/CS gel beads by dual crosslinking： the ionic gelation and the polyelectrolyte complexation. The preparation procedure was that the weight ratio of SA（2%, m/v） to HA（2%, m/v） was kept at 2：1, then the mixture was dripped into the Ca^2＋ solution for ion-crosslinking, and finally polyelectrolyte crosslinked with 2% low molecular weight CS（LMW-CS） for 1.5 hours. The optimal formulation was achieved by adjusting the concentration and the weight ratio of SA, HA and LMW-CS. Due to the incorporation of HA and LMWCS, the swelling ratio of the beads at pH 7.4 was increased up to 120, and the time for the maximum swelling degree was prolonged to 7.5 h. The swelling behavior was obviously improved compared to the pure SA/Ca^2＋ system. The preliminary results clearly suggest that the SA/HA/CS gel beads may be a potential candidate for biomedical delivery vehicles.

Immobilization study of biosorption of heavy metal ions onto activated sludge

Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10\_100 mg/L was studied by using both entrapped activated sludge and inactivated free biomass at pH≤5. A biphasic metal adsorption pattern was observed in all immobilized biomass experiments. The biosorption of metal ions by the biosorbents increased with the initial concentration increased in the medium. The adsorption rate of immobilized pre-treated activated sludge(PAS) was much lower than that of free PAS due to the increase in mass transfer resistance resulting from the polymeric matrix. Biosorption equilibrium of beads was established in about 20 h and the adsorbed heavy metal ions did not change further with time. No significant effect of temperature was observed in the test for free biomass while immobilized PAS appeared to be strong temperature dependent in the test range of 10 and 40℃. Besides, the content of activated sludge in the calcium alginate bead has an influence on the uptake of heavy metals. The sorption equilibrium was well modeled by Langmuir isotherm, implying monomolecular adsorption mechanism. Carboxyl group in cell wall played an important role in surface adsorption of heavy metal ions on PAS.

Formulation development and evaluation of gastroretentive floating beads with Brucea javanica oil using ionotropic gelation technology

In the present study, a gastric retention floating system for Brucea javanica oil, composed of alginate and carrageenan, was prepared using ionotropic gelation. Parameters for floatability, drug load, encapsulation efficiency, bead morphology, in vitro release, and in vivo gastric retention were evaluated. The optimized formulation via Box–Behnken design consisted of 1.7% alginate(W/V), 1.02% carrageenan(W/V), 1.4% CaCO_3(W/V), and a gelling bath of pH 0.8. The alginate–carrageenan–Brucea javanica oil beads had a porous structure and exhibited up to 24 h of in vitro floatability with a load capacity of 45%–55% and an encapsulation efficiency of 70%–80%. A 6-h sustained release was observed in vitro. The beads had a prolonged gastric retention(> 60% at 6 h) in fasted rats, compared to non-floating beads(15% at 6 h), as measured by gamma scintigraphy with single-photon emission tomography/computed tomography(SPET/CT). In conclusion, the alginate–carrageenan–Brucea javanica oil system showed enhanced oil encapsulation efficiency, excellent floating and gastric retention abilities, and a favorable release behavior.

Bio-fabrication of liver cancer stem cells and testing of gemcitabine

Aim:Cancer stem cells are cell populations that are essential in drug resistance and cancer metastasis.Some liver cancer cells exhibit the characteristics of cancer stem cells,and it is crucial to study the activities and interactions of drugs in these cells.Huh7 is a human liver cancer cell with stem cell biomarkers and is used with induced pluripotent stem cells to form various cancer organoids through encapsulation methods.Due to their ease of use without animal testing,bio-fabrication studies of cell-encapsulated models have gained importance in the pharmaceutical industry in recent years.This study aimed to biofabricate Huh7 human liver cancer stem cells by alginate encapsulation and test gemcitabine’s efficacy.Methods:Huh7 cells were encapsulated with alginate(0.8%w/v)and fibronectin,and their viability was evaluated with 3.2μM gemcitabine on days 1,3,6,9,and 12.Furthermore,gene expressions of stem cell markers CD90 and AFP were evaluated in encapsulated Huh7 cells by qPCR.In addition,IL-6 secretion in the cell medium was measured by ELISA for the tumor microenvironment.Results:Encapsulation of Huh7 cells was found to maintain their viability and stem cell properties for up to 12 days.In addition,alginate-encapsulated Huh7 cells were bio-fabricated to demonstrate long-term gemcitabine response.While the effect of the gemcitabine was evaluated in alginate-encapsulated Huh7 cells,CD90 and AFP mRNA levels were significantly reduced in the cells and IL-6 secretion was decreased in the tumor microenvironment.Conclusion:This study demonstrated that bio-fabrication of alginate-encapsulated Huh7 cells is a novel approach for long-term drug testing in liver cancer models.Bio-fabricated alginate-encapsulated cancer stem cells may be a cheaper and faster method for the testing of many drugs.

Co-Free High-Entropy Alloys Powders Immobilized by Electrospray and Microf luidics for Decolorization of Azo Dye

In recent years,high-entropy alloys(HEAs)have received more and more attention due to their unique microstructure and properties.Several researchers have reported that some ball-milled(BM)HEAs powders possess prominent decolorization performance for azo dyes.Three kinds of Co-free HEA powders(AlCrFeMn,AlCrFeNi and FeCrNiMn)have been synthesized by ball milling in this work,of which AlCrFeMn shows the best decolorization efficiency for DB6 aqueous solution.However,at this time,the BM HEAs are in powder state and not easy to be reused,so the loss rate of the powders is high during the reaction.Sometimes,the reaction between reacted the powders and the dye solution is too fast to control.While,in order to solve these problems,this work proposes to immobilize bare BM AlCrFeMn HEA powders in calcium alginate beads(CAB s)by electrospray and microfluidics.Through four cycles of reaction,the loss rate of the AlCrFeMn powders can be reduced from 40 to 5 wt%if the powders are immobilized by CABs with an average diameter of 0.55 mm obtained at the DC voltage of 30 kV.In addition,in the four cycles of experiment,the AlCrFeMn HEA-CABs with an average diameter of0.55 mm shows better stability and easier separation than that of the bare AlCrFeMn powders.These findings provide new ideas for HEAs to decolorize azo dyes and are of great significance for protecting freshwater resources.