Eco-friendly calcium alginate microspheres enable enhanced profile control and oil displacement

Polymer microspheres(PMs),such as polyacrylamide,have been widely applied for enhanced oil recovery(EOR),yet with environmental concerns.Here,we report a microfluid displacement technology containing a bio-based eco-friendly material,i.e.,calcium alginate(CaAlg)microspheres for EOR.Two dominant mechanisms responsible for EOR over Ca Alg fluid have been verified,including the microscopic oil displacement efficacy augmented by regulating capillary force(determined by the joint action of interfacial tension and wettability between different phases)and macroscopic sweep volume increment through profile control and mobility ratio reduction.This comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate(SDS).The core flooding and nuclear magnetic resonance(NMR)tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation(wettability alteration and IFT reduction)and rheology properties,enabling simultaneous profile control and oil displacement.Excessive introduction of SDS will have a negative impact on rheological properties,which is not favored for EOR.Our results show that the involvement of 4-m M SDS will provide the best behavior,with an EOR rate of 34.38%.This cost-effective and environmentally-friendly bio-microspherebased microfluidic displacement technology is expected to achieve“green”oil recovery in future oilfield exploitation.

Application of sodium alginate microspheres in ischemic stroke modeling in miniature pigs

The miniature pig is an optimal animal model for studying nervous system disease because of its physiologic and pathologic features. However, the rete mirabile composed of arteries and veins at the skull base limits their application as a model of ischemic stroke by middle cerebral artery occlusion. The present study investigated the possibility of establishing an ischemic stroke model in the miniature pig by blocking the skull base retia with sodium alginate microspheres. Three Bama miniature pigs were used. Using the monitor of C-arm X-ray machine, sodium aiginate microspheres （100-300 pm）, a novel embolic material, were injected through the femoral artery, aortic arch, common carotid artery, ascending pharyngeal artery and the retia. Results were evaluated using carotid arteriography, MRI, behavior observation and histology. The unilateral rete mirabile was completely blocked, resulting in disturbance in blood supply to the basal ganglia, astasia of the dght hind limb and salivation. MRI and hematoxylin-eosin staining showed an evident infarction focus in the basal ganglia. These findings indicate that sodium alginate microspheres are a suitable embolic material for blocking the skull base retia in miniature pigs to establish an ischemic stroke models.

Removal and recovery of titanium(Ⅳ) from leach liquor of high-sulfur bauxite using calcium alginate microspheres impregnated with di-(2-ethylhexyl) phosphoric acid

In the leaching solution of high-sulfur bauxite roasted by sulfuric acid,a high concentration of aluminum presented along with titanium and iron.The present work was to remove Ti(IV)from the leach liquor by calcium alginate microsphere sorbent material(CA-P204)based on natural alginate impregnated with di-(2-ethylhexyl)phosphoric acid(D2EHPA)to purify leaching solution.Cation exchange and chelation make major contributions to the adsorption mechanism according to Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis.The results showed that Ti(IV)was successfully removed by the CA-P204 adsorbent from the Ti(IV)-Al(III)-Fe(III)ternary system with a dynamic column experiment.The removal rate of titanium was nearly 95%under optimal conditions and the maximum adsorption capacity was 66.79 mg/g at pH 1.0.Reusability of CA-P204 was evaluated over three consecutive adsorption/desorption cycles.The adsorption process was simple,low-cost,and had no waste discharge,suggesting that the CA-P204 was promising,efficient,and economical for removing Ti(IV)from high-sulfur bauxite leaching solution.

Physicochemical properties and release characteristics of calcium alginate microspheres loaded with Trichoderma viride spores

Novel agroformulations for simultaneous delivery of chemical and biologically active agents to the plants were prepared by encapsulation of Trichoderma viride spores in calcium alginate microspheres.The impact of calcium ions concentration on the viability and sporulation of T.viride spores as well as on the microsphere important physicochemical properties were investigated.Intermolecular interactions in microspheres are complex including mainly hydrogen bonds and electrostatic interactions.T.viride germination inside matrix and germ tubes penetration out of microspheres revealed calcium alginate microspheres provide a supportive environment for T.viride growth.Differences in physicochemical properties and bioactive agents release behaviour from microspheres were ascribed to the changes in microsphere structure.Fitting to Korsmeyer-Peppas empirical model revealed the underlying T.viride release mechanism as anomalous transport kinetics(a combination of two diffusion mechanisms and the Type II transport(polymer swelling and relaxation of the polymeric matrix)).The increasing amount of T.viride spores in the surrounding medium is closely related to the release from microspheres and germination.The rate controlling mechanism of calcium release is Fickian diffusion.A decrease in the release rate with increasing calcium ion concentrations is in accordance with the calcium ions effect on the strength of the alginate network structure.T.viride germination inside microsphere diminished the amount of released calcium ions and slowed release kinetics in comparison with microspheres prepared without T.viride.The results indicated investigated agroformulations have a great potential to be used for plant protection and nutrition.

Preparation of sodium alginate gel microspheres catalysts and its high catalytic performance for treatment of ciprofloxacin wastewater

The discharge of the antibiotic wastewater has increased dramatically in our country with the development of medical science and wide application of antibiotic,resulting in serious harm to human body and ecological environment.In this work,ciprofloxacin(CIP)was selected as one of typical antibiotics and heterogeneous Fenton-like catalysts were prepared for the treatment of ciprofloxacin wastewater.The sodium alginate(SA)gel microspheres catalysts were prepared by polymerization method using double metal ions of Fe^(3+)and Mn^(2+)as cross-linking agents.Preparation conditions such as metal ions concentration,mass fraction of SA,polymerization temperature and dual-metal ions as crosslinking agent were optimized.Moreover,the effects of operating conditions such as initial concentration of CIP,pH value and catalyst dosage on CIP removal were studied.The kinetic equation showed that the effect of the initial concentration of CIP on the degradation rate was in line with second-order kinetics,and the effects of catalyst dosage and pH value on the degradation rate of CIP were in line with first-order kinetics.The SA gel microspheres catalysts prepared by dual-metal ions exhibited a high CIP removal and showed a good reusability after six recycles.The SA gel microspheres catalysts with an easy recovery performance provided an economical and efficient method for the removal of antibiotics in the future.

A novel bio‑active microsphere for meniscus regeneration via inducing cell migration and chondrocyte differentiation

Abstract Meniscus injury is a common disease in clinic.If it was not treated in time,it leads to osteoarthritis which brings unbearable pain and heavy economic burden to the patients.At present,meniscectomy and meniscus suture are widely used in the treatment for meniscus injury.Nevertheless,It is not ideal for poor self-healing ability of meniscus.The recruitment of endogenous stem cells is an attractive option for wounded meniscus healing.Fully reduced high-mobility group box 1 protein(HMGB1)can accelerate the regeneration of multiple tissues by endogenous stem cell activation,migration and differentiation.Kartogenin(KGN)has shown to induce the chondrogenesis of the stem cells.However,no study has explored such effects of HMGB1 and KGN in wounded meniscus healing.Therefore,in order to improve the regeneration of meniscus,we intend to use a novel bioactive microsphere which was developed by combining fully reduced high mobility group box 1(frHMGB1)and kartogenin(KGN)with alginate gel which slowly release high concentrations of HMGB1 and KGN to activate rat bone marrow stem cells(BMSCs)and promote cell proliferation.The results showed that this HMGB1–KGN microsphere released and kept high concentrations of HMGB1 and KGN in the wound area for more than 2 weeks.In vitro experimental results showed that the HMGB1–KGN microsphere can promote cell proliferation via recruiting rat bone marrow stem cells(BMSCs)and activating the BMSCs from G_(0) to G_(Alert) stage as evidenced by cell migration testing and 5-bromo-2′-deoxyuridine(BrdU)incorporation assay.In vivo results indicated that this HMGB-KGN microsphere can recruit GFP-labeled BMSCs from tail vein to wounded meniscus and induce these GFP-labeled BMSCs to differentiate into chondrocytes.Our results demonstrated that the HMGB1–KGN-containing bioactive microsphere induced cell migration in vitro and recruited the cells to wound area to promote wounded rat meniscus healing in vivo.