Crosslinked Starch Microspheres Research Articles

Fabrication of crosslinked starch microspheres via water-in-water Pickering emulsion and their application in controlled release of Vitamin C

Green technology for the fabrication of bio-degradable microspheres is exciting and needed. In this study, a new water-in-water Pickering emulsion green technology is proposed for the fabrication of the crosslinked starch microspheres with sodium tripolyphosphate as the crosslinker, polyethylene glycol aqueous solution as the continuous phase (PEG phase) and starch aqueous solution as the dispersed phase (starch phase). The factors that affect the morphology and particle sizes of cross-linked starch microspheres are investigated by laser scanning confocal microscope (LCM) and laser particle size analyzer. The results reveal that the particle sizes of crosslinked starch microspheres are increasing with increased starch concentration. The particle sizes of crosslinked starch microspheres show a first increase and then decrease trend with the increase of the concentration of PEG 20,000 in the PEG phase. The hydrophobic nano silica is used as an emulsifier to form water-in-water Pickering emulsion and shows an obvious effect on the morphology of starch microspheres. When the starch concentration is 20.00 wt%, PEG 20000 concentration is 32.56 wt%, the ratio of starch to PEG phase is 0.20 and the amount of silica is 5.00 wt% of starch, starch microspheres with regular shapes are obtained with the size of about 32.30 ± 0.22 µm. The fabricated cross-linked starch microspheres are non-crystalline and show good water and oil absorption performances. The application of fabricated crosslinked starch microspheres in the adsorption and release of Vitamin C is conducted. The maximum adsorption capacity of crosslinked starch microspheres for Vitamin C reaches 309.9 mg/g. Starch microspheres show a controlled release of Vitamin C in water. This study indicated that crosslinked starch microspheres can be fabricated through a green water-in-water Pickering emulsion technology and may find potential applications in degradable controlled-release microspheres.

Titanium surface polyethylene glycol hydrogel and gentamicin-loaded cross-linked starch microspheres release system for anti-infective drugs

Objective To design and construct a hydrogel drug-controlled release system loaded with gentamicin on a titanium surface, and to evaluate the in vitro drug release behaviour and antibacterial properties and biocompatibility of the controlled release system. Methods Titanium (Ti) surface was coated with poly dopamine (PDA) substrate, and then polyethylene glycol (PEG) was attached to PDA. The composite drug microsphere controlled release layer formed by gentamicin (GEN) and cross-linked starch (CSt) were subsequently covered with poly lactic⁃co⁃glycolic acid (PLGA) as a barrier to construct a Ti-GEN-Cst-PLGA anti-infective drug controlled release system. Results The hydrogel drug release system was successfully constructed. The results of in vitro anti-staphylococcus aureus (SAU) assay, anti-staphylococcus epidermidis (SEP) assay and anti-Escherichia coli (ECO) assay showed that Ti-GEN-Cst-PLGA could effectively inhibit the growth of three bacteria. Assay in the New Zealand rabbit found that Ti-GEN-Cst-PLGA could promote wound healing at the 3rd week after implantation, and the pathology assay found that the Ti-GEN-Cst-PLGA group had less inflammatory reactions and significant tissue proliferation at the endophyte contact surface. Conclusion Ti-GEN-Cst-PLGA can effectively inhibit the inflammatory response and promote wound healing, or may be a potential treatment for orthopaedic endophytes.

Hydration and dehydration induced changes in porosity of starch microspheres

Characterization and tuning of the porosity of amorphous starch materials are important for many applications, including controlled release of encapsulated proteins. The porosities of these materials in dry and hydrated states can have different physicochemical origins and properties. Here, porosities of dry cross-linked starch microspheres and their hydration-induced transformations were characterized by small angle X-ray scattering, scanning electron and optical microscopies, thermogravimetric analysis, sorption calorimetry, nitrogen sorption, and helium-pycnometry. The analyses revealed that dry microspheres consist of porous cores with pore diameters below 100 nm and shells which appeared to be denser but contained wider pores (100–300 nm). The outer crust of the microspheres shell is non-porous, which restricts diffusion of nitrogen, water, and ethanol. Partial hydration triggered an irreversible collapse of dry porosity at 12 wt% water. Further hydration resulted in interfacial changes and promoted wet porosity, related to characteristic distances between polymer chains.

Absorbable Hemostatic Material with High Water Absorption Based on Polysaccharide

An absorbable hemostatic material based on polysaccharide was prepared. The concentration of blood cells and coagulation factors was increased by reducing the water content in the blood, so as to reduce the coagulation time and achieve the purpose of rapid hemostasis. The specific surface area of starch was increased by using hydrochloric acid to hydrolyze potato starch, which made it easier to combine with α-amylase and increased the degradation rate. Starch was crosslinked into microspheres by crosslinking agent, which made the particle size uniform and greatly improved the water absorption. The surface modification of crosslinked starch microspheres with carboxymethyl group can further improve the water absorption of hemostatic materials. The results showed that the water absorption rate of our hemostatic material was more than 800%, and the average hemostatic time in the animal model was 138.7s. Compared with the imported products on the market, our hemostatic material have better hemostatic performance.

Degradable porous carboxymethyl chitin hemostatic microspheres

Lethal hemorrhage could endanger lives. Although many hemostatic agents are commercially available with good clinical effect, it is necessary to develop novel hemostatic materials with high efficacy, biological safety, low cost, easily preparation and excellent biodegradability and biocompatibility. Here, novel biodegradable and uniform microspheres with regular spherical architecture and porous microstructure were prepared by thermosensitive carboxymethyl chitin (CMCH) with low substitution degree and low deacetylation through physical-crosslinking at high temperature without using any toxic crosslinkers. The obtained CMCH microspheres (CMCH-MS) were non-cytotoxic, low hemolytic potential and biodegradable in the presence of lysozyme. In vitro blood clotting evaluation indicated that the porous microsphere network structures and the hydrophilicity of the CMCH could promote hemostasis due to the quick blood absorption and local concentration of the coagulation factors for the CMCH-MS. The CMCH-MS showed much better hemorrhage control than negative control and traditional hemostatic chitosan, similar hemostatic performance as commercialized cross-linked starch microspheres in both rat tail and liver models. Thus, the new biodegradable porous CMCH-MS may hold great potential for hemorrhage control in medical treatment.

Hydration and swelling of amorphous cross-linked starch microspheres

Hydration of cross-linked starch microspheres, commercially available as a medical device, was investigated using a multi-method approach. We found that the uptake of water is accompanied by substantial swelling and changes of the polymer structure. Sorption calorimetry provided information about thermodynamics of water sorption, revealed presence of isothermal glass transition and absence of hydration-induced crystallization, observed in non-cross linked starch material. The changes in the surface and bulk properties of microspheres at different water–starch concentrations were investigated using synchrotron radiation X-ray scattering and analyzed using concept of fractals. The obtained information, combined with the results of differential scanning calorimetry, was used to construct a phase diagram of the studied material. Finally, hydration induced evolution of polymer structure revealed by the X-ray scattering was linked to the changes observed during swelling with optical microscopy.

Adsorption Properties of Crosslinked Starch Microspheres toward Pyridine

The adsorption of pyridine onto crosslinked starch microspheres (CSMs) was investigated by experimental and theoretical methods. The adsorption capacity of CSMs towards pyridine increases with the increasing of pyridine concentration, and by lowering the temperature, adsorption would be accelerated. The adsorption behaviour of CSMs to pyridine is in agreement with the Langmuir isothermal equation. The research results show that the adsorption process is exothermic, and the adsorption force mainly derives from enthalpy changes. The thermodynamic parameters of adsorption process show that the adsorption behaviour of CSMs towards pyridine is of a physical type.

Microwave synthesis and adsorption performance of a novel crosslinked starch microsphere

A new crosslinked starch microsphere (CSM) was synthesized in a microwave-assisted inversed emulsion system with soluble starch (ST) as a raw material, MBAA as a crosslinker, and K2S2O8–NaHSO3 as an initiator. The synthesized starch microsphere was characterized and examined by scanning electron microscope (SEM), FTIR spectroscopy and adsorption isotherms of N2 at 77K. Adsorption performance was investigated in methyl violet solution. The results showed that the maximum adsorption capacity for MV was 99.3mg/g at 298K, and the adsorption fitted pseudo-second-order kinetic model well with correlation coefficients greater than 0.99. The isothermal data obeyed the Langmuir model better compared to Freundlich model and Tempkin model, and the adsorption was exothermic and spontaneous. pH variations (2.0–10.0) did not significantly affect the adsorption of MV onto CSM.

Study on Adsorption of Crosslinked Starch Microspheres towards Heavy Metal Ions<sup></sup>

A type of cross-linking starch microsphere (CSMs) has been synthesized via reversed phase suspension method. Crosslinked starch microsphere has good adsorption performance to metal ions in water. The adsorption kinetics of Co (II) on the CSMs, selectivity of adsorption CSMs towards Co (II),Cu (II),Pb (II),Cd (II) and adsorption effects of media towards Co (II) were investigated. The CSMs and its adsorption product were comparatively characterized by X-ray diffraction (XRD). The results showed that The adsorption rate is mainly controlled by liquid film diffusion, and the constant of adsorption rate is 0.0686min-1 at 308K. The crystal structure of the CSMs decreased greatly after the incorporation of Co (II). Co (II) has better adsorption selectivity on CSMs. Ions coexist and other substances in the solution have certain impact on adsorption. Those data are helpful for treatment of the wastewater containing heavy ions.

Preparation and Thermodynamics Adsorption Performance of Cobalt Ions on the Crosslinked Starch Microspheres

A type of cross-linking starch microspheres (CSMs) has been synthesized by reversed phase suspension method using soluble starch as raw material. Crosslinked starch microsphere has good adsorption performance to metal ions in water. The static adsorption behaviors of Co2+on the cross-linked starch microspheresand were investigated. The CSMs and its adsorption product were comparatively characterized by Fourier Transform Infrared Spectroscopy (FTIR). The adsorption behaviour of CSMs in different temperatures is in agreement with the Freundlich isothermal equation and isothermal equation of Langmiur. The thermodynamic parameters of adsorption process indicate that entropy is the main adsorption driving force, and physical adsorption is main about the adsorption behaviors of CSMs on Co2+.These data are helpful for the adsorption separation of metal ions and the treatment of the wastewater containing Co2+. Keywords: cross-linked starch microspheres;cobalt ions;adsorption mechanism;thermodynamics adsorption

Adsorption Capability of Starch Microspheres Cross-Linked with N, N'-Methylene-Bis-Acrylamide

The crosslinked starch microspheres(CSM) were synthesized from soluble starch by inverse suspension polymerization with N,N′-methylenebisacrylamide as cross-linking agent. Experiments showed that adsorption isotherms of CSM for Cd(II) and Pb(II) could be described by Freundlich model, while that for Cu(II), Cr(III) fits well with Langmuir equation. The equilibrium capacity of Cu(II), Cr(III), Cd(II) and Pb(II) on the CSM were 1.10, 0.87, 0.35 and 0.31 mmol•g-1 respectively at 25°C, when adsorption process was undertaken with initial concentration from 0.7 to 11.5 mmol•L-1, and adsorption kinetics were examined according to the adsorption isotherm. Furthermore, the impact bring by other ions to CSM adsorption of Cu(II) were investigated in details.

Adsorption of Methylene Blue on Starch Microsphere from Aqueous Solutions

In order to resolve the pollution of coloured wastewater, starch microsphere was used to absorb methylene blue from aqueous solutions in this paper. Starch microsphere is artificial starch derivative, can be synthesized by cross-linking reaction from crude starch and modified starch. The cross-linked starch microsphere was prepared from soluble starch and N, N'-methylenebisacrylamide, and starch microsphere has characteres of irregular appearance, uniform size, suitable swelling, three-dimensional network structure, suitable shell pore diameter and specific surface area, good mechanical intensity. The microporous structure of starch microsphere was determined using Scanning Electronic Microscopy (SEM). The adsorption capacity of starch microsphere to methylene blue was studied. It could be shown that the adsorption capacity increases with the increase of concentration of methylene blue. Also, the lower the temperature was, the bigger the adsorption capacity of SM was in the same concentration. So, starch microsphere could effectively absorb methylene blue from aqueous solutions and thus the influencing factors of the adsorption were discussed in detail.

Preparation of Environmentally Friendly Microspheres Based on Starch

Starch microsphere is artificial starch derivative, can be synthesized by cross-linking reaction from crude starch and modified starch. In this study, a new type of crosslinked starch microspheres with degradability was prepared by crosslinking reaction of soluble starch with N, N'-methylenebisacrylamide (MBAA) in inverse suspension using K2S2O8-Na2SO3 as initiator. The microsphere size and size distribution of the starch microsphere were determined, and the structures were studied by SEM and FT-IR. And then, the starch microsphere was expected to been used in nasal drug delivery system, artery embolization, radiotherapy, immunoassay and so on.

Preparation and characterization of crosslinked starch microspheres using a two-stage water-in-water emulsion method

Crosslinked starch microspheres (CSMs) were prepared using a novel two-stage water-in-water emulsion method (WWEM). The results show that the yield and crosslinking density of CSMs were affected significantly (p < 0.05) by molecular weight and concentration of polyethylene glycol (PEG) in continuous phase, crosslinker concentration as well as incubation time. The increase in any one of these variables resulted into increase in the crosslinking density. The yield and crosslinking density of CSMs prepared by WWEM (WWEM-CSMs) were lower than those prepared by water-in-oil emulsion method (WOEM). The morphology, chemical composition and amorphous/crystalline nature of the CSMs were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). SEM analysis indicated that the WWEM-CSMs were spherical, compact and nonporous in nature. FTIR and XRD analysis indicated that WWEM-CSMs were PEG-free and amorphous in structure. These characteristics were very similar to the characteristics of CSMs prepared by WOEM.

Synthesis and Adsorption Properties of Crosslinked Starch Microspheres (CSM)

Starch as the material, MBAA as the cross-linking agent, Tween60 and Span60 as the emulsifier, K2S2O8-Na2SO4 as the initiator, the cyclohexane as the oil phase and the removal rate of methyl violet as an index, crosslinked starch microspheres (CSM) was synthetized by means of reverse suspension emulsion and graft-copolymerization method through orthogonal test and single factor optimization experiment. The results showed the optimal conditions of the preparation of the crosslinked starch microspheres(CSM) were as follow: the concentration of the starch is 5%, the dosage of the MBAA, initiator and emulsifier are 0.125g, 0.5g and 0.6g, the volume ratios between the Span60 and Tween60 is 85:15, and the volume ratio between the cyclohexane and water is 4:1.

Novel crosslinked starch microspheres as adsorbents of Cu2+

AbstractA novel adsorbent, a crosslinked starch microsphere (CSM), was prepared from soluble starch and N,N′‐methylenebisacrylamide. The microporous structure of the CSM was determined with scanning electron microscopy. The diameter distribution of the CSMs was quite uniform, and the average diameter of the microparticles was estimated to be 50 μm. Cu2+ was introduced into the CSM. The successful adsorption of Cu2+ in the CSM was confirmed with Fourier transform infrared spectroscopy. The crystal structure of the CSM was destroyed after the incorporation of Cu2+. This was proven with X‐ray diffraction. The thermal stability of the CSM was weakened with the introduction of Cu2+ during simultaneous thermal analysis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Synthesis, characterization, and adsorption capacity of crosslinked starch microspheres with N,N′‐methylene bisacrylamide

AbstractCrosslinked starch microspheres (CSMs) were prepared in an inverse suspension system. Scanning electron microscopy observation indicated that the CSMs were uniform in granularity with a smooth spherical particulate surface. The particle size analysis revealed that the average diameter was 18.2 μm and that 85.8% of the microspheres were of a diameter below 30 μm. The structural characteristics of the carbonyl group and the second acrylamide by Fourier transform infrared spectroscopy of the CSMs showed that the soluble starch obviously crosslinked with N,N′‐methylene bisacrylamide. The physical properties of the CSMs were analyzed by way of X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The results show that the crosslinking resulted in an increase in thermal stability and a decrease in crystallinity of the CSMs compared with soluble starch. The adsorption capacity of the CSMs increased with increasing concentration of methylene blue. The lower temperature was in favor of the adsorption capacity of the CSMs. The adsorption mode of methylene blue by the CSMs agreed more with the Langmuir isothermal equation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Preparation of crosslinked starch microspheres and their drug loading and releasing properties

Crosslinked anionic starch microspheres were prepared with sodium trimetaphosphate (STMP) as crosslinking agent through 5 h w/o emulsification-crosslinking reaction at 50 °C. Laser diffraction technique and scanning electron microscopy revealed that microspheres had narrow size distribution, good sphericity and fine dispersibility. In addition, drug loading and releasing properties were investigated with Methylene Blue as a model drug on the basis of single-factor study. It was found that the loading ratio of MB was significantly influenced by loading time, dissolution medium, loading temperature as well as MB concentration ( P < 0.05). Either the increase of loading time or drug concentration could lead to the increase of drug loading amount of microspheres, however, drug loading amount reached its maximum in NaCl (0.9%) dissolution medium at room temperature. Furthermore, the release profile contained two main expulsion processes: an initial burst release followed by a sustained swelling-controlled release.

Dynamics of controlled release of heparin from swellable crosslinked starch microspheres

The microspheres of crosslinked starch have been prepared and characterized by IR spectral analysis and SEM technique. The prepared microspheres were loaded with an anticoagulant drug 'heparin' and the kinetics of in-vitro release of heparin was investigated spectrophotometrically at physiological pH (7.4) and body temperature (37 degrees C). The influence of percent loading of heparin, chemical architecture of the microspheres and pH of the release medium were examined on the release profiles of the drug. The chemical stability of heparin was tested in phosphate buffer saline (pH 7.4) and the release was also studied in various simulated biological fluids.

Cross-linked starch microspheres: Effect of cross-linking condition on the microsphere characteristics

Cross-linked starch microspheres were prepared using different kinds of cross-linking agents. The influence of several parameters on morphology, size, swelling ratio and drug release rate from these microspheres were evaluated. These parameters included cross-linker type, concentration and the duration of cross-linking reaction. Microspheres cross-linked with glutaraldehyde had smooth surface compared with those prepared with epichlorhydrine or formaldehyde. The particle size increased with increasing the cross-linking time and increasing the drug loading. Swelling ratio of the particles was a function of cross-linker type but not the concentration or time of cross-linking. Drug release from starch microspheres was measured in phosphate buffer and also in phosphate buffer containing alpha-amylase. Results showed that microspheres cross-linked with epichlorhydrine released all their drug content in the first 30 minutes. However, cross-linking of the starch microspheres with glutaraldehyde or formaldehyde decreased drug release rate. SEM and drug release studies showed that cross-linked starch microspheres were susceptible to the enzymatic degradation under the influence of alpha-amylase. Changing the enzyme concentration from 5000 to 10,000 IU/L, increased drug release rate but higher concentration of enzyme (20,000 IU/L) caused no more acceleration.