Zein Microspheres Research Articles

Simple coacervates of zein to encapsulate Gitoxin

This work reports the use of simple coacervates of the hydrophobic protein zein to encapsulate Gitoxin, a cardiotonic glycoside. The microspheres obtained using ethanol, methanol, iso-propyl alcohol were characterized using viscosity index, scanning electron microscopy (SEM) and laser light scattering particle analyzer. Scanning electron micrographs indicated that the zein film was made of microspheres with diameter in the 1–1.5 μm range, which could be controlled. Sizes of Gitoxin-loaded zein microspheres changed little before and after release of the drug because of conglutination among zein microspheres. Release of Gitoxin from zein microspheres, were performed in vitro to investigate the mechanism of model drug release. The results show that the zein microspheres obtained using ethanol are best suited for use as a sustained-release form of Gitoxin. The microspheres may also be useful in drug targeting system since the diameter of the microspheres is appropriate for phagocytosis by macrophages. Both zein film and Gitoxin-loaded zein microsphere film were effective in suppressing platelet adhesion.

Zein microspheres as drug/antigen carriers: A study of their degradation and erosion, in the presence and absence of enzymes

In the laboratory, zein microspheres are being investigated as drug/vaccine delivery systems. Preliminary experiments revealed that the release of an entrapped solute (ovalbumin, a model antigen) was limited when particles were incubated in phosphate buffered saline over a number of days. To understand the slow and limited release of the guest molecule and predict microsphere fate in vivo, the degradation of zein microspheres in different media, in the presence and in the absence of enzymes, was investigated in vitro. Zein microspheres were incubated in five different media: Chloride Buffer (pH 2), Acetate Buffer (pH 5), Phosphate Buffered Saline (pH 7.4), gastric simulated fluid and gastro-intestinal simulated fluid for 1 week. Changes in suspension turbidity and pH, microsphere morphology and zein composition in the release medium was followed with time. The results showed that zein microspheres were extremely resistant to degradation in the absence of enzymes (which explains the slow release of entrapped solute), but were degraded by pepsin and pancreatin enzymes in simulated gastric and intestinal fluids, respectively (which indicates that release is likely to be much faster following oral microsphere administration). However, when administered via routes where enzymes are not present, e.g. intra-muscular, release is likely to be slow.

Heparin-loaded zein microsphere film and hemocompatibility

Zein was studied as a drug-eluting coating film composed of zein microspheres for cardiovascular devices (e.g. stent). In vitro 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) analysis showed that both zein film and its degraded product had better biocompatibility compared with Corning culture plate on the growth of human umbilical veins endothelial cells (HUVECs, p < 0.05, n = 6), and the effect of zein degraded product on HUVECs was dose-dependent. The best result was obtained at 0.3 mg/ml of the addition. The encapsulation efficiency of heparin and heparin loading varied with the amount of both zein and heparin, and the highest encapsulation efficiency (heparin 1.33 mg/ml and zein 16 mg/ml) was 22.77 ± 1.33% ( n = 3). Scanning electron microscope (SEM) observation indicated that the zein film was made of microspheres in diameter from nano- to micrometer, which could be controlled. Sizes of heparin-loaded zein microspheres changed before and after release of heparin because of conglutination among zein microspheres. Release rate of heparin from microsphere film reached to 33.5 ± 1.2% within 12 h, and began to get into subsequent “slow release” phase; about 55% of the entrapped heparin was released after 20 days. Both zein film and heparin-loaded zein microsphere film were effective in suppressing platelet adhesion, and the heparin-loaded film showed a better anticoagulation as determined with thrombin time (TT) assay. These results suggest that zein film could be used directly as a new type of coating material for its better biocompatibility with HUVECs. Moreover, the heparin-loaded zein microsphere film can significantly improve the hemocompatibility.

Formulation and characterisation of zein microspheres as delivery vehicles

We report on the formulation of non-porous, spherical microspheres composed of zein (a protein from corn) for drug/vaccine delivery. Microspheres were prepared by a simple coacervation technique and a 33 factorial design was used to understand the effects of experimental variables on the particles formed. Ovalbumin, as a model antigen, was loaded into zein microspheres with a loading efficiency of 52%. SDS-PAGE analysis showed that the process of microsphere preparation did not have a deleterious effect on the structural integrity of ovalbumin. Thus, our zein microspheres may be further investigated as potential drug/vaccine delivery systems.

Microspheres of corn protein, zein, for an ivermectin drug delivery system

A novel microsphere drug delivery system of ivermectin (IVM) using hydrophobic protein zein was prepared by the phase separation method and characterized by a scanning electron microscope and laser light scattering particle size analyzer. Releases of model drug IVM from zein microspheres, tabletted microspheres and pepsin degradation of tabletted microspheres were also performed in vitro to investigate the mechanism of model drug release. The results show that the zein microspheres and tabletted microspheres are suitable for use as a sustained-release form of IVM. The microspheres may also be useful in drug targeting system since the diameter of the microspheres is appropriate for phagocytosis by macrophages. Moreover, the release of IVM from enzymatic degraded tabletted microspheres shows a zero-order release, implying a potential application in tissue engineering for preparing scaffold, which is composed of microspheres encapsulating bioactive components for stimulating cell differentiation and proliferation.

Novel preparation of zein microspheres conjugated with PS-K available for cancer immunotherapy.

Microspheres which entrapped PS-K were prepared using Zein as a carrier matrix by a one-step or two-step process in dimethyl sulfoxide-H2O media. Microspheres prepared by the latter process provided satisfactory recovery and uptake of PS-K. Use of a catalytic amount of dl-camphorsulfonic acid, glutaraldehyde and rapid addition of aqueous solution of polyvinylpyrrolidone into the reaction media are crucial for the preparation of fine and mono-dispersed microspheres. The release rate of PS-K could be controlled by altering the ratio of PS-K to Zein and the conditions of the medium. In the presence of actinase E, drug release was considerably increased to 70-80% after 24 h incubation. Sonication of the aggregated microspheres readily yielded a mono-dispersed preparation with a particle diameter of less than 1 micron, which would be a suitable size for phagocytosis by macrophages.

Preparation of zein microspheres conjugated with antitumor drugs available for selective cancer chemotherapy and development of a simple colorimetric determination of drugs in microspheres.

Zein microspheres conjugated with antitumor drugs (mitomycinc (MMC), daunomycin hydrochloride (DM), peplomycin sulfate (PEP] were prepared by using a dimethyl sulfoxide (DMSO)-H2O system. MMC with low solubility in H2O was easily entrapped by the standard procedure, whereas some modifications were required for moderately and highly soluble drugs such as DM and PEP. Colorimetric determination of the drugs in microspheres was easily achieved by use of the phenol-sulfuric acid method for drugs with sugar moieties in their molecules, such as DM and PEP, while a simple treatment of the microspheres with concentrated sulfuric acid was applied in the case of drugs having a chromophore in their molecules, such as DM and MMC.