Zein Microspheres Research Articles

One-step preparation of macroporous zein microspheres by solvent diffusion for dye adsorption

Macroporous microspheres have attracted significant interest in various fields since macropores endow with fast mass transfer. However, constructing the macropore mostly requires additional porogenic agents and complex steps. Here, a simple solvent diffusion strategy has been developed for the rapid preparation of macroporous protein microspheres. Based on the strategy, the macropores in the microspheres are created by the removal of the trapped aqueous phase. The results show that the average particle size of the prepared microspheres is centered at about 10 µm. The pore size of the microspheres ranges from 50 nm to about 1 µm and can be controlled by adjusting the parameters of surfactant, temperature, and concentration during the preparation process for different requirements. Finally, the macropore microspheres are characterized by the adsorption of Congo red dyes, which show excellent adsorption ability. According to these results, these macroporous protein microspheres have a practical potential for applications in adsorption and biomedicine fields.

3D printing of multi-functional artificial conduits against acute thrombosis and clinical infection

Post-surgical infections and acute thrombosis are two common clinical complications of implantable devices. Here, we designed series of artificial conduits, using 3D printing, composed of biodegradable polylactic acid and ciprofloxacin/heparin-loaded zein microspheres to overcome postoperative infection and acute thrombosis. Overall, the 3D printing technique accomplished the personalized customization and precise printing of subtle structure with 400 μm resolution in the x, y and z axes. FTIR, XPS, contact angle analysis and microscope techniques demonstrated that the multi-functional coating was uniform and composed of microspheres. The thickness and drug loading efficiency could be adjusted by changing process parameters. The multi-functional artificial conduits kept good mechanical properties with sustained release of loaded drugs in different rate kinetics. Cell experiments and hematology experiments showed that the multi-functional artificial conduits had good cytocompatibility, hemocompatibility and anticoagulant activity. The in vitro and in vivo experiments demonstrated that the loading of ciprofloxacin and heparin with the aid of zein microspheres could endow the artificial conduits with dual functions of preventing acute thrombosis and protecting the implantation site against infection. These data supplied an alternative strategy for 3D printing of multi-functional conduits against postoperative infection and acute thrombosis.

One-Step Preparation of Macroporous Zein Microspheres by Solvent Diffusion for Dye Adsorption

One-Step Preparation of Macroporous Zein Microspheres by Solvent Diffusion for Dye Adsorption

Essential oil loaded edible films prepared by continuous casting method: Effects of casting cycle and loading position on the release properties

The fast evaporation rate and burst release of essential oils during the film preparation and application jeopardize the long-term antimicrobial efficiency of essential oil loaded active films. In the present study, oregano essential oil (OEO) loaded zein/gelatin (Z/G) monolayer and multilayer films were prepared via a continuous casting method. The self-assembly behavior of zein in continuous gelatin matrix was affected by the casting cycle, where zein microspheres with different sizes distributed in different casting layers. The cross-section structure of Z/G films then affected the retention rate of OEO and the water vapor permeability. The mechanical and thermal properties were not significantly affected by increasing the casting cycle, indicating that cohesive films were obtained by continuous casting method and the prolonged drying time did not jeopardize the thermal stability. By concentrating the position of OEO loaded layers in the intermediate and/or upper layer, films exhibited higher retention rate with preferable release properties featuring the sustained-release profile in the aqueous food simulant and the higher release rate and content in the fatty food simulant, and prolonged antimicrobial effect was observed in the preservation test on strawberries. Our work adds new knowledges to the effects of casting cycle and loading position of OEO during continuous casting process on the physicochemical properties and antimicrobial efficiency of active films.

Current therapeutic applications and pharmacokinetic modulations of ivermectin.

Ivermectin is considered to be a wonder drug due to its broad-spectrum antiparasitic activity against both ectoparasites and endoparasites (under class of endectocide) and has multiple applications in both veterinary and human medicine. In particular, ivermectin is commonly used in the treatment of different kinds of infections and infestations. By altering the vehicles used in the formulations, the pharmacokinetic properties of different ivermectin preparations can be altered. Since its development, various vehicles have been evaluated to assess the efficacy, safety, and therapeutic systemic concentrations of ivermectin in different species. A subcutaneous route of administration is preferred over a topical or an oral route for ivermectin due to superior bioavailability. Different formulations of ivermectin have been developed over the years, such as stabilized aqueous formulations, osmotic pumps, controlled release capsules, silicone carriers, zein microspheres, biodegradable microparticulate drug delivery systems, lipid nanocapsules, solid lipid nanoparticles, sustained-release ivermectin varnish, sustained-release ivermectin-loaded solid dispersion suspension, and biodegradable subcutaneous implants. However, several reports of ivermectin resistance have been identified in different parts of the world over the past few years. Continuous use of suboptimal formulations or sub-therapeutic plasma concentrations may predispose an individual to resistance toward ivermectin. The current research trend is focused toward the need for developing ivermectin formulations that are stable, effective, and safe and that reduce the number of doses required for complete clinical cure in different parasitic diseases. Therefore, single-dose long-acting preparations of ivermectin that provide effective therapeutic drug concentrations need to be developed and commercialized, which may revolutionize drug therapy and prophylaxis against various parasitic diseases in the near future. The present review highlights the current advances in pharmacokinetic modulation of ivermectin formulations and their potent therapeutic applications, issues related to emergence of ivermectin resistance, and future trends of ivermectin usage.

Use of zein microspheres to anchor carbon black and hemoglobin in electrochemical biosensors to detect hydrogen peroxide in cosmetic products, food and biological fluids

Hemoglobin-containing electrochemical biosensors are useful for detecting hydrogen peroxide through oxidation of the iron ion, but high efficiency can only be reached with appropriate immobilization strategies for hemoglobin. In this work, we combined zein from corn seed with carbon black to immobilize hemoglobin, as proof of concept, and form an electroactive film that could determine hydrogen peroxide within the concentration range from 4.9 × 10−6 to 3.9 × 10−4 mo L−1, and limit of detection of 4.0 × 10−6 mol L−1, using differential pulse voltammetry. The biosensor could also detect hydrogen peroxide in commercial samples of oxygenated water, synthetic serum (physiological and glycoside) and milk. The high performance is ascribed to the large surface area and conductive nature of the porous film that had carbon black and hemoglobin anchored on zein microspheres, according to scanning and transmission electron microscopies. It is significant that a protein from renewable sources (zein) combined with a low-cost carbon material (carbon black) serves as matrix for immobilization of biomolecules.

Zein self-assembly using the built-in ultrasonic dialysis process: microphase behavior and the effect of dialysate properties

The microphase behavior at different time scales was investigated to understand the mechanism of zein self-assembly during the built-in ultrasonic dialysis process (BUDP) in this study. The results indicated that the mutual mass transfer between zein solution and dialysate changed the solvent polarity, which caused the conformational transition of zein molecules, formation of stable droplets under the ultrasonic field, and further solidification of the compact microspheres. The effects of dialysate properties on zein self-assembly were investigated. The results showed that both pH and ionic strength had a great effect on the size, zeta potential, and morphology of the obtained zein particles, where zein microspheres with a size around 1–2 μm and zeta potential > 30 mV were obtained at pH 4–pH 8 and NaCl concentration ≤ 10 mM. And non-ionic Tween 60 could be used as a potential surfactant to improve the stability of zein samples through a physical combination.

A simple screening method for analysis of cell adhesive strength cultured on zein microspheres

Cell adhesion plays an important role in the microcarrier culture. Therefore, it is necessary to find a simple method to evaluate the cell adhesive strength. By the glycerol method, we prepared zein microcarriers. Both microcarrier surface morphology and cells on the microcarriers could be observed clearly when the microcarriers and the cells were stained by acridine orange (AO). Pre-treatment of soaking and sterilizing processes was necessary for cell culture, but it did not alter the morphology of zein microcarriers. Three kinds of cells were cultured on zein microcarriers for 24 h. Vero cells showed the strongest adhesion, while L929 cells were easily detached from the microcarriers after a simple beating operation. The proliferation curve of Vero cells cultured on the microcarriers displayed no difference with that on Cytodex 1.

Incorporation of 10-hydroxycamptothecin nanocrystals into zein microspheres

Incorporation of drug nanocrystal (DNC) into a particulate carrier to form the DNC delivery system was conducted in this study, where 10-hydroxycamptothecin (HCPT) was selected as the model drug and zein was the carrier. The supercritical anti-solvent (SAS) process or the built-in ultrasonic dialysis process (BUDP) was applied to prepare HCPT NC-loaded zein microspheres (HCPT NC-Zein MS) at first respectively, but the results showed that the products obtained were unsatisfactory in their particle microstructures. Fortunately, by combining the SAS process with BUDP, i.e. the co-precipitation of HCPT and zein prepared using the SAS process was dispersed into ethanol–water as the dialysis solution for BUDP, the results showed that desirable HCPT NC-Zein MS were obtained. The formulations were evaluated quantitatively by an overall desirability function (DF), and the optimized HCPT NC- Zein MS was prepared according to the range analysis results of DF. Under the optimized conditions, HCPT NC-Zein MS with a mean particle size=1.10±0.12µm, drug loading=5.98% and encapsulation efficiency=95.68% were obtained. The further characterizations of SEM, FT-IR, XRD and DSC demonstrated that HCPT NC was successfully incorporated into the interior of zein microspheres. The effects of the process parameters and the formation mechanism of HCPT NC-Zein MS were discussed in detail. Furthermore, it is presented that HCPT NC-Zein MS sustained HCPT release rate successfully, where about 50% HCPT was fast released in the first 20h, then the release trend followed zero order kinetics and reached 70% in 82h.

Self-assembly of zein microspheres with controllable particle size and narrow distribution using a novel built-in ultrasonic dialysis process

Zein microspheres with controllable particle size and narrow size distribution were self-assembled using a novel built-in ultrasonic dialysis process (BUDP). The effects of different variables on the microstructures of obtained zein particles were investigated using an OA16 (45) orthogonal experimental design. The results showed that zein particles prepared by the BUDP possessed a spherical morphology with mean particle size (Dp50) from 431.2±69.6nm to 2335±406.1nm under different process parameters. Zein microspheres prepared at optimized conditions presented much smaller particle size and narrower size distribution (Dp50=398.2±41.3nm) than those obtained without ultrasound (Dp50=1776±1181.1nm). FT-IR, 1H NMR, XRD, TG and DSC characterization results showed that the chemical structure, crystal structure and thermal behavior of the zein microspheres obtained by BUDP were similar with raw zein and that prepared without ultrasound. The ultrasound power and zein concentration were the most important process parameters affecting particle formation. The formation mechanisms of zein microspheres and the influence mechanisms of the operating parameters were discussed in detail. Also, a semi-empirical model was developed for predicting particle size. Furthermore, curcumin was encapsulated into zein microspheres using BUDP, and curcumin-loaded zein microspheres sustained curcumin release rate successfully in vitro.

Oil-in-water Pickering Emulsions Stabilized by Nanometer Zein Microspheres

Oil-in-water Pickering Emulsions Stabilized by Nanometer Zein Microspheres

Selective interactions of zein microspheres with different class of drugs: an in vitro and in silico analysis.

In this study, we have evaluated the interactions of zein microspheres with different class of drugs (hydrophobic, hydrophilic, and amphiphilic) using in vitro and in silico analysis. Zein microspheres loaded with aceclofenac, metformin, and promethazine has been developed by solvent evaporation technique and analyzed for its compatibility. The physical characterization depicted the proper encapsulation of hydrophobic drug in the microspheres. The in vitro release study revealed the sustaining ability of the microspheres in the following order: hydrophobic > hydrophilic > amphiphilic. In silico analysis also confirmed the better binding affinity and greater interactions of hydrophobic drug with zein. The above results revealed that zein is more suitable for hydrophobic drugs in the development of sustained drug delivery systems using solvent evaporation technique. The study therefore envisages a scope for identifying the most suitable polymer for a sustained drug delivery system in accordance with the nature of the drug.

Formation of zein spheres by evaporation-induced self-assembly

Zein is an amphiphilic protein capable of self-assembly into microspheres. Zein microspheres may form by evaporation-induced self-assembly (EISA) of zein solutions in ethanol/water. The formation of microspheres is of particular interest for the development of delivery systems. Zein solutions in ethanol/water 75 % (v/v) were slowly evaporated to promote self-assembly of microspheres. The ethanol content of the solvent decreased during EISA changing solvent polarity which induced self-assembly of zein particles. The growth of zein spheres was modeled from the hydrophobic and hydrophilic contributions to the interfacial free energy (R2 = 0.92). The good fit indicated that during EISA zein microspheres increased in size due to hydrophobic interactions between zein molecules. The model may allow the prediction of evaporation time and thus control over microsphere size.

Mineralization of hydroxyapatite crystallites on zein microspheres

AbstractBioinspired mineralization process has been extended to the formation of bonelike hydroxyapatite (HAp) coatings on biodegradable polymer substrates. HAp‐coated zein microspheres were prepared through phase separation procedure, followed by incubation in modified simulated body fluids (mSBF). The morphologies of mineralized zein microspheres with different diameters and incubation time were investigated by scanning electron microscopy (SEM). The nature of the deposited mineral phase was characterized by energy‐dispersive spectroscopy (EDS) and wide‐angle X‐ray diffraction (XRD). The results showed that as the average diameter of zein microspheres increased to 1.13 μm, randomly oriented minerals were observed on the surface of microspheres. Two characteristic HAp diffraction reflections 002 and 211 centered at 2θ of 25.6° and 32.0° were ascertained on the XRD patterns of the mineralized microspheres. Incubation of zein microspheres with larger diameters in mSBF led to nucleation and growth of minerals on the surface. Even larger number of minerals were deposited and a porous structure of platelike HAp crystals was obtained after incubation for 21 days. The novel zein/HAp microspheres may have a wide variety of potential applications in bone regeneration and tissue engineering. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Pectin–zein microspheres as drug delivery systems

The formation of microspheres from various pectin hydrogel complexes and corn zein in the presence of calcium and zinc ions has been studied. It is shown that the formation of microspheres and their loading capacity for a drug (piroxicam) depend on the type of biopolymers, their ratio, the sizes of the bivalent ions, and the molecular mass of the pectin. Complex formation between the two biopolymers results predominantly from bivalent metal cross-linking for low-methylated pectins and from hydrophobic interaction for high-methylated pectins. As a result, a series of microspheres have been prepared from biodegradable and biocompatible polymers and may find application as controlled-release drug delivery systems.

In Vitro Study of the Release Properties of Soy−Zein Protein Microspheres with a Dynamic Artificial Digestive System

The purpose of this work was to study the performance of microspheres of soy protein isolate (SPI), zein, or SPI-zein complex as vehicles of nutraceutical delivery under fasting and prandial conditions in an artificial digestive system (TIM-1). Riboflavin availability for absorption from the small intestine compartments reached 90% of the total load within 4 h, most of it (65-80%) turning up in the jejunum dialysis fluid, suggesting that this segment is the main site of absorption, regardless of the nature of the microspheres. However, the riboflavin concentrations and the availability for absorption profiles depended on microsphere formulation. Release from pure SPI and zein microspheres in the stomach compartment occurred within 15 min. The availability for absorption from both the jejunum and ileum compartment followed first-order kinetics, indicating that the limiting step in nutrient uptake with these two formulations is absorption by passive diffusion. SPI-zein complex microspheres provided sustained release of riboflavin over 4 h and a near-zero-order nutrient availability for absorption profile in both fasting and prandial states. Suspending SPI-zein complex microspheres in yogurt significantly delayed nutrient release, which would increase the likelihood of gastric-sensitive nutrients passing intact into the intestine for absorption. SPI-zein complex microspheres thus show potential for use as nutraceutical delivery vehicles in the creation of novel functional foods.

Tablets Based on Compressed Zein Microspheres for Sustained Oral Administration: Design, Pharmacokinetics, and Clinical Study

In our previous study, we reported a novel tablet based on compressed zein microspheres as a universal drug delivery system using the hydrophobic protein zein, which shows zero-order release in the presence of pepsin. However, this formulation had difficulty with disintegration under physiological conditions within 48 h, and thus could not be used directly for oral administration. In the present study, a formulation of ivermectin (IVM) tablets based on compressed zein microspheres was improved as a new dosage form. The plasma disposition pharmacokinetics of IVM tablets based on compressed zein microspheres after oral administration was studied over a 7-day period with six dogs (Canis familiaris), using a commercial IVM tablet (5 mg/piece, Yilijia(®) ) as a control. Clinical efficacy was tested using 270 dogs presented as veterinary patients for the treatment of demodicidosis. A formulation with disintegration time within 15 min could be obtained. The acquired C( max), T(max), and AUC were 9.89 ± 0.34 ng/mL, 11.33 ± 2.63 h, and 883.87 ng h/mL for IVM tablets based on compressed zein microspheres and 9.64 ± 1.05 ng/mL, 7.26 ± 2.09 h, and 666.30 ng h/mL for Yilijia(®), respectively. The bioavailability of the tablets based on compressed zein microspheres was 132.65% that of Yilijia( ®). Efficacy for the dogs in all the IVM tablets based on compressed zein microspheres-treated groups reached 100% at 7, 14, and 21 days post administration.

Elaboration and Characterization of Soy/Zein Protein Microspheres for Controlled Nutraceutical Delivery

Microspheres (15-25 microm) of soy protein isolate (SPI), zein, and SPI/zein blends were prepared using a cold gelation method as possible delivery systems for nutraceutical products. Microsphere matrix crystalline structure, swelling behavior, and nutrient load release kinetics in simulated gastrointestinal fluids were investigated. SPI microspheres showed early burst release of the model nutrient, whereas zein microspheres showed very slow release in both simulated gastric and intestinal fluids. Blending of SPI and zein provides a convenient method of adjusting the hydrophobicity and crystallinity of the protein matrix and hence its swelling behavior and in vivo nutrient release kinetics. Diffusion plays a major role in regulating nutrient release. SPI/zein microspheres blended at ratios of 5:5 and 3:7 showed near zero-order release kinetics over the test period in simulated intestinal buffer and thus have potential as delivery vehicles for nutraceutical products in functional foods.

Antibacterial activity of ciprofloxacin-loaded zein microsphere films

Our aim was to produce an antibiotic-emitting coating composed of zein microspheres for the prevention of bacterial infection on implanted devices. Ciprofloxacin-loaded zein microspheres were prepared using a phase separation procedure, with particle sizes between 0.5 and 2 µm. Drug encapsulation and drug loading varied with the amount of both zein and ciprofloxacin, and the highest encapsulation efficiency was 8.27% (2 mg/ml ciprofloxacin and 20 mg/ml zein; n = 3). A ciprofloxacin-loaded zein microsphere film (CF-MS film) was generated via solvent evaporation. Continuous drug release from a trypsin-degraded microsphere film was observed for up to 28 days. The liberation of ciprofloxacin from the trypsin-degraded film and the biodegradation of the microsphere film were highly correlated. Proliferation assay of the growth of human umbilical vein endothelial cells (HUVECs) by the MTT method showed that the microsphere film had no toxicity when compared with cells grown on Corning culture plates alone and plates with a zein film alone. Quantification of bacteria adhesion showed that adhesion on the microsphere film is significantly suppressed. In addition, according to the results of bacterial growth tests, ciprofloxacin-loaded microsphere films maintained antibacterial activity for more than 6 days. In contrast, a control medium containing a zein film allowed constant bacterial growth. These results indicate that CF-MS films might be useful as antibacterial films on implanted devices.

An investigation into the adjuvanticity and immunogenicity of zein microspheres being researched as drug and vaccine carriers

We have determined whether zein microspheres could act as vaccine adjuvants i.e. increase the immune responses to co-administered immunogens. Ovalbumin (model antigen)-loaded zein microspheres, blank zein microspheres and ovalbumin solution were intramuscularly administered to mice and the sera antibody levels were determined by ELISA. Another group of mice was orally dosed with blank zein microspheres, and serum and faecal antibody levels were determined. As expected, negligible antibody titres were obtained with the ovalbumin solution. Surprisingly, intramuscular administrations of blank zein microspheres elicited high levels of serum IgG which bound to the ovalbumin antigen coated on ELISA microtitre plates. This indicated that anti-zein antibodies had been elicited by blank zein microspheres and that these antibodies were cross-reacting with ovalbumin antigen coated onto ELISA plates. Such cross-reactivity inhibited the determination of the adjuvant activity of zein microspheres, if any. Additional ELISA assays, where zein was used as the coating antigen, confirmed the generation of anti-zein antibodies by blank zein microspheres i.e. zein microspheres were immunogenic following intramuscular administration. Upon oral administration of blank zein microspheres, serum IgG levels remained low but intestinal IgA levels increased following booster doses i.e. systemic tolerance, but not mucosal tolerance, to oral zein particles was achieved. Zein microspheres were immunogenic when administered intramuscularly and orally.