Development of a stable and efficient zein based nanopesticides through green and simple way for improving utilization efficiency

Nanopesticides represent one of the effective ways of reducing the use of pesticides and the environmental pollution. Natural zein as a potential carrier for nanoencapsulation of pesticides has the disadvantages of large amount of organic solvents and poor dispersibility. In this study, a water soluble of zein peptides was obtained by hydrolyzed under alkaline conditions with heated and stability of nanopesticides were prepared through crosslinked after self-assemble. As the results, the zein peptides spontaneously assembled into spherical particles in an aqueous solution, the nanopesticides (avermectin, AVM), with uniform size distribution and size can be adjusted by the glutaraldehyde, have a great stability, and redispersed in water after freeze-drying. Moreover, nanoencapsulation protects avermectin from UV light, with 24% of the encapsulated AVM remaining intact after exposure to UV for 60 min, compared to less than 6% for the bare AVM. In addition, the nanoformulation had similar insecticidal activity to commercial EC and the cross-linking of particles slowed down the release rate and the curves were consistent with Higuchi model different from the abnormal diffusion in the uncross linked state. In short, this study provides a simple method to obtain stabilizable nanopesticides based on natural polymer on a green way.     

Effect of pH and salts on the binding of free amino acids to the corn protein zein studied by thin-layer chromatography

Summary. The interaction of free amino acids with the corn protein zein was studied by thin-layer chromatography carried out on cellulose layers covered with zein and the effect of pH and salts on the strength of interaction was elucidated. Only the binding of Arg, His, Lys, Orn and Trp to zein was verified, other amino acids were not retained. Retention of Arg, His, Lys and Orn decreased linearly with increasing concentration of salts the mobile phase indicating the hydrophilic character of amino acid–zein interaction. Both alkaline and acidic pH influenced the strength of binding. Principal component analysis indicated the different character of the influence of pH and salts on the interaction. The results suggest that these amino acid residues may account for the binding of other peptides and proteins to zein.     

Development and Characterization of Zein-Based Micro Carrier System for Sustained Delivery of Aceclofenac Sodium

Nonsteroidal anti-inflammatory drugs (NSAIDs) induce gastric injury on long-term usage. This study aims at reducing the side effect of NSAIDs by encapsulating in zein, an acid-resistant biopolymer. Aceclofenac-loaded zein microspheres were prepared by emulsification and solvent evaporation method. The stability of zein microspheres at gastric pH retarded the release of the entrapped drug and hence reduces the possibility of gastric injury. However, the in vitro release of aceclofenac was sustained up to 72 h at intestinal pH. Thus, zein microspheres pave the way for the development of safe and sustained delivery system for NSAIDs thereby achieving the desired therapeutic potential with reduced side effects for chronic inflammatory disorders.     

Influence of Formulation Factors on the Preparation of Zein Nanoparticles

The main objective of the present study was to investigate the influence of various formulation parameters on the preparation of zein nanoparticles. 6,7-dihydroxycoumarin (DHC) was used as a model hydrophobic compound. The influence of pH of the aqueous phase, buffer type, ionic strength, surfactant, and zein concentration on particle size, polydispersity index, and zeta potential of DHC-loaded zein nanoparticles were studied. Smaller nanoparticles were formed when the pH was close to the isoelectric point of zein. DHC-loaded zein nanoparticles prepared using citrate buffer (pH 7.4) was better than phosphate buffer in preventing particle aggregation during lyophilization. The ionic strength did not have a significant influence on the particle size of DHC-loaded zein nanoparticles. A combination of Pluronic F68 and lecithin in 2:1 ratio stabilized the zein nanoparticles. An increase in zein concentration led to increase in particle size of DHC-loaded zein nanoparticles. The use of optimal conditions produced DHC-loaded nanoparticles of 256 ± 30 nm and an encapsulation efficiency of 78 ± 7%. Overall, the study demonstrated the optimal conditions to prepare zein nanoparticles for drug encapsulation.KEY WORDS: drug delivery, particle size distribution, pH nanoprecipitation, protein polymers, zein, zeta potential     

Ionic liquids as solvents for biopolymers: Acylation of starch and zein protein

Biopolymers such as starch and zein protein were found to be soluble at 80 °C in ionic liquids such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-butyl-3-methylimidazolium dicyanamide (BMIMdca) in concentrations up to 10% (w/w). Higher concentrations of biopolymers in these novel solvents resulted in solutions with too high viscosity to stir. Solutions of both starch and zein in BMIMCl were acylated with anhydrides in presence of pyridine to give acetyl starch and benzoyl zein with various degrees of substitution. Without pyridine the acylation reaction did not proceed. ¹H NMR and IR spectroscopies were used to determine the degree of substitution of starch. Viscosity studies indicated that the starch underwent slight reduction in molecular weight during the course of acylation. Starch was also soluble in other non-conventional solvents such as choline chloride/oxalic acid and choline chloride/ZnCl₂. However, zein was insoluble in these solvents.     

Molecular weight of an extremely hydrophobic protein, zein, in dimethylformamide and in formamide.

Both alpha zein purified from a commericial preparation and beta zein prepared fresh from corn are soluble in the nonaqueous solvents formamide and dimethylformamide; in this regard zein resembles water soluble proteins such as insulin, ribonuclease, and lysozyme. On the basis of osmotic pressure measurements made in both formamide and dimethylformamide, alpha zein has a number average moleular weight of 21000-24000 daltons and shows no tendency to aggregate or dissociate. Beta zein exists in an aggregated state (dimer and higher forms) in dimethylformamide. Formamide dissociates the beta zein dimer into monomer units but aggregation to higher species occurs with increasing protein concentration.     

Preparation and Evaluation of Electrospun Zein/HA Fibers Based on Two Methods of Adding HA Nanoparticles

Zein/HA fibrous membranes were successfully prepared by electrospinning the zein/HA solution mixed by magnetic stirrer （Method I） or ultrasonic power （Method Ⅱ）. The morphology of zeirdHA nanocomposite fibers and the distribution of HA within the fibers electrospun by two methods were researched by Scanning Electron Microscopy （SEM） and Energy-dispersive X-ray spectroscopy （EDX）. In Method I, the distribution of HA nanoparticles is not homogeneous and HA particles tend to agglom- erate. The relatively homogeneous HA distribution can be observed in the membranes electrospun by Method Ⅱ. Using mag- netic stirrer to prepare the electrospinning solution improves the wettability of zein/HA membranes. From the viewpoint of application, electrospun zein/HA membranes fabricated by the solution mixed via Methods I and II both possessed reasonable tensile strength and elongation at break for both handling and sterilization. Considering two aspects of strength and elongation, electrospun zein/HA membranes fabricated by Method I are more balanced than those fabricated by Method Ⅱ. Biological performances of the control zein and zein/HA membranes were assessed by in vitro culture of hMSCs. Results show that both types of the membranes can support cell proliferation. The cells cultured on the zein/HA membranes electrospun by Method I with 5 wt% HA （on weight ofzein） show significantly higher proliferation than those cultured on the control zein membranes on the seventh day. The electrospun zein/HA fibrous membranes show promises for bone tissue engineering applications.     

The physiological availability of some essential amino acids present in zein,in the acid and in the enzymatic hydrolyzate of zein

Analysis of an enzymatic digest of zein by paper chromatography indicates the absence of proline and threonine. The chromatograms show the presence of three spots, probably peptides, which disappear upon acid hydrolysis of the mentioned digest. Simultaneously, proline and threonine appear in the chromatogram. Analysis of the feces of zein-fed rats indicates that considerable quantities of valine are excreted.     

Cell-Membrane Inspired Multifunctional Nanocoating for Rescuing the Active-Material Microenvironment in High-Capacity Sulfur Cathode

Achieving healthy active-material microenvironment (ME@AM) for stable and efficient electron/ion transport around each active-material particle is crucial for high-performance battery electrodes. However, this goal has been proved extremely challenging for most high-capacity AMs such as sulfur, owing to its notable volume change and severe shuttle effect. Here, a multifunctional hybrid material with zein protein reinforced catalytic single Cu atom/carbon composite (Cu─C) (zein/Cu─C) is coated onto sulfur/carbon (SC) particle, to prepare the advanced zein/Cu─C@SC core–shell particle. Similar to the multifunctional cell membrane well-known in biology, this multifunctional zein/Cu─C coating helps build a healthy and stable ME@AM within sulfur cathode. Specifically, it can simultaneously provide robust protective shell for the AM particle, adsorption and catalyst function to the dissolved polysulfides, and AM surface treatment to improve AM/conductive agent interface. All these functions are the keys to build and maintain a healthy ME@AM in sulfur cathode. This study not only brings effective solutions to the challenges in volume-change high-capacity sulfur active materials and beyond, but also helps achieve comprehensive understanding of the key factors controlling the structuring and final quality of ME@AM.     

Adsorption of zein on surfaces with controlled wettability and thermal stability of adsorbed zein films

Adsorption characteristics of zein protein on hydrophobic and hydrophilic surfaces have been investigated to understand the orientation changes associated with the protein structure on a surface. The protein is adsorbed by a self-assembly procedure on a monolayer-modified gold surface. It is observed that zein shows higher affinity toward hydrophilic than hydrophobic surfaces on the basis of the initial adsorption rate followed by quartz crystal microbalance studies. Reflection absorption infrared (RAIR) spectroscopic studies reveal the orientation changes associated with the adsorbed zein films. Upon adsorption, the protein is found to be denatured and the transformation of alpha-helix to beta-sheet form is inferred. This transformation is pronounced when the protein is adsorbed on hydrophobic surfaces as compared to hydrophilic surfaces. Electrochemical techniques (cyclic voltammetry and impedance techniques) are very useful in assessing the permeability of zein film. It is observed that the zein moieties adsorbed on hydrophilic surfaces are highly impermeable in nature and act as a barrier for small molecules. The topographical features of the deposits before and after adsorption are analyzed by atomic force microscopy. The protein adsorbed on hydrophilic surface shows rod- and disclike features that are likely to be the base units for the growth of cylindrical structures of zein. The thermal stability of the adsorbed zein film has been followed by variable-temperature RAIR measurements.     

Growth-promoting Activity of an Aqueous Extract of Soybean Seeds for Some Microorganisms

The metabolic fates of the carbon skeletons of leucine, lysine, and threonine were studied in growing rats on the diets containing graded levels of protein calorie percentages (10, 20, 30, and 40PC%) by use of either gluten or zein at 4100 kcal of metabolizable energy per kg of diets. In growth experiment for 21 days, body weight gain, food intake, and body fat increased at higher PC% in the gluten diets, but rats given zein did not maintain their initial weight even at 40PC%. The concentration of plasma free lysine remained low with the zein diets, but plasma threonine increased at 10 and 20PC% in the gluten and zein diets, respectively. Plasma leucine increased as the protein level increased either dietary protein. More than 70% of ¹⁴C was incorporated into body protein 12 h after an intraperitoneal injection of labeled lysine in all groups, but little ¹⁴CO₂ was expired in rats on the gluten and zein diets. About 79% of ¹⁴C-threonine was incorporated into body protein in rats given the gluten and zein diets at 10PC%, but the values were gradually decreased with increasing the dietary protein levels. Some 40–50% of ¹⁴C-leucine was incorporated into the body protein in rats given the gluten diets, and the values for the zein diets were extensively decreased in the higher PC% groups where the expired ¹⁴CO₂ was inversely increased to a great extent. These results showed that, when a specific amino acid was limiting or deficient in the diet, the major portion of the labeled amino acid was utilized for body protein synthesis and little was oxidized to carbon dioxide, whereas the oxidative degradation of essential amino acid other than limiting one was increased and the efficiency of the amino acid utilization was relatively decreased.     

Storage Protein Synthesis in Maize: II. Reduced Synthesis of a Major Zein Component by the Opaque-2 Mutant of Maize

Two zein proteins (Z1 and Z2) represent the majority of the protein synthesized during maize endosperm development. Undegraded membrane-bound polysomes isolated from normal maize synthesized these proteins when incubated in a cell-free protein-synthesizing system from wheat germ. The proteins synthesized in vitro were similar to authentic zein in ethanol solubility and electrophoretic mobility. Zein synthesis was associated with large size classes of membrane bound polysomes in normal maize.Membrane-bound polysomes isolated from developing kernels of opaque-2 mutant synthesized less total zein in vitro, and dramatically reduced incorporation into the Z1 component. The reduction in total zein corresponded to a 50% reduction in the level of membrane-bound polysomes in opaque-2, and the near absence of the large polysome size classes, which synthesized zein in normal maize. We concluded that the opaque-2 mutation results in a decreased "availability" of the zein mRNAs, reflected in a reduced level of membrane-bound polysomes.     

An enzyme-linked immunosorbent assay for zein and other proteins using unconventional solvents for antigen adsorption

An enzyme-linked immunosorbent assay (ELISA) performed in polystyrene microtiter plates that can detect and quantitate the maize prolamin zein is described. The assay yields positive reactions with as little as 1 ng of antigen and uses solvents not ordinarily employed in ELISA methods. A systematic investigation of zein adsorption to polystyrene in various solvents supports the hypothesis that antigen binding occurs through nonpolar interactions. The method was also used to determine structural relationships among three zein polypeptides differing in size and charge. Additional experiments indicate that a number of soluble proteins are absorbed to polystyrene in the denaturing agent urea and retain immunological reactivity. The retention of antigen reactivity after solubilization in 6-8 M urea suggests that ELISA methods may be applicable to other proteins which are insoluble, or rendered insoluble, in aqueous buffers.