Heparin-loaded zein microsphere film and hemocompatibility

Biomedical applications of soy protein: A brief overview

Soy protein (SP) based materials are gaining increasing interest for biomedical applications because of their tailorable biodegradability, abundance, being relatively inexpensive, exhibiting low immunogenicity, and for being structurally similar to components of the extracellular matrix (ECM) of tissues. Analysis of the available literature indicates that soy protein can be fabricated into different shapes, being relatively easy to be processed by solvent or melt based techniques. Furthermore soy protein can be blended with other synthetic and natural polymers and with inorganic materials to improve the mechanical properties and the bioactive behavior for several demands. This review discusses succinctly the biomedical applications of SP based materials focusing on processing methods, properties and applications highlighting future avenues for research.

Heparin-based nanocapsules as potential drug delivery systems

Herein, the synthesis and characterization of heparin-based nanocapsules (NCs) as potential drug delivery systems is described. For the synthesis of the heparin-based NCs, the versatile method of miniemulsion polymerization at the droplets interface was achieved resulting in narrowly distributed NCs with 180 nm in diameter. Scanning and transmission electron microscopy images showed clearly NC morphology. A highly negative charge density for the heparin-based NCs was determined by measuring the electro-kinetic potential. Measuring the activated clotting time demonstrated the biological intactness of the polymeric shell. The ability of heparin-based NCs to bind to antithrombin (AT III) was investigated using isothermal titration calorimetry and dynamic light scattering experiments. The chemical stability of the NCs was studied in physiological protein-containing solutions and also in medically interesting fluids such as sodium chloride 0.9%, Ringer's solution, and phosphate buffer saline using dynamic light scattering and measuring the fluorescence intensity. The impressive uptake of NCs in different cells was confirmed by fluorescence-activated cell sorting, confocal laser scanning microscopy, and transmission electron microscopy. The low toxicity of all types of NCs was demonstrated.

Fabrication of zein/quaternized chitosan nanoparticles for the encapsulation and protection of curcumin

In this article, we report the successful assembly of nanoparticles (NPs) from a water-soluble chitosan (CS) derivative (N-(2-hydroxyl)propyl-3-trimethyl ammonium chitosan chloride, HTCC) and zein via a low-energy phase separation method.

Self-assembled zein–sodium carboxymethyl cellulose nanoparticles as an effective drug carrier and transporter

In this work, biodegradable nanoparticles (NPs) were assembled with sodium carboxymethyl cellulose (CMC) and zein to produce zein–CMC NPs.

Nano- and microdelivery systems for marine bioactive lipids

There is an increasing body of evidence of the positive impact of several marine lipids on human health. These compounds, which include ω-3 polyunsaturated fatty acids, have been shown to improve blood lipid profiles and exert anti-inflammatory and cardioprotective effects. The high instability of these compounds to oxidative deterioration and their hydrophobicity have a drastic impact in their pharmacokinetics. Thus, the bioavailability of these compounds may be affected, resulting in their inability to reach the target sites at effective concentrations. In this regard, micro/nanoparticles can offer a wide range of solutions that can prevent the degradation of targeted molecules, increase their absorption, uptake and bioavailability. In this work we will present the options currently available concerning micro- and nanodelivery systems for marine lipids; with emphasis on micro/nanoparticles; such as micro/nanocapsules and emulsions. A wide range of bottom-up approaches using casein, chitosan, cyclodextrins, among others; will be discussed.

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.

Zein in controlled drug delivery and tissue engineering

Controlled delivery of a bioactive to specific organ, cellular and sub-cellular level is a desired feature of a drug carrier system. In order to achieve this goal, formulation scientists search for better alternatives of biomaterials to deliver the therapeutics in more precise and controlled manner in vivo. Zein, a plant protein obtained from corn, is a useful biomaterial for several industrial applications including agriculture, cosmetics, packaging and pharmaceuticals. Being a hydrophobic protein, which is biodegradable, biocompatible, economic to use and with generally regarded safe "GRAS" status, it is an attractive biomaterial for human use. Novel biomedical applications of zein such as controlled and targeted delivery of bioactives and tissue engineering are the current research interests of the scientific fraternity. Here we attempt to review the literature on zein as a biopolymer for drug/vaccine/gene delivery and its applicability in tissue engineering.

One-step fabrication of agent-loaded biodegradable microspheroids for drug delivery and imaging applications

Non-spherical particles may offer advantages over conventional spherical systems for drug delivery applications. This work describes the fabrication of agent-loaded poly(lactic-co-glycolic acid) (PLGA) spheroids via the emulsion solvent evaporation (ESE) method. The versatility of this technique for loading a variety of therapeutics is demonstrated via loading of paclitaxel, bovine serum albumin, and cadmium sulfide nanoparticles into PLGA spheroids. The encapsulation efficiency for spheroids fabricated via oil-in-water (O/W) emulsions is highest at low aqueous phase surfactant concentrations while the encapsulation efficiency for spheroids made via water-in-oil-in-water (W/O/W) is highest at high aqueous phase surfactant concentrations and basic aqueous phase pH values. Particle aspect ratio polydispersity can be minimized via the use of high aqueous phase PVA concentration and pH. The ESE technique is an attractive alternative to recently described methods for fabrication of non-spherical particles due to its simplicity in setup, high particle yield and adaptability to a variety of biodegradable polymers and therapeutics.

Fabrication and evaluation of physical properties and cytotoxicity of zein-based polyurethanes

Polyurethane prepolymer (PUP) was first synthesized from polycaprolactone diol and isophorone diisocyanate; and then a series of zein-based polyurethane (ZEPU) sheets was fabricated from PUP and zein (ZE) using a hot press and moulding process without addition of other additives. Effects of ZE content (WZE) on the structure and properties of the resultant ZEPU sheets were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic mechanical analysis, tensile testing, and dissolubility testing in alcohol. The results indicated that cross-linking and grafting reactions occurred between ZE and PUP to form new polyurethane showing a higher thermal stability, flexibility, and alcohol-resistance than the neat ZE sheets. For example, the elongation at break of ZEPU with 50 % WZE was 211.2 %, which was 47 times higher than that of neat ZE sheet. ZE molecules acted as both cross-linkers and polymer fillers in ZEPU sheets. The cytotoxicity and cytocompatibility of ZEPU sheets were evaluated by cell culture in vitro. The ZEPU sheets showed non- or low-cytotoxicity, and L929 cells grew and expanded well on the surfaces of the sheets with WZE over 50 %. Undoubtedly, the fabrication of ZE-based polyurethanes without toxic additives such as catalysts, cross-linkers and chain extenders improved the physical properties and cytocompatibility of zein, thus widening the possible range of applications for zein-based biomaterials.

Fabricating a novel porous releaser of heparin

Reduced graphene oxide (rGO) could adsorb heparin of 112 mg g⁻¹ and released 80% of them within 30 days.

Anticoagulant surface coating using composite polysaccharides with embedded heparin-releasing mesoporous silica

Release of heparin from the surface of biomaterials is a feasible and efficient manner for preventing blood coagulation because of the high bioactivity of free heparin and a low application dosage compared to intravenous injection of heparin. Here we report a novel method featuring a blend of heparin-loaded SBA-15, catechol-modified chitosan (CCS), and heparin as a heparin-releasing film. The release of heparin was based on its leakage from heparin-loaded amino-functionalized mesoporous silica SBA-15 (SBA-15-NH2), which was controlled by the amino density of the SBA-15-NH2. Heparin-loaded SBA-15-NH2, CCS, and heparin were mixed together, and the mixture was cast onto the surface of a polydopamine-modified substrate, forming a heparin-releasing film on the surface of the substrate. The polydopamine acted as an adhesive interlayer that stabilized the film coated on the substrate. The sustained release rates of heparin from the film ranged from 15.8 to 2.1 μg/cm(2)/h within 8 h. The heparin-releasing film showed low fibrinogen adsorption, platelet adhesion, and hemolysis rate, indicating that it has good blood compatibility. This new approach would be very useful for modifying the surface of versatile blood-contacting biomaterials and ultimately improve their anticoagulation performance.

Role of γ-kafirin in the formation and organization of kafirin microstructures

The possible importance of the cysteine-rich γ-prolamin in kafirin and zein functionality has been neglected. The role of γ-kafirin in organized microstructures was investigated in microparticles. Residual kafirin (total kafirin minus γ-kafirin) "microparticles" were non-discrete (amorphous mass of material), as viewed by electron microscopy and atomic force microscopy. Adding 15% γ-kafirin to residual kafirin resulted in the formation of a mixture of non-discrete material and nanosize discrete spherical structures. Adding 30% γ-kafirin to the residual kafirin resulted in discrete spherical nanosize particles. Fourier transform infrared spectroscopy indicated that γ-kafirin had a mixture of random-coil and β-sheet conformations, in contrast to total kafirin, which is mainly α-helical conformation. γ-Kafirin also had a very high glass transition temperature (Tg) (≈270 °C). The conformation and high Tg of γ-kafirin probably confer structural stability to kafirin microstructures. Because of its ability to form disulfide cross-links, γ-kafirin appears to be essential to form and stabilize organized microstructures.

Use of 1H NMR STD, waterLOGSY, and Langmuir monolayer techniques for characterization of drug-zein protein complexes

Zein is a protein based natural biopolymer containing a large amount of nonpolar amino acids, which has shown the ability to form aggregates and entrap solutes, such as drugs and amino acids to form stable protein-drug complexes. In this work, π-A isotherm, NMR, and Dynamic light scattering were used to detect the formation of protein aggregates and the affinity between zein and two different drugs: tetracycline and indomethacin. An effective interaction of zein and the two drugs was evidenced by means of liquid NMR reinforced by means of changes in the surface pressure by π-A isotherm. The effective interactions zein/drugs under air/water interface were evidenced as a change in the surface pressure of the π-A isotherm of zein in the presence of drug solutions. The presence of tetracycline in the subphase decreased the area occupied by the monolayer at the expanded region until pressures of 12 mN/m were the areas became similar, but indomethacin produces an increment of the area in both expanded and collapsed region. The feasible methodology employed, focused in the functionality of the protein-drug interaction, can be very promising in the drug delivery field.

Encapsulation of hydrocortisone and mesalazine in zein microparticles

Zein was investigated for use as an oral-drug delivery system by loading prednisolone into zein microparticles using coacervation. To investigate the adaptability of this method to other drugs, zein microparticles were loaded with hydrocortisone, which is structurally related to prednisolone; or mesalazine, which is structurally different having a smaller LogP and ionizable functional groups. Investigations into the in vitro digestibility, and the electrophoretic profile of zein, and zein microparticles were conducted to shed further insight on using this protein as a drug delivery system. Hydrocortisone loading into zein microparticles was comparable with that reported for prednisolone, but mesalazine loading was highly variable. Depending on the starting quantities of hydrocortisone and zein, the average amount of microparticles equivalent to 4 mg hydrocortisone, (a clinically used dose), ranged from 60–115 mg, which is realistic and practical for oral dosing. Comparatively, an average of 2.5 g of microparticles was required to deliver 250 mg of mesalazine (a clinically used dose), so alternate encapsulation methods that can produce higher and more precise mesalazine loading are required. In vitro protein digestibility revealed that zein microparticles were more resistant to digestion compared to the zein raw material, and that individual zein peptides are not preferentially coacervated into the microparticles. In combination, these results suggest that there is potential to formulate a delivery system based on zein microparticles made using specific subunits of zein that is more resistant to digestion as starting material, to deliver drugs to the lower gastrointestinal tract.

Fabrication and characterization of DNA-loaded zein nanospheres

Background

Particulates incorporating DNA are promising vehicles for gene delivery, with the ability to protect DNA and provide for controlled, localized, and sustained release and transfection. Zein, a hydrophobic protein from corn, is biocompatible and has properties that make it a promising candidate material for particulate delivery, including its ability to form nanospheres through coacervation and its insolubility under physiological conditions, making it capable of sustained release of encapsulated compounds. Due to the promise of this natural biomaterial for drug delivery, the objective of this study was to formulate zein nanospheres encapsulating DNA as the therapeutic compound, and to characterize size, charge, sustained release, cell cytotoxicity and cellular internalization of these particles.

Results

Zein nanospheres encapsulating DNA were fabricated using a coacervation technique, without the use of harsh solvents or temperatures, resulting in the preservation of DNA integrity and particles with diameters that ranged from 157.8 ± 3.9 nm to 396.8 ± 16.1 nm, depending on zein to DNA ratio. DNA encapsulation efficiencies were maximized to 65.3 ± 1.9% with a maximum loading of 6.1 ± 0.2 mg DNA/g zein. The spheres protected encapsulated DNA from DNase I degradation and exhibited sustained plasmid release for at least 7 days, with minimal burst during the initial phase of release. Zein/DNA nanospheres demonstrated robust biocompatibility, cellular association, and internalization.

Conclusions

This study represents the first report on the formation of zein particles encapsulating plasmid DNA, using simple fabrication techniques resulting in preservation of plasmid integrity and tunable sizes. DNA encapsulation efficiencies were maximized to acceptable levels at higher zein to DNA ratios, while loading was comparable to that of other hydrophilic compounds encapsulated in zein and that of DNA incorporated into PLGA nano- and microspheres. The hydrophobic nature of zein resulted in spheres capable of sustained release of plasmid DNA. Zein particles may be an excellent potential tool for the delivery of DNA with the ability to be fine-tuned for specific applications including oral gene delivery, intramuscular delivery, and in the fabrication of tissue engineering scaffolds.

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.

Physicochemical modification of kafirin microparticles and their ability to bind bone morphogenetic protein-2 (BMP-2), for application as a biomaterial

Vacuolated spherical kafirin microparticles with a mean diameter of 5 μm can be formed from an acidic solution with water addition. Three-dimensional scaffolds for hard tissue repair require large structures with a high degree of interconnected porosity. Cross-linking the formed kafirin microparticles using wet heat or glutaraldehyde treatment resulted in larger structures (approximately 20 μm), which, while similar in size and external morphology, were apparently formed by further assisted assembly by two significantly different mechanisms. Heat treatment, which increased the vacuole size, involved kafirin polymerization by disulfide bonding with the microparticles being formed from round, coalesced nanostructures, as shown by atomic force microscopy (AFM). Kafirin polymerization of glutaraldehyde-treated microparticles was not by disulfide bonding, and the nanostructures, as revealed by AFM, were spindle shaped. Both treatments enhanced BMP-2 binding to the microparticles, probably due to their increased size. Thus, these modified kafirin microparticles have potential as natural, nonanimal protein bioactive scaffolds.

Sustained release of heparin on enlarged-pore and functionalized MCM-41

Mesoporous silica MCM-41 and SBA-15 were chosen to study the adsorption and release of bulky biomolecule heparin, in order to develop new heparin controlled delivery system and expand the application of mesoporous materials in life science. To explore how the structure of support such as pore size and surface state affects the accommodation and release of heparin, we used decane as swelling agent to enlarge pores of MCM-41, introduced amino groups for improving the biocompatibility of support, and controllably retained templates in the as-synthesized sample. The influence of modification on the structure of samples was investigated by XRD and N(2) adsorption-desorption, whereas their performance of adsorbing and releasing heparin was assessed with that of toluidine blue method. Both enlarged pore and organic modification significantly promoted the adsorption and prolonged the release of heparin in MCM-41, and the release was characterized with a three-stage release model. The mechanism of heparin release from mesoporous material was studied by fitting the release profiles to the theoretical equation. As expected, some mesoporous composites could release heparin in the long term with tuned dosage.

Preparation and in vitro release of zein microparticles loaded with prednisolone for oral delivery

Zein has been proposed as a polymer for targeted-drug delivery via the oral route. Zein microparticles were loaded with prednisolone and evaluated as an oral delivery system. Microparticles were formulated using phase separation. Starting quantities of zein and prednisolone, along with the agitation method and temperature were found to significantly impact drug loading and loading efficiency. Vortex mixing produced the highest drug loading and loading efficiency. Drug release was measured in simulated conditions of the stomach and small intestine using the microparticles made with the method that best improved drug loading. In simulated stomach and small intestine conditions, prednisolone release reached almost 70% over 3 and 4 h, respectively. While a clinically relevant dose may be delivered using c. 100 mg of zein microparticles, prednisolone release from the microparticles indicates that they may not be suited as a controlled- or targeted-delivery system.

Small-caliber vascular prosthesis prototype based on controlled release of heparin from mesochannels and its enhanced biocompatibility

A novel small-caliber vascular prosthesis prototype is proposed on the basis of a new heparin release system, that is, the controlled delivery of heparin from mesochannels. Fabrication of mesochannels on artificial biomaterials is successfully achieved through epitaxial growth of mesoporous silica nanoparticles on expanded polytetrafluoroethylene grafts, and thus heparin can be immobilized through a space limitation effect, thereby avoiding the loss of bioactivity and enabling long-lasting release. The adsorption and release of heparin are controlled by adjusting the adsorbate-adsorbent interaction through tailoring the mesostructure. Owing to the continuous and sustained release of heparin, the performances of artificial vessels are greatly improved, thus paving a new way to prepare functional blood-contacting biomaterials with high biocompatibility.

Development and characterization of zein-based microcarrier 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.

Evaluation of Antithrombogenicity and Hydrophilicity on Zein-SWCNT Electrospun Fibrous Nanocomposite Scaffolds

Design of blood compatible surfaces is required to minimize platelet surface interactions and increase the thromboresistance of foreign surfaces when they are used as biomaterials especially for artificial blood prostheses. In this study, single wall carbon nanotubes (SWCNTs) and Zein fibrous nanocomposite scaffolds were fabricated by electrospinning and evaluated its antithrombogenicity and hydrophilicity. The uniform and highly smooth nanofibers of Zein composited with different SWCNTs content (ranging from 0.2 wt% to 1 wt%) were successfully prepared by electrospinning method without the occurrence of bead defects. The resulting fiber diameters were in the range of 100-300 nm without any beads. Composite nanofibers with and without SWCNT were characterized through a variety of methods including scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, and tensile mechanical testing. The water uptake and retention ability of composite scaffolds decreased whereas thermal stability increased with an addition of SWCNTs. Hemolytic property and platelet adhesion ability of the nanocomposite (Zein-SWCNTs) were explored. These observations suggest that the novel Zein-SWCNTs composite scaffolds may possibly hold great promises as useful antithrombotic material and promising biomaterials for tissue engineering application.

Improvement in water stability and other related functional properties of thin cast kafirin protein films

Improvement in the water stability and other related functional properties of thin (<50 μm) kafirin protein films was investigated. Thin conventional kafirin films and kafirin microparticle films were prepared by casting in acetic acid solution. Thin kafirin films cast from microparticles were more stable in water than conventional cast kafirin films. Treatment of kafirin microparticles with heat and transglutaminase resulted in slightly thicker films with reduced tensile strength. In contrast, glutaraldehyde treatment resulted in up to a 43% increase in film tensile strength. The films prepared from microparticles treated with glutaraldehyde were quite stable in ambient temperature water, despite the loss of plasticizer. This was probably due to the formation of covalent cross-linking between free amino groups of the kafirin polypeptides and carbonyl groups of the aldehyde. Thus, such thin glutaraldehyde-treated kafirin microparticle films appear to have good potential for use as biomaterials in aqueous applications.