The biodegradation of zein in vitro and in vivo and its application in implants

Zein and hydroxypropyl methylcellulose acetate succinate microfibers combined with metronidazole benzoate and/or metronidazole-incorporated cellulose nanofibrils for potential periodontal treatment

The development of flexible and porous materials to control antibacterial delivery is a pivotal endeavor in medical science. In this study, we aimed to produce long and defect-free fibers made of zein and hydroxypropyl methylcellulose acetate succinate (HPMCAS) to be used as a platform for the release of metronidazole (MDZ) and metronidazole benzoate (BMDZ) to be potentially used in periodontal treatment. Microfibers prepared via electrospinning under a 2:3 (w/w) zein to HPMCAS ratio, containing 0.5 % (w/w) poly(ethylene oxide) (PEO) and 1 % (w/w) cellulose nanofibril (CNF) were loaded with 40 % (w/w) MDZ, 40 % (w/w) BMDZ, or a combination of 20 % (w/w) of each drug. The addition of CNF improved the electrospinning process, resulting in long fibers with reduced MDZ and BMDZ surface crystallization. MDZ- and BMDZ-incorporated fibers were semicrystalline and displayed commendable compatibility among drugs, nanocellulose and polymeric chains. Release tests showed that zein/HPMCAS/PEO fibers without CNF and with 20 % (w/w) MDZ/ 20 % (w/w) BMDZ released the drug at a slower and more sustained rate compared to other samples over extended periods (up to 5 days), which is a favorable aspect concerning periodontitis treatment.

Transferrin-Bearing, Zein-Based Hybrid Lipid Nanoparticles for Drug and Gene Delivery to Prostate Cancer Cells

Gene therapy holds great promise for treating prostate cancer unresponsive to conventional therapies. However, the lack of delivery systems that can transport therapeutic DNA and drugs while targeting tumors without harming healthy tissues presents a significant challenge. This study aimed to explore the potential of novel hybrid lipid nanoparticles, composed of biocompatible zein and conjugated to the cancer-targeting ligand transferrin. These nanoparticles were designed to entrap the anti-cancer drug docetaxel and carry plasmid DNA, with the objective of improving the delivery of therapeutic payloads to prostate cancer cells, thereby enhancing their anti-proliferative efficacy and gene expression levels. These transferrin-bearing, zein-based hybrid lipid nanoparticles efficiently entrapped docetaxel, leading to increased uptake by PC-3 and LNCaP cancer cells and significantly enhancing anti-proliferative efficacy at docetaxel concentrations exceeding 1 µg/mL. Furthermore, they demonstrated proficient DNA condensation, exceeding 80% at polymer-DNA weight ratios of 1500:1 and 2000:1. This resulted in increased gene expression across all tested cell lines, with the highest transfection levels up to 11-fold higher than those observed with controls, in LNCaP cells. These novel transferrin-bearing, zein-based hybrid lipid nanoparticles therefore exhibit promising potential as drug and gene delivery systems for prostate cancer therapy.

Levofloxacin HCl-Incorporated Zein-Based Solvent Removal Phase Inversion In Situ Forming Gel for Periodontitis Treatment

Zein is composed of nonpolar amino acids and is a water-insoluble protein used as the matrix-forming agent of localized in situ forming gel (ISG). Therefore, this study prepared solvent removal phase inversion zein-based ISG formulations to load levofloxacin HCl (Lv) for periodontitis treatment using dimethyl sulfoxide (DMSO) and glycerol formal (GF) as the solvents. Their physicochemical properties were determined, including viscosity, injectability, gel formation, and drug release. The topography of dried remnants after drug release was revealed using a scanning electron microscope and X-ray computed microtomography (μCT) to investigate their 3D structure and % porosity. The antimicrobial activities were tested against Staphylococcus aureus (ATCC 6538), Escherichia coli ATCC 8739, Candida albicans ATCC 10231, and Porphyromonas gingivalis ATCC 33277 with agar cup diffusion. Increasing zein concentration or using GF as the solvent notably enhanced the apparent viscosity and injection force of the zein ISG. However, its gel formation slowed due to the dense zein matrix barrier's solvent exchange: the higher loaded zein or utilization of GF as an ISG solvent prolonged Lv release. The SEM and μCT images revealed the scaffold of dried ISG in that their % porosity corresponded with their phase transformation and drug release behavior. In addition, the sustainability of drug diffusion promoted a smaller antimicrobial inhibition clear zone. Drug release from all formulations was attained with minimum inhibitory concentrations against pathogen microbes and exhibited a controlled release over 7 days. Lv-loaded 20% zein ISG using GF as a solvent exhibited appropriate viscosity, Newtonian flow, acceptable gel formation and injectability, and prolonged Lv release over 7 days with efficient antimicrobial activities against various test microbes; thus, it is the potential ISG formulation for periodontitis treatment. Consequently, the Lv-loaded solvent removal zein-based ISGs proposed in this investigation offer promising potential as an efficacious drug delivery system for periodontitis treatment by local injection.

Biomaterials for Tissue Engineering Applications and Current Updates in the Field: A Comprehensive Review

Tissue engineering has emerged as an interesting field nowadays; it focuses on accelerating the auto-healing mechanism of tissues rather than organ transplantation. It involves implanting an In Vitro cultured initiative tissue or a scaffold loaded with tissue regenerating ingredients at the damaged area. Both techniques are based on the use of biodegradable, biocompatible polymers as scaffolding materials which are either derived from natural (e.g. alginates, celluloses, and zein) or synthetic sources (e.g. PLGA, PCL, and PLA). This review discusses in detail the recent applications of different biomaterials in tissue engineering highlighting the targeted tissues besides the in vitro and in vivo key findings. As well, smart biomaterials (e.g. chitosan) are fascinating candidates in the field as they are capable of elucidating a chemical or physical transformation as response to external stimuli (e.g. temperature, pH, magnetic or electric fields). Recent trends in tissue engineering are summarized in this review highlighting the use of stem cells, 3D printing techniques, and the most recent 4D printing approach which relies on the use of smart biomaterials to produce a dynamic scaffold resembling the natural tissue. Furthermore, the application of advanced tissue engineering techniques provides hope for the researchers to recognize COVID-19/host interaction, also, it presents a promising solution to rejuvenate the destroyed lung tissues.

Engineering a sustainable future for point-of-care diagnostics and single-use microfluidic devices

Single-use, disposable, point-of-care diagnostic devices carry great promise for global health, including meeting urgent needs for testing and diagnosis in places with limited laboratory facilities. Unfortunately, the production and disposal of single-use devices, whether in lateral flow assay, cartridges, cassettes, or lab-on-chip microfluidic format, also poses significant challenges for environmental and human health. Point-of-care devices are commonly manufactured from unsustainable polymeric materials derived from fossil sources. Their disposal often necessitates incineration to reduce infection risk, thereby creating additional release of CO2. Many devices also contain toxic chemicals, such as cyanide derivatives, that are damaging to environmental and human health if not disposed of safely. Yet, in the absence of government regulatory frameworks, safe and sustainable waste management for these novel medical devices is often left unaddressed. There is an urgent need to find novel solutions to avert environmental and human harm from these devices, especially in low- and middle-income countries where waste management infrastructure is often weak and where the use of point-of-care tests is projected to rise in coming years. We review here common materials used in the manufacture of single-use point-of-care diagnostic tests, examine the risks they pose to environmental and human health, and investigate replacement materials that can potentially reduce the impact of microfluidic devices on the production of harmful waste. We propose solutions available to point-of-care test developers to start embedding sustainability at an early stage in their design, and to reduce their non-renewable plastic consumption in research and product development.

Preparation of Zein-Based Nanoparticles: Nanoprecipitation versus Microfluidic-Assisted Manufacture, Effects of PEGylation on Nanoparticle Characteristics and Cellular Uptake by Melanoma Cells

Background

The manufacture of nanoparticles using manual methods is hampered by its challenging scale-up and poor reproducibility. To overcome this issue, the production of zein nanoparticles entrapping a lipophilic drug model, coumarin-6, by using a microfluidic system was assessed in this study. The influence of PEG density and chain length on zein nanoparticle characteristics, as well as their uptake efficacy in melanoma cancer cells, was also evaluated.

Methods

Zein nanoparticles were prepared by both manual and microfluidic approaches to allow comparison between the two processes. PEGylated zein nanoparticles with various PEG densities and chain lengths were produced by nanoprecipitation and characterized. Their cellular uptake was evaluated on B16F10 melanoma cancer cells in vitro.

Results

Zein nanoparticles have successfully been produced by both manual and microfluidic approaches. Parameters such as total flow rate and flow rate ratio of the aqueous and organic phases in microfluidic process, as well as the method preparation and aqueous to organic phase volume ratio during nanoprecipitation, have been shown to strongly influence the characteristics of the resulting nanoparticles. Continuous microfluidics led to the production of nanoparticles with low yield and drug entrapment, unlike nanoprecipitation, which resulted in zein nanoparticles with an appropriate size and an optimal drug entrapment efficiency of 64%. The surface modification of the nanoparticles produced by nanoprecipitation, with lower PEG density and shorter PEG chain length made mPEG5K-zein (0.5:1) the most favorable formulation in our study, resulting in enhanced stability and higher coumarin-6 uptake by melanoma cancer cells.

Conclusion

mPEG5K-zein (0.5:1) nanoparticles prepared by nanoprecipitation were the most promising formulation in our study, exhibiting increased stability and enhancing coumarin-6 uptake by melanoma cancer cells.

Nitric Oxide-Releasing Nanofibrous Scaffolds Based on Silk Fibroin and Zein with Enhanced Biodegradability and Antibacterial Properties

Clinical applications of scaffolds and implants have been associated with bacterial infection resulting in impaired tissue regeneration. Nanofibers provide a versatile structure for both antimicrobial molecule delivery and tissue engineering. In this study, the nitric oxide (NO) donor molecule S-nitrosoglutathione (GSNO) and the natural biodegradable polymer zein (ZN) were combined with silk fibroin (SF) to develop antibacterial and biodegradable nanofibrous scaffolds for tissue engineering applications. The compatibility and intermolecular interactions of SF and ZN were studied using differential scanning calorimetry and Fourier transform infrared spectroscopy. The incorporation of ZN increased the hydrophobicity of the fibers and resulted in a more controlled and prolonged NO release profile lasting for 48 h. Moreover, the degradation kinetics of the fibers was significantly improved after blending with ZN. The results of tensile testing indicated that the addition of ZN and GSNO had a positive effect on the strength and stretchability of SF fibers and did not adversely affect their mechanical properties. Finally, due to the antibacterial properties of both NO and ZN, the SF-ZN-GSNO fibers showed a synergistically high antibacterial efficacy with 91.6 ± 2.5% and 77.5 ± 3.1% reduction in viability of adhered Staphylococcus aureus and Escherichia coli after 24 h exposure, respectively. The developed NO-releasing fibers were not only antibacterial but also non-cytotoxic and successfully enhanced the proliferation and growth of fibroblast cells, which was quantitatively studied by a CCK-8 assay and visually observed through fluorescent staining. Overall, SF-ZN-GSNO fibers developed in this study were biodegradable and highly antibacterial and showed great cytocompatibility with fibroblasts, indicating their promising potential for a range of tissue engineering and medical device applications.

Limited Impact of the Protein Corona on the Cellular Uptake of PEGylated Zein Micelles by Melanoma Cancer Cells

The formation of a protein layer “corona” on the nanoparticle surface upon entry into a biological environment was shown to strongly influence the interactions with cells, especially affecting the uptake of nanomedicines. In this work, we present the impact of the protein corona on the uptake of PEGylated zein micelles by cancer cells, macrophages, and dendritic cells. Zein was successfully conjugated with poly(ethylene glycol) (PEG) of varying chain lengths (5K and 10K) and assembled into micelles. Our results demonstrate that PEGylation conferred stealth effects to the zein micelles. The presence of human plasma did not impact the uptake levels of the micelles by melanoma cancer cells, regardless of the PEG chain length used. In contrast, it decreased the uptake by macrophages and dendritic cells. These results therefore make PEGylated zein micelles promising as potential drug delivery systems for cancer therapy.

Dual-Drug Delivery via Zein In Situ Forming Implants Augmented with Titanium-Doped Bioactive Glass for Bone Regeneration: Preparation, In Vitro Characterization, and In Vivo Evaluation

In situ forming implants (IFIs) are non-surgical approach using biodegradable polymers to treat bone fractures. The study aimed at preparing dual-drug-loaded IFIs to deliver pitavastatin (osteogenic drug) and tedizolid (antibiotic) using zein as the implant matrix via solvent-induced phase inversion method. At first, several investigations were done on pitavastatin-loaded zein IFIs, where three concentrations of zein were used (10, 20, and 30% w/v). IFIs were evaluated for their solidification time, rheological properties, injectability, and in vitro release. IFIs containing bioactive glass nanoparticles were prepared by the addition of non-doped bioactive glass nanoparticles (BGT0; 1, 3, 5, and 10% w/v) or titanium-doped bioactive glass nanoparticles (BGT5; 1% w/v) to the selected concentration of zein (30% w/v) and then evaluated. The optimized dual-medicated implant (D-ZIFI 1) containing pitavastatin, tedizolid, sodium hyaluronate (3% w/v), and BGT5 (1% w/v) was prepared and compared to IFI lacking both sodium hyaluronate and BGT5 (D-ZIFI 2). D-ZIFI 1 and 2 sustained the release profiles of both drugs for 28 days. SEM images proved the interconnected porous structure of D-ZIFI 1 due to sodium hyaluronate. In vivo studies on surgically induced bone defects in Sprague-Dawley rats signified the proper accelerated bone healing ability of D-ZIFI 1 over D-ZIFI 2. Results presented D-ZIFI 1 as a promising, effective, non-surgical approach for bone healing.

Protein-Based Systems for Topical Antibacterial Therapy

Recently, proteins are gaining attention as potential materials for antibacterial therapy. Proteins possess beneficial properties such as biocompatibility, biodegradability, low immunogenic response, ability to control drug release, and can act as protein-mimics in wound healing. Different plant- and animal-derived proteins can be developed into formulations (films, hydrogels, scaffolds, mats) for topical antibacterial therapy. The application areas for topical antibacterial therapy can be wide including bacterial infections in the skin (e.g., acne, wounds), eyelids, mouth, lips, etc. One of the major challenges of the healthcare system is chronic wound infections. Conventional treatment strategies for topical antibacterial therapy of infected wounds are inadequate, and the development of newer and optimized formulations is warranted. Therefore, this review focuses on recent advances in protein-based systems for topical antibacterial therapy in infected wounds. The opportunities and challenges of such protein-based systems along with their future prospects are discussed.

Zein as a versatile biopolymer: different shapes for different biomedical applications

In recent years, the interest regarding the use of proteins as renewable resources has deeply intensified. The strongest impact of these biomaterials is clear in the field of smart medicines and biomedical engineering. Zein, a vegetal protein extracted from corn, is a suitable biomaterial for all the above-mentioned purposes due to its biodegradability and biocompatibility. The controlled drug delivery of small molecules, fabrication of bioactive membranes, and 3D assembly of scaffold for tissue regeneration are just some of the topics now being extensively investigated and reported in the literature. Herein, we review the recent literature on zein as a biopolymer and its applications in the biomedical world, focusing on the different shapes and sizes through which it can be manipulated.

Zein a versatile biomaterial in the biomedical field. Easy to chemically functionalize with good emulsification properties, can be employed in drug delivery, fabrication of bioactive membranes and 3D scaffolds for tissue regeneration.

Electrospinning Proteins for Wound Healing Purposes: Opportunities and Challenges

With the growth of the aging population worldwide, chronic wounds represent an increasing burden to healthcare systems. Wound healing is complex and not only affected by the patient's physiological conditions, but also by bacterial infections and inflammation, which delay wound closure and re-epithelialization. In recent years, there has been a growing interest for electrospun polymeric wound dressings with fiber diameters in the nano- and micrometer range. Such wound dressings display a number of properties, which support and accelerate wound healing. For instance, they provide physical and mechanical protection, exhibit a high surface area, allow gas exchange, are cytocompatible and biodegradable, resemble the structure of the native extracellular matrix, and deliver antibacterial agents locally into the wound. This review paper gives an overview on cytocompatible and biodegradable fibrous wound dressings obtained by electrospinning proteins and peptides of animal and plant origin in recent years. Focus is placed on the requirements for the fabrication of such drug delivery systems by electrospinning as well as their wound healing properties and therapeutic potential. Moreover, the incorporation of antimicrobial agents into the fibers or their attachment onto the fiber surface as well as their antimicrobial activity are discussed.

Antibacterial, pro-angiogenic and pro-osteointegrative zein-bioactive glass/copper based coatings for implantable stainless steel aimed at bone healing

Stainless steel implants are suitable candidates for bone replacement due to their cytocompatibility and mechanical resistance, but they suffer from lack of bioactivity and are prone to bacterial infections. Accordingly, to overcome those limitations, in this study we developed by electrophoretic deposition (EPD), an innovative surface coating made of (i) zein, a natural fibroblast-friendly polymer, (ii) bioactive glass, a pro-osteogenic inorganic material and (iii) copper containing bioactive glass, an antibacterial and pro-angiogenic material. FESEM images confirmed that porous, uniform and free of cracks coatings were obtained by EPD; moreover, coatings were resistant to mechanical stress as demonstrated by the tape test, resulting in a 4B classification of adhesion to the substrate. The coatings were cytocompatible as indicated by metabolism evaluation of human fibroblasts, endothelial cells and mature or progenitor osteoblasts cultivated in direct contact with the specimens. They also maintained pro-osteogenic properties towards undifferentiated progenitor cells that expressed osteogenic genes after 15 days of direct cultivation. Copper conferred antibacterial properties as biofilm formation of the joint pathogens Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli was significantly reduced in comparison with copper-free coatings (p < 0.05). Moreover, this anti-infective activity resulted as targeted towards bacteria while the cells viability was preserved when cells and bacteria were cultivated in the same environment by a co-culture assay. Finally, copper ability to recruit blood vessels and to inhibit bacterial infection was confirmed in vivo where the growth of S. aureus biofilm was inhibited and the formation of new (<50 μm diameter spread) blood vessels was observed.

The Effect of Size, Dose, and Administration Route on Zein Nanoparticle Immunogenicity in BALB/c Mice

Background

Zein-based carriers are a promising delivery system for biomedical applications. However, few studies involve systematic investigation on their in vivo biocompatibility and immunogenicity.

Purpose

The objective of this study was to identify the immunogenicity, type of immune response, biocompatibility and systemic recall immune response of zein nanoparticles administrated via different routes in mice.

Animals and methods

Female Balb/c mice were selected as the animal model in this paper. The effect of particle size, dose and inoculation routes on immunogenicity were systematically explored. The mice were challenged at week 50 via intramuscular and subcutaneous routes to investigate the systemic recall immune responses of zein nanoparticles. Hematoxylin and eosin staining was performed to investigate the biocompatibility of zein nanoparticles at injection sites.

Results

The administration of zein particles by parenteral routes led to a long-term systemic immune response. Particle size did not affect zein-specific IgG antibody titers. IgG antibody titers and inflammatory cell infiltration at the injection sites resulting from intramuscular zein particle injection were significantly higher than those from subcutaneous injection of the same dose. For intramuscular inoculation, dose-dependent IgG antibody titers were observed after the third inoculation, while no significant difference was found via the subcutaneous route. For both routes, IgG titer showed a time-dependent decrease at all dose levels from week 5 onward, and finally plateaued at week 28. The IgG subtype assay showed a predominant Th2-type immune response for both administration routes. Challenge with zein nanoparticles at week 50 led to a significant increase in specific IgG titer at all dose levels, indicating systemic recall immune responses. Interestingly, IgG antibody levels in the subcutaneous groups showed a delayed decrease compared to those of the intramuscular injection groups at all dose levels.

Conclusion

This study indicated that immunogenicity may be one of the key challenges of using zein nanoparticles as carriers via parenteral administration. Further investigation is needed to illustrate zein immunogenicity in other forms, and the possible effect of systemic recall immune response on in vivo pharmacokinetic characteristics.

The effect of dietary supplementation of low crude protein on intestinal morphology in pigs

To explore the effects of reducing the Cp levels on intestinal barrier function, low Cp (LP) and NRC standard Cp (NP) diets were fed to pigs from 45 to 160 days, and in vitro experiments were performed using monolayers of IPEC-J2 cells. The number of goblet cells, expression of proteins related to cell junction, amino acid transport, glucose transport, transepithelial electrical resistance (TEER), dextran permeability, and IL-6 secretion level were detected in pigs. The results demonstrated that a moderate reduction of Cp levels did not affect intestinal morphology, as demonstrated by a normal villi height, crypt depth and normal numbers of goblet cells. The maintenance of the intestinal structure obtained with LP was also confirmed by stable mRNA expression levels of muc2 and E-cadherin in the jejunum. We also found that LP did not affect the protein expression of cationic amino acid transporter 1 (CAT-1) and alanine serine cysteine transporter 1 (ASCT1) from 45 to 160 days. Moreover, the excitatory amino acid transporter 3 (EAAT3), sodium-glucose cotransporter 1 (SGLT1) and glucose transporter (GLUT2) protein expression levels in the jejunum were significantly increased at a certain age during the rearing period. Furthermore, we also demonstrated that a reduction in protein concentration up to 15% in the cultural medium of IPEC-J2 cells did not impact the mucosal barrier function. This study demonstrated that a moderate reduction of the protein level did not affect intestinal mucosal barrier function and morphology in the jejunum.

Transcriptome Analysis and Postprandial Expression of Amino Acid Transporter Genes in the Fast Muscles and Gut of Chinese Perch (Siniperca chuatsi)

The characterization of the expression and regulation of growth-related genes in the muscles of Chinese perch is of great interest to aquaculturists because of the commercial value of the species. The transcriptome annotation of the skeletal muscles is a crucial step in muscle growth-related gene analysis. In this study, we generated 52 504 230 reads of mRNA sequence data from the fast muscles of the Chinese perch by using Solexa/Illumina RNA-seq. Twenty-one amino acid transporter genes were annotated by searching protein and gene ontology databases, and postprandial changes in their transcript abundance were assayed after administering a single satiating meal to Chinese perch juveniles (body mass, approximately 100 g), following fasting for 1 week. The gut content of the Chinese perch increased significantly after 1 h and remained high for 6 h following the meal and emptied within 48-96 h. Expression of eight amino acid transporter genes was assayed in the fast muscles through quantitative real-time polymerase chain reaction at 0, 1, 3, 6, 12, 24, 48, and 96 h. Among the genes, five transporter transcripts were markedly up-regulated within 1 h of refeeding, indicating that they may be potential candidate genes involved in the rapid-response signaling system regulating fish myotomal muscle growth. These genes display coordinated regulation favoring the resumption of myogenesis responding to feeding.

The Encapsulation of Hemagglutinin in Protein Bodies Achieves a Stronger Immune Response in Mice than the Soluble Antigen

Zein is a water-insoluble polymer from maize seeds that has been widely used to produce carrier particles for the delivery of therapeutic molecules. We encapsulated a recombinant model vaccine antigen in newly formed zein bodies in planta by generating a fusion construct comprising the ectodomain of hemagglutinin subtype 5 and the N-terminal part of γ-zein. The chimeric protein was transiently produced in tobacco leaves, and H5-containing protein bodies (PBs) were used to immunize mice. An immune response was achieved in all mice treated with H5-zein, even at low doses. The fusion to zein markedly enhanced the IgG response compared the soluble H5 control, and the effect was similar to a commercial adjuvant. The co-administration of adjuvants with the H5-zein bodies did not enhance the immune response any further, suggesting that the zein portion itself mediates an adjuvant effect. While the zein portion used to induce protein body formation was only weakly immunogenic, our results indicate that zein-induced PBs are promising production and delivery vehicles for subunit vaccines.

Preparation, characterization and application of a novel biodegradable macromolecule: carboxymethyl zein

Zein, a naturally biocompatible and biodegradable macromolecule, is widely used as plastic film material; however, the poor water solubility limits its other applications. In this study, we aimed to obtain carboxymethyl zein (CM-zein) by modifying it with sodium monochloroacetate in weakly basic environment. CM-zein showed a new FTIR peak of C-O-C bond at 1080 cm(-1), with a new signal region appearing at 4.0-4.05 ppm that assigned to the protons of the CH2 group from a carboxymethyl on (1)H NMR and a Tg of 168.0 °C by thermal analysis. Compared with the -12.3 mV of zeta potential of unmodified zein, CM-zein increased it significantly to -23.9 mV as a consequence of carboxymethylation. 5-Fluorouracil (5-FU), a model drug used in CM-zein-based tablet, was rarely detected in 0.1 mol/L HCl (pH 1.0) but it was released massively and quickly in phosphates buffer (pH 6.8) in vitro assays. The unmodified zein-based tablet illustrated much lower release level in these two fluids. Furthermore, the pharmacokinetic study of rats showed that CM-zein released 5-FU in intestine but not in stomach after dissolving. These findings indicated that CM-zein has the potential to be used for enteric preparation as a novel pH-selective biomaterial.

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.