Diffusional properties of zein membranes and matrices

Fabrication and optimization of itraconazole-loaded zein-based nanoparticles in coated capsules as a promising colon-targeting approach pursuing opportunistic fungal infections

Itraconazole (ITZ), a broad-spectrum antifungal drug, was formulated into colon-targeting system aiming to treat opportunistic colonic fungal infections that commonly infect chronic inflammatory bowel diseases (IBD) patients due to immunosuppressive therapy. Antisolvent precipitation technique was employed to formulate ITZ-loaded zein nanoparticles (ITZ-ZNPs) using various zein: drug and aqueous:organic phase ratios. Central composite face-centered design (CCFD) was used for statistical analysis and optimization. The optimized formulation was composed of 5.5:1 zein:drug ratio and 9.5:1 aqueous:organic phase ratio with its observed particle size, polydispersity index, zeta potential, and entrapment efficiency of 208 ± 4.29 nm, 0.35 ± 0.04, 35.7 ± 1.65 mV, and 66.78 ± 3.89%, respectively. ITZ-ZNPs were imaged by TEM that revealed spherical core-shell structure, and DSC proved ITZ transformation from crystalline to amorphous form. FT-IR showed coupling of zein NH group with ITZ carbonyl group without affecting ITZ antifungal activity as confirmed by antifungal activity test that showed enhanced activity of ITZ-ZNPs over the pure drug. Histopathological examination and cytotoxicity tests ensured biosafety and tolerance of ITZ-ZNPs to the colon tissue. The optimized formulation was then loaded into Eudragit S100-coated capsules and both in vitro release and in vivo X-ray imaging confirmed the success of such coated capsules in protecting ITZ from the release in stomach and intestine while targeting ITZ to the colon. The study proved that ITZ-ZNPs is promising and safe nanoparticulate system that can protect ITZ throughout the GIT and targeting its release to the colon with effectual focused local action for the treatment of colon fungal infections.

Preparation of ciprofloxacin loaded zein conduits with good mechanical properties and antibacterial activity

Conduit scaffolds have potential applications in tissue engineering as nerve conduits, urological stent and blood vessel graft. Zein is a well-reported biopolymer in tissue engineering and drug delivery systems. Herein, we prepared ciprofloxacin loaded zein conduits using a facile rolling method. Zein conduits (ZCs) were evaluated for physical structure, porosity, bending stiffness, degradation, drug release, in vitro and in vivo antibacterial efficacy and cells toxicity. ZCs showed porous structure with porosity > 60 % and good mechanical strength with bending stiffness of 28.54 N.mm². Slow enzymatic degradation (87 % in 30 days) was also observed for ZCs. Slow release of ciprofloxacin up to 42 days was observed that could assure prevention of post-implantation infection. In vitro and in vivo antibacterial study verified the short-time and long-time antibacterial efficacy of zein conduits on Gram-positive and Gram-negative bacteria. Live/dead measurement and CCK-8 assay on L929 cells demonstrated good cell compatibility for all zein conduits (>90 % cell viability and cells proliferation in 3 days). Overall, the rolling method could be exploited for preparation of ciprofloxacin loaded zein conduits, which had the potential for tissue engineering applications.

Swelling of Zein Matrix Tablets Benchmarked against HPMC and Ethylcellulose: Challenging the Matrix Performance by the Addition of Co-Excipients

Zein is an insoluble, yet swellable, biopolymer that has been extensively studied for its applications in drug delivery. Here, we screened the effect of co-excipients on the swelling and drug release of zein tablets. All throughout the study the behavior of zein was benchmarked against that of hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC). Tablets containing either zein, HPMC, or EC alone or in combination with co-excipients, namely lactose, dicalcium phosphate (DCP), microcrystalline cellulose (MCC), polyvinylpyrrolidone (PVP), or sodium lauryl sulfate (SLS) were prepared by direct compression. Matrix swelling was studied by taking continuous pictures of the tablets over 20 h, using a USB microscope connected to a PC. The overall size change and the axial and radial expansion of the tablets were automatically extrapolated from the pictures by image analysis. Moreover, drug release from tablets containing ternary mixtures of zein, co-excipients and 10% propranolol HCl was also studied. Results showed that zein matrices swelled rapidly at first, but then a plateau was reached, resulting in an initial rapid drug burst followed by slow drug release. HPMC tablets swelled to a greater extent and more gradually, providing a more constant drug release rate. EC did not practically swell, giving a nearly constant drug release pattern. Among the additives studied, only MCC increased the swelling of zein up to nearly three-fold, and thus suppressed drug burst from zein matrices and provided a nearly constant drug release over the test duration. Overall, the incorporation of co-excipients influenced the swelling behavior of zein to a greater extent compared to that of HPMC and EC, indicating that the molecular interactions of zein and additives are clearly more complex and distinct.

Effect of zein additive on perfume evaporation

OBJECTIVE

Zein is known to have filmogen properties. We wanted to show if a zein film containing eugenol (eugenol as model) would retain the fragrances, slow their evaporation and therefore produce a long-lasting perception of perfume.

METHODS

We added corn zein to eugenol in a hydro-alcoholic solution to form a film in vitro and at the surface of the human skin. We have studied the trapping and release of eugenol from zein film by GC/MS. Also we labelled eugenol with deuterium to image specifically its distribution in the zein film using Secondary Ion Mass Spectrometry technique (NanoSIMS 50). Finally, we applied the zein/D-eugenol formulation onto skin to image the eugenol location on and in skin by SIMS (Secondary Ion Mass Spectrometry).

RESULTS

We showed that eugenol evaporation from zein film can be divided in three periods. The first period (≤2 h) corresponds to the simultaneous solvent and eugenol evaporation occurring during film formation. The second period corresponds to the continuous and slow eugenol evaporation during a few hours (about 10 h) but not to its completion. The third period (at least up to 48 h) results from the trapping of eugenol in zein film. After 24 or 48 h, trapped eugenol can be released and evaporated under mechanical deformations of the film. Moreover we showed that zein addition does not favour the eugenol penetration into viable epidermis which may cause allergenic cutaneous reaction.

CONCLUSION

The zein additive is safe to use, does not impact the olfactory perception, allows a better perception of the fragrance (long-lasting effect) in a more protective way and can be used in perfume.

Zein as a Pharmaceutical Excipient in Oral Solid Dosage Forms: State of the Art and Future Perspectives

Zein is the main storage protein of corn and it has several industrial applications. Mainly in the last 10-15 years, zein has emerged as a potential pharmaceutical excipient with unique features. Zein is a natural, biocompatible and biodegradable material produced from renewable sources. It is insoluble, yet due to its amphiphilic nature, it has self-assembling properties, which have been exploited for the formation of micromicroparticle and nanoparticle and films. Moreover, zein can hydrate so it has been used in swellable matrices for controlled drug release. Other pharmaceutical applications of zein in oral drug delivery include its incorporation in solid dispersions of poorly soluble drugs and in colonic drug delivery systems. This review describes the features of zein significant for its use as a pharmaceutical excipient for oral drug delivery, and it summaries the literature relevant to macroscopic zein-based oral dosage forms, i.e. tablets, capsules, beads and powders. Particular attention is paid to the most novel formulations and applications of zein. Moreover, gaps of knowledge as well as possible venues for future investigations on zein are highlighted.

Facile encapsulation of hydroxycamptothecin nanocrystals into zein-based nanocomplexes for active targeting in drug delivery and cell imaging

Nano-drug delivery systems that integrate inorganic and organic or even bioactive components into a single nanoscale platform are playing a hugely important role in cancer treatment. In this article, the fabrication of a versatile nanocarrier based on self-assembled structures of gold nanoparticles (AuNPs)-zein is reported, which displays high drug-loading efficiency for needle-shaped hydroxycamptothecin (HCPT) nanocrystals. The surface modification with folate-conjugated polydopamine (PFA) renders them stable and also facilitates their selective cellular internalization and enhancement of endocytosis. The release of payloads from nanocomplexes (NCs) was shown to be limited at physiological pH (17.1±2.8%) but significantly elevated at endosomal/lysosomal pH (58.4±3.0%) and at enzymatic environment (81.4±4.2%). Compared to free HCPT and its non-targeting equivalent, HCPT@AuNPs-Zein-PFA exerted a superior tumor suppression capacity as well as low side effects due to its active and passive targeting delivery both in vitro and in vivo. These results suggest that the NCs with well-defined core@shell nanostructures encapsulated with HCPT nanocrystals hold great promise to improve cancer therapy with high efficiency in the clinic.

STATEMENT OF SIGNIFICANCE

A novel nanocomplex with HCPT nanocrystals encapsulated was designed to achieve selective cellular uptake by endocytosis, acid responsive release in the tumor microenvironment and excellent tumor suppression without toxicity. This nanocomplex with conjugation of folate was stable in the bloodstream, with minimal drug release in extracellular conditions, leading to prolonged blood circulation and high accumulation in tumor tissues. The entrapment of a nanocrystal drug into nanomaterials might be capable of delivering drugs in a predictable and controllable manner.

Controlled Release from Zein Matrices: Interplay of Drug Hydrophobicity and pH

Purpose

In earlier studies, the corn protein zein is found to be suitable as a sustained release agent, yet the range of drugs for which zein has been studied remains small. Here, zein is used as a sole excipient for drugs differing in hydrophobicity and isoelectric point: indomethacin, paracetamol and ranitidine.

Methods

Caplets were prepared by hot-melt extrusion (HME) and injection moulding (IM). Each of the three model drugs were tested on two drug loadings in various dissolution media. The physical state of the drug, microstructure and hydration behaviour were investigated to build up understanding for the release behaviour from a zein based matrix for drug delivery.

Results

Drug crystallinity of the caplets increases with drug hydrophobicity. For ranitidine and indomethacin, swelling rates, swelling capacity and release rates were pH dependent as a consequence of the presence of charged groups on the drug molecules. Both hydration rates and release rates could be approached by existing models.

Conclusion

The drug state and pH dependant electrostatic interactions are hypothesised to influence release kinetics. Both factors can potentially be used to influence release kinetics release, thereby broadening the horizon for zein as a tuneable release agent.

Electronic supplementary material

The online version of this article (doi:10.1007/s11095-015-1818-8) contains supplementary material, which is available to authorized users.