Fabrication, Characterization, and Formation Mechanism of Zein-Gum Arabic Nanocomposites in Aqueous Ethanol Solution with a High Ethanol Content

The antisolvent precipitation method is widely applied to produce zein colloidal particles. The process involves dissolving zein in 55-90% (v/v) alcohol/water mixtures and then shearing such solutions into deionized water to lower the ethanol content. In the present work, on the basis of the preliminary result that gum arabic (GA) was able to well disperse in 70% (v/v) alcohol/water mixtures, a new way was created to produce zein-GA nanocomposites by simply mixing their aqueous alcohol solution with a high alcohol level of 70% (v/v) at pH 8.0. Findings showed that the multimodal size distribution of zein or GA alone was shifted to be the monomodal peak after zein and GA aqueous ethanol solution was mixed, indicating the successful formation of zein-GA nanocomposites. A core-shell structure was observed for zein-GA nanocomposites, with zein as a core and GA as a shell. In addition, the incorporation of GA caused the conformational and second structural changes of zein. A two-step mechanism was involved to explain the formation of zein-GA nanocomposites. The first step was that GA addition changed the polarity of zein aqueous ethanol solution and zein nanoparticles formed, and the second step was that hydrogen bonds and hydrophobic interactions promoted the adsorption of GA onto the particle surfaces. Results in this work would provide a new sight into the design of zein-based nanocomplexes, which may have potential applications, such as constructing delivery systems, for bioactive compounds.

Preparation, characterization and preliminary pharmacokinetic study of pH-sensitive Hydroxyapatite/Zein nano-drug delivery system for doxorubicin hydrochloride

OBJECTIVES

Zein nanoparticles (Zein NPs) were used as a hydroxyapatite (HA) biomineralization template to generate HA/Zein NPs. Doxorubicin hydrochloride (DOX) was loaded on HA/Zein NPs (HA/Zein-DOX NPs) to improve its pH-sensitive release, bioavailability and decrease cardiotoxicity.

METHODS

HA/Zein-DOX NPs were prepared by phase separation and biomimetic mineralization method. Particle size, polydispersity index (PDI), Zeta potential, transmission electron microscope, X-ray diffraction and Fourier-transform infrared spectroscopy of HA/Zein-DOX NPs were characterized. The nanoparticles were then evaluated in vitro and in vivo.

KEY FINDINGS

The small PDI and high Zeta potential demonstrated that HA/Zein-DOX NPs were a stable and homogeneous dispersed system and that HA was mineralized on Zein-DOX NPs. HA/Zein-DOX NPs showed pH-sensitive release. Compared with free DOX, HA/Zein-DOX NPs increased cellular uptake which caused 7 times higher in-vitro cytotoxicity in 4T1 cells. Pharmacokinetic experiments indicated the t_1/2β and AUC_{0- t} of HA/Zein-DOX NPs were 2.73- and 3.12-fold higher than those of DOX solution, respectively. Tissue distribution exhibited HA/Zein-DOX NPs reduced heart toxicity with lower heart targeting efficiency (18.58%) than that of DOX solution (37.62%).

CONCLUSION

In this study, HA/Zein-DOX NPs represented an antitumour drug delivery system for DOX in clinical tumour therapy with improved bioavailability and decreased cardiotoxicity.

Current Applications of Biopolymer-based Scaffolds and Nanofibers as Drug Delivery Systems

BACKGROUND

The high surface-to-volume ratio of polymeric nanofibers makes them an effective vehicle for the release of bioactive molecules and compounds such as growth factors, drugs, herbal extracts and gene sequences. Synthetic polymers are commonly used as sensors, reinforcements and energy storage, whereas natural polymers are more prone to mimicking an extracellular matrix. Natural polymers are a renewable resource and classified as an environmentally friendly material, which might be used in different techniques to produce nanofibers for biomedical applications such as tissue engineering, implantable medical devices, antimicrobial barriers and wound dressings, among others. This review sheds some light on the advantages of natural over synthetic polymeric materials for nanofiber production. Also, the most important techniques employed to produce natural nanofibers are presented. Moreover, some pieces of evidence regarding toxicology and cell-interactions using natural nanofibers are discussed. Clearly, the potential extrapolation of such laboratory results into human health application should be addressed cautiously.

Status of Plant Protein-Based Green Scaffolds for Regenerative Medicine Applications

In recent decades, regenerative medicine has merited substantial attention from scientific and research communities. One of the essential requirements for this new strategy in medicine is the production of biocompatible and biodegradable scaffolds with desirable geometric structures and mechanical properties. Despite such promise, it appears that regenerative medicine is the last field to embrace green, or environmentally-friendly, processes, as many traditional tissue engineering materials employ toxic solvents and polymers that are clearly not environmentally friendly. Scaffolds fabricated from plant proteins (for example, zein, soy protein, and wheat gluten), possess proper mechanical properties, remarkable biocompatibility and aqueous stability which make them appropriate green biomaterials for regenerative medicine applications. The use of plant-derived proteins in regenerative medicine has been especially inspired by green medicine, which is the use of environmentally friendly materials in medicine. In the current review paper, the literature is reviewed and summarized for the applicability of plant proteins as biopolymer materials for several green regenerative medicine and tissue engineering applications.

Sinapic acid-loaded chitosan nanoparticles in polycaprolactone electrospun fibers for bone regeneration in vitro and in vivo

Sinapic acid (SA) is a plant-derived phenolic compound known for its multiple biological properties, but its role in the promotion of bone formation is not yet well-studied. Moreover, the delivery of SA is hindered by its complex hydrophobic nature, limiting its bioavailability. In this study, we fabricated a drug delivery system using chitosan nanoparticles (nCS) loaded with SA at different concentrations. These were incorporated into polycaprolactone (PCL) fibers via an electrospinning method. nCS loaded with 50 μM SA in PCL fibers promoted osteoblast differentiation. Furthermore, SA treatment activated the osteogenesis signaling pathways in mouse mesenchymal stem cells. A critical-sized rat calvarial bone defect model system identified that the inclusion of SA into PCL/nCS fibers accelerated bone formation. Collectively, these data suggest that SA promoted osteoblast differentiation in vitro and bone formation in vivo, possibly by activating the TGF-β1/BMP/Smads/Runx2 signaling pathways, suggesting SA might have therapeutic benefits in bone regeneration.

Biomineralization of Calcium Phosphate and Calcium Carbonate within Iridescent Chitosan/Iota-Carrageenan Multilayered Films

This work systematically explores the biomineralization of calcium phosphate (CaP) and carbonate (CaCO₃) within chitosan/iota-carrageenan multilayer films. Multilayer films of chitosan and iota-carrageenan (up to 128-coupled layers) were prepared on glass substrates by a layer-by-layer dip-coating technique. Cryo-scanning electron microscopy revealed dense interfaces between the chitosan and iota-carrageenan layers with thicknesses in the range 250 and 350 nm in the hydrated state, accounting for the iridescent nature of multilayer films when wet. Immersion of the multilayered films in simulated body fluid or simulated seawater at 25 °C resulted in the mineralization of CaP and CaCO₃, respectively, at the interfaces between the biopolymer layers and modified the iridescence of the films. Lamellar scattering features in small-angle neutron scattering measurements of the mineralized films provided evidence of the localized mineralization. Further evidence of this was found through the lack of change in the dynamic and static correlation lengths of the polymer networks within the bulk phase of the chitosan and iota-carrageenan layers. CaP mineralization occurred to a greater extent than CaCO₃ mineralization within the films, evidenced by the higher lamellar density and greater rigidity of the CaP-mineralized films. Results provide valuable new insights into CaP and CaCO₃ biomineralization in biopolymer networks.

3-D mineralized silk fibroin/polycaprolactone composite scaffold modified with polyglutamate conjugated with BMP-2 peptide for bone tissue engineering

In the field of bone tissue engineering, an ideal three-dimensional (3-D) scaffold should not only structurally mimic the extracellular matrix (ECM) in large tissues but also mechanically support the bone healing process and provide biochemical cues to induce osteogenesis. In this study, we investigated the feasibility of functionalisation of scaffolds by coupling polyglutamate acid conjugated with BMP-2 peptide onto silk fibroin (SF)/polycaprolactone (PCL) (SF/PCL) blend nanofibers. The morphology, composition, and mineralisation, were confirmed by FE-SEM, XRD, and FT-IR spectroscopy. The FE-SEM images revealed that wet-electrospun nanofibrous scaffolds exhibited inter-connected nano/micro-pores at different levels, and a different morphology was observed on the 3-D SF/PCL scaffold after mineralisation. Furthermore, the binding property and release behaviour of the peptide were investigated on this mineralized structure, and adipose-derived stem cells were seeded on the composite scaffolds to assay their cytocompatibility and osteogenic differentiation capacities. Results suggest that the polyglutamate motif (repetitive glutamate amino acids) exhibited markedly improved binding properties to mineralized nanofibers, and the mineralized 3-D scaffolds with the conjugated with peptide enhances the mRNA expression of osteogenic genes. The sponge-like 3-D nanofibrous scaffold mechanically and biochemically mimics the regenerative process for applications in bone tissue engineering, including the regeneration of calvarial defects.

Quercetagetin-Loaded Zein-Propylene Glycol Alginate Ternary Composite Particles Induced by Calcium Ions: Structure Characterization and Formation Mechanism

The complexation of zein and propylene glycol alginate (PGA) was confirmed to improve the entrapment efficiency and loading capacity of quercetagetin (Q) in our previous study. The present work focused on the influence and induction mechanism of calcium ions on structures of Q-loaded zein-PGA ternary composite particles. The incorporation of Ca²⁺ resulted in the formation of aggregates with a large dimension between zein particles, led to obvious conformational, secondary, and tertiary structural changes of zein, and caused the disappearance of crystalline structure of zein. PGA exhibited a fine filamentous network structure and became much thicker and stronger in the presence of Ca²⁺. The presence of Q promoted the affinity and binding capacity of Ca²⁺ to zein and PGA. An interwoven network structure with enhanced firmness and density was observed in Q-loaded zein-PGA composite particles, leading to improved thermal stability. Three potential mechanisms were proposed to explain the structural characteristics induced by Ca²⁺, including particle-particle collision for zein particles, chain-chain association for PGA molecules, and simultaneous cross-linking coupled with aggregating for Q-loaded zein-PGA composite particles.

Electrospun protein nanofibers in healthcare: A review

Electrospun nanofibers are being utilized for a wide range of healthcare applications. A plethora of natural and synthetic polymers are exploited for their ability to be electrospun and replace the complex habitat provided by the extracellular matrix for the cells. The fabrication of nanofibers can be tuned to act as a multicarrier system to deliver drugs, growth factors and health supplements etc. in a sustained manner. Owing to its pliability, nanofibers reached its heights in tissue engineering and drug delivery applications. This review mainly focuses on various standardized parameters and optimized blending ratios for animal and plant proteins to yield fine, continuous nanofibers for effective utilization in various healthcare applications.