Fabrication of sub-micron protein-chitosan electrostatic complexes for encapsulation and pH-Modulated delivery of model hydrophilic active compounds

Enhancing storage and gastroprotective viability of Lactiplantibacillus plantarum encapsulated by sodium caseinate-inulin-soy protein isolates composites carried within carboxymethyl cellulose hydrogel

Probiotics are subjected to various edible coatings, especially proteins and polysaccharides, which serve as the predominant wall materials, with ultrasound, a sustainable green technology. Herein, sodium caseinate, inulin, and soy protein isolate composites were produced using multi-frequency ultrasound and utilized to encapsulateLactiplantibacillus plantarumto enhance its storage, thermal, and gastrointestinal viability. The physicochemical analyses revealed that the composites with 5 % soy protein isolate treated with ultrasound at 50 kHz exhibited enough repulsion forces to maintain stability, pH resistance, and the ability to encapsulate larger particles and possessed the highest encapsulation efficiency (95.95 %). The structural analyses showed changes in the composite structure at CC, CH, CO, and amino acid residual levels. Rheology, texture, and water-holding capacity demonstrated the production of soft hydrogels with mild chewing and gummy properties, carried the microcapsules without coagulation or sedimentation. Moreover, the viability attributes ofL. plantarumevinced superior encapsulation, protecting them for at least eight weeks and against heat (63 °C), reactive oxidative species (H2O2), and GI conditions.

Chitosan and sodium alginate nanocarrier system: Controlling the release of rapeseed-derived peptides and improving their therapeutic efficiency of anti-diabetes

Rapeseed-derived peptides (RPPs) can maintain the homeostasis of human blood glucose by inhibiting Dipeptidyl Peptidase-IV (DPP-IV) and activating the calcium-sensing receptor (CaSR). However, these peptides are susceptible to hydrolysis in the gastrointestinal tract. To enhance the therapeutic potential of these peptides, we developed a chitosan/sodium alginate-based nanocarrier to encapsulate two RPP variants, rapeseed-derived cruciferin peptide (RCPP) and rapeseed-derived napin peptide (RNPP). A convenient three-channel device was employed to prepare chitosan (CS)/sodium alginate (ALG)-RPPs nanoparticles (CS/ALG-RPPs) at a ratio of 1:3:1 for CS, ALG, and RPPs. CS/ALG-RPPs possessed optimal encapsulation efficiencies of 90.7 % (CS/ALG-RNPP) and 91.4 % (CS/ALG-RCPP), with loading capacities of 15.38 % (CS/ALG-RNPP) and 16.63 % (CS/ALG-RCPP) at the specified ratios. The electrostatic association between CS and ALG was corroborated by zeta potential and near infrared analysis. 13C NMR analysis verified successful RPPs loading, with CS/ALG-RNPP displaying superior stability. Pharmacokinetics showed that both nanoparticles were sustained release and transported irregularly (0.43 < n < 0.85). Compared with the control group, CS/ALG-RPPs exhibited significantly increased glucose tolerance, serum GLP-1 (Glucagon-like peptide 1) content, and CaSR expression which play pivotal roles in glucose homeostasis (*p < 0.05). These findings proposed that CS/ALG-RPPs hold promise in achieving sustained release within the intestinal epithelium, thereby augmenting the therapeutic efficacy of targeted peptides.

Wet-Spun Chitosan-Sodium Caseinate Fibers for Biomedicine: From Spinning Process to Physical Properties

We designed and characterized chitosan-caseinate fibers processed through wet spinning for biomedical applications such as drug delivery from knitted medical devices. Sodium caseinate was either incorporated directly into the chitosan dope or allowed to diffuse into the chitosan hydrogel from a coagulation bath containing sodium caseinate and sodium hydroxide (NaOH). The latter route, where caseinate was incorporated in the neutralization bath, produced fibers with better mechanical properties for textile applications than those formed by the chitosan-caseinate mixed collodion route. The latter processing method consists of enriching a pre-formed chitosan hydrogel with caseinate, preserving the structure of the semicrystalline hydrogel without drastically affecting interactions involved in the chitosan self-assembly. Thus, dried fibers, after coagulation in a NaOH/sodium caseinate aqueous bath, exhibited preserved ultimate mechanical properties. The crystallinity ratio of chitosan was not significantly impacted by the presence of caseinate. However, when caseinate was incorporated into the chitosan dope, chitosan-caseinate fibers exhibited lower ultimate mechanical properties, possibly due to a lower entanglement density in the amorphous phase of the chitosan matrix. A standpoint is to optimize the chitosan-caseinate composition ratio and processing route to find a good compromise between the preservation of fiber mechanical properties and appropriate fiber composition for potential application in drug release.

Effect of Soft Preheating of Bovine Serum Albumin on the Complexation with Oligochitosan: Structure and Conformation of BSA in the Complex

Phase analysis, spectroscopic, and light scattering methods are applied to investigate the peculiarities of the interaction of oligochitosan (OCHI) with native and preheated bovine serum albumin (BSA) as well as the conformational and structural changes of BSA in BSA/OCHI complex. As shown, untreated BSA binds with OCHI mainly forming soluble electrostatic nanocomplexes, with the binding causing an increase in BSA helicity without a change in the local tertiary structure and thermal stability of BSA. In contrast, soft preheating at 56 °C enhances the complexation of BSA with OCHI and slightly destabilizes the secondary and local tertiary structures of BSA within the complex particles. Preheating at 64 °C (below the irreversible stage of BSA thermodenaturation) leads to further enhancement in the complexation and formation of insoluble complexes stabilized by both Coulomb forces and hydrophobic interactions. The finding can be promising for the preparation of biodegradable BSA/chitosan-based drug delivery systems.

Complexation of oligochitosan with sodium caseinate in alkalescent and weakly acidic media

Сomplexation of oligochitosan (OCHI) having the degree of acetylation (DA 26 %) with sodium caseinate (SC) at pH 5.8 and 7.2 is described and compared with the complexation of OCHI (DA 2 %) at pH 5.8. In the alkalescent medium, the complexation of OCHI (DA 26 %) is weaker and dualistic depending on SC concentration in the system. In the diluted alkalescent system, the formation of only soluble complexes is observed at OCHI/SC ratio ≤0.9. In the semi diluted one, the complexation results in the formation of insoluble complexes those composition changes symbatically with the OCHI/SC ratio in the system. At pH 5.8, OCHI/SC ratio in insoluble complexes remains the same regardless of OCHI/SC ratio in the solution. At pH 5.8, the electrostatic complexation weakens with an increase in DA and is completely suppressed at a high ionic strength. These results can be promising for construction of biodegradable protein/chitosan drug delivery systems.

Rheology and tribology of chitosan/Acacia gum complex coacervates

Acacia gum (Gum Arabic; GA) and chitosan (CTS) form complex coacervates in acidic environments, providing a polymer-rich aqueous material with interesting bio-lubricant properties. We investigate the interplay of the tribology and rheology of these coacervates, demonstrating that they dramatically reduce the friction coefficient between lubricated soft model surfaces as compared to solutions of the individual polymers. We characterize the phase separation behavior using microscopy, electrophoretic mobility and thermogravimetric analysis. The macroscopic rheological behaviour is predominantly viscous and ranges from weakly to strongly shear thinning: viscosity levels and strength of shear thinning increase with decreasing ionic strength, but no apparent yield stress or predominant elasticity were observed even in the absence of salt. Conversely, friction coefficients measured between soft and rough surfaces increase with a rise in ionic strength and can be scaled onto a Stribeck-type master curve across varying ionic strength and pH in the mixed and hydrodynamic lubrication regimes.

Succinylated whey protein isolate-chitosan core-shell composite particles as a novel carrier: Self-assembly mechanism and stability studies

Single protein [whey protein isolate (WPI) or succinylated whey protein isolate (SWPI)] and composite particles of proteins with chitosan (CS) were tested for their ability to encapsulate and protect curcumin (CUR). Combining protein and CS resulted in changes in zeta-potential and surface hydrophobicity, particularly in the SWPI-H (high degree of succinylation, 90 %) and CS composite particle (H-CS). Furthermore, the secondary and tertiary structures were dramatically altered using Fourier transform infrared (FTIR), circular dichroism (CD), and X-ray diffraction (XRD). Scanning electron microscopy (SEM) and atomic force microscope (AFM) analyses revealed that H-CS exhibited a soft core-rigid shell morphology due to electrostatic interactions, hydrophobic interactions, and H-bond interactions. Fluorescence quenching results demonstrated that H-CS had a higher binding constant (K, 1.69 ×104 M-1) and encapsulation effectiveness (EE, 88.3 %) of CUR. Because of increased binding sites and steric hindrance, CUR was stabilized more effectively in H-CS in photostability and thermostability tests,. These results show that SWPI-CS composite particles can be utilized to build a protection system for water-insoluble nutritional supplements.

Advances in preparation, interaction and stimulus responsiveness of protein-based nanodelivery systems

The improved understanding of the connection between diet and health has led to growing interest in the development of functional foods designed to improve health and wellbeing. Many of the potentially health-promoting bioactive ingredients that food manufacturers would like to incorporate into these products are difficult to utilize because of their chemical instability, poor solubility, or low bioavailability. For this reason, nano-based delivery systems are being developed to overcome these problems. Food proteins possess many functional attributes that make them suitable for formulating various kinds of nanocarriers, including their surface activity, water binding, structuring, emulsification, gelation, and foaming, as well as their nutritional aspects. Proteins-based nanocarriers are therefore useful for introducing bioactive ingredients into functional foods, especially for their targeted delivery in specific applications.This review focusses on the preparation, properties, and applications of protein-based nanocarriers, such as nanoparticles, micelles, nanocages, nanoemulsions, and nanogels. In particular, we focus on the development and application of stimulus-responsive protein-based nanocarriers, which can be used to release bioactive ingredients in response to specific environmental triggers. Finally, we discuss the potential and future challenges in the design and application of these protein-based nanocarriers in the food industry.

Interactions of the molecular assembly of polysaccharide-protein systems as encapsulation materials. A review

Studying the interactions of biopolymers like polysaccharides and proteins is quite important mainly due to the wide number of applications such as the stabilization and encapsulation of active compounds in complex systems. Complexation takes place when materials like proteins and polysaccharides are blended to promote the entrapment of active compounds. The interaction forces between the charged groups in the polymeric chains allow the miscibility of the components in the complex system. Understanding the interactions taking place between the polymers as well as between the wall material and the active compound is important when designing delivery systems. However, some features of the biopolymers like structure, functional groups, or electrical charge as well as extrinsic parameters like pH or ratios might affect the structure and the performance of the complex system when used in encapsulation applications. This work summarizes the recent progress of the polysaccharide/protein complexes for encapsulation and the influence of the pH on the structural modifications during the complexation process.

Modulating properties of polysaccharides nanocomplexes from enzymatic hydrolysis of chitosan

Synthesis of nanocomplexes is a simple and low-cost technique for the production of encapsulation systems aiming industrial applications, based on the interaction of at least two oppositely charged molecules. Gellan gum (anionic) is a water-soluble biopolymer resistant to stomach pH conditions, therefore an interesting alternative as an encapsulating matrix. Chitosan (cationic) is also widely used due to its biocompatibility and mucoadhesive properties, although its low water solubility is an important step to be overcome for the production of the complexes. To improve this property, many techniques have been employed, but most of them use unsustainable techniques and chemical agents. The enzymatic hydrolysis of chitosan using proteases emerges as an alternative to these drawbacks and, therefore, this study aimed to evaluate the electrostatic nanocomplexation of native (C) or hydrolyzed (HC) chitosan (by porcine pepsin protease) with gellan gum (G). Polysaccharides and nanocomplexes formed with different G:C or G:HC ratio were evaluated by zeta potential measurements, particle size distribution, X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Transmission Electron Microscopy (STEM), intrinsic viscosity and turbidity analyses. Chitosan hydrolysis allowed the formation of a smaller (445.3 nm in pH 4.5) and more soluble structure (3 kDa), which positively influenced the formation of the complexes. The ratios G:HC of 7:3 and 8:2 formed complexes with lower values of zeta potential (13.9 mV and -5.0 mV, respectively), particle size (635.8 nm and 533.6 nm, respectively) and polydispersity (0.28 and 0.23) compared to complexes formed with native chitosan. Overall, our results show that enzymatic hydrolysis of chitosan favored the formation of electrostatic complexes with reduced size and low polydispersity, which can be used as efficient encapsulating matrices for improved targeted delivery and controlled release of bioactive compounds.

Formation of soy protein isolate (SPI)-citrus pectin (CP) electrostatic complexes under a high-intensity ultrasonic field: Linking the enhanced emulsifying properties to physicochemical and structural properties

In this study, a high-intensity ultrasonic field was applied to the electrostatic interactions between soy protein isolate (SPI) and citrus pectin (CP). The emulsifying properties of SPI-CP soluble complexes formed under different ultrasound powers and durations were investigated and peaked at 630 W for 10 min. Micrographs of emulsions revealed that ultrasound-treated complexes generated a more homogeneous emulsion with significantly reduced and uniformly-distributed droplet sizes. To better understand the mechanism for the improved emulsifying properties, the physicochemical and structural properties of the SPI-CP complexes at pH 3.5 with and without ultrasound treatment were investigated. It was revealed that ultrasound increased the absolute values of the zeta potential and surface hydrophobicity of complexes, but significantly decreased their particle sizes, fluorescence intensity and turbidity. Results indicated that cavitation effects resulted in structural modifications in both biomacromolecules, as well as enhanced the electrostatic interactions between SPI and CP, which in combination contributed to the more desirable emulsifying properties of the complex.

Ultrasound-assisted preparation of different nanocarriers loaded with food bioactive ingredients

Developing green and facile approaches to produce nanostructures suitable for bioactives, nanoencapsulation faces some challenges in the nutraceutical and food bioactive industries due to potential risks arising from nanomaterials fabrication and consumption. High-intensity ultrasound is an effective technology to generate different bio-based structures in sub-micron or nanometer scale. This technique owing to some intrinsic advantages such as safety, straightforward operation, energy efficiency, and scale-up potential, as well as, ability to control over size and morpHology has stood out among various nanosynthetic routes. Ultrasonically-provided energy is mainly transferred to the droplets and particles via acoustic cavitation (which is formation, growth, and implosive collapse of bubbles in solvent). This review provides an outlook on the fundamentals of ultrasonication and some applicable setups in nanoencapsulation. Different kinds of nanostructures based on surfactants, lipids, proteins and carbohydrates formed by sonication, along with their advantages and disadvantages are assessed from the viewpoint of stability, particle size, and process impacts on some functionalities. The gastrointestinal fate and safety issues of ultrasonically prepared nanostructures are also discussed. Sonication, itself or in combination with other encapsulation approaches, alongside biopolymers generate nano-engineered carriers with enough stability, small particle sizes, and a low polydispersity. The nano-sized systems improve techno-functional activities of encapsulated bioactive agents including stability, solubility, dissolution, availability, controlled and targeted release profile in vitro and in vivo plus other bioactive properties such as antioxidant and antimicrobial capacities. Ultrasonically prepared nanocarriers show a great potential in fortifying food products with desired bioactive components, especially for the industrial applications.

Effects of frequency ultrasound on the properties of zein-chitosan complex coacervation for resveratrol encapsulation

In this study, resveratrol was successfully encapsulated using zein-chitosan complex coacervation. The encapsulation efficiency was markedly improved (51.4%) after chitosan coating at 1:2.5 zein/chitosan ratio, compared with 38.6% using native zein. Analysis of multi-model frequency ultrasound treatment effects on resveratrol encapsulation using zein-chitosan complex coacervation showed that 28/40 kHz dual-frequency ultrasound led to the highest encapsulation efficiency (65.2%; 31.9% increase) and loading capacity (5.9%; 31.1% increase) of resveratrol, followed by multi-frequency ultrasound at 20/28/40 kHz (17.8% encapsulation efficiency increase; 17.8% loading capacity increase). Dual-frequency ultrasound treatment significantly reduced the zein-chitosan complex coacervation particle size and reduced their distribution, however, did not change the zeta potential. Fourier transform infrared spectroscopy and fluorescence spectroscopy analysis demonstrated that ultrasound treatment had no effect on secondary structure of zein-chitosan complex but markedly decreased the fluorescence emission intensity. Differential scanning calorimetry and X-ray diffraction results indicated that Dual-frequency ultrasound treatment improved the thermal stability of zein-chitosan complex coacervation but had no effect on the crystal structure. Atomic force microscopy and scanning electron microscopy images revealed uniform distribution of zein-chitosan complex coacervation followed by ultrasonic treatment.

A simple, efficient and economic method for obtaining iodate-rich chili pepper based chitosan edible thin film

The present study was aimed at designing an iodine supplement in form of edible film made of iodate-coated chitosan (CS-IO₃). Inclusion of so obtained films in diet can help in preventing thyroid cancer, leading to improved public health. Chili pepper was coated with iodate thin film (1.5 µm). The iodate-rich film is ready-to-eat serving valuable nutrients. Stability studies of CS-IO₃ film using water dipping revealed that there was no leaching of iodate ion, due to the strong interactions between cationic amino group of chitosan and iodate ion. The film showed no change in its antioxidant activity. Iodate concentration in the film was determined at 620 nm selectively, based on the decolorization of malachite green economic method. Iodate content in fruits coated with 1.5% (w/v) CS-IO₃ was 11.5 mg g^-1 of dry film sample. The iodate-rich samples could be stored without much effect on its freshness, indicating a good shelf life.

Biopolymer-based strategies in the design of smart medical devices and artificial organs

Advances in regenerative medicine and in modern biomedical therapies are fast evolving and set goals causing an upheaval in the field of materials science. This review discusses recent developments involving the use of biopolymers as smart materials, in terms of material properties and stimulus-responsive behavior, in the presence of environmental physico-chemical changes. An overview on the transformations that can be triggered in natural-based polymeric systems (sol-gel transition, polymer relaxation, cross-linking, and swelling) is presented, with specific focus on the benefits these materials can provide in biomedical applications.

Annatto-entrapped casein-chitosan complexes improve whey color quality after acid coagulation of milk

A fraction of annatto is often transferred to the whey fluid during Cheddar cheese processing, which negatively impacts the visual and sensory attributes of the resultant whey powder. Alternatives to reduce the color in the powder are still needed. In this study, casein-chitosan complexes were prepared to deliver annatto preferentially to the curd and reduce the amount of carryover colorant in whey powder. These complexes were relatively spherical, with a mean complex diameter of 8.3 ± 1.9 µm, zeta-potential of +39.4 ± 1.3 mV, and entrapment efficiency of 38.2 ± 3.1%. FT-IR spectroscopy confirmed the electrostatic interaction between casein and chitosan. Complexes and commercial annatto powder were incorporated into homogenized, reduced-fat, and fat-free milk, and subjected to acid coagulation. Whey powder produced from casein-chitosan-complex-treated samples exhibited better color quality than that prepared with annatto powder, indicating that the approach considered in this study was efficient in preventing the migration of colorant to the whey.

Surface behavior and bulk properties of aqueous chitosan and type-B gelatin solutions for effective emulsion formulation

The behavior of aqueous chitosan (CH), type-B gelatin (GB) and CH-GB coacervate was studied on oil-in-water emulsion formulation at various pH and concentration ratio. The coacervate was formed by phase separation at ratios CH:GB, 1:10 to 1:1 with total biopolymer concentrations of 0.55%-1.0% (w/v) at pH 4.0-5.5. Soluble complexes were formed below pH 5.0 and coacervate formation was confirmed at pH 5.0 and above by zeta potential and UV-spectroscopy measurements. The coacervate formation was found maximum at the CH-GB ratios of 1:10 and 1:5 at pH 5.5. Formulated emulsions (>10μm droplets) using 1% (w/v) chitosan and GB were found stable (+52.5mv and creaming index 86%) and unstable respectively. Emulsion stabilized by mixed CH:GB 1:5 (3%w/v) had no creaming effect. The instability was attributed to the lower surface activity (K=5.0Lg^-1) of pure GB compared to CH (K=14.3Lg^-1). The formulation and methods can successfully tune the stability of the emulsions.

Effect of chitosan on the heat stability of whey protein solution as a function of pH

BACKGROUND

Chitosan was reported to interact with proteins through electrostatic interactions. Their interaction was influenced by pH, which was not fully characterized. Further research on the interactions between protein and chitosan at different pH and their influence on the thermal denaturation of proteins is necessary.

RESULTS

In this research, the effect of chitosan on the heat stability of whey protein solution at pH 4.0-6.0 was studied. At pH 4.0, a small amount chitosan was able to prevent the heat-induced denaturation and aggregation of whey protein molecules. At higher pH values (5.5 and 6.0), whey proteins complexed with chitosan through electrostatic attraction. The formation of chitosan-whey protein complexes at pH 5.5 improved the heat stability of dispersions and no precipitation could be detected up to 20 days. The dispersion with a medium amount of chitosan (chitosan:whey protein 1:5) produced the most stable particles, which had an average radius of 135 ± 14 nm and a zeta potential value of 36 ± 1 mV. In contrast, at pH 6.0 only the dispersion with a high amount of chitosan (chitosan:whey protein 1:2) showed good shelf stability up to 20 days.

CONCLUSIONS

It was possible to produce heat-stable whey protein beverages by regulating the interaction between chitosan and whey protein molecules. © 2016 Society of Chemical Industry.

Encapsulation of active ingredients in polysaccharide-protein complex coacervates

Polysaccharide-protein complex coacervates are amongst the leading pair of biopolymer systems that has been used over the past decades for encapsulation of numerous active ingredients. Complex coacervation of polysaccharides and proteins has received increasing research interest for the practical application in encapsulation industry since the pioneering work of complex coacervation by Bungenburg de Jong and co-workers on the system of gelatin-acacia, a protein-polysaccharide system. Because of the versatility and numerous potential applications of these systems essentially in the fields of food, pharmaceutical, cosmetics and agriculture, there has been intense interest in recent years for both fundamental and applied studies. Precisely, the designing of the micronscale and nanoscale capsules for encapsulation and control over their properties for practical applications garners renewed interest. This review discusses on the overview of polysaccharide-protein complex coacervates and their use for the encapsulation of diverse active ingredients, designing and controlling of the capsules for delivery systems and developments in the area.