Nanostructured lipid carriers incorporated in alginate hydrogel: Enhanced stability and modified behavior in gastrointestinal tract

Design and development of multibiocomponent hybrid alginate hydrogels and lipid nanodispersion as new materials for medical and cosmetic applications

The multibiocomponent hybrid alginate hydrogels based on brown and sea algae, containing 100 % ingredients of natural origin were prepared by ionic crosslinking reaction of a polymeric matrix with lipid nanodispersion. To the best of the Authors' knowledge such multicomponent biobased hydrogel of promising medical and cosmetical applications for the first time was obtained in the environment of flower water, received earlier as a waste by-product from various chemical processes. An innovative hybrid alginate hydrogel that is completely biodegradable and eco-friendly was obtained following waterless and upcycling trends that are in line with the principles of sustainable development. The optimal composition of the lipid nanodispersion and the polymeric matrix was selected using the statistical method of design of the experiment. Based on obtained results, multibiocomponent hybrid alginate hydrogels with various ratios of lipid nanodispersion were obtained. Subsequently, the porous structure and elasticity of the hybrid hydrogels were analyzed. Moreover, to confirm the safety of the multibiocomponent alginate hybrid hydrogels the cytotoxic tests were carried out using human fibroblasts and keratinocytes cell lines. As the final product hybrid of hydrolate-swollen alginate hydrogel and lipid nanodispersion containing several active ingredients (silymarin, bakuchiol, spirulina) was obtained.

Novel diacylglycerol oil-based nanostructured lipid carriers improves the stability and digestibility of lycopene

Diacylglycerol (DAG) has garnered attention for its safe and nutritious qualities, and its utilization in emulsion systems to encapsulate hydrophobic bioactives is anticipated to enhance their bioaccessibility. Thus, this study aimed to evaluate the influence of DAG oil as a carrier on the stability and digestive characteristics of nanostructured lipid carriers (NLCs) containing lycopene (LYC). The results indicated that DAG oil demonstrated superior storage and heating stability in comparison to triacylglycerol (TAG) oil. Furthermore, NLCs formulated with DAG oil exhibited a faster rate of lipolysis (>76.3%) and higher loading capacity (1.48%), resulting in an approximate 11% enhancement in the bioaccessibility of LYC (reaching up to 31.4%). DAG oils show considerable potential for enhancing and prolonging the properties and bioactivity of NLC carriers, thereby boosting bioaccessibility. The incorporation of DAG oil in food systems holds promise for enriching their functionality over traditional TAG oil.

Smart/stimuli-responsive chitosan/gelatin and other polymeric macromolecules natural hydrogels vs. synthetic hydrogels systems for brain tissue engineering: A state-of-the-art review

Currently, there are no viable curative treatments that can enhance the central nervous system's (CNS) recovery from trauma or illness. Bioengineered injectable smart/stimuli-responsive hydrogels (SSRHs) that mirror the intricacy of the CNS milieu and architecture have been suggested as a way to get around these restrictions in combination with medication and cell therapy. Additionally, the right biophysical and pharmacological stimuli are required to boost meaningful CNS regeneration. Recent research has focused heavily on developing SSRHs as cutting-edge delivery systems that can direct the regeneration of brain tissue. In the present article, we have discussed the pathology of brain injuries, and the applicable strategies employed to regenerate the brain tissues. Moreover, the most promising SSRHs for neural tissue engineering (TE) including alginate (Alg.), hyaluronic acid (HA), chitosan (CH), gelatin, and collagen are used in natural polymer-based hydrogels and thoroughly discussed in this review. The ability of these hydrogels to distribute bioactive substances or cells in response to internal and external stimuli is highlighted with particular attention. In addition, this article provides a summary of the most cutting-edge techniques for CNS recovery employing SSRHs for several neurodegenerative diseases.

Regulate structure and properties of κ-carrageenan/konjac glucomannan composite hydrogel by filling effects of Quillaja saponin-stabilized solid lipid nanostructure

κ-Carrageenan/konjac glucomannan (κ-CA/KGM) composite hydrogels often fail to meet industrial requirements due to their low gel strength and poor mechanical properties, while solid lipid nanoparticles are potential materials to address this challenge due to their good biocompatibility. In the study, we propose using Quillaja saponin-stabilized solid lipid nanoparticle (QSLN) as nanofillers to enhance properties of κ-carrageenan/konjac glucan (κ-CA/KGM) composite hydrogels, and with emphasis on the effect of QSLN filling concentration on the structure and properties of composite hydrogels and the possible mechanisms were investigated. The best performance of QSLN-filled composite hydrogels was achieved at the QSLN concentration of 2.4 %. QSLN was uniformly distributed in the hydrogel matrix and formed electrostatic interactions and hydrogen bonding interactions with the matrix at an appropriate filling level, which enhanced the textural and rheological properties of the hydrogel greatly. In addition, the results of low-field NMR experiments showed that the filling of QSLN reduced the water mobility by enhancing the entanglement of polymer chains in the hydrogel matrix, which improved the freeze-thaw stability and regulated the swelling and deswelling behavior of the composite hydrogel. However, with the increasing of QSLN filling concentration, the above improvements were weakened by the depletion of van der Waals interactions due to the large amount of QSLN aggregation and the weakening of electrostatic interaction. In turn, the hydrogel was found to modulate the crystalline behavior of QSLN by X-ray diffraction and differential scanning calorimeter monitoring. Overall, the optimal synergistic effect between structure and properties could be achieved when the QSLN filling concentration was 2.4 %. These results provide a basis for the development of products that require excellent gel properties and structure.

Preparation and in vitro characterization studies of astaxanthin-loaded nanostructured lipid carriers with antioxidant properties

The purpose of this study was to evaluate the astaxanthin-loaded nanostructured lipid carriers (ASX-NLC) prepared using a high-pressure homogenization transport system for local application of astaxanthin. Dynamic light scattering (DLS) and X-ray diffraction (XRD) were used to study the effect of microencapsulation on the properties of ASX-NLC. The mean size of ASX-NLC was about 108.43 ± 0.26 nm and PdI was 0.176 ± 0.002. The ASX-NLC had high encapsulation efficiency which was 95.69 ± 0.13%. Good light stability and temperature stability were shown at the ASX-NLC, indicating that the preparation process was feasible. The 2,2-diphenyl-1-pyridylohydrazinyl (DPPH) scavenging test showed that ASX-NLC could still play an antioxidant role. In vitro release studies showed that compared with an astaxanthin ethanol solution, an ASX-NLC could maintain astaxanthin release more effectively. In vitro permeation studies showed that ASX-NLC could increase astaxanthin retention in the skin. In conclusion, ASX-NLC could significantly enhance astaxanthin accumulation during dermal applications. The research results have important reference significance for local skin applications and provide a basis for the development of nanostructured lipid carriers. ASX-NLC might be suitable carriers for the local application of astaxanthin.

Nanoemulsions Embedded in Alginate Beads as Bioadhesive Nanocomposites for Intestinal Delivery of the Anti-Inflammatory Drug Tofacitinib

Oral administration of nanoparticles (NPs) is a promising strategy to overcome solubility and stability issues of many active compounds. However, this route faces major obstacles related to the hostile gastrointestinal (GI) environment, which impairs the efficacy of orally administered nanomedicines. Here, we propose nanocomposites as a promising approach to increase the retention time of NPs in the intestinal tract by using bio- and mucoadhesive matrixes able to protect the cargo until it reaches the targeted area. A microfluidic-based approach has been applied for the production of tailored nanoemulsions (NEs) of about 110 nm, used for the encapsulation of small hydrophobic drugs such as the anti-inflammatory JAK-inhibitor tofacitinib. These NEs proved to be efficiently internalized into a mucus-secreting human intestinal monolayer of Caco-2/HT29-MTX cells and to deliver tofacitinib to subepithelial human THP-1 macrophage-like cells, reducing their inflammatory response. NEs were then successfully encapsulated into alginate hydrogel microbeads of around 300 μm, which were characterized by rheological experiments and dried to create a long-term stable system for pharmaceutical applications. Finally, ex vivo experiments on excised segments of rats' intestine proved the bioadhesive ability of NEs embedded in alginate hydrogels compared to free NEs, showing the advantage that this hybrid system can offer for the treatment of intestinal pathologies.

Effect of gelation technique on lipid digestibility of emulsion-loaded alginate microparticles: a systematic review and meta-analysis

Alginate microparticles fabricated via calcium gelation or layer-by-layer assembly are commonly used for encapsulating emulsions. In this study, the impact of these two gelation methods on the lipid digestibility of emulsions was reviewed through a systematic screening of relevant studies. From the literature search (Scopus, PubMed, and Web of Science databases), 604 records were screened and 25 articles were included in the analysis. The fold change of free fatty acid release rate at the end of in vitro digestion process between alginate-encapsulated emulsion and emulsions not encapsulated by alginate was calculated for calcium gelation (weighted mean of response ratio 0.64, 95% CI 0.54-0.75) and layer-by-layer assembly (weighted mean of response ratio 0.89, 95% CI 0.81-0.98). Alginate-calcium hydrogels showed stronger inhibition of the extent of lipid digestion than alginate-coated multilayer emulsions. The structural and particle size differences between alginate microparticles acquired using different techniques may contribute to this phenomenon.

Encapsulation of resveratrol-loaded Pickering emulsions in alginate/pectin hydrogel beads: Improved stability and modification of digestive behavior in the gastrointestinal tract

In this study, alginate/pectin hydrogel beads were prepared with different mixing ratios (9:1, 8:2, 7:3, 6:4, and 5:5) to encapsulate resveratrol-loaded Pickering emulsions using Ca²⁺ crosslinking. The system with a suitable ratio of pectin and alginate can enhance the encapsulation efficiency and loading capacity. Scanning electron microscopy (SEM) study confirmed that the hydrogel beads were spherical, in which Pickering emulsion was distributed evenly within the polymer network. Fourier Transform Infrared Spectroscopy (FTIR) study indicated that the hydrogel beads were formed by physical cross-linking. X-ray diffraction (XRD) study demonstrated that resveratrol existed in hydrogel beads with an amorphous or dissolved form. Besides, the stability and antioxidant capacity suggested that hydrogel beads could offer protection to resveratrol by preventing degradation through environmental stresses, while maintaining its antioxidant capacity. Importantly, hydrogels significantly reduced the release of free fatty acids and resveratrol during in vitro digestion compared to emulsions, especially with the appropriate ratio of sodium alginate and pectin. Overall, Pickering emulsions-loaded alginate/pectin hydrogel beads could offer a novel option for the preparation of low-calorie foods and a potential substitute model for controlling the release of free fatty acids contributing to the transportation of resveratrol.

Alginate-based nanocarriers for the delivery and controlled-release of bioactive compounds

Alginate-based nanocarriers are propitious vehicles used for the delivery of bioactive compounds (bioactives). In this area, calcium alginate and sodium alginate are the most promising wall materials because they are nontoxic, comparatively cheap, simple in production, biocompatible and biodegradable. In this review, we have highlighted different alginate-based nanocarriers such as nanoparticles, nanofibers, nanoemulsions, nanocomplexes, and nanohydrogels; also entrapment of different bioactives within alginate nanocarriers and their bioavailability in the gastric environment has been comprehensively discussed. Being biopolymers, alginates can be exploited as emulsifiers/ encapsulants for entrapment and delivery of different bioactives such as vitamins, minerals, essential fatty acids, peptides, essential oils, bioactive oils, polyphenols and carotenoids. Furthermore, the use of alginate-based nanocarriers in combination with other polysaccharides/ emulsifiers was recognized as the most effective and favorable approach for the protection, delivery and sustained release of bioactives.

New Insights of Scaffolds Based on Hydrogels in Tissue Engineering

In recent years, biomaterials development and characterization for new applications in regenerative medicine or controlled release represent one of the biggest challenges. Tissue engineering is one of the most intensively studied domain where hydrogels are considered optimum applications in the biomedical field. The delicate nature of hydrogels and their low mechanical strength limit their exploitation in tissue engineering. Hence, developing new, stronger, and more stable hydrogels with increased biocompatibility, is essential. However, both natural and synthetic polymers possess many limitations. Hydrogels based on natural polymers offer particularly high biocompatibility and biodegradability, low immunogenicity, excellent cytocompatibility, variable, and controllable solubility. At the same time, they have poor mechanical properties, high production costs, and low reproducibility. Synthetic polymers come to their aid through superior mechanical strength, high reproducibility, reduced costs, and the ability to regulate their composition to improve processes such as hydrolysis or biodegradation over variable periods. The development of hydrogels based on mixtures of synthetic and natural polymers can lead to the optimization of their properties to obtain ideal scaffolds. Also, incorporating different nanoparticles can improve the hydrogel’s stability and obtain several biological effects. In this regard, essential oils and drug molecules facilitate the desired biological effect or even produce a synergistic effect. This study’s main purpose is to establish the main properties needed to develop sustainable polymeric scaffolds. These scaffolds can be applied in tissue engineering to improve the tissue regeneration process without producing other side effects to the environment.

Nanostructured-lipid carriers-Chitosan hydrogel beads carrier system for loading of resveratrol: A new method of topical application

The aim of this study was to develop nanostructured-lipid carriers (NLC) encapsulated by Chitosan hydrogel beads for the efficient topical carrier. Dynamic light scattering (DLS), X-ray diffraction (XRD), Differential scanning calorimetry (DSC), and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) were conducted to study the influence of the encapsulation on the characteristic of resveratrol-loaded NLC, and the results showed that there was no impact on resveratrol-loaded NLC. Chitosan hydrogel beads could significantly improve the physical stability of resveratrol-loaded NLC. In vitro release study revealed that resveratrol-loaded NLC-Chitosan hydrogel beads had a more significant sustained-release effect on resveratrol. In vitro transdermal studies suggested that the skin permeation of resveratrol was promoted by the effect of Chitosan hydrogel beads and increased resveratrol distribution in the skin. In vitro cytotoxicity showed that resveratrol-loaded NLC-Chitosan hydrogel beads did not exert a hazardous effect on L929 cells. Hence, NLC-Chitosan hydrogel beads might be a promising method for topical applications of resveratrol.

Effect of Ca2+ cross-linking on the properties and structure of lutein-loaded sodium alginate hydrogels

In order to construct nano-lutein hydrogels with sustained release properties, the basic properties and structure of nano-lutein hydrogels cross-linked with different concentrations of Ca²⁺ were investigated. The results showed that the highest loading capacity for lutein reached 770.88 μg/g, while the encapsulation efficiency was as high as 99.39%. When Ca²⁺ concentration was lower than 7.5 mM, the filling of lutein nanoparticles reduced the hardness and gumminess of the hydrogel. The resilience and cohesiveness of the hydrogel decreased as the concentration of Ca²⁺ increased. Filling with lutein nanoparticles and increasing Ca²⁺ concentration both increased the G' and G″. The hydrogel loaded with lutein showed different swelling properties in different pH environments, the filling of lutein nanoparticles inhibited the swelling of the hydrogel. When Ca²⁺ concentration was greater than 7.5 mM, the cut-off amount of lutein on the surface of the Ca²⁺ cross-linked hydrogel was larger. The digestive enzymes quickly degraded the hydrogel structure, resulting in a high initial release of lutein. DSC and FTIR results showed that lutein nanoparticles were mainly physically trapped in the hydrogel network structure. Lutein nanoparticles and excessive Ca²⁺ affected the stability of cross-linked ionic bonds in the hydrogel, thereby reducing its thermodynamic stability.

Sodium alginate/soybean protein-epigallocatechin-3-gallate conjugate hydrogel beads: evaluation of structural, physical, and functional properties

Sodium alginate (SA) hydrogel beads have been extensively studied as delivery systems for bioactive compounds. Key challenges include overcoming the highly porous and poor emulsifying properties of SA hydrogels. Herein, soy protein isolate (SPI) was modified by covalent and noncovalent conjugation with epigallocatechin-3-gallate (EGCG), followed by complexation with SA to change the SA structure and fabricate hydrogel beads with low porosities. Microencapsulation beads were fabricated from SA-, SA/SPI-, and SA/SPI-modified EGCG complexes with a corn oil/quercetin mixture core. After the covalent and noncovalent SPI-modified EGCG complexes were combined with SA, the OH stretching vibration shifted, indicating that hydrogen bonds formed between the protein and SA, and the crystal structure of SA was destroyed. To achieve crosslinking, the beads were injected into a CaCl₂ solution, whereby Ca²⁺ ions replaced the Na⁺ ions in SA. Meanwhile, the addition of covalent and noncovalent SPI-modified EGCG complexes promoted the binding capacity of Ca²⁺ and SA. All hydrogel beads possessed open-cell microstructures with interconnecting pores. The SA/SPI-modified EGCG hydrogel beads exhibited smoother surfaces, thicker shells, and lower porosity than the SA hydrogel beads. Moreover, they exhibited significantly higher antioxidant activities. During digestion, all types of hydrogel bead maintained their structure, and only a small part of the encapsulated oil and quercetin was digested in the upper part of the gastrointestinal tract. In short, the formation mechanism of hydrogel beads was clarified, and hydrogel beads with low porosity and high antioxidation activities were successfully fabricated.

Nanocomposite systems for precise oral delivery of drugs and biologics

Oral delivery is considered the favoured route of administration for both local and systemic delivery of active molecules. Formulation of drugs in conventional systems and nanoparticles has provided opportunities for targeting the gastrointestinal (GI) tract, increasing drug solubility and bioavailability. Despite the achievements of these delivery approaches, the development of a product with the ability of delivering drug molecules at a specific site and according to patients' needs remains a challenging endeavour. The complexity of the physicochemical properties of colloidal systems, their stability in different regions of the gastrointestinal tract, and interaction with the restrictive biological barriers hampered their success for oral precise medicine. To overcome these issues, nanoparticles have been combined with polymers to create hybrid nanosystems, namely nanocomposites. They offer enormous possibilities of structural and mechanical modifications to both nanoparticles and polymeric matrixes to generate systems with new properties, functions, and applications for oral delivery. In this review, nanocomposites' physicochemical and functional properties intended to target specific regions of the GI tract-oral cavity, stomach, small bowel, and colon-are analysed. In parallel, it is provided an insight in the nanocomposite solutions for oral delivery intended for systemic and local absorption, together with a focus on inflammatory bowel diseases (IBDs). Additional difficulties in managing IBD related to the alteration in the physiology of the intestine are described. Finally, future perspectives and opportunities for advancement in this field are discussed.

Recent Advances in the Structural Design of Photosensitive Agent Formulations Using "Soft" Colloidal Nanocarriers

The growing demand for effective delivery of photosensitive active compounds has resulted in the development of colloid chemistry and nanotechnology. Recently, many kinds of novel formulations with outstanding pharmaceutical potential have been investigated with an expansion in the design of a wide variety of "soft" nanostructures such as simple or multiple (double) nanoemulsions and lipid formulations. The latter can then be distinguished into vesicular, including liposomes and "smart" vesicles such as transferosomes, niosomes and ethosomes, and non-vesicular nanosystems with solid lipid nanoparticles and nanostructured lipid carriers. Encapsulation of photosensitive agents such as drugs, dyes, photosensitizers or antioxidants can be specifically formulated by the self-assembly of phospholipids or other amphiphilic compounds. They are intended to match unique pharmaceutic and cosmetic requirements and to improve their delivery to the target site via the most common, i.e., transdermal, intravenous or oral administration routes. Numerous surface modifications and functionalization of the nanostructures allow increasing their effectiveness and, consequently, may contribute to the treatment of many diseases, primarily cancer. An increasing article number is evidencing significant advances in applications of the different classes of the photosensitive agents incorporated in the "soft" colloidal nanocarriers that deserved to be highlighted in the present review.