Swelling studies and in vitro release of verapamil from calcium alginate and calcium alginate–chitosan beads

Chitosan-alginate microcapsules: A strategy for improving stability and antibacterial potential of bovine Lactoferrin

Lactoferrin, a multifunctional glycoprotein with significant biological properties, presents significant potential for the prevention and treatment of infectious diseases. However, the effectiveness of oral Lactoferrin is limited by its susceptibility to degradation in harsh stomach conditions, reducing its bioavailability and therapeutic efficacy. To address this challenge, this study employs Chitosan/Alginate microparticles to enhance Lactoferrin stability and antibacterial activity. Microparticles were synthesized through external ionic gelation and thoroughly characterized. Chitosan/Alginate microparticles were significantly smaller than Alginate microparticles, with a high loading efficiency of 93.65 %. Fourier transform infrared (FT-IR) spectroscopy confirmed the successful incorporation of Lactoferrin. Release studies demonstrated minimal Lactoferrin release in simulated gastric fluid, while a controlled release was observed in simulated intestinal fluid. Notably encapsulated Lactoferrin retained its structural integrity after exposure to simulated gastrointestinal conditions. Antibacterial assay against Escherichia coli showed that Chitosan/Alginate microcapsules maintain Lactoferrin antibacterial activity after its passage through simulated gastrointestinal conditions. Furthermore, FT-IR spectroscopy and zeta-potential analysis provided novel insights into the mechanism of Lactoferrin's interaction with bacterial LPS, highlighting its ability to destabilize bacterial membrane of this Escherichia coli strain. These findings underscore the Chitosan/Alginate system as a promising strategy for enhancing the therapeutic potential of Lactoferrin.

Diatom contained alginate-chitosan hydrogel beads with enhanced hydrogen bonds and ionic interactions for extended release of gibberellic acid

Hydrogels in agriculture offer controlled release, however, face issues with rapid disintegration, swift release, and inability to protect active ingredients. To overcome this, the study presents a hydrogel delivery system that uses dopamine-functionalized nanoporous diatom (DE-PDA) microparticles entrapped in alginate and chitosan matrices to deliver plant growth hormone, gibberellic acid (GA) that suffers from instability, limiting its field application. Developed GA@hydrogel beads exhibited an encapsulation efficiency of 85.2 % and demonstrated thermal and functional properties that suggested complex interactions between biopolymers. They showed enhanced stability, retention, and extended release for GA, improving tomato seed germination and plant growth. The GA release was governed by Fickian diffusion and the polymer relaxation with 86.3 % release by the 15th day, with a high swelling rate compared to a system without DE-PDA that only sustained GA release for 5 h. The GA@hydrogel system boosts tomato seed germination rates to 100 % on the third day for a 0.05 % GA@hydrogel formulation, demonstrating enhanced seedling growth. Also, they prove more effective than free GA in increasing the physiological parameters of tomato plants. Further, the pot experiments show enhanced plant growth, suggesting a new trend of GA delivery to plants through soil.

Enhancing therapeutic effects alginate microencapsulation of thyme and calendula oils using ionic gelation for controlled drug delivery

This study focuses on encapsulating and characterizing essential oils such as thyme and calendula oils, which are known for their therapeutic properties but are limited in pharmaceutical formulations due to their low water solubility and instability, with alginate microspheres. Alginate presents an excellent option for microencapsulation due to its biocompatibility and biological degradability. The ionic gelation (IG) technique, based on the ionic binding between alginate and divalent cations, allows the formation of hydrogel materials with high water content, mechanical strength, and biocompatibility. The microspheres were characterized using FT-IR, SEM, and swelling analyses. After determining the encapsulation efficiency and drug loading capacity, the microspheres were subjected to dissolution studies under simulated digestion conditions. It was observed that the swelling percentage of the microspheres in simulated gastric fluid (SGF) ranged from ∼15% to 100%, while in simulated intestinal fluid (SIF) it ranged from ∼150% to 325%. Thyme oil, with low viscosity, exhibited higher encapsulation efficiency than marigold oil. The highest encapsulation efficiency was observed in A-TO-2 microspheres, while the highest drug loading capacity was observed in A-TO-5 microspheres. During the examination of the dissolution profiles of the microspheres, dissolution rates ranging from 10.98% to 23.56% in SGF and from 52.44% to 63.20% in SIF were observed.

W/O/W emulsion-filled sodium alginate hydrogel beads for co-encapsulation of vitamins C and E: Insights into the fabrication, lipolysis, and digestion behavior

In this study, vitamins C and E were simultaneously encapsulated in water-in-oil-in-water (W/O/W) emulsion-filled sodium alginate (SA) hydrogel beads, as well as the effects of SA concentrations (0.5%, 1.0%, 1.5%, and 2.0%) on the structures and lipolysis the of hydrogel beads were investigated. With increasing SA concentration, the beads showed larger sizes, denser structures and better textures. The droplets tightly penetrated the gel network at high SA concentrations. Digestion behavior revealed the disintegrated intramolecular structure at low SA concentrations. The beads with 0.5% SA were fragmented, losing the initial shape during digestion in the intestinal fluid. Additionally, lipid phases were released as W/O/W and O/W emulsion droplets after digestion. However, the high SA concentration-containing beads exhibited a well-preserved morphological structure after digestion, and the release profiles of lipid phase were mainly O/W emulsion droplets. Furthermore, vitamins C and E encapsulated in the beads exhibited high bioaccessibility (vitamin C: 90.20% and vitamin E: 95.19%).

Synthesis of agro-industrial wastes/sodium alginate/bovine gelatin-based polysaccharide hydrogel beads: Characterization and application as controlled-release microencapsulated fertilizers

Synthesis of novel agro-industrial wastes/sodium alginate/bovine gelatin-based polysaccharide hydrogel beads, micromeritic/morphometric characteristics of the prepared formulations, greenhouse trials using controlled-release microencapsulated fertilizers, and acute fish toxicity testing were conducted simultaneously for the first time within the scope of an integrated research. In the present analysis, for the first time, 16 different morphometric features, and 32 disinct plant growth traits of the prepared composite beads were explored in detail within the framework of a comprehensive digital image analysis. The hydrogel beads composed of 19 different agro-industrial wastes/materials were successfully synthesized using the ionotropic external gelation technique and CaCl2 as cross-linker. According to micromeritic characteristics, the ionotropically cross-linked beads exhibited 77.86 ± 3.55 % yield percentage and 2.679 ± 0.397 mm average particle size. The dried microbeads showed a good swelling ratio (270.02 ± 80.53 %) and had acceptable flow properties according to Hausner's ratio (1.136 ± 0.028), Carr's index (11.94 ± 2.17 %), and angle of repose (25.03° ± 5.33°) values. The settling process of the prepared microbeads was observed in the intermediate flow regime, as indicated by the average particle Reynolds numbers (169.17 ± 82.81). Experimental findings and non-parametric statistical tests reveal that dried fertilizer matrices demonstrated noteworthy performance on the cultivation of red hot chili pepper plant (Capsicum annuum var. fasciculatum) according to the results of greenhouse trials. Surface morphologies of the best-performing fertilizer matrices were also characterized by Scanning Electron Microscopy. Moreover, the static fish bioassay experiment confirmed that no abnormalities and acute toxic reactions occurred in shortfin molly fish (Poecilia sphenops) fed with dried leaves of red hot chili pepper plants grown with formulated fertilizers. This study showcased a pioneering investigation into the synthesis of microcapsules using synthesized hydrogel beads along with digital image processing for bio-waste management and sustainable agro-application.

Chitosan-graphene quantum dot-based molecular imprinted polymer for oxaliplatin release

Molecularly imprinted polymers (MIPs) have garnered the interest of researchers in the drug delivery due to their advantages, such as exceptional durability, stability, and selectivity. In this study, a biocompatible MIP drug adsorption and delivery system with high loading capacity and controlled release, was prepared based on chitosan (CS) and graphene quantum dots (GQDs) as the matrix, and the anticancer drug oxaliplatin (OXAL) as the template. Additionally, samples without the drug (non-imprinted polymers, NIPs) were created for comparison. GQDs were produced using the hydrothermal method, and samples underwent characterization through FTIR, XRD, FESEM, and TGA. Various experiments were conducted to determine the optimal pH for drug adsorption, along with kinetic and isotherm studies, selectivity assessments, in vitro drug release and kinetic evaluations. The highest drug binding capacity was observed at pH 6.5. The results indicated the Lagergren-first-order kinetic model (with rate constant of 0.038 min-1) and the Langmuir isotherm (with maximum adsorption capacity of 17.15 mg g-1) exhibited better alignment with the experimental data. The developed MIPs displayed significant selectivity towards OXAL, by an imprinting factor of 2.88, in comparison to two similar drugs (cisplatin and carboplatin). Furthermore, the analysis of the drug release profile showed a burst release for CS-Drug (87% within 3 h) at pH 7.4, where the release from the CS-GQD-Drug did not occur at pH 7.4 and 10; instead, the release was observed at pH 1.2 in a controlled manner (100% within 28 h). Consequently, this specific OXAL adsorption and delivery system holds promise for cancer treatment.

Influence of Chitosan on the Viability of Encapsulated and Dehydrated Formulations of Vegetative Cells of Actinomycetes

This study focuses on developing an encapsulated and dehydrated formulation of vegetative actinobacteria cells for an efficient application in sustainable agriculture, both as a fungicidal agent in crop protection and as a growth-stimulating agent in plants. Three strains of actinobacteria were used: one from a collection (Streptomyces sp.) and two natives to agricultural soil, which were identified as S3 and S6. Vegetative cells propagated in a specific liquid medium for mycelium production were encapsulated in various alginate-chitosan composites produced by extrusion. Optimal conditions for cell encapsulation were determined, and cell damage from air-drying at room temperature was evaluated. The fresh and dehydrated composites were characterized by porosity, functional groups, size and shape, and their ability to protect the immobilized vegetative cells' viability. Actinomycetes were immobilized in capsules of 2.1-2.7 mm diameter with a sphericity index ranging from 0.058 to 0.112. Encapsulation efficiency ranged from 50% to 88%, and cell viability after drying varied between 44% and 96%, depending on the composite type, strain, and airflow. Among the three immobilized and dried strains, S3 and S6 showed greater resistance to encapsulation and drying with a 4 L·min-1 airflow when immobilized in coated and core-shell composites. Encapsulation in alginate-chitosan matrices effectively protects vegetative actinobacteria cells during dehydration, maintaining their viability and functionality for agricultural applications.

Incorporation of carboxymethyl chitosan (CMCS) for the modulation of physio-chemical characteristics and cell proliferation environment of the composite hydrogel microspheres

Hydrogels have excellent swelling properties and have been widely applied in tissue engineering because of their similarity to the extracellular matrix (ECM). Sodium alginate (SA) and carboxymethyl chitosan (CMCS) were prepared into hydrogel microspheres with Ca2+crosslinking in our study. The morphology, inner structure, mechanical properties, water content, swelling rate and BMP-2 loading and releasing properties were characterized. Our results showed that the composite SA /CMCS hydrogel microspheres were translucent and spherical in shape with uniform particle size. The incorporation of CMCS further increased the diameters of the microspheres, internal pore structure, water content, and mechanical properties of the SA/CMCS hydrogel microspheres. At the same SA concentration, with the increase of CMSC concentration, the diameter of microspheres could be increased by about 0.4 mm, the water content can be increased about 1%-2%. As for the mechanical properties, the compressive strength can be increased by 0.04-0.1 MPa, and the modulus of elasticity can be increased by 0.1-0.15 MPa. BMP-2 was chosen as a model agent and it could be loaded into SA/CMCS microspheres, and the incorporation of CMCS increased BMP-2 loading. The encapsulated BMP-2 was sustainably releasedin vitro. The leaching solutions of the SA/CMCS hydrogel microspheres exhibited good cytocompatibility and could increase ALP activity, ALP expression, and biomineralization on MC3T3-E1 cells. After 7 d of co-culture, ALP activities in S2.5C2 and S2.5C3 groups was increased by 50% and 45% compared with that of the control group. When embedded in the SA/CMCS microspheres, the MC3T3-E1 cells were evenly distributed inside the hydrogel microspheres and remained viable. Transcriptomic studies showed that incorporation of CMCS induced upregulation of 1141 differentially expressed genes (DEGs) and downregulation of 1614 DEGs compared with SA microspheres. The most significantly enriched pathways were the Wnt and MAPK signaling pathways induced by the incorporation of CMCS and BMP-2. In conclusion, our results indicated that the physiochemical characteristics of the SA hydrogel microspheres could be greatly modulated by CMCS to better mimic the ECM microenvironment and induce osteo-inductive activities of MC3T3-E1 cells.

Transforming the Stability, Encapsulation, and Sustained Release Properties of Calcium Alginate Beads through Gel-Confined Coacervation

Calcium alginate (Ca2+/alginate) gel beads find use in diverse applications, ranging from drug delivery and tissue engineering to bioprocessing, food formulation, and agriculture. Unless modified, however, these gels have limited stability in alkaline media (including phosphate buffers), and their high solute permeability limits their ability to efficiently encapsulate and slowly release water-soluble small molecules. Here, we show how these limitations can be addressed by mixing the alginate solutions used in the bead preparation with the nontoxic anionic polymer polyphosphate (PP). Upon complexing Ca2+ ions, PP undergoes complex coacervation (i.e., liquid/liquid phase separation into a Ca2+/PP-rich coacervate phase and a dilute supernatant phase). At lower PP concentrations, the Ca2+/PP coacervate appears to simply remain dispersed within the beads. Though its presence makes the beads more stable in alkaline media (phosphate-buffered saline and seawater), it has little impact on the bead stiffness, morphology, and (at least in the absence of substantial payload/coacervate association) encapsulation and release properties. When the PP concentrations exceed a critical value, however, Ca2+/PP coacervation within the gelling Ca2+/alginate beads collapses the resulting beads into more compact, interpenetrating polymer networks. Besides their enhanced stability to alkaline environments, these hybrid beads exhibit irregular morphologies with wrinkled and dimpled surface structures and macroscopic (closed) internal pores, and their collapse into these polymer-rich networks also makes them significantly stiffer than their PP-free counterparts. Crucially, these beads also exhibit a much lower solute permeability, which enables highly efficient encapsulation and multiday release of water-soluble small molecules (with the beads encapsulating >90% of the added model payload and sustaining its release over 3-5 d). Collectively, these findings provide a mild and simple (single-step) pathway to generating ionically cross-linked alginate beads with significantly enhanced stability, encapsulation efficiency, and sustained release.

Chitosan for improved encapsulation of thyme aqueous extract in alginate-based microparticles

Ionotropic gelation is a low-cost, easy and green microencapsulation technique. However, the encapsulation of highly soluble compounds is challenging because of the wide loss of material into the external water phase by passive diffusion and the consequent low encapsulation efficiency. In this work an important increase of encapsulation efficiency for Thymus vulgaris L. aqueous extract in alginate-based microparticles has been obtained. A formulation with the proper thyme extract/alginate ratio (30:70) was used as reference and then optimized by adding different co-carrier excipients. Microparticles obtained by dropping a solution containing thyme extract and alginate into a chitosan/calcium-chloride/acid acetic solution lead to a high encapsulation efficiency (70.43 ± 5.28 %). After drying, microparticles had a particle size of 1096 ± 72 μm, 20.087 ± 1.487 % of extract content, 6.2 % of residual water, and showed a complete release of thyme extract within one hour. Combining alginate and chitosan as polymeric co-carrier was a valuable option for efficiently encapsulating an aqueous extract by ionotropic gelation.

Encapsulation in Alginates Hydrogels and Controlled Release: An Overview

This review aims to gather the current state of the art on the encapsulation methods using alginate as the main polymeric material in order to produce hydrogels ranging from the microscopic to macroscopic sizes. The use of alginates as an encapsulation material is of growing interest, as it is fully bio-based, bio-compatible and bio-degradable. The field of application of alginate encapsulation is also extremely broad, and there is no doubt it will become even broader in the near future considering the societal demand for sustainable materials in technological applications. In this review, alginate's main properties and gelification mechanisms, as well as some factors influencing this mechanism, such as the nature of the reticulation cations, are first investigated. Then, the capacity of alginate gels to release matter in a controlled way, from small molecules to micrometric compounds, is reported and discussed. The existing techniques used to produce alginates beads, from the laboratory scale to the industrial one, are further described, with a consideration of the pros and cons with each techniques. Finally, two examples of applications of alginate materials are highlighted as representative case studies.

Multi-layer encapsulation of pumpkin (Cucurbita maxima L.) seed protein hydrolysate and investigating its release and antioxidant activity in simulated gastrointestinal digestion

Because of their high protein content, easy access and low cost, pumpkin seeds are a valuable raw material for the preparation of antioxidant protein hydrolysates. Micro-coating is an effective method to protect bioactive compounds against destruction. In order to strengthen the alginate hydrogel network loaded with pumpkin seed protein hydrolysate (PSPH), CMC was added as part of its formulation in the first step, and chitosan coating was used in the second step. Then, swelling amount, release in the simulated gastrointestinal environment (SGI), antioxidant activity after SGI, Fourier transform infrared spectroscopy (FTIR), zeta potential, dynamic light scattering (DLS), polydispersity index (PDI) and scanning electron microscopy (SEM) of the samples were evaluated. The results showed that, the swelling amount of the chitosan-alginate hydrogel was lower than the chitosan-alginate-CMC sample, and with the increase in chitosan concentration, the swelling amount decreased. The release amount in the chitosan-alginate sample was higher than that in the chitosan-alginate-CMC sample, and with the increase in chitosan concentration, the release rate decreased. Also, the amount of release increased with the passage of time. The highest antioxidant activity belonged to the chitosan-alginate sample in SGI, and it increased with increasing the chitosan concentration. All findings demonstrated that the use of multi-component hybrid systems is a useful method for the protection of bioactive compounds against destruction, their antioxidant activities and their release behavior.

Anionic species from multivalent metal salts are differentially retained during aqueous ionic gelation of sodium alginate and could fine-tune the hydrogel properties

The role of anionic counterions of divalent metal salts in alginate gelation and hydrogel properties has been thoroughly investigated. Three anions were selected from the Hofmeister series, namely sulphate, acetate and chloride, paired in all permutations and combinations with divalent metal cations like calcium, zinc and copper. Spectroscopic analysis revealed the presence of anions and their interaction with the respective metal cations in the hydrogel. The data showed that the gelation time and other hydrogel properties were largely controlled by cations. However, subtle yet significant variations in viscoelasticity, water uptake, drug release and cytocompatibility properties were anion dependent in each cationic group. Computational modelling based study showed that metal-anion-alginate configurations were energetically more stable than the metal-alginate models. The in vitro and in silico studies concluded that acetate anions preceded chlorides in the drug release, swelling and cytocompatibility fronts, followed by sulphate anions in each cationic group. Overall, the data confirmed that anions are an integral part of the metal-alginate complex. Furthermore, anions offer a novel option to further fine-tune the properties of alginate hydrogels for myriads of applications. In addition, full exploration of this novel avenue would enhance the usability of alginate polymers in the pharmaceutical, environmental, biomedical and food industries.

Metal-polyphenol microgels for oral delivery of puerarin to alleviate the onset of diabetes

Puerarin (Pue) is a naturally bioactive compound with many potential functions in regulating blood glucose and lipid metabolism. However, the low bioavailability and rapid elimination in vivo limit the application of Pue in diabetic treatment. Here, we developed a metal-polyphenol-functionalized microgel to effectively deliver Pue in vivo and eventually alleviate the onset of diabetes. Pue was initially encapsulated in alginate beads through electrospray technology, and further immersed in Fe3+ and tannic acid solution from tannic acid (TA)-iron (Fe) coatings (TF). These constructed Pue@SA-TF microgels exhibited uniform spheres with an average size of 367.89 ± 18.74 µm and high encapsulation efficiency of Pue with 61.16 ± 1.39%. In vivo experiments proved that compared with free Pue and microgels without TF coatings, the biological distribution of Pue@SA-TF microgels specifically accumulated in the small intestine, prolonged the retention time of Pue, and achieved a high effectiveness in vivo. Anti-diabetic experimental results showed that Pue@SA-TF microgels significantly improved the levels of blood glucose, blood lipid, and oxidative stress in diabetic mice. Meanwhile, histopathological observations indicated that Pue@SA-TF microgels could significantly alleviate the damage to the liver, kidney, and pancreas in diabetic mice. Our study provided an effective strategy for oral delivery of Pue and achieved high anti-diabetic efficacy.

Effect of Molecules' Physicochemical Properties on Whey Protein/Alginate Hydrogel Rheology, Microstructure and Release Profile

The encapsulation of molecules with different physicochemical properties (theophylline, blue dextran, salicylic acid and insulin) in whey protein (WP) and alginate (ALG) microparticles (MP) for oral administration was studied. MP based on WP/ALG were prepared by a cold gelation technique and coated with WP solution after reticulation. Molecules influenced polymer solution viscosity and elasticity, resulting in differences regarding encapsulation efficiency (from 23 to 100%), MP structure and swelling (>10%) and in terms of pH tested. Molecule release was due to diffusion and/or erosion of MP and was very dependent on the substance encapsulated. All the loaded MP were successfully coated, but variation in coating thickness (from 68 to 146 µm) and function of the molecules encapsulated resulted in differences in molecule release (5 to 80% in 1 h). Gel rheology modification, due to interactions between WP, ALG, calcium and other substances, was responsible for the highlighted differences. Measuring rheologic parameters before extrusion and reticulation appeared to be one of the most important aspects to study in order to successfully develop a vector with optimal biopharmaceutical properties. Our vector seems to be more appropriate for anionic high-molecular-weight substances, leading to high viscosity and elasticity and to MP enabling gastroresistance and controlled release of molecules at intestinal pH.

Alginate-Based Carriers Loaded with Mulberry (Morus alba L.) Leaf Extract: A Promising Strategy for Prolonging 1-Deoxynojirimicyn (DNJ) Systemic Activity for the Nutraceutical Management of Hyperglycemic Conditions

The iminosugar 1-deoxynojirimicyn (DNJ) contained in mulberry leaves has displayed systemic beneficial effects against disorders of carbohydrate metabolism. Nevertheless, its effect is impaired by the short half-life. Alginate-based carriers were developed to encapsulate a DNJ-rich mulberry extract: Ca-alginate beads, obtained by external gelation, and spray-dried alginate microparticles (SDMs). Mean size and distribution, morphology, drug loading, encapsulation efficiency, experimental yield, and release characteristics were determined for the two formulations. Ca-alginate beads and SDMs exhibited an encapsulation efficiency of about 54% and 98%, respectively, and a DNJ loading in the range of 0.43-0.63 μg/mg. The in vitro release study demonstrated the carriers' capability in controlling the DNJ release in acid and basic conditions (<50% in 5 h), due to electrostatic interactions, which were demonstrated by 1H-NMR relaxometry studies. Thus, alginate-based particles proved to be promising strategies for producing food supplements containing mulberry leaf extracts for the management of hyperglycemic state.

Carboxymethyl konjac glucomannan-chitosan complex nanogels stabilized emulsions incorporated into alginate as microcapsule matrix for intestinal-targeted delivery of probiotics: In vivo and in vitro studies

In this study, we developed a novel delivery system using carboxymethyl konjac glucomannan-chitosan (CMKGM-CS) nanogels stabilized single and double emulsion incorporated into alginate hydrogel as microcapsule matrix for intestinal-targeted delivery of probiotics. Through in vitro experiments, it was demonstrated that alginate hydrogel provided favorable biocompatible growth conditions for the proliferation of Lactobacillus reuteri (LR). The alginate hydrogel containing single (ASE) or double emulsions (ACG) enhanced the resistance of LR to various adverse environments. Simulated gastrointestinal digestion experiments revealed that the survivability of LR in free, CON, ASE and ACG group decreased by 6.45 log CFU/g, 4.21 log CFU/g, 1.26 log CFU/g and 0.65 log CFU/g, respectively. In vivo studies conducted in mice showed that ACG maintained its integrity during passage through the stomach and released the probiotics in the targeted intestinal area, whereas the pure alginate hydrogels (CON) were prematurely released in the gastrointestinal tract. Moreover, the viable counts of ACG in different intestinal segments (jejunum, ileum, cecum, and colon) were increased by 1.11, 1.42, 1.68, and 1.89 log CFU/g, respectively, after 72 h of oral administration compared to the CON group. This research contributed valuable insights into the development of an effective microbial delivery system with potential applications in the biopharmaceutical and food industries.

Development of Efficient Sodium Alginate/Polysuccinimide-Based Hydrogels as Biodegradable Acetaminophen Delivery Systems

Efficient drug delivery systems are essential for improving patient outcomes. Acetaminophen (AP), which is a kind of oral administration, is a commonly used pain reliever and fever reducer. However, oral administration carries various health risks, especially overdose and frequent use; for instance, AP is administered approximately 4 times per day. Therefore, the aim of this study is to develop an efficient delivery system for once-daily administration by combining sodium alginate and polysuccinimide (PSI) hydrogels to delay the release of analgesic AP. PSI is a biodegradable polymer that can be used safely and effectively in drug delivery systems because it is eliminated by hydrolysis in the intestine. The use of PSI also improves the mechanical properties of hydrogels and prolongs drug release. In this study, hydrogel characterizations such as mechanical properties, drug dissolution ability, and biodegradability were measured to evaluate the hydrolysis of PSI in the intestine. Based on the results, hydrogels could be designed to improve the structural mechanical properties and to allow the drug to be completely dissolved, and eliminated from the body through PSI hydrolysis in the intestines. In addition, the release profiles of AP in the hydrogels were evaluated, and the hydrogels provided continuous release of AP for 24 h. Our research suggests that sodium alginate/PSI hydrogels can potentially serve as biodegradable delivery systems for AP. These findings may have significant implications for developing efficient drug delivery systems for other classes of drugs.

Biomimetic Apatite/Natural Polymer Composite Granules as Multifunctional Dental Tissue Regenerative Material

This study presents a comprehensive evaluation of novel composite biomaterials designed for dental applications, aiming to potentially address the prevalent challenge of dental and periodontal tissue loss. The composites consisted of biomimetic hydroxyapatite (mHA) enriched with Mg2+, CO32-, and Zn2+ ions, type I collagen, alginate, and, additionally, chitosan and sericin. The granules were loaded with ibuprofen sodium salt. The investigation encompassed a morphology characterization, a porosity analysis, a chemical structure assessment, and an examination of the swelling behavior, drug release kinetics (ibuprofen), and release profiles of zinc and magnesium ions. The granules exhibited irregular surfaces with an enhanced homogeneity in the chitosan-coated granules and well-developed mesoporous structures. The FT-IR spectra confirmed the presence of ibuprofen sodium, despite overlapping bands for the polymers. The granules demonstrated a high water-absorption capacity, with delayed swelling observed in the chitosan-coated granules. Ibuprofen displayed burst-release profiles, especially in the G1 and G3 samples. In the case of the chitosan-coated granules (G2 and G4), lower amounts of ibuprofen were released. In turn, there was a significant difference in the released amount of magnesium and zinc ions from the granules, which was most likely caused by their different location in the hydroxyapatite crystals. The cytotoxicity assays confirmed the non-cytotoxic behavior of the biomaterial. These findings suggest the potential applicability of these biomaterials in dental scenarios, emphasizing their multifunctional and biocompatible nature.

A chitosan-coated lentinan-loaded calcium alginate hydrogel induces broad-spectrum resistance to plant viruses by activating Nicotiana benthamiana calmodulin-like (CML) protein 3

Control of plant virus diseases largely depends on the induced plant defence achieved by the external application of synthetic chemical inducers with the ability to modify defence-signalling pathways. However, most of the molecular mechanisms underlying these chemical inducers remain unknown. Here, we developed a chitosan-coated lentinan-loaded hydrogel and discovered how it protects plants from different virus infections. The hydrogel was synthesized by coating chitosan on the surface of the calcium alginate-lentinan (LNT) hydrogel (SL-gel) to form a CSL-gel. CSL-gels exhibit the capacity to prolong the stable release of lentinan and promote Ca2+ release. Application of CSL-gels on the root of plants induces broad-spectrum resistance against plant viruses (TMV, TRV, PVX and TuMV). RNA-seq analysis identified that Nicotiana benthamiana calmodulin-like protein gene 3 (NbCML3) is upregulated by the sustained release of Ca2+ from the CSL-gel, and silencing and overexpression of NbCML alter the susceptibility and resistance of tobacco to TMV. Our findings provide evidence that this novel and synthetic CSL-gel strongly inhibits the infection of plant viruses by the sustainable release of LNT and Ca2+ . This study uncovers a novel mode of action by which CSL-gels trigger NbCML3 expression through the stable and sustained release of Ca2+ .

Adsorptive exclusion of crystal violet dye using barium encapsulated alginate/carbon composites: characterization and adsorption modeling studies

The present study is devoted to the removal of crystal violet dye using the synthesized barium alginate/carbon composites abbreviated as BA (barium alginate), BAAC (barium alginate/activated carbon), BASC (barium alginate/starch carbon), and BASSC (barium alginate/starch carbon modified with CTAB). The adsorptive removal of crystal violet as a function of contact time, pH of solution, composite dose, initial dye concentration, and temperature was studied. The uptake of crystal violet (CV) dye for the composites was recorded in the range of 36 mg g-1 to 50 mg g-1 at pH 8.03 ± 0.03 for an equilibrium time of 120 min. The adsorption kinetics and isotherms in compliance with the CV sorption onto BA/carbon composites corroborated the utmost fit of pseudo-second-order and Freundlich isotherm models, respectively. The recycling process was achieved using the barium alginate-treated bead carbons for different initial CV dye concentrations of 10-30 mg L-1 with a scope of zero disposal. The practicability of BA/carbon composites in a groundwater sample spiked with 30 mg L-1 of CV was successfully achieved with a removal efficiency of about 65-74%. Characterization studies for the composites using FTIR, SEM (with EDS), XRD, TGA, and BET were carried out and discussed in the paper.

Recent developments in natural biopolymer based drug delivery systems

Targeted delivery of drug molecules to diseased sites is a great challenge in pharmaceutical and biomedical sciences. Fabrication of drug delivery systems (DDS) to target and/or diagnose sick cells is an effective means to achieve good therapeutic results along with a minimal toxicological impact on healthy cells. Biopolymers are becoming an important class of materials owing to their biodegradability, good compatibility, non-toxicity, non-immunogenicity, and long blood circulation time and high drug loading ratio for both macros as well as micro-sized drug molecules. This review summarizes the recent trends in biopolymer-based DDS, forecasting their broad future clinical applications. Cellulose chitosan, starch, silk fibroins, collagen, albumin, gelatin, alginate, agar, proteins and peptides have shown potential applications in DDS. A range of synthetic techniques have been reported to design the DDS and are discussed in the current study which is being successfully employed in ocular, dental, transdermal and intranasal delivery systems. Different formulations of DDS are also overviewed in this review article along with synthesis techniques employed for designing the DDS. The possibility of these biopolymer applications points to a new route for creating unique DDS with enhanced therapeutic qualities for scaling up creative formulations up to the clinical level.

Ionically bridged dexamethasone sodium phosphate-zinc-PLGA nanocomplex in alginate microgel for the local treatment of ulcerative colitis

Colon-targeted oral drug delivery systems comprising nanoparticles and microparticles have emerged as promising tools for the treatment of ulcerative colitis (UC) because they minimize side effects and maximize the local drug concentration. Dexamethasone sodium phosphate (DSP) is a potent anti-inflammatory glucocorticoid used for the treatment of UC. However, it remains a rather short-term treatment option owing to its side effects. In the present study, we developed the alginate gel encapsulating ionically bridged DSP-zinc-poly(lactic-co-glycolic acid) (PLGA) nanocomplex (DZP-NCs-in-microgel) for the oral local treatment of UC. The successful encapsulation of DSP-zinc-PLGA nanocomplex (DZP-NCs) in alginate microgel was confirmed by SEM imaging. The prepared gel released DZP-NCs in the stimulated intestinal fluid and dampened the release of DSP in the upper gastrointestinal tract. Furthermore, DZP-NCs-in-microgel alleviated colonic inflammation in a mouse model of dextran sodium sulfate-induced colitis by relieving clinical symptoms and histological marks. Our results suggest a novel approach for the oral colon-targeted delivery of dexamethasone sodium phosphate for the treatment of UC.

Celastrol-encapsulated microspheres prepared by microfluidic electrospray for alleviating inflammatory pain

Inflammatory pain is induced by trauma, infection, chemical stimulation, etc. It causes severe physical and psychological agony to patients. Celastrol has powerful anti-inflammatory property and has achieved good results in various inflammation-related diseases. However, the low water solubility and multi-system toxicity limit its clinical application. Herein, we proposed alginate microspheres with core-shell structure which encapsulated celastrol by microfluidic electrospray to effectively overcome the shortcomings and improve the therapeutic effect. The microspheres had uniform size and good biocompatibility, and could release the loaded drugs in the gut. The behavioral tests showed that the celastrol-loaded microspheres effectively alleviated inflammatory pain, and the hematoxylin and eosin staining (HE staining), immunofluorescence and detection of inflammatory cytokines showed the anti-inflammatory effect. These results indicated that the microspheres could reduce dose and toxicity without affecting efficacy, and facilitate the application of celastrol in different clinical situations.

Producing mixed-soy protein adsorption layers on alginate microgels to controlled-release β-carotene

In this study, the effects of soy protein isolate (SPI) on the morphology, encapsulation efficiency, storage stability, swelling behavior, and in vitro digestion behavior of calcium alginate (CA) microgels were investigated. CA and calcium alginate-SPI (CAS) microgels with encapsulated β-carotene were prepared by extruding a mixture of alginate and SPI using a co-extrusion technique, followed by cross-linking with Ca²⁺. All microgels exhibited homogeneous sizes and spherical shapes, and CAS microgels showed high levels of protein loading efficiency. The encapsulation efficiency and storage stability of β-carotene within CAS microgels were higher than those within CA microgels. The introduction of SPI into CAS microgels resulted in a higher degree of gel size shrinkage in gastric fluid and a lower degree of swelling in intestinal fluid compared to CA microgels. In vitro digestion was conducted to investigate the effects of the addition of SPI on the release behavior of CA and CAS microgels. Results obtained showed that CAS microgels were more resistant to simulated gastric fluid than CA microgels. Cryo-scanning electron microscopy (cryo-SEM) and confocal laser scanning microscopy (CLSM) observations indicated that the release behavior was dependent on the porosity of the CA and CAS microgels, and the porosity was influenced by the concentration of SPI. This study showed that the introduction of SPI to CA microgels can lead to the development of an effective controlled release delivery system.

Polymeric Nanogel for Oral Delivery of the Chemotherapeutic Agent: Fabrication and Evaluation Alongside Toxicological Studies and Histopathological Examination

Nanogel has attracted considerable attention as one of the most versatile drug delivery systems, especially for site-specific and/or time-controlled delivery of the chemotherapeutic agent. The main objective of this study was to prepare the polymeric nanogel characterized by Fourier transform infrared spectroscopy, x-ray diffraction, thermogravimetric analysis, differential scanning, and oral acute toxicity. Free radical polymerization was done for the fabrication of polymeric nanogel. Fourier transform infrared spectroscopy was used to confirm the successful free radical polymerization. Various techniques such as x-ray diffraction, differential scanning calorimetric, and thermogravimetric analysis measurement were used to investigate the thermal behavior and crystallinity of developed nanogel. Parameters such as swelling, drug loading, and in vitro drug release is enhanced as polymers and monomers concentrations increase while these parameters decrease in case of increasing crosslinker concentration. The oral biocompatibility results of developed nanogel exhibited no toxicity in rabbits. Histopathological changes were observed between empty and loaded group. The nanosized gel offers a specific surface area which increases the stability of loaded drug (oxaliplatin) and bioavailability of the drug (oxaliplatin) as compared to the conventional drug delivery systems.

Study on physical properties of four pH responsive Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) microcapsules as controlled release carriers

This study provides a promising controlled release form of nuclear polyhedrosis virus (NPV) for targeted control of lepidopteran pests. However, the application of NPV is limited due to its sensitivity to UV inactivation. This study investigated the anti-UV properties of microcapsules of SeMNPV occlusion bodies (OBs) encapsulated by calcium alginate (CA), and also the influence of the modification of CA by chitosan (CS), whey protein (WP), and polydopamine (PDA). These capsules were used to deliver, in a controlled release manner virions under alkaline pH conditions. Characterization of the structure, morphology, particle size, encapsulation efficiency, contact angle, insecticidal activity, UV resistance and in vitro release of the microcapsules was conducted. The modified microcapsules had better sphericity, and were devoid of SeMNPV OBs on the surface. The encapsulation rate was 84.76 ± 0.59%. PDA@CA-NPV had the highest wettability and the contact angle was 74.51 ± 0.53°. The 50% lethal concentration values (LC₅₀) of CA-NPV, CS@CA-NPV, WP@CA-NPV and PDA@CA-NPV were 11.5, 10.7, 10.5 and 1.2 times that of SeMNPV OBs alone. The modified microcapsules all improved the anti-UV performance of the virus, and PDA@CA-NPV was the most UV-resistant. Using qPCR, it was observed that under alkaline conditions, a large number of virions were released from PDA@CA-NPV, CA-NPV and SeMNPV OBs. Microencapsulated virus under alkaline conditions did not change the release pattern of virions.

Rapid and label-free Listeria monocytogenes detection based on stimuli-responsive alginate-platinum thiomer nanobrushes

In this work, we demonstrate the development of a rapid and label-free electrochemical biosensor to detect Listeria monocytogenes using a novel stimulus-response thiomer nanobrush material. Nanobrushes were developed via one-step simultaneous co-deposition of nanoplatinum (Pt) and alginate thiomers (ALG-thiomer). ALG-thiomer/Pt nanobrush platform significantly increased the average electroactive surface area of electrodes by 7 folds and maintained the actuation properties (pH-stimulated osmotic swelling) of the alginate. Dielectric behavior during brush actuation was characterized with positively, neutral, and negatively charged redox probes above and below the isoelectric point of alginate, indicating ALG-thiomer surface charge plays an important role in signal acquisition. The ALG-thiomer platform was biofunctionalized with an aptamer selective for the internalin A protein on Listeria for biosensing applications. Aptamer loading was optimized and various cell capture strategies were investigated (brush extended versus collapsed). Maximum cell capture occurs when the ALG-thiomer/aptamer is in the extended conformation (pH > 3.5), followed by impedance measurement in the collapsed conformation (pH < 3.5). Low concentrations of bacteria (5 CFU mL-1) were sensed from a complex food matrix (chicken broth) and selectivity testing against other Gram-positive bacteria (Staphylococcus aureus) indicate the aptamer affinity is maintained, even at these pH values. The new hybrid soft material is among the most efficient and fastest (17 min) for L. monocytogenes biosensing to date, and does not require sample pretreatment, constituting a promising new material platform for sensing small molecules or cells.

Alginate Particles for Encapsulation of Phenolic Extract from Spirulina sp. LEB-18: Physicochemical Characterization and Assessment of In Vitro Gastrointestinal Behavior

Encapsulation can be used as a strategy to protect and control the release of bioactive extracts. In this work, an extract from Spirulina sp. LEB-18, rich in phenolic compounds, was encapsulated in biopolymeric particles (i.e., composed of alginate) and characterized concerning their thermal behavior using differential scanning calorimetry (DSC), size, morphology, swelling index (S), and encapsulation efficiency (EE%); the release profile of the phenolic compounds at different pHs and the particle behavior under in vitro gastrointestinal digestion were also evaluated. It was shown that it is possible to encapsulate the phenolic extract from Spirulina sp. LEB-18 in alginate particles with high encapsulation efficiency (88.97%). It was also observed that the particles are amorphous and that the encapsulated phenolic compounds were released at a pH 7.2 but not at pH 1.5, which means that the alginate particles are able to protect the phenolic compounds from the harsh stomach conditions but lose their integrity under intestinal pH conditions. Regarding bioaccessibility, it was observed that the encapsulated phenolic compounds showed higher bioaccessibility compared to phenolic compounds in free form. This work increases the knowledge about the behavior of alginate particles encapsulating phenolic compounds during in vitro gastrointestinal digestion. It also provides essential information for designing biopolymeric particle formulations encapsulating phenolic compounds for application in pharmaceutical and food products.

Prestrain Programmable 4D Printing of Nanoceramic Composites with Bioinspired Microstructure

Four-dimensional (4D) printing enables programmable, predictable, and precise shape change of responsive materials to achieve desirable behaviors beyond conventional three-dimensional (3D) printing. However, applying 4D printing to ceramics remains challenging due to their intrinsic brittleness and inadequate stimuli-responsive ability. Here, this work proposes a conceptional combination of bioinspired microstructure design and a programmable prestrain approach for 4D printing of nanoceramics. To overcome the flexibility limitation, the bioinspired concentric cylinder structure in the struts of 3D printed lattices are replicated to develop origami nanoceramic composites with high inorganic content (95 wt%). Furthermore, 4D printing is achieved by applying a programmed prestrain to the printed lattices, enabling the desired deformation when the prestrain is released. Due to the bioinspired concentric cylinder microstructures, the printed flexible nanoceramic composites exhibit superior mechanical performance and anisotropic thermal management capability. Further, by introducing oxygen vacancies to the ceramic nanosheets, conductive nanoceramic composites are prepared with a unique sensing capability for various sensing applications. Hence, this research breaks through the limitation of ceramics in 4D printing and achieves high-performance shape morphing materials for applications under extreme conditions, such as space exploration and high-temperature systems.

Design, development and characterization of interpenetrating polymer network hydrogel bead for controlled release of glipizide drug

In the current study, a novel interpenetrating polymer network (IPN) hydrogel bead was developed by encapsulation of antidiabetic drug glipizide using sodium alginate (SAL) and xanthan gum (XAG) biopolymers by ionotropic gelation technique with calcium chloride as cross-linking agent. In light of the fact that IPN hydrogel beads posses greater benefits in controlling the release of such short acting drug, sodium alginate and xanthan gum IPN hydrogel beads were prepared at different mass ratios (SAL:XAG =10:0, 9:1, 8:2, 7:3, 6:4, 5:5). Similarly, drug-loaded IPN hydrogel beads were also developed. The prepared hydrogel beads were investigated using Fourier transform infrared spectroscopy, X-ray powder diffraction, and thermogravimetric studies to understand the type of interactions between the composite beads. Surface morphology changes were studied by scanning electron microscopy. The particle size, drug entrapment efficiency, and swelling behavior of prepared hydrogel beads were also studied. Based on In-vitro drug dissolution studies, it was observed that SXF4 preparation containing SAL and XAG polymers at 7:3 ratio showed extended drug release of 97.53% at 9 h. This study demonstrated that inclusion of XAG has extended the drug release and able to achieve zero-order drug release profile.

Impact of internal aqueous phase gelation on in vitro lipid digestion of epigallocatechin gallate-loaded W1 /O/W2 double emulsions incorporated in alginate hydrogel beads

Our objective was to investigate if the internal aqueous phase gelation of Water-in-oil-in-water double emulsions encapsulated in alginate beads would affect their structural stability and lipid hydrolysis during in vitro digestion. Therefore, bioactive molecules such as (-)-epigallocatechin gallate were encapsulated into different types of delivery systems: original double emulsions (as control) and incorporated double emulsions (filled in alginate hydrogel beads), both with non-gelled or gelled internal aqueous phase by locust bean gum and κ-carrageenan. After 2 h of gastric digestion, the gelled original emulsions showed smaller mean droplet diameters and less coalescence during the in vitro simulated gastrointestinal digestion compared to the non-gelled original emulsions. For the incorporated emulsions, oil droplets released from beads aggregated under intestinal conditions, and the rate of lipolysis was delayed. Interestingly, the internal aqueous phase gelation also impacted the rate and cumulative amount of free fatty acids (FFA) released. PRACTICAL APPLICATION: The combination of incorporating (-)-epigallocatechin gallate-loaded double emulsions into the alginate hydrogel matrix and gelling the internal aqueous phase was a benefit to regulating the rate and extent of lipid digestion for specific applications in foods, such as to control blood lipid levels and appetite.

Development of a calcium alginate-cellulose nanocrystal-based coating to reduce the impact of oil spills on shorelines

It is well known that oil stranded on shoreline substrates can be difficult to remove and cause serious environmental effects. To address this issue, a calcium alginate-cellulose nanocrystal (CA-CNC)-based coating with a unique surface structure and superhydrophobic properties was developed to reduce the extent of shoreline oiling. The results of batch washing test showed that not only did the introduction of CNC not reduce the oil removal efficiency; it also improved the environmental stability of the coating to resist the effects associated with seawater immersion and erosion (especially in the case of 0.4 wt% of CNC). The oil-repellent performance of the coated gravels implied that both oscillation time and oil concentration had almost no effects on the amount of adhered oil. Assessment of oiling prevention based on the laboratory shoreline tank simulator proved the coated gravel performed very well as more oil floated and less oil remained on substrates and penetrated into the subsurface. Biotoxicity analysis showed that the coating powders reduced impacts on the toxicity of the oil to algae at low doses. There is a good potential for the use of this CA-CNC based coating technique to improve shoreline oil spill response.

Preparation and Characterization of Methyl Jasmonate Microcapsules and Their Preserving Effects on Postharvest Potato Tuber

Potato tubers tend to sprout during long-term storage, resulting in quality deterioration and shortened shelf life. Restrictions on the use of chlorpropham, the major potato sprout suppressant, have led to a need to seek alternative methods. In this study, the effects of methyl jasmonate (MeJA) solutions and MeJA microcapsules on sprouting and other key quality attributes of the potato tuber were investigated. The results showed that the MeJA solution was most effective at 300 μmol L⁻¹ according to TOPSIS analysis. To prepare MeJA microcapsules, the optimal formulation is with 0.04% emulsifier, 2.5% sodium alginate, 0.5% chitosan and 3% CaCl₂. Compared to 300 μmol L⁻¹ MeJA solution, MeJA microcapsules consumed a lower dose of MeJA but demonstrated a better retaining effect on the overall quality attributes of potato tubers. MeJA microcapsules are promising agents for the preservation of postharvest potato tubers.

Design of chemically defined synthetic substrate surfaces for the in vitro maintenance of human pluripotent stem cells: A review

Human pluripotent stem cells (hPSCs) have the potential of long-term self-renewal and differentiation into nearly all cell types in vitro. Prior to the downstream applications, the design of chemically defined synthetic substrates for the large-scale proliferation of quality-controlled hPSCs is critical. Although great achievements have been made, Matrigel and recombinant proteins are still widely used in the fundamental research and clinical applications. Therefore, much effort is still needed to improve the performance of synthetic substrates in the culture of hPSCs, realizing their commercial applications. In this review, we summarized the design of reported synthetic substrates and especially their limitations in terms of cell culture. Moreover, much attention was paid to the development of promising peptide displaying surfaces. Besides, the biophysical regulation of synthetic substrate surfaces as well as the three-dimensional culture systems were described.

Cross linked alginate beads of montelukast sodium coated with eudragit for chronotherapy: statistical optimization, in vitro and in vivo evaluation

BACKGROUND

Chronotherapy is the administration of medication according to the biological rhythm to maximize pharmacological effects and minimize side effects. The objective of the current investigation is to prepare delayed-release beads (DRBs) containing montelukast sodium (MKS) for chronotherapy of asthma.

METHODS

Delayed-release beads of alginate were prepared using a simple method, i.e., ionotropic gelation. The effect of cross-linking agents (zinc or calcium ions) and the concentration of chitosan on the properties of the beads were investigated. The prepared beads were coated by a polymer having pH-independent solubility, i.e., Eudragit RSPO and Eudragit RLPO in different ratios to achieve the desired lag time of 4-5 h. Beads were evaluated for surface morphology, practical yield, encapsulation efficiency, XRD, and in vitro release study. The pharmacokinetic study was carried out in New Zealand white male rabbits.

RESULTS

There are no major differences in the drug release profile observed between Ca++ & Zn++ cross-linked beads. Although, a slight slow release was seen in the case of chitosan reinforced beads. MKS releases from cross-linked alginate beads were slightly altered with sodium alginate concentration, cross-linking time, and talc. At a higher concentration of alginate, slow drug release was observed whereas the addition of talc to alginate increased the release rate. The in vitro release study shows that the optimal formulation of DRBs has a lag time (4.5 h) and the release at 6 h is 74.9%. In vivo pharmacokinetic study of the beads has shown Tmax at 7 h with an initial lag time of 4 h. Concluion: The prepared cross-linked beads when dosed at sleep time may deliver Montelukast Sodium when required to relief from early morning symptoms in asthmatic patients.

Optimization of Ultrasound-Assisted Extraction and Encapsulation of Antioxidants from Orange Peels in Alginate-Chitosan Microparticles

The recovery of bioactive compounds from waste and modification of their properties by encapsulation are the main challenges today. In this study, the ultrasound-assisted extraction of antioxidants from orange peels was optimized using a central composite design. Ethanol (50%, v/v) was the solvent of choice for their extraction. The obtained total antioxidant contents were fitted using the second-order polynomial equation. The optimal conditions were the extraction time of 30 min, temperature of 60 °C, and the liquid-to-solid ratio of 15 mL/g. After that, the optimal extract was encapsulated in alginate-chitosan beads to modify the release of antioxidants under gastrointestinal tract conditions. The average size of beads was 252 µm, while the encapsulation efficiency was 89.2%. The results of the FTIR analysis indicated that there are no interactions between compounds of the extract and alginate-chitosan. In vitro release studies showed an initial rapid and then slow release of antioxidants. This release followed the simple Fickian diffusion. The encapsulation of orange peel extract provided improvement in the delivery of antioxidants after gastrointestinal digestion. The obtained encapsulated beads can be applied as the natural active ingredient of food, cosmetics, and pharmaceutical products.

Immobilization of Aspergillus oryzae DSM 1863 for l-Malic Acid Production

Whole-cell immobilization by entrapment in natural polymers can be a tool for morphological control and facilitate biomass retention. In this study, the possibility of immobilizing the filamentous fungus Aspergillus oryzae for l-malic acid production was evaluated with the two carbon sources acetate and glucose. A. oryzae conidia were entrapped in alginate, agar, and κ-carrageenan and production was monitored in batch processes in shake flasks and 2.5-L bioreactors. With glucose, the malic acid concentration after 144 h of cultivation using immobilized particles was mostly similar to the control with free biomass. In acetate medium, production with immobilized conidia of A. oryzae in shake flasks was delayed and titers were generally lower compared to cultures with free mycelium. While all immobilization matrices were stable in glucose medium, disintegration of bead material and biomass detachment in acetate medium was observed in later stages of the fermentation. Still, immobilization proved advantageous in bioreactor cultivations with acetate and resulted in increased malic acid titers. This study is the first to evaluate immobilization of A. oryzae for malic acid production and describes the potential but also challenges regarding the application of different matrices in glucose and acetate media.

The Layered Encapsulation of Vitamin B2 and β-Carotene in Multilayer Alginate/Chitosan Gel Microspheres: Improving the Bioaccessibility of Vitamin B2 and β-Carotene

This research underlines the potential of alginate multilayered gel microspheres for the layered encapsulation and the simultaneous delivery of vitamin B₂ (VB) and β-carotene (BC). Chitosan was used to improve the stability and controlled release ability of alginate-based gel microspheres. It was shown that a clear multilayered structure possessed the characteristics of pH response, and excellent thermal stability. The sodium alginate concentration and the number of layers had notable effects on mechanical properties and particle size of gel microspheres. Fourier-transform infrared spectroscopy and X-ray diffraction analyses further proved that VB and BC were encapsulated within the gel microspheres. Compared with the three-layer VB-loaded gel microspheres, the total release of VB from the three-layer VB and BC-loaded gel decreased from 93.23% to 85.58%. The total release of BC from the three-layer VB and BC-loaded gel increased from 66.11% to 69.24% compared with three-layer BC-loaded gel. The simultaneous encapsulation of VB and BC in multilayered gel microspheres can markedly improve their bioaccessibility and bioavailability. These results showed the multilayer gel microspheres synthesized herein have potential for applications in the layered encapsulation and simultaneous delivery of various bioactive substances to the intestinal tract.

Exploring the use of alginate hydrogel coating as a new initiative for emergent shoreline oiling prevention

Marine oil spills are often reported as a result of activities associated with oil exploration, production and transportation. The spilled oil may reach the shoreline, and then the stranded oil can persist for a long time, exerting many negative effects on coastal ecosystems. Conventional shoreline cleanup methods cannot effectively remove the oil residues from affected areas and are very expensive. Therefore, the use of alginate hydrogel coatings was proposed as a new initiative for emergent shoreline oiling prevention. The alginate hydrogel-coated gravels showed high surface roughness, as well as remarkable water wetting and low-oil-adhesion properties. There was a low oil adhesion on the coated gravels in the continuous test with oil/water emulsion flow, indicating the excellent oil-repellent properties of the coated substrate. The results of batch oil-repellent tests showed that independent of the kind or weathering degree of the oil used, oil can be easily washed out from the coated gravels. The coated gravels had good environmental stability and the slightly partial de-crosslinking of alginate structure would not reduce the oil repellence performance. Moreover, the performance of the alginate hydrogel-coated gravel was further proved with a laboratory shoreline tank simulator, in which more stranded oil floated to the water surface and less oil remained on gravels and entered into subsurface. This proposed oiling prevention method can be used not only for shorelines but also for coastal piers, seaports, and solid manmade shorelines. The coating material is derived from the biomass in the ocean and can be degraded under natural conditions. This study may provide a unique direction for the future development of green oil spill control strategy.