Degradation of PEG and non-PEG alginate–chitosan microcapsules in different pH environments

Hydrogel capsules as new delivery system for Trichoderma koningiopsis Th003 to control Rhizoctonia solani in rice (Oryza sativa)

The incorporation of biological control agents (BCAs) such as Trichoderma spp. in agricultural systems favors the transition towards sustainable practices of plant nutrition and diseases control. Novel bioproducts for crop management are called to guarantee sustainable antagonism activity of BCAs and increase the acceptance of the farmers. The encapsulation in polymeric matrices play a prominent role for providing an effective carrier/protector and long-lasting bioproduct. This research aimed to study the influence of biopolymer in hydrogel capsules on survival and shelf-life of T. koningiopsis. Thus, two hydrogel capsules prototypes based on alginate (P1) and amidated pectin (P2), containing conidia of T. koningiopsis Th003 were formulated. Capsules were prepared by the ionic gelation method and calcium gluconate as crosslinker. Conidia releasing under different pH values of the medium, survival of conidia in drying capsules, storage stability, and biocontrol activity against rice sheath blight (Rhizoctonia solani) were studied. P2 prototype provided up to 98% survival to Th003 in fluid bed drying, faster conidia releasing at pH 5.8, storage stability greater than 6 months at 18 °C, and up to 67% of disease reduction. However, both biopolymers facilitate the antagonistic activity against R. solani, and therefore can be incorporated in novel hydrogel capsules-based biopreparations. This work incites to develop novel biopesticides-based formulations with potential to improve the delivery process in the target site and the protection of the active ingredient from the environmental factors.

Improving rhamnolipids production using fermentation-foam fractionation coupling system: cell immobilization and waste frying oil emulsion

This work focused on the development of an inexpensive carbon source and the improvement of the fermentation-foam fractionation coupling system. The rhamnolipids production capacity of waste frying oil (WFO) was evaluated. The suitable bacterial cultivation of seed liquid and the addition amount of WFO was 16 h and 2% (v/v), respectively. A combined strategy of cell immobilization and oil emulsion avoid cell entrainment inside foam and improves the oil mass transfer rate. The immobilization conditions of bacterial cells into alginate-chitosan-alginate (ACA) microcapsules were optimized using the response surface method (RSM). Under the optimal conditions, rhamnolipids production using batch fermentation with immobilized strain reached 7.18 ± 0.23% g/L. WFO was emulsified into a fermentation medium using rhamnolipids as emulsifier (0.5 g/L). By monitoring dissolved oxygen, 30 mL/min was selected as a suitable air volumetric flow rate for fermentation-foam fractionation coupling operation. The total production and recovery percentage of rhamnolipids were 11.29 ± 0.36 g/L and 95.62 ± 0.38%, respectively.

Accelerating effect of Shilajit on osteogenic property of adipose-derived mesenchymal stem cells (ASCs)

BACKGROUND

Shilajit has been widely used remedy for treating a numerous of illness such as bone defects in Iran traditional folk medicine since hundreds of years ago. The aim of the present study was to explore the effect of Shilajit on the osteogenic differentiation of human adipose-derived mesenchymal stem cells (ASCs) in two- (2D) and three-dimensional (3D) cultures.

MATERIALS AND METHODS

ASCs were seeded in 3D 1% alginate (Alg) hydrogel with or without Shilajit (500 µg/mL) and compared with 2D cultures. Then, characterization was done using electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX), alkaline phosphatase (ALP) activity, alizarin red staining and Raman confocal microscopy.

RESULTS

Adding Shilajit had no impact on the Alg scaffold degradability. In the 3D hydrogel and in the presence of osteogenic medium (OM), Shilajit acted as enhancer to increase ALP activity and also showed osteoinductive property in the absence of OM compared to the 2D matched groups at all time points (days 7 and 21 both P = 0.0006, for 14 days P = 0.0006 and P = 0.002, respectively). In addition, calcium deposition was significantly increased in the cultures exposed to Shilajit compared to 2D matched groups on days 14 (P < 0.0001) and 21 (P = 0.0003 and P = 0.003, respectively). In both 3D and 2D conditions, Shilajit induced osteogenic differentiation, but Shilajit/Alg combination starts osteogenic differentiation in a short period of time.

CONCLUSION

As Shilajit accelerates the differentiation of ASCs into the osteoblasts, without changing the physical properties of the Alg hydrogel, this combination may pave the way for more promising remedies considering bone defects.

High-Throughput Assessments for Storage Stability, In Vitro Release, and Particle Size of Encapsulated Biocontrol Fungi in Hydrogel Beads

Use of biocontrol fungi (BF) such as Trichoderma spp. minimizes fungicide input and increases both plant nutrition and protection from disease. Thus, the introduction of BF by novel inoculants in crop management is an excellent strategy to promote sustainable antagonism activity. Within these strategies, encapsulation in polymeric matrices such as hydrogel beads will play a prominent role in providing an effective carrier/protector and long-lasting bioproduct. These studies have used biomaterials with tunable physicochemical features, providing differential morphologies, compaction, and disintegration, among other parameters. Aiming at developing bioproducts within polymeric hydrogel beads, viability of encapsulated conidia, storage stability, release of active ingredient, and particle size are essential. However, there are no reports that detail standardized and comprehensive methods to evaluate the characterization of these bioproducts. We describe step-by-step protocols that go from sample preparation to testing the viability and storage stability using vacuum-sealed aluminum foil bags. We also describe a high-throughput in vitro method for quantifying released fungal conidia of BF at different pH values. Finally, the particle size of beads is established by bright-field microscopy. These protocols could be transferable to other biological actives, accessible to researchers in the microbiology and bioengineering communities. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Viability of encapsulated conidia Basic Protocol 2: Study of stability of prototypes under storage Basic Protocol 3: Release profile of encapsulated conidia at different pH conditions Basic Protocol 4: Determination of capsule size.

Degradation Behavior of Polymers Used as Coating Materials for Drug Delivery-A Basic Review

The purpose of the work was to emphasize the main differences and similarities in the degradation mechanisms in the case of polymeric coatings compared with the bulk ones. Combined with the current background, this work reviews the properties of commonly utilized degradable polymers in drug delivery, the factors affecting degradation mechanism, testing methods while offering a retrospective on the evolution of the controlled release of biodegradable polymeric coatings. A literature survey on stability and degradation of different polymeric coatings, which were thoroughly evaluated by different techniques, e.g., polymer mass loss measurements, surface, structural and chemical analysis, was completed. Moreover, we analyzed some shortcomings of the degradation behavior of biopolymers in form of coatings and briefly proposed some solving directions to the main existing problems (e.g., improving measuring techniques resolution, elucidation of complete mathematical analysis of the different degradation mechanisms). Deep studies are still necessary on the dynamic changes which occur to biodegradable polymeric coatings which can help to envisage the future performance of synthesized films designed to be used as medical devices with application in drug delivery.

Optimal conditions for the encapsulation of Weissella cibaria JW15 using alginate and chicory root and evaluation of capsule stability in a simulated gastrointestinal system

The delivery of active probiotic cells in capsules can reduce probiotic cell loss induced by detrimental external factors during digestion. In this study, we determined the optimal conditions for the encapsulation of Weissella cibaria JW15 (JW15) within calcium and polyethylene glycol (PEG)-alginate with chicory root extract powder (CREP). JW15 was encapsulated as the core material (109 cells/mL, 2 mL/min), and a solution containing a mixture of 1.5% sodium alginate and 1% CREP was extruded into a receiving bath with 0.1 M calcium chloride (CaCl2 ) and 0.05% PEG. Capsule morphology and size were measured using optical microscopy. The optimal air pressure and frequency vibration for capsules containing alginate only (Al) were 200 mbar and 200 Hz, respectively and 100 mbar and 350 Hz for capsules containing alginate with CREP (Ch), respectively. The voltage for both capsules types was fixed at 1.35 kV. Then, the capsules were incubated in a simulated gastrointestinal (GI) system for 6 hr at 37 °C. The addition of PEG in a CaCl2 hardening solution led to degradation of the Ch capsule (Ch-PEG) and the release of cells into the small intestine vessel in the simulated GI system. By contrast, the cells were trapped within the Al capsules. Based on these data, effective encapsulation using alginate with CREP and PEG can enable JW15 to be released at a targeted anatomical site of activity within the GI system, thereby, enhancing the efficacy of probiotic cells. These protective effects can be leveraged during the development of probiotic products. PRACTICAL APPLICATION: Weissella cibaria JW15 (109 cells/mL) was encapsulated in biodegradable and biocompatible capsules, prepared by mixing 1.5% alginate with 1% chicory root extract powder (CREP) in 0.1 M CaCl2 and 0.05% PEG using an encapsulator. The optimal processing parameters were as follows: pressure, 100 mbar; vibration frequency, 350 Hz; voltage, 1.35 kV; and core flow rate, 2 mL/min. When the resulting capsules were subjected to a simulated gastrointestinal system for 6 hr, the cells were released into the small intestine, and up to 95% cell viability was preserved. These results suggest that capsules made from alginate with CREP and formulated using calcium and PEG are a promising delivery system for probiotic cells.

Strengthening calcium alginate microspheres using polysulfone and its performance evaluation: Preparation, characterization and application for enhanced biodegradation of chlorpyrifos

Bacterial cell immobilization offer considerable advantages over traditional biotreatment systems using free cells. Calcium alginate matrix usually used for bacterial immobilization is susceptible to biodegradation in harsh environment. Current study aimed to produce and characterize stable macrocapsules (MCs) of Chlorpyrifos (CP) degrading bacterial consortium using biocompatible calcium alginate matrix coupled with environmentally stable polysulfone. In current study bacterial consortium capable of CP biodegradation was immobilized using calcium alginate in a form of microcapsule (MC) reinforced by being coated with a synthetic polymer polysulfone (PSf) through phase inversion. Consortium comprised of five bacterial strains was immobilized using optimized concentration of sodium alginate (2.5gL^-1), calcium chloride (6gL^-1), biomass (600mgL^-1) and polysulfone (10gL^-1). It has been observed that MCs have high thermal, pH and chemical stability than CAMs. In synthetic media complete biodegradation of CP (100-600mgL^-1) was achieved using macrocapsules (MCs) within 18h. CAMs could be reused effectively only upto 5cycles, contrary to this MCs could be used 13 times to achieve more than >96% CP degradation. Shelf life and reusability studies conducted for MCs indicated unaltered biomass retention and CP biodegradation activity (95%) over 16weeks of storage. MCs achieved complete biodegradation of CP (536mgL^-1) in real industrial wastewater and reused several times effectively. Metabolites (3,5,6-trichloro-2-pyridinol (TCP), 3,5,6-trichloro-2-methoxypyridine (TMP) and diethyl-thiophosphate (DETP) were traced using GC-MS and possible metabolic pathway was constructed. Study indicated MCs could be used for cleanup of CP contaminated wastewater repeatedly, safely, efficiently for a longer period of time.

Correction of MHS Viscosimetric Constants upon Numerical Simulation of Temperature Induced Degradation Kinetic of Chitosan Solutions

The Mark⁻Houwink⁻Sakurada (MHS) equation allows for estimation of rheological properties, if the molecular weight is known along with good understanding of the polymer conformation. The intrinsic viscosity of a polymer solution is related to the polymer molecular weight according to the MHS equation, where the value of the constants is related to the specific solvent and its concentration. However, MHS constants do not account for other characteristics of the polymeric solutions, i.e., Deacetilation Degree (DD) when the solute is chitosan. In this paper, the degradation of chitosan in different acidic environments by thermal treatment is addressed. In particular, two different solutions are investigated (used as solvent acetic or hydrochloric acid) with different concentrations used for the preparation of chitosan solutions. The samples were treated at different temperatures (4, 30, and 80 °C) and time points (3, 6 and 24 h). Rheological, Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analyses (TGA) were performed in order to assess the degradation rate of the polymer backbones. Measured values of molecular weight have been integrated in the simulation of the batch degradation of chitosan solutions for evaluating MHS coefficients to be compared with their corresponding experimental values. Evaluating the relationship between the different parameters used in the preparation of chitosan solutions (e.g., temperature, time, acid type and concentration), and their contribution to the degradation of chitosan backbone, it is important to have a mathematical frame that could account for phenomena involved in polymer degradation that go beyond the solvent-solute combination. Therefore, the goal of the present work is to propose an integration of MHS coefficients for chitosan solutions that contemplate a deacetylation degree for chitosan systems or a more general substitution degree for polymers in which viscosity depends not only on molecular weight and solvent combinations.

Cell microencapsulation with synthetic polymers

The encapsulation of cells into polymeric microspheres or microcapsules has permitted the transplantation of cells into human and animal subjects without the need for immunosuppressants. Cell-based therapies use donor cells to provide sustained release of a therapeutic product, such as insulin, and have shown promise in treating a variety of diseases. Immunoisolation of these cells via microencapsulation is a hotly investigated field, and the preferred material of choice has been alginate, a natural polymer derived from seaweed due to its gelling conditions. Although many natural polymers tend to gel in conditions favorable to mammalian cell encapsulation, there remain challenges such as batch to batch variability and residual components from the original source that can lead to an immune response when implanted into a recipient. Synthetic materials have the potential to avoid these issues; however, historically they have required harsh polymerization conditions that are not favorable to mammalian cells. As research into microencapsulation grows, more investigators are exploring methods to microencapsulate cells into synthetic polymers. This review describes a variety of synthetic polymers used to microencapsulate cells.

Advances in biocompatibility and physico-chemical characterization of microspheres for cell encapsulation

Cell encapsulation has already shown its high potential and holds the promise for future cell therapies to enter the clinics as a large scale treatment option for various types of diseases. The advancement in cell biology towards this goal has to be complemented with functional biomaterials suitable for cell encapsulation. This cannot be achieved without understanding the close correlation between cell performance and properties of microspheres. The ongoing challenges in the field of cell encapsulation require a critical view on techniques and approaches currently utilized to characterize microspheres. This review deals with both principal subjects of microspheres characterization in the cell encapsulation field: physico-chemical characterization and biocompatibility. The up-to-day knowledge is summarized and discussed with the focus to identify missing knowledge and uncertainties, and to propose the mandatory next steps in characterization of microspheres for cell encapsulation. The primary conclusion of this review is that further success in development of microspheres for cell therapies cannot be accomplished without careful selection of characterization techniques, which are employed in conjunction with biological tests.

Bioactivated protein-based porous microcarriers for tissue engineering applications

Lipoaspirate-derived extracellular matrix enrichment was able to provide the necessary cell adhesion receptors and biological factors for improving cell–material interactions of porous OVA microcarriers.

Alginate-Based Biomaterials for Regenerative Medicine Applications

Alginate is a natural polysaccharide exhibiting excellent biocompatibility and biodegradability, having many different applications in the field of biomedicine. Alginate is readily processable for applicable three-dimensional scaffolding materials such as hydrogels, microspheres, microcapsules, sponges, foams and fibers. Alginate-based biomaterials can be utilized as drug delivery systems and cell carriers for tissue engineering. Alginate can be easily modified via chemical and physical reactions to obtain derivatives having various structures, properties, functions and applications. Tuning the structure and properties such as biodegradability, mechanical strength, gelation property and cell affinity can be achieved through combination with other biomaterials, immobilization of specific ligands such as peptide and sugar molecules, and physical or chemical crosslinking. This review focuses on recent advances in the use of alginate and its derivatives in the field of biomedical applications, including wound healing, cartilage repair, bone regeneration and drug delivery, which have potential in tissue regeneration applications.