Preparation, physicochemical characterization and swelling properties of composite hydrogel microparticles based on gelatin and pectins with different structure.

Composite hydrogel microparticles based on pectins with different structures (callus culture pectin (SVC) and apple pectin (AU)) and gelatin were developed. Hydrogel microparticles were formed by the ionotropic gelation and electrostatic interaction of COO- groups of pectin and NH3+ groups of gelatin, which was confirmed by FTIR spectroscopy. The addition of gelatin to pectin-based gel formulations resulted in a decrease in gel strength, whereas increasing gelatin concentration enhanced this effect. The microparticle gel strength increased in proportion to the increase in the pectin concentration. The DSC and TGA analyzes showed that pectin-gelatin gels had the higher thermal stability than individual pectins. The gel strength, Ca2+ content and thermal stability of the microparticles based on gelatin and SVC pectin with a lower degree of methylesterification (DM) (14.8 %) were higher compared to that of microparticles based on gelatin and AU pectin with a higher DM (40 %). An increase in the SVC concentration, Ca2+ content and gel strength of SVC-gelatin microparticles led to a decrease in the swelling degree in simulated gastrointestinal fluids. The addition of 0.5 % gelatin to gels based on AU pectin resulted in increased stability of the microparticles in gastrointestinal fluids, while the microparticles from AU without gelatin were destroyed.

Characterization and swelling properties of composite gel microparticles based on the pectin and κ-carrageenan.

The aim of this research was to produce composite gel microparticles based on the pectin (campion callus culture (SVC) and commercial apple (AU) pectins) and κ-carrageenan and investigate the relationship between the characteristics and swelling properties of the composite microparticles. The microparticles were obtained using emulsion dehydration techniques with successive incubation in calcium chloride solution. A significant positive correlation between the Ca2+ content and the SVC concentration in gel formulations was shown. Decreasing degree of methyl esterification (DM) of the SVC pectin promoted Ca2+ binding in comparison with the AU pectin. Increasing concentration of the pectin promoted increasing gel strength of the composite microparticles. The higher gel strength of the composite microparticles based on the SVC pectin was probably due to the lower DM and a higher linearity in comparison with the AU pectin. The microparticle gel formulations with a higher pectin concentration had a lower swelling degree in the simulated digestive fluids. The addition of the carrageenan to the gel formulations led to an increase in the swelling degree in comparison with that without carrageenan. The correlation analysis indicated that increasing initial Ca2+ content and gel strength of the microparticles promoted decreasing swelling degree of the composite microparticles.

Physicochemical and swelling properties of composite gel microparticles based on alginate and callus cultures pectins with low and high degrees of methylesterification.

Composite gel microparticles based on alginate and callus culture pectins with low and high degrees of methylesterification or apple pectin were produced. By varying the chemical composition of the pectic samples and the ratio of alginate to pectin, the gel strength, morphology, and swelling properties of composite microparticles can be altered. The inclusion of increasing concentrations of alginate in gel formulations promoted an increase in the microparticle gel strength and the formation of a smoother surface microrelief independently of the pectin chemical composition. Microparticles based on the pectin with a low degree of methylesterification (DM) and a higher concentration of alginate exhibited an increased swelling degree in the simulated digestive fluids. Microparticles based on the pectin with high DM and low alginate concentration were destroyed in the simulated intestinal fluid within 1 h due to the low Ca2+ content, gel strength, and grooved and rough surface of these microparticles. An increase in alginate concentration of gel formulations based on pectin with high DM led to increased stability of the microparticles in the simulated intestinal and colonic fluids due to increased Ca2+ content, microparticle gel strength and degree of crosslinking.

Pectin-glycerol gel beads: Preparation, characterization and swelling behaviour.

Low methyl-esterified pectin (AU701) was found to form gel beads with glycerol. Wet AU701-glycerol gel beads exhibited similar diameter and hardness compared to the AU701-Ca gel beads, prepared by ionotropic gelation with Ca2+ and used for comparison. The morphology of dry pectin gel beads determined by scanning electron microscopy revealed that the beads exhibited rough and grooved surface. The AU701-glycerol gel beads absorbed more grams of water than AU701-Ca gel beads (12.2 g vs 3.9 g per 1 g of the beads). Rheological properties and hardness of the AU701-glycerol gel beads improved with the increase of the pectin/glycerol ratio. Swelling behavior of the AU701-glycerol gel beads was determined after sequential incubation in simulated gastric (SGF) and intestinal (SIF) fluids. The AU701-glycerol gel beads swelled in SGF to a greater extent and revealed higher stability in SIF than the gel beads cross-linked by Ca2+.

Preparation and properties of the pectic gel microparticles based on the Zn2+, Fe3+ and Al3+ cross-linking cations.

The aim of this work was to evaluate the relationship between the cross-linking cation content in the microparticles, chemical characteristics of pectins and swelling properties of the gel microparticles based on the Zn2+, Fe3+ and Al3+ cross-linking cations. A significant negative correlation between the Zn2+ content and DM of pectin indicated that decreasing DM of pectin promoted Zn2+ binding. The microparticles from the pectins with a higher linearity had a higher content of Fe3+. The microparticles from the pectins with a lower Mw, branching of rhamnogalacturonan I, amount of RG, specific viscosity and a higher linearity had a higher content of Al3+. The content of the Fe3+ ions in the microparticles was higher than the Zn2+ content. The Al3+ content in the microparticles was lowest. The Fe3+ and Zn2+ ions, which are more electronegative, bind more strongly to pectin in comparison with the less electronegative Al3+ cations. The microparticles with a higher Zn2+, Fe3+, and Al3+ content had a lower swelling degree in the simulated digestive fluids. Moreover, the higher swelling of the microparticles can be due to their porous or wrinkled surface. Variation of specific cations and pectins can influence the functionality of the gel microparticles, in particular swelling properties.

Mechanical properties of the pectin hydrogels and inflammation response to their subcutaneous implantation.

We studied the influence of the mechanical properties of pectin hydrogels on acute inflammation and tissue repair after subcutaneous implantation. We used hard and soft pectin hydrogels. The results of histology and the analysis of serum-level cytokines demonstrated that the intensity of acute inflammation increased with increasing hardness of the pectin hydrogels. We also showed that the pectin hydrogels did not inhibit tissue repair. The results of the morphometric and texture analysis of the pectin hydrogels showed that the in vivo biodegradation kinetics of hard hydrogels were greater than those of soft pectin hydrogels. We also observed that on the surface of the hard and soft pectin hydrogels, a network of collagen fibers was formed. The surface of the pectin hydrogel was shown to prevent the adhesion of infiltrating inflammatory cells. The results of the in vitro experiments demonstrated that pectin hydrogels inhibited the functional activity of macrophages and minimally activated the complement system. Therefore, we showed that soft pectin hydrogels have low proinflammatory potential and can be used in surgery as a barrier material as prevention of adhesions in the abdominal cavity. The hard pectin hydrogel can be used in tissue engineering. The hard pectin hydrogels can be used in the reconstruction of skin because are overpopulated with collagen fibers and contribute to the formation of new connective tissue, their elasticity is comparable to the skin and can be adjusted. They are biodegradable, and no additional manipulation is required to remove them.

Swelling behavior and satiating effect of the gel microparticles obtained from callus cultures pectins.

Gel microparticles were prepared from pectins of campion (SVCgel) and duckweed (LMCgel) callus cultures, as well as from commercial apple pectin (APgel) by emulsion dehydration techniques with successive ionotropic gelation. The morphology and swelling behavior of the microparticles were determined after successive incubation in simulated gastric (SGF), intestinal (SIF), and colonic (SCF) fluids. Both SVCgel and LMCgel microparticles were found to swell in SGF and SIF gradually, and at oral administration decreased food intake by laboratory mice during the first 5 h of free-feeding. The SVCgel microparticles demonstrated the higher stability in SCF within 24 h than LMCgel ones. Only the SVCgel microparticles were shown to decrease food intake by 24% during the 21 h of free-feeding and decreased body weight of mice by 4% during 24 h after oral administration. The APgel microparticles lost their shape in SIF, then fully disintegrated after 0.5 h of incubation in SCF, and failed to affect food intake or mice body weight. The data obtained indicated that sustainability and swelling of the gel microparticles from the SVC pectin in the colonic fluid may provide the stronger satiating effect compared to that of the LMCgel microparticles.

Pectin gelling in acidic gastric condition increases rheological properties of gastric digesta and reduces glycaemic response in mice.

The rheological characteristics and transit time of gastric digesta and the postprandial glycaemic response in mice orally administered with water (control) or pectin solutions supplemented (AP-Ca) or not supplemented (AP) with CaCO3 were elucidated. AP and AP-Ca increased viscosity, storage and loss moduluses (G' and G'') of mice gastric digesta. The gelling capacity of AP-Ca in acidic gastric conditions appeared to provide a greater enhancement of gastric digesta viscosity compared with AP. The postprandial blood glucose concentration was lower in mice orally administered with AP or AP-Ca compared with control mice. The transit time of gastric digesta and the blood glucose concentration were affected in mice orally administered with AP during the early postprandial period. The effect of AP-Ca on the gastric digesta rheology and transit time was stronger than that of AP. Both of the pectin solutions failed to reduce food intake in mice.

Preparation and release characteristics of mesalazine loaded calcium pectin-silica gel beads based on callus cultures pectins for colon-targeted drug delivery.

The aim of this work is to produce calcium pectin-silica gel beads containing mesalazine as a drug model in order to control the drug release in the colon. The mesalazine loaded calcium pectin-silica gel beads were prepared using the ionotropic gelation method. Energy-dispersive X-ray analysis revealed that increasing the Na2SiO3 concentration led to an increase of the silicon content on the surface and in the cross-sections of the beads. The addition of Na2SiO3 to the gel formulations made from the duckweed callus culture pectin led to a decrease in the swelling degree that appeared to be related to the higher gel strength of these beads. The beads made from pectins of campion and duckweed callus cultures with adding of 22.2 mg/ml of Na2SiO3 showed the lowest release of mesalazine in simulated gastric and intestinal fluids. An increase in the reaction time up to 60 min during incubation in the cross-linking solution of CaCl2 led to a slower release of drug from the beads. An elevated release of mesalazine was achieved in the simulated colonic fluid. Prepared calcium pectin-silica gel beads containing mesalazine as a drug model can be proposed for controlled drug release in the colon.

Adhesive properties of calcium pectinate gels prepared from callus cultures pectins.

The aim of this research is to investigate the influence of the surface morphology of the calcium pectinate gel (CaPG) beads as well as the physicochemical characteristics of pectins and the CaPG beads on the adhesive properties of gels against the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Bacillus subtilis. The adhesion of the bacteria depends on the type of pectin and the surface morphology of the beads. The faster adhesion on CaPG beads appeared to be related to a lower degree of methyl esterification (DE), a higher molecular weight (Mw) and specific viscosity of the pectin and a higher gel strength. Surface roughness measurements were performed using an atomic force microscope. The beads from pectins with a higher Mw, a higher specific viscosity and a lower DE had a higher surface roughness. The surface roughness was one of the factors promoting adhesion of the bacteria onto the calcium pectinate gels. The surface morphology was observed under a scanning electron microscope (SEM). SEM images illustrated that E. coli and B. subtilis adhered on the beads with a rough surface. CaPG beads obtained from callus culture pectins can be proposed for the preparation of gels with adhesive and antiadhesive properties.

Mechanical properties, structure, bioadhesion, and biocompatibility of pectin hydrogels.

The surface structure, biocompatibility, textural, and adhesive properties of calcium hydrogels derived from 1, 2, and 4% solutions of apple pectin were examined in this study. An increase in the pectin concentration in hydrogels was shown to improve their stability toward elastic and plastic deformation. The elasticity of pectin hydrogels, measured as Young's modulus, ranged from 6 to 100 kPa. The mechanical properties of the pectin hydrogels were shown to correspond to those of soft tissues. The characterization of surface roughness in terms of the roughness profile (Ra) and the root-mean-square deviation of the roughness profile (Rq) indicated an increased roughness profile for hydrogels depending on their pectin concentration. The adhesion of AU2% and AU4% hydrogels to the serosa abdominal wall, liver, and colon was higher than that of the AU1% hydrogel. The adhesion of macrophages and the non-specific adsorption of blood plasma proteins were found to increase as the pectin concentration in the hydrogels increased. The rate of degradation of all hydrogels was higher in phosphate buffered saline (PBS) than that in DMEM and a fibroblast cell monolayer. The pectin hydrogel was also found to have a low cytotoxicity. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2572-2581, 2017.

Pectin-silica gels as matrices for controlled drug release in gastrointestinal tract.

The synthesis of pectin-silica gels for controlled drug release in gastrointestinal tract (GIT) using low methoxyl (LM) and high methoxy (HM) pectins and tetraethoxysilane (TEOS) as precursor is described. The FTIR spectra of the pectin-silica gels show intense absorption bands at 1246cm-1 and 802cm-1 corresponding to the vibrations COSi bonds, which absent in the FTIR spectra of the native pectins that indicate the formation covalent bond between silica and pectin macromolecules in the pectin-silica gels. Pectin-TEOS, pectin-Ca-TEOS and pectin-TEOS-Ca beads with mesalazine are synthesized by different combinations of sol-gel method using TEOS and ionotropic gelation method using calcium chloride. The best resistant of pectin-TEOS and pectin-Ca-TEOS beads during incubation in simulated gastric fluid for 2h and subsequently in simulated intestinal fluids for 18h is indicated. Pectin-TEOS beads are characterized by higher encapsulation efficiency (to 28%) than pectin-Ca-TEOS beads (to 16%). The drug release of pectin-silica beads in simulated GIT occurs gradually up to 80% and is directly dependent on the hardness of the beads. The surface morphology of beads is shown. The use of pectin-silica beads is promising with regard to the development of controlled release of drug formulations.

In vitro gastrointestinal-resistant pectin hydrogel particles for ß-glucuronidase adsorption.

Pectin hydrogel particles (PHPs) were prepared by ionotropic gelation of low methylesterified pectin of Tanacetum vulgare L. with calcium ions. Wet PHPs prepared from TVF exhibited a smaller diameter and the lower weight as well as exhibited the best textural properties in terms of hardness and elasticity compared to the PHPs prepared from commercial low methylesterified pectin (CU701) used for comparison. Upon air drying, PHPs prepared from CU701 became small and dense microspheres whereas the dry PHPs prepared from TVF exhibited a drop-like shape. The morphology of dry PHPs determined by scanning electron microscopy revealed that the surface of the TVF beads exhibited fibred structures, whereas the PHPs prepared from CU701 exhibited a smooth surface. The characterization of surface roughness using atomic force microscopy indicated less roughness profile of the PHPs prepared from TVF than CU701. PHPs prepared from TVF were found to possess in vitro resistance to successive incubations in simulated gastric (SGF), intestinal (SIF), and colonic fluid (SCF) at 37 °C for 2, 4 and 18 h, respectively. The PHPs prepared from CU701 swelled in SGF and then lost their spherical shape and were fully disintegrated after 4 h of incubation in SIF. The PHPs from TVF, which were subjected to treatment with SGF, SIF and SCF, were found to adsorb microbial ß-glucuronidase (ßG) in vitro. The data obtained offered the prospect for the development of the PHPs from TVF as sorbents of colonic ßG for the inhibition of re-absorption of estrogens.

Swelling and morphology of calcium pectinate gel beads obtained from Silene vulgaris callus modified pectins.

The aim of this research is to investigate the swelling properties and morphology of the calcium pectinate gel (CaPG) beads made from pectins of campion callus cultured using various medium nutrients (carbon sources, concentration of sucrose, calcium and 2,4-dichlorophenoxyacetic acid (2,4-D)). Gelled spheres were prepared by ionotropic gelation. The mean diameter, total surface area and volume of the dried beads varied depending on the plant cell culture conditions. The swelling of dried CaPG beads in solutions with pH 2 and pH 4 was demonstrated to occur more slowly (within 4 or 24h) with increasing sucrose and calcium concentrations or in the absence of auxin. All beads swelled less when placed in acidic media (pH 2 and pH 4) and swelled most extensively in NaCl (pH 6). The surface morphology of the CaPG beads was demonstrated to depend on the presence of sugars, calcium and auxin in the plant cell culture medium used. The slow swelling of dried CaPG beads was apparently related to their grooved surfaces. An applied strategy involving changing the composition and concentration of media components altered the swelling behavior of the CaPG beads and enhanced the acid and water resistance of the resultant pectinate hydrogels in physiological environments. In particular, the swelling of Ca 4.5, 2,4-D0, Suc30 and Suc100 CaPG beads occurred more slowly.