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.

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.

Preparation and biocompatibility evaluation of pectin and chitosan cryogels for biomedical application.

Today, there is a need for the development of biomaterials with novel properties for biomedical purposes. The biocompatibility of materials is a key factor in determining its possible use in biomedicine. In this study, composite cryogels were obtained based on pectin and chitosan using ionic cryotropic gelation. For cryogel preparation, apple pectin (AP), Heracleum L. pectin (HP), and chitosan samples with different physical and chemical characteristics were used. The properties of pectin-chitosan cryogels were found to depend on the structural features and physicochemical characteristics of the pectin and chitosan within them. The addition of chitosan to cryogels can increase their mechanical strength, cause change in surface morphology, increase the degradation time, and enhance adhesion to biological tissues. Cryogels based on AP were less immunogenic when compared with cryogels from HP. Cryogels based on AP and HP were hemocompatible and the percentage of red blood cells hemolysis was less than 5%. Unlike cryogels based on HP, which exhibited moderate cytotoxicity, cryogels based on AP exhibited light cytotoxicity. Based on the results of low immunogenicity, light cytotoxicity data as well as a low level of hemolysis of composite cryogels based on AP and chitosan are biocompatible and can potentially be used in biomedicine. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 547-556, 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.

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.