Phosphated crosslinked pectin as a potential excipient for specific drug delivery: preparation and physicochemical characterization

Fabrication, Functional Properties, and Potential Applications of Mixed Gellan-Polysaccharide Systems: A Review

Gellan, an anionic heteropolysaccharide synthesized by Sphingomonas elodea, is an excellent gelling agent. However, its poor mechanical strength and high gelling temperature limit its application. Recent studies have reported that combining gellan with other polysaccharides achieves desirable properties for food- and biomaterial-related applications. This review summarizes the fabrication methods, functional properties, and potential applications of gellan-polysaccharide systems. Starch, pectin, xanthan gum, and konjac glucomannan are the most widely used polysaccharides in these composite systems. Heating-cooling and ionic-induced cross-linking approaches have been used in the fabrication of these systems. Composite gels fabricated using gellan and various polysaccharides exhibit different functional properties, possibly because of their distinct molecular interactions. In terms of applications, mixed gellan-polysaccharide systems have been extensively used in texture modification, edible coatings and films, bioactive component delivery, and tissue-engineering applications. Further scientific studies, including structural determinations of mixed systems, optimization of processing methods, and expansion of applications in food-related fields, are needed.

Novel Pectic Polysaccharides Isolated from Immature Honey Pomelo Fruit with High Immunomodulatory Activity

A novel pectic polysaccharide (HPP-1) with high immunomodulatory activity was extracted and isolated from the immature honey pomelo fruit (Citrus grandis). Characterization of its chemical structure indicated that HPP-1 had a molecular weight of 59,024 D. In addition, HPP-1 was primarily composed of rhamnose, arabinose, fucose, mannose, and galactose at a molar ratio of 1.00:11.12:2.26:0.56:6.40. Fourier-transform infrared spectroscopy, periodic acid oxidation, and Smith degradation results showed that HPP-1 had α- and β-glycosidic linkages and 1 → 2, 1 → 4, 1 → 6, and 1 → 3 glycosidic bonds. ¹³C NMR and ¹H NMR analyses revealed that the main glycogroups included 1,4-D-GalA, 1,6-β-D-Gal, 1,6-β-D-Man, 1,3-α-L-Ara, and 1,2-α-L-Rha. Immunomodulatory bioactivity analysis using a macrophage RAW264.7 model in vitro revealed that NO, TNF-α, and IL-6 secretions were all considerably increased by HPP-1. Moreover, RT-PCR results showed that HPP-1-induced iNOS, TNF-α, and IL-6 expression was significantly increased in macrophages. HPP-1-mediated activation in macrophages was due to the stimulation of the NF-κB and MAPK signaling pathways based on western blot analyses. HPP-1 extracted from immature honey pomelo fruit has potential applications as an immunomodulatory supplement.

The gelation behavior of thiolated citrus high-methoxyl pectin induced by sodium phosphate dibasic dodecahydrate

The present study found that sodium phosphate dibasic dodecahydrate (Na₂HPO₄) was capable of inducing the gelation of thiolated citrus high-methoxyl pectin (TCHMP). TCHMP was synthesized by amidation of citrus high-methoxyl pectin. The gel formation exhibited an obvious concentration-dependence, including TCHMP and Na₂HPO₄ concentration. For Na₂HPO₄-induced TCHMP gels (TCHMPGs), gel strength and water holding capacity (WHC) increased, while the microcellular network structure was more compact with the increase of TCHMP and Na₂HPO₄ concentration. Dynamic viscoelastic experiment showed when Na₂HPO₄ concentration was more than or equal to 0.5 mol/L, TCHMP sols could be transferred into gels within 30 min. Crystal property was not changed while thermal stability was improved after phase transition. Gelling forces analysis indicated that disulfide bonds were the main interaction forces in TCHMPGs. Consequently, TCHMPGs were covalently crosslinked and exhibited satisfactory gel performance. The results provide a theoretical basis for the formation of gels by Na₂HPO₄ induced TCHMP.

Enhanced Cu(II) adsorption using sodium trimetaphosphate-modified cellulose beads: equilibrium, kinetics, adsorption mechanisms, and reusability

The current study is focused on the simple synthesis of two novel biosorbent beads: BASB/STMP and CNFB/STMP, derived respectively from bleached almond shell (BAS) and cellulose nanofiber from almond shell (CNF) by means of chemical crosslinking with sodium trimetaphosphate (STMP). These biosorbents were thoroughly characterized in terms of structure (FTIR), texture (N₂ adsorption-desorption), thermal behavior (TGA/DTG), morphology (SEM), and surface properties (XPS). The adsorption kinetics of Cu(II) ions onto BASB/STMP and CNFB/STMP materials proved the chemisorption interaction between Cu(II) ions and the STMP functionalized beads. The BASB/STMP equilibrium data were successfully described by the Redlich-Peterson model and the CNFB/STMP data by the Sips model which disclosed maximum adsorption capacities of 141.44 mg g^-1 and 147.90 mg g^-1, respectively. Furthermore, the BASB/STMP bioadsorbent offers easy regeneration and better reusability with high efficiency (> 83%). This study sheds light on the preparation of low-cost adsorbents for wastewater treatment in order to improve the competitiveness and eco-friendliness of agrowaste-based processes.

The production of gel beads of soybean hull polysaccharides loaded with soy isoflavone and their pH-dependent release

Core-shell hydrogel beads were successfully produced from soybean hull polysaccharides (SHP). Using electron microscopy, the beads were found to be spherical with smooth surfaces and have tight gel network internal structures. Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction were used to investigate the interaction between soy isoflavone and SHP in the gel beads mesh-like structure. Furthermore, the encapsulation efficiency and loading capacity of gel beads for soy isoflavone are 66.90% and 4.67%, respectively, and have the ability of pH-responsive release in vitro. Through the mathematical model of kinetics, we found that the release of soy isoflavone from gel beads showed Fickian diffusion in release media (pH 2.0 and 7.4), but showed non-Fickian diffusion at pH 4.0 and 6.8. This polymer can be extended to prepare more versatile delivery and controlled release system, appealing for food, pharmaceutical, biomedicine and cosmetics applications.

α-Gluco-oligosaccharide in the research and development of a polymeric material for modified drug delivery

This research aimed to analyse the influence of the incorporation of α-gluco-oligosaccharide (GOS-α) in the formation of isolated films of different combinations of polymethyl by applying physicochemical analyses such as Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM). Polymer films were prepared by evaporation associating Eudragit® RS30D with α-GOS. FTIR results confirmed the incorporation of α-GOS. The intermolecular interaction involving carbonyl and hydroxyl groups of Eudragit® with α-GOS was not detected. By TG and DSC, it was possible to detect that there were no changes in the thermal properties between the proposed combinations and the standard film. Upon SEM analysis, the appearance of pores for the association 90:10 was evidenced. Possibly, these pores act as output ports for the drug. These results sharpen the perspective of applying this material to the coating of pharmaceutical formulations of modified drug delivery.

Evaluation of Rosin Gum and Eudragit® RS PO as a Functional Film Coating Material

Polymers are essential tools in the research and development of new therapeutic devices. The diversity and flexibility of these materials have generated high expectations in the composition of new materials with extraordinary abilities, especially in the design of new systems for the modified release of pharmaceutically active ingredients. The natural polymer rosin features moisture protection and pH-dependent behavior (i.e., it is sensitive to pH > 7.0), suggesting its possible use in pharmaceutical systems. The synthetic polymer Eudragit® RS PO is a low-permeability material, the disintegration of which depends on the time of residence in the gastrointestinal tract. The present study developed a polymeric material with desirable physicochemical characteristics and synergistic effects that resulted from the inherent properties of the associated polymers. Isolated films were obtained by solvent evaporation and subjected to a water vapor transmission test, scanning electron microscopy, calorimetry, Fourier transform-infrared (FT-IR) spectroscopy, micro-Raman spectroscopy, and mechanical analysis. The new polymeric material was macroscopically continuous and homogeneous, was appropriately flexible, had low water permeability, was vulnerable in alkaline environments, and was thermally stable, maintaining an unchanged structure up to temperatures of ∼400°C. The new material also presented potentially suitable characteristics for application in film coatings for oral solids, suggesting that it is capable of carrying therapeutic substances to distal regions of the gastrointestinal tract. These findings indicate that this new material may be added to the list of functional excipients.

Porous cellulose spheres: Preparation, modification and adsorption properties

Porous cellulose spheres (PCS) were fabricated by precipitating the spheres from a cellulose ionic liquid solution, followed by freezing, solvent exchange, and drying. PCS had low crystallinity and a large surface area that facilitated modification with trisodium trimetaphosphate (STMP) to introduce phosphate ester groups into the porous structure of the heterogeneous system. The STMP-modified PCS (SPCS) were used to remove heavy metal ions from aqueous solution. With increasing STMP dosage, the adsorption capacity of SPCS obviously improved due to chelation between Pb²⁺ and phosphate ester groups. The kinetic adsorption and isotherm data matched the pseudo-second order model and the Langmuir model well. The maximum adsorption capacity reached 150.6 mg g^-1 for SPCS. SPCS were competitive with other absorbents because the phosphate ester groups and porous structure contributed to Pb²⁺ adsorption. Moreover, SPCS can be regenerated with ethylenediamine tetraacetic acid disodium salt (EDTA) solution for repetitious adsorption of Pb²⁺.

Development and characterization of crosslinked hyaluronic acid polymeric films for use in coating processes

The aim of this work was to develop and characterize new hyaluronic acid-based responsive materials for film coating of solid dosage forms. Crosslinking of hyaluronic acid with trisodium trimetaphosphate was performed under controlled alkaline aqueous environment. The films were produced through casting process by mixing crosslinked or bare biopolymer in aqueous dispersion of ethylcellulose, at different proportions. Films were further characterized regarding morphology by scanning electron microscopy, robustness by permeation to water vapor transmission, and ability to hydrate in simulated gastric and intestinal physiological fluids. The safety and biocompatibility of films were assessed against Caco-2 and HT29-MTX intestinal cells. The permeation to water vapor transmission was favored by increasing hyaluronic acid content in the final formulation. When in simulated gastric fluid, films exhibited lower hydration ability compared to more extensive hydration in simulated intestinal fluids. Simultaneously, in simulated intestinal fluids, films partially lost weight, revealing ability for preventing drug release at gastric pH, but tailoring the release at higher intestinal pH. The physiochemical characterization suggests thermal stability of films and physical interaction between compounds of formulation. Lastly, cytotoxicity tests demonstrated that films and individual components of the formulations, when incubated for 4h, were safe for intestinal cells Overall, these evidences suggest that hyaluronic acid-based responsive films, applied as coating material of oral solid dosage forms, can prevent the premature release of drugs in harsh stomach conditions, but control the release it in gastrointestinal tract distal portion, assuring safety to intestinal mucosa.

Effect of drying technique on some physical properties of cross-linked high amylose/pectin mixtures

Polymers mixtures as well as cross-linking reactions are approaches that have been used successfully to modulate the polymers characteristics in order to improve the control over drug release rate. High amylose and pectin are polysaccharides frequently used to prepare drug delivery systems. Since the drying technique can strongly influence the properties of such systems, the aim of this work was to characterize high amylose/pectin mixtures cross-linked with sodium trimetaphosphate and dried by different techniques - oven and lyophilization. The results showed that samples dried by lyophilization presented reduced particle size, higher porosity and higher swelling ability than the samples dried in oven. Besides, lower thermal stability and different diffraction patterns showed by the former particles should reflect the structural changes as a function of drying technique.

A pH/enzyme-responsive polymer film consisting of Eudragit FS 30 D and arabinoxylane as a potential material formulation for colon-specific drug delivery system

Polymer film based on pH-dependent Eudragit FS 30 D acrylic polymer in association with arabinoxylane, a polysaccharide issued from gum psyllium, was produced by way of solvent casting. Physical-chemical characterization of the polymer film samples was performed by means of thermogravimetry (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Furthermore, water-equilibrium swelling index (I(s)) and weight loss of the films in KCl buffer solution of pH 1.2, in KH(2)PO(4) buffer solution of pH 5.0, or in KH(2)PO(4) buffer solution of pH 5.0 consisting of 4% enzyme Pectinex 3X-L (w/v) were also carried out for the film characterization. No chemical interactions between the Eudragit FS 30 D and the arabinoxylane polymer chains were evidenced, thus suggesting that the film-forming polymer structure was obtained from a physical mixture of both polymers. The arabinoxylane-loader films showed a more pronounced weight loss after their immersion in buffer solution containing enzyme Pectinex 3X-L. The introduction of the arabinoxylane makes the film more susceptible to undergo an enzymatic degradation. This meant that the enzyme-dependent propriety issued from the arabinoxylane has been imprinted into the film formulation. This type of polymer film is an interesting system for applications in colon-specific drug delivery system.

Review of in vitro digestion models for rapid screening of emulsion-based systems

There is increasing interest in understanding and controlling the digestion of emulsified lipids within the food and pharmaceutical industries. Emulsion-based delivery systems are being developed to encapsulate, protect, and release non-polar lipids, vitamins, nutraceuticals, and drugs. These delivery systems are also being used to control the stability and digestion of lipids within the human gastrointestinal tract so as to create foods that enhance satiety and reduce hunger. In vitro digestion models are therefore needed to test the efficacy of different approaches of controlling lipid digestion under conditions that simulate the human gastrointestinal tract. This article reviews the current status of in vitro digestion models for simulating lipid digestion, with special emphasis on the pH stat method. The pH stat method is particularly useful for the rapid screening of food emulsions and emulsion-based delivery systems with different compositions and structures. Successful candidates can then be tested with more rigorous in vitro digestion models, or using animal or human feeding studies.