Fully physically crosslinked pectin-based hydrogel with high stretchability and toughness for biomedical application

Experimental assessment of biostimulants on mung bean growth on a soilless culture system using superabsorbent pectin based hydrogel

Sustainable agriculture initiatives are needed to ensure the food security of the people all over the world. Soilless cultivation methods using hydrogels may give a revolutionary response as well as a more ecological and productive alternative to conventional farming. This study attempted extraction of pectin from the rind of albedo yellow passion fruit (Passiflora edulis var. flavicarpa Degener)and hydrogels from pectin and activated carbon was compared with pure pectin hydrogel; Pectin- Activated Carbon hydrogels (PAC) showed a microporous structure with excellent hydrophilicity and showed superior water holding capacity. Then the prepared hydrogels were examined with various instrumental techniques like FTIR, SEM, XRD, Raman, BET and rheological properties. In the BET analysis, PAC3 shows the highest surface area of 28.771 m2/g when compared to PAC0 at 15.063 m2/g. The germination experiments were performed using mung beans. This study provides an opportunity for the application of pectin hydrogels in agriculture field specifically for home garden or rooftop cultivation.

Tissue regeneration properties of hydrogels derived from biological macromolecules: A review

The successful tissue engineering depends on the development of biologically active scaffolds that possess optimal characteristics to effectively support cellular functions, maintain structural integrity and aid in tissue regeneration. Hydrogels have emerged as promising candidates in tissue regeneration due to their resemblance to the natural extracellular matrix and their ability to support cell survival and proliferation. The integration of hydrogel scaffold into the polymer has a variable impact on the pseudo extracellular environment, fostering cell growth/repair. The modification in size, shape, surface morphology and porosity of hydrogel scaffolds has consequently paved the way for addressing diverse challenges in the tissue engineering process such as tissue architecture, vascularization and simultaneous seeding of multiple cells. The present review provides a comprehensive update on hydrogel production using natural and synthetic biomaterials and their underlying mechanisms. Furthermore, it delves into the application of hydrogel scaffolds in tissue engineering for cardiac tissues, cartilage tissue, adipose tissue, nerve tissue and bone tissue. Besides, the present article also highlights various clinical studies, patents, and the limitations associated with hydrogel-based scaffolds in recent times.

Cytotoxicity and Degradation Resistance of Cryo- and Hydrogels Based on Carboxyethylchitosan at Different pH Values

Background: The use of chitosan-based gels is still limited due to their restricted solubility in acid solutions, where the molecules have a positive charge. The functionalization of chitosan makes it possible to significantly expand the possibilities of using both the polymer itself and hydrogels based on its derivatives. Objective: To evaluate the effect of the conditions for the production of cryo- and hydrogels based on carboxyethylchitosan (CEC) crosslinked with glutaraldehyde on gel swelling and its resistance to degradation depending on pH and cytotoxic effects and to test the hypothesis that the amount of crosslinking agent during synthesis may affect the cytotoxicity of the gel. Methods: Gels' swelling values and degradation resistance were determined using the gravimetric method. The cytotoxic effect was evaluated during the co-cultivation of gels in the presence of human fibroblasts using light optical microscopy and flow cytometry. Results: All CEC-based cryogels had a higher equilibrium swelling value and degradation time than the CEC hydrogel in the pH range from 4.6 to 8.0. This demonstrates the superiority of cryogels relative to CEC-based hydrogels in terms of swelling potential and degradation resistance, while an increase in the number of crosslinks with glutaraldehyde contributes to longer swelling of the cryogel. The positive control (intact fibroblasts) and all gel samples were statistically identical in the number of viable cells. On the third day, the viability of the fibroblast cells was consistently high (above 95%) and did not differ between all tested CEC-based gels. And in general, the cell morphology analysis results corresponded with the results obtained in the flow cytometry-based cytotoxicity test. We also did not find proof in our experiment to support our hypothesis that the amount of crosslinking agent during synthesis may affect the cytotoxicity of the material.

Pectin hydrogels for controlled drug release: Recent developments and future prospects

Pectin hydrogels have emerged as a highly promising medium for the controlled release of pharmaceuticals in the dynamic field of drug delivery. The present review sheds light on the broad range of applications and potential of pectin-based hydrogels in pharmaceutical formulations. Pectin, as a biopolymer, is a versatile candidate for various drug delivery systems because of its wide range of properties and characteristics. The information provided on formulation strategies and crosslinking techniques provides researchers with tools to improve drug entrapment and controlled release. Furthermore, this review provides a more in-depth understanding of the complex factors influencing drug release from pectin hydrogels, such as the impact of environmental conditions and drug-specific characteristics. Pectin hydrogels demonstrate adaptability across diverse domains, ranging from applications in oral and transdermal drug delivery to contributions in wound healing, tissue engineering, and ongoing clinical trials. While standardization and regulatory compliance remain significant challenges, the future of pectin hydrogels appears to be bright, opening up new possibilities for advanced drug delivery systems.

Aldehyde group pendant-grafted pectin-based injectable hydrogel

Periodate oxidation has been the widely accepted route for obtaining aldehyde group-functionalized polysaccharides but significantly influenced the various physicochemical properties due to the ring opening of the backbone of polysaccharides. The present study, for the first time, presents a novel method for the preparation of aldehyde group-functionalized polysaccharides that could retain the ring structure and the consequent rigidity of the backbone. Pectin was collected as the representative of polysaccharides and modified with cyclopropyl formaldehyde to obtain pectin aldehyde (AP), which was further crosslinked by DL-lysine (LYS) via the Schiff base reaction to prepare injectable hydrogel. The feasibility of the functionalization was proved by FT-IR and 1H NMR techniques. The obtained hydrogel showed acceptable mechanical properties, self-healing ability, syringeability, and sustained-release performance. Also, as-prepared injectable hydrogel presented great biocompatibility with a cell proliferation rate of 96 %, and the drug-loaded hydrogel exhibited clear inhibition of cancer cell proliferation. Overall, the present study showed a new method for the preparation of aldehyde group-functionalized polysaccharides, and the drug-loaded hydrogel has potential in drug release applications.

Tough, high conductivity pectin polysaccharide-based hydrogel for strain sensing and real-time information transmission

Hydrogels from natural polymers are eco-friendly, biocompatible and adjustable for manufacturing wearable sensors. However, it is still challenging to prepare natural polymer hydrogel sensors with excellent properties (e.g., high conductivity). Here, we developed a physically cross-linked, highly conductive and multifunctional hydrogel (named PPTP) to address this challenge. The natural renewable pectin-based PPTP hydrogel is synthesized by introducing tannic acid (TA), calcium chloride (CaCl2), and sodium chloride (NaCl) into the pectin/polyvinyl alcohol (PVA) dual network structure. The hydrogel exhibits excellent characteristics, including unique tensile strength (2.6155 MPa), high electrical conductivity (7 S m-1), and high sensitivity (GF = 3.75). It is also recyclable, further enhancing its eco-friendly nature. The PPTP hydrogel can be used for monitoring human joint activities, as flexible electrodes for monitoring electrocardiogram (ECG) signals, and touchable screen pen for electronic skin. Moreover, when combined with Morse code and wireless Bluetooth technology, PPTP hydrogels can be used for underwater and land information encryption, and decryption. Our unique PPTP hydrogel offers promising opportunities for medical monitoring, information transfer, and human-computer interaction.

Supramolecular hydrogels for wound repair and hemostasis

The unique network characteristics and stimuli responsiveness of supramolecular hydrogels have rendered them highly advantageous in the field of wound dressings, showcasing unprecedented potential. However, there are few reports on a comprehensive review of supramolecular hydrogel dressings for wound repair and hemostasis. This review first introduces the major cross-linking methods for supramolecular hydrogels, which includes hydrogen bonding, electrostatic interactions, hydrophobic interactions, host-guest interactions, metal ligand coordination and some other interactions. Then, we review the advanced materials reported in recent years and then summarize the basic principles of each cross-linking method. Next, we classify the network structures of supramolecular hydrogels before outlining their forming process and propose their potential future directions. Furthermore, we also discuss the raw materials, structural design principles, and material characteristics used to achieve the advanced functions of supramolecular hydrogels, such as antibacterial function, tissue adhesion, substance delivery, anti-inflammatory and antioxidant functions, cell behavior regulation, angiogenesis promotion, hemostasis and other innovative functions in recent years. Finally, the existing problems as well as future development directions of the cross-linking strategy, network design, and functions in wound repair and hemostasis of supramolecular hydrogels are discussed. This review is proposed to stimulate further exploration of supramolecular hydrogels on wound repair and hemostasis by researchers in the future.

Polysaccharide-Based Double-Network Hydrogels: Polysaccharide Effect, Strengthening Mechanisms, and Applications

Polysaccharides are carbohydrate polymers that are major components of plants, animals, and microorganisms, with unique properties. Biological hydrogels are polymeric networks that imbibe and retain large amounts of water and are the major components of living organisms. The mechanical properties of hydrogels are critical for their functionality and applications. Since synthetic polymeric double-network (DN) hydrogels possess unique network structures with high and tunable mechanical properties, many natural functional polysaccharides have attracted increased attention due to their rich and convenient sources, unique chemical structure and chain conformation, inherently desirable cytocompatibility, biodegradability and environmental friendliness, diverse bioactivities, and rheological properties, which rationally make them prominent constituents in designing various strong and tough polysaccharide-based DN hydrogels over the past ten years. This review focuses on the latest developments of polysaccharide-based DN hydrogels to comprehend the relationship among the polysaccharide properties, inner strengthening mechanisms, and applications. The aim of this review is to provide an insightful mechanical interpretation of the design strategy of novel polysaccharide-based DN hydrogels and their applications by introducing the correlation between performance and composition. The mechanical behavior of DN hydrogels and the roles of varieties of marine, microbial, plant, and animal polysaccharides are emphatically explained.

A Carboxyethylchitosan Gel Cross-Linked with Glutaraldehyde as a Candidate Carrier for Biomedical Applications

To date, few publications describe CEC's properties and possible applications-thus, further evaluation of these properties is a point of interest. The present in vitro model study aimed to evaluate a carboxyethylchitosan (CEC) gel with a degree of substitution of 1, cross-linked with glutaraldehyde at a polymer:aldehyde molar ratio of 10:1, as a potential carrier for delivering bacteriophages to various pH-fixed media (acidic, alkaline), and including gastrointestinal tract (GIT) variable medium. A quantitative analysis of bacteriophages released from the gel was performed using photon correlation spectrophotometry, and phage activity after emission into medium was evaluated using the spot test. The results showed that the CEC gel's maximum swelling ratios were at a nearly neutral alkaline pH. Increasing temperature enhances the swelling ratio of the gel independent from pH, up to 1127% at 37 °C and alkaline pH. The UV and photon correlation spectrophotometry showed equal gel release kinetics in both fixed media with acidic (pH = 2.2) and alkaline (pH = 7.4) pH environments at 37 °C, with the maximum release within two hours. However, phage lytic activity in the spot test during this simulation was absent. At the same time, we obtained an opaque phage lytic activity in the alkaline pH-fixed medium for at least three hours. Phages released from the tested CEC gel in different pHs suggest that this gel could be used for applications that require fast release at the treatment site both in acidic and alkaline pH. Such treatment sites could be a wound or even soil with mild acidic or alkaline pH. However, such CEC gel is not suitable as a delivery system to the GIT because of possible transported acid-sensitive agent (such as phages) release and destruction already in the stomach.

An effective DLP 3D printing strategy of high strength and toughness cellulose hydrogel towards strain sensing

Photocurable 3D printing technology has outperformed extrusion-based 3D printing technology in material adaptability, resolution, and printing rate, yet is still limited by the insecure preparation and selection of photoinitiators and thus less reported. In this work, we developed a printable hydrogel that can effectively facilitate various solid or hollow structures and even lattice structures. The chemical and physical dual-crosslinking strategy combined with cellulose nanofibers (CNF) significantly improved the strength and toughness of photocurable 3D printed hydrogels. In this study, the tensile breaking strength, Young's modulus, and toughness of poly(acrylamide-co-acrylic acid)_D/cellulose nanofiber (PAM-co-PAA)_D/CNF hydrogels were 375 %, 203 % and 544 % higher than those of the traditional single chemical crosslinked (PAM-co-PAA)_S hydrogels, respectively. Notably, its outstanding compressive elasticity enabled it to recover under 90 % strain compression (about 4.12 MPa). Resultantly, the proposed hydrogel can be utilized as a flexible strain sensor to monitor the motions of human movements, such as the bending of fingers, wrists, and arms, and even the vibration of a speaking throat. The output of electrical signals can still be collected through strain even under the condition of energy shortage. In addition, photocurable 3D printing technology can provide customized services for hydrogel-based e-skin, such as hydrogel-based bracelets, fingerstall, and finger joint sleeves.

Polymeric hydrogels-based materials for wastewater treatment

Low-cost and reliable wastewater treatment is a relevant issue worldwide to reduce the concentration of environmental pollutants. Industrial effluents containing dyes, heavy metals, and other inorganic and organic compounds can pollute water resources; therefore, novel technologies are required to mitigate and control their release into the environment. Adsorption is one of the simplest methods for treating contaminated water in which a wide spectrum of adsorbents can be used to remove emerging compounds. Hydrogels are interesting materials with high adsorption capacities that can be synthesized via green routes. These adsorbents are promising for large-scale industrial wastewater treatment applications; however, gaps still exist in achieving sustainable commercial implementation. This review focuses on the discussion and analysis of preparation, characterization, and adsorption properties of hydrogels for water purification. The advantages of these polymeric materials for water treatment were analyzed, including their performance in the removal of different organic and inorganic contaminants. Recent advances in the functionalization of hydrogels and the synthesis of novel composites have also been described. The adsorption capacities of hydrogel-based adsorbents are higher than 500 mg/g for different organic and inorganic pollutants, and can reach values of up to >2000 mg/g for organic compounds, significantly outperforming other materials reported for water cleaning. The main interactions involved in the adsorption of water pollutants using hydrogel-based adsorbents were described and explained to allow the interpretation of their removal mechanisms. The current challenges in the implementation of hydrogels for water purification in real-life operations are also highlighted. This review provides an updated picture of hydrogels as interesting materials to address water depollution worldwide.

Natural Solid-State Hydrogel Electrolytes Based on 3D Pure Cotton/Graphene for Supercapacitor Application

A conductive cotton hydrogel with graphene and ions can come into contact with electrodes in solid electrolytes at the molecular level, leading to a more efficient electrochemical process in supercapacitors. The inherently soft nature of cotton mixed with hydrogel provides superior flexibility of the electrolyte, which benefits the devices in gaining high flexibility. Herein, we report on the current progress in solid-state hydrogel electrolytes based on 3D pure cotton/graphene and present an overview of the future direction of research. The ionic conductivity of a complex hydrogel significantly increased by up to 13.9 × 10^-3 S/cm at 25 °C, due to the presence of graphene, which increases ionic conductivity by providing a smooth pathway for the transport of charge carriers and the polymer. Furthermore, the highest specific capacitance of 327 F/g at 3 mV/s was achieved with cyclic voltammetry measurement and a galvanostatic charge-discharge measurement showed a peak value of 385.4 F/g at 100 mA/g current density. Furthermore, an electrochemical analysis demonstrated that a composite cotton/graphene-based hydrogel electrolyte is electrically stable and could be used for the design of next-generation supercapacitors.

Supramolecular structure of banana peel pectin and its transformations during extraction by acidic methods

In this study, the approaches to describe the mesh structure in the homogalacturonate domains of pectin and the effect of the native structure violations on the stabilization effectiveness of the oil-in-water emulsion were demonstrated. Pectin with a native structure was isolated from banana peel by enzymolysis of insoluble dietary fibres. This pectin was compared with pectins, which were isolated using hydrochloric and citric acids. The properties of pectins were analyzed taking into account the ratio of galacturonate units in nonsubstituted, methoxylated and calcium-pectate forms. The content of calcium-pectate units determines the density of inter-molecular crosslinking formation. The simulation results reflect the structure of rigid "egg-box" crosslinking blocks and flexible segments formed in native pectin mainly by methoxylated links. Hydrochloric acid extraction is accompanied by the destruction of the crosslinking blocks and depolymerization of pectin. Citric acid partially demineralizes the crosslinking blocks contributing to the release of macromolecular chains that do not have calcium-pectate units. The granulometric data indicates that the individual macromolecules take the thermodynamically stable form of a statistical tangle. Such conformation is an ideal basis for the formation of "host-guest" microcontainers having a hydrophilic shell and a hydrophobic core with an oil-soluble functional substance.

Characterization and In Vivo Assay of Allantoin-Enriched Pectin Hydrogel for the Treatment of Skin Wounds

This work describes a liquid allantoin-enriched pectin hydrogel with hydrophilic behavior that is supported by the presence of functional groups related to healing efficacy. A topical study shows the effect of the hydrogel application on surgically induced skin wound healing in a rat model. Contact angle measurements confirm hydrophilic behavior (11.37°), while Fourier-transform infrared spectroscopy indicates the presence of functional groups related to the healing effectiveness (carboxylic acid and amine groups). Allantoin is distributed on the surface and inside the amorphous pectin hydrogel surrounded by a heterogeneous distribution of pores. This promotes wound drying with better interaction between the hydrogel and cells involved in the wound healing process. An experimental study with female Wistar rats indicates that the hydrogel improves wound contraction, reducing around 71.43% of the total healing time and reaching total wound closure in 15 days.

A Review of Pectin-Based Material for Applications in Water Treatment

Climate change and water are inseparably connected. Extreme weather events cause water to become more scarce, polluted, and erratic than ever. Therefore, we urgently need to develop solutions to reduce water contamination. This review intends to demonstrate that pectin-based materials are an excellent route to detect and mitigate pollutants from water, with several benefits. Pectin is a biodegradable polymer, extractable from vegetables, and contains several hydroxyl and carboxyl groups that can easily interact with the contaminant ions. In addition, pectin-based materials can be prepared in different forms (films, hydrogels, or beads) and cross-linked with several agents to change their molecular structure. Consequently, the pectin-based adsorbents can be tuned to remove diverse pollutants. Here, we will summarize the existing water remediation technologies highlighting adsorption as the ideal method. Then, the focus will be on the chemical structure of pectin and, from a historical perspective, on its structure after applying different cross-linking methods. Finally, we will review the application of pectin as an adsorbent of water pollutants considering the pectin of low degree methoxylation.

Current and future outlook of loaded components in hydrogel composites for the treatment of chronic diabetic ulcers

Due to recalcitrant microangiopathy and chronic infection, traditional treatments do not easily produce satisfactory results for chronic diabetic ulcers. In recent years, due to the advantages of high biocompatibility and modifiability, an increasing number of hydrogel materials have been applied to the treatment of chronic wounds in diabetic patients. Research on composite hydrogels has received increasing attention since loading different components can greatly increase the ability of composite hydrogels to treat chronic diabetic wounds. This review summarizes and details a variety of newly loaded components currently used in hydrogel composites for the treatment of chronic diabetic ulcers, such as polymer/polysaccharides/organic chemicals, stem cells/exosomes/progenitor cells, chelating agents/metal ions, plant extracts, proteins (cytokines/peptides/enzymes) and nucleoside products, and medicines/drugs, to help researchers understand the characteristics of these components in the treatment of diabetic chronic wounds. This review also discusses a number of components that have not yet been applied but have the potential to be loaded into hydrogels, all of which play roles in the biomedical field and may become important loading components in the future. This review provides a "loading component shelf" for researchers of composite hydrogels and a theoretical basis for the future construction of "all-in-one" hydrogels.

Serosal Adhesion Ex Vivo of Hydrogels Prepared from Apple Pectin Cross-Linked with Fe3+ Ions

The study aims to investigate the adhesion of a hydrogel made of cross-linked low-methyl esterified pectin to rat intestinal serosa ex vivo. The adhesivity of the FeP hydrogel, which was cross-linked by Fe³⁺ cations, exceeded that of hydrogels cross-linked by Ca²⁺, Zn²⁺, and Al³⁺ cations. The concentration of the cross-linking cation failed to influence the adhesion of the pectin hydrogel to the serosa. The mechanical properties and surface microrelief of the pectin hydrogel were influenced by the type and concentration of the cross-linking cations. Fe³⁺ cations form a harder and more elastic gel than Ca²⁺ cations. Scanning electron microscopy analysis revealed the characteristic surface pattern of FeP hydrogel and its denser internal structure compared to Ca²⁺ cross-linked hydrogel. The effect of the salt composition of the adhesion medium was shown since the FeP hydrogel's adhesion to the serosa was lower in physiological solutions than in water, and adhesion in Hanks' solution was higher than in phosphate buffered saline. Serum proteins and peritoneal leukocytes did not interfere with the serosal adhesion of the FeP hydrogel. Pre-incubation in Hanks' solution for 24 h significantly reduced the adhesion of the FeP hydrogel to the serosa, regardless of the pH of the incubation. Thus, serosal adhesion combined with excellent stability and mechanical properties in physiological environments appeared to be advantages of the FeP hydrogel, demonstrating it to be a promising bioadhesive for tissue engineering.

Alginate/pectin dressing with niosomal mangosteen extract for enhanced wound healing: evaluating skin irritation by structure-activity relationship

Most modern wound dressings assist the wound-healing process. In contrast, conventional wound dressings have limited antibacterial activity and promote sporadic fibroblast growth. Therefore, wound dressings with prolonged substance release must be improved. This research aimed to develop hydrogel films. These were synthesized from alginate and pectin, incorporated with mangosteen extract (ME), and encapsulated in niosomes (ME-loaded niosomes). Subsequently, we examined the in vitro release and physical characteristics of ME-loaded niosomes. These characteristics included particle pH, size, charge, polydispersity index (PDI), and drug loading properties. These properties included drug loading content (DLC), entrapment efficiency (EE), and yield (Y). Additionally, we examined the swelling ratio and biological characteristics of the hydrogel film. These characteristics included antibacterial activity, cytotoxicity (L929), cell attachment to the tested materials, cell migration, hemocompatibility, and in vivo irritation. Significant results were obtained using a 2:1 niosome preparation containing Span60 and cholesterol. Ratio influenced size, charge, PDI, DLC, EE, and Y. The results were 225.5 ± 5.83 nm, negatively charged, 0.38, 16.2 ± 0.87%, 64.8 ± 3.49%, and 87.3 ± 3.09%, respectively. Additionally, the release of encapsulated ME was pH sensitive because 85% of the ME can be released at a pH of 5.5 within seven days and decrease to 70% at a pH of 7.4. The maximum swelling ratios of patches with 0.5% and 1% Ca2+ crosslinking were 867 wt% and 1,025 wt%, respectively, after 30 min. These results suggested that a medium dose (15 mg) of niosomal ME incorporated in a hydrogel film provided better bacterial inhibition, cell migration, and cell adhesion in an in vitro model. Additionally, no toxicity was observed in the fibroblasts and red blood cells. Therefore, given the above-mentioned advantages, this product can be a promising candidate for wound dressing applications.

Effect of Cross-Linking Cations on In Vitro Biocompatibility of Apple Pectin Gel Beads

The study aimed to compare the in vitro biocompatibility of pectin gels formed by different cross-linking cations. Hydrogel beads named CaPG, ZnPG, FePG, and AlPG were prepared from 4% solutions of apple pectin using ionotropic gelling with CaCl2, ZnCl2, FeCl3, and AlCl3, respectively. Cations influenced the gel strength of the wet gel beads in the following order (least strong) Ca2+ < Zn2+ < Fe3+~Al3+ (most strong). The swelling degree of the CaPG beads after 24 h of incubation in the RPMI-1640 medium was 104%, whereas the ZnPG, FePG, and AlPG beads swelled by 76, 108, and 134%, respectively. The strength of the pectin gel decreased significantly after incubation in the RPMI-1640 medium for 24 h, regardless of the cross-linking cation, although the FePG beads remained the strongest. All the pectin beads adsorbed serum proteins to a low degree, however the serum protein adsorption by the ZnPG and FePG beads (1.46 ± 0.87 and 1.35 ± 0.19 µg/mm2) was more than the CaPG and AlPG beads (0.31 ± 0.36 and 0.44 ± 0.25 µg/mm2). All the pectin beads reduced the production of TNF-α and IL-10 by hPBMCs in response to LPS stimulation. The IL-1β response of cells to LPS was significantly reduced by the CaPG, ZnPG, and FePG beads, whereas the AlPG beads enhanced it twofold. The CaPG, FePG, and AlPG beads had no cytotoxicity. The viability of hPBMCs and human fibroblasts incubated with ZnPG beads was 5.3 and 7.2%, respectively. Thus, the use of different cross-linking cations changed the properties of the pectin gel, which is important for biocompatibility.

Potential of pectin for biomedical applications: a comprehensive review

Pectin is a polysaccharide extracted from various plants, such as apples, oranges, lemons, and it possesses some beneficial effects on human health, including being hypoglycemic and hypocholesterolemic. Therefore, pectin is used in various pharmaceutical and biomedical applications. Meanwhile, its low mechanical strength and fast degradation rate limit its usage as drug delivery devices and tissue engineering scaffolds. To enhance these properties, it can be modified or combined with other organic molecules or polymers and/or inorganic compounds. These materials can be prepared as nano sized drug carriers in the form of spheres, capsules, hydrogels, self assamled micelles, etc., for treatment purposes (mostly cancer). Different composites or blends of pectin can also be produced as membranes, sponges, hydrogels, or 3D printed matrices for tissue regeneration applications. This review is concentrated on the properties of pectin based materials and focus especially on the utilization of these materials as drug carriers and tissue engineering scaffolds, including 3D printed and 3D bioprinted systems covering the studies in the last decade and especially in the last 5 years.

Exploiting Polymeric Films as a Multipurpose Drug Delivery System: a Review

Polymeric films are drug delivery systems that maintain contact with the delivery tissue and sustain a controlled release of therapeutic molecules. These systems allow a longer time of drug contact with the target site in the case of topical treatments and allow the controlled administration of drugs. They can be manufactured by various methods such as solvent casting, hot melt extrusion, electrospinning, and 3D bioprinting. Furthermore, they can employ various polymers, for example PVP, PVA, cellulose derivatives, chitosan, gelling gum, pectin, and alginate. Its versatility is also applicable to different routes of administration, as it can be administered to the skin, oral mucosa, vaginal canal, and eyeballs. All these factors allow numerous combinations to obtain a better treatment. This review focuses on exploring some possible ways to develop them and some particularities and advantages/disadvantages in each case. It also aims to show the versatility of these systems and the advantages and disadvantages in each case, as they bring the opportunity to develop different medicines to facilitate therapies for the most diverse purposes .

An overview of substrate stiffness guided cellular response and its applications in tissue regeneration

Cell-matrix interactions play a critical role in tissue repair and regeneration. With gradual uncovering of substrate mechanical characteristics that can affect cell-matrix interactions, much progress has been made to unravel substrate stiffness-mediated cellular response as well as its underlying mechanisms. Yet, as a part of cell-matrix interaction biology, this field remains in its infancy, and the detailed molecular mechanisms are still elusive regarding scaffold-modulated tissue regeneration. This review provides an overview of recent progress in the area of the substrate stiffness-mediated cellular responses, including 1) the physical determination of substrate stiffness on cell fate and tissue development; 2) the current exploited approaches to manipulate the stiffness of scaffolds; 3) the progress of recent researches to reveal the role of substrate stiffness in cellular responses in some representative tissue-engineered regeneration varying from stiff tissue to soft tissue. This article aims to provide an up-to-date overview of cell mechanobiology research in substrate stiffness mediated cellular response and tissue regeneration with insightful information to facilitate interdisciplinary knowledge transfer and enable the establishment of prognostic markers for the design of suitable biomaterials.

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Substrate stiffness physically determines cell fate and tissue development.

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Rational design of scaffolds requires the understanding of cell-matrix interactions.

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Substrate stiffness depends on scaffold molecular-constituent-structure interaction.

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Substrate stiffness-mediated cellular responses vary in different tissues.

Plant Polysaccharides in Engineered Pharmaceutical Gels

Hydrogels are a great ally in the pharmaceutical and biomedical areas. They have a three-dimensional polymeric structure that allows the swelling of aqueous fluids, acting as an absorbent, or encapsulating bioactive agents for controlled drug release. Interestingly, plants are a source of biogels, specifically polysaccharides, composed of sugar monomers. The crosslinking of these polymeric chains forms an architecture similar to the extracellular matrix, enhancing the biocompatibility of such materials. Moreover, the rich hydroxyl monomers promote a hydrophilic behavior for these plant-derived polysaccharide gels, enabling their biodegradability and antimicrobial effects. From an economic point of view, such biogels help the circular economy, as a green material can be obtained with a low cost of production. As regards the bio aspect, it is astonishingly attractive since the raw materials (polysaccharides from plants-cellulose, hemicelluloses, lignin, inulin, pectin, starch, guar, and cashew gums, etc.) might be produced sustainably. Such properties make viable the applications of these biogels in contact with the human body, especially incorporating drugs for controlled release. In this context, this review describes some sources of plant-derived polysaccharide gels, their biological function, main methods for extraction, remarkable applications, and properties in the health field.

Polysaccharide-based nanosystems: a review

Polysaccharide-based nanosystem is an umbrella term for many areas within research and technology dealing with polysaccharides that have at least one of their dimensions in the realm of a few hundreds of nanometers. Nanoparticles, nanocrystals, nanofibers, nanofilms, and nanonetworks can be fabricated from many different polysaccharide resources. Abundance in nature, cellulose, starch, chitosan, and pectin of different molecular structures are widely used to fabricate nanosystems for versatile industrial applications. This review presents the dissolution and modification of polysaccharides, which are influenced by their different molecular structures and applications. The dissolution ways include conventional organic solvents, ionic liquids, inorganic strong alkali and acids, enzymes, and hydrothermal treatment. Rheological properties of polysaccharide-based nano slurries are tailored for the purpose functions of the final products, e.g., imparting electrostatic functions of nanofibers to reduce viscosity by using lithium chloride and octenyl succinic acid to increase the hydrophobicity. Nowadays, synergistic effects of polysaccharide blends are increasingly highlighted. In particular, the reinforcing effect of nanoparticles, nanocrystals, nanowhiskers, and nanofibers to hydrogels, aerogels, and scaffolds, and the double network hydrogels of a rigid skeleton and a ductile substance have been developed for many emerging issues.

Recent advances on biomedical applications of pectin-containing biomaterials

There is a growing demand for biomaterials developing with novel properties for biomedical applications hence, hydrogels with 3D crosslinked polymeric structures obtained from natural polymers have been deeply inspected in this field. Pectin a unique biopolymer found in the cell walls of fruits and vegetables is extensively used in the pharmaceutical, food, and textile industries due to its ability to form a thick gel-like solution. Considering biocompatibility, biodegradability, easy gelling capability, and facile manipulation of pectin-based biomaterials; they have been thoroughly investigated for various potential biomedical applications including drug delivery, wound healing, tissue engineering, creation of implantable devices, and skin-care products.

Pectin gels based on H+/(NH4)2SO4 and its potential in sustained release of NH4. Int J Biol Macromol 2022;208:486-493. [PMID: 35304200 DOI: 10.1016/j.ijbiomac.2022.03.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

A gelling strategy for HP was proposed in this study, ammonium sulfate (AS) as a co-solute could induce the gelling of HP in acidic environment. The solubility and Zeta potential of HP dramatically decreased in AS solution, which indicated AS could promote the aggregation of HP. The rheological results confirmed the gelling of HP (G' > G″) with AS: 25-30 wt% and pH ≤ 3.0, and the gel strength is mainly depended on HP rather than AS concentration. Smaller AS crystals (SEM) and reduced T₂ values (LF-NMR) were observed in HP gels, suggested the gel network of HP could limit the migration of AS and water. Finally, it was found that the release process of NH₄⁺ in HP + AS gel was lagged behind that of pure AS, which verified the potential of HP + AS gel in the field of sustained-release fertilizers.

Facile preparation of thermosensitive and antibiofouling physically crosslinked hydrogel/powder for wound healing

To improve the therapeutic effect of hydrogel for damaged tissue, a series of hydroxybutyl chitosan (HBC) and poly (sulfobetaine methacrylate) (PSBMA) composite hydrogels (HBC-PSB) with thermosensitivity, self-healing, antibiofouling, and synergistic...

Chitosan-based hydrogel crosslinked through an aza-Michael addition catalyzed by boric acid

Polysaccharide-based hydrogels are particularly attractive materials for biomedical applications. However, their use is restricted due to their brittleness and poor mechanical properties. Here, to overcome such limitations, we report an original, green, simple, and efficient strategy to synthesize a polysaccharide-based hydrogel of chitosan (Cht) and a vinyl-functionalized PVA (PVA-MA), a non-toxic synthetic polymer that is widely known to improve the mechanical properties and stability of materials containing polysaccharides. The hydrogel was crosslinked through an aza-Michael addition among the amino groups of Cht with the vinyl moieties of PVA-MA catalyzed by boric acid (B(OH)₃), an eco-friendly inorganic compound. Characterization analyses revealed that the prepared hydrogel has a porous-like morphology, an outstanding liquid uptake capacity (>665%), and improved stability in a physiological fluid for long periods. In summary, this original and simple strategy showed to be efficient in the synthesis of hydrogels with attractive properties for the biomedical field application.

Recent advances in utilization of pectins in biomedical applications: a review focusing on molecular structure-directing health-promoting properties

The numerous health benefits of pectins justify their inclusion in human diets and biomedical products. This review provides an overview of pectin extraction and modification methods, their physico-chemical characteristics, health-promoting properties, and pharmaceutical/biomedical applications. Pectins, as readily available and versatile biomolecules, can be tailored to possess specific functionalities for food, pharmaceutical and biomedical applications, through judicious selection of appropriate extraction and modification technologies/processes based on green chemistry principles. Pectin's structural and physicochemical characteristics dictate their effects on digestion and bioavailability of nutrients, as well as health-promoting properties including anticancer, immunomodulatory, anti-inflammatory, intestinal microflora-regulating, immune barrier-strengthening, hypercholesterolemia-/arteriosclerosis-preventing, anti-diabetic, anti-obesity, antitussive, analgesic, anticoagulant, and wound healing effects. HG, RG-I, RG-II, molecular weight, side chain pattern, and degrees of methylation, acetylation, amidation and branching are critical structural elements responsible for optimizing these health benefits. The physicochemical characteristics, health functionalities, biocompatibility and biodegradability of pectins enable the construction of pectin-based composites with distinct properties for targeted applications in bioactive/drug delivery, edible films/coatings, nano-/micro-encapsulation, wound dressings and biological tissue engineering. Achieving beneficial synergies among the green extraction and modification processes during pectin production, and between pectin and other composite components in biomedical products, should be key foci for future research.

Chitosan/Hyaluronic acid/Alginate and an assorted polymers loaded with honey, plant, and marine compounds for progressive wound healing-Know-how

Biomaterials are being extensively used in regenerative medicine including tissue engineering applications, as these enhance tissue development, repair, and help in the process of angiogenesis. Wound healing is a crucial biological process of regeneration of ruptured tissue after getting injury to the skin and other soft tissue in humans and animals. Besides, the accumulation of microbial biofilms around the wound surface can increase the risk and physically obstruct the wound healing activity, and may even lead to amputation. Hence, in both acute and chronic wounds, prominent biomaterials are required for wound healing along with antimicrobial agents. This review comprehensively addresses the antimicrobial and wound healing effects of chitosan, chitin, cellulose acetate, hyaluronic acid, pullulan, bacterial cellulose, fibrin, alginate, etc. based wound dressing biomaterials fabricated with natural resources such as honey, plant bioactive compounds, and marine-based polymers. Due to their excellent biocompatibility and biodegradability, bioactive compounds derived from honey, plants, and marine resources are commonly used in biomedical and tissue engineering applications. Different types of polymer-based biomaterials including hydrogel, film, scaffold, nanofiber, and sponge dressings fabricated with bioactive agents including honey, curcumin, tannin, quercetin, andrographolide, gelatin, carrageenan, etc., can exhibit significant wound healing process in, diabetic wounds, diabetic ulcers, and burns, and help in cartilage repair along with good biocompatibility and antimicrobial effects. Among the reviewed biomaterials, carbohydrate polymers such as chitosan-based biomaterials are prominent and widely used for wound healing applications followed by hyaluronic acid and alginate-based biomaterials loaded with honey, plant, and marine compounds. This review first provides an overview of the vast natural resources used to formulate different biomaterials for the treatment of antimicrobial, acute, and chronic wound healing processes.

Electrospun pectin/modified copper-based metal-organic framework (MOF) nanofibers as a drug delivery system

Pectin has been regarded as a drug carrier accelerating the healing process due to its bioactivities, abundance and lower cost of resources. However, a big challenge related to its practical application is its poor mechanical strength. In this study the modified Cu-based MOF containing Folic acid was synthesized and incorporated in the suitable pectin electrospun nanofibers which not only improved the copper ions release behavior but also made the fiber mat stronger, antibacterial and induce angiogenesis, fibroblast migration, and proliferation due to loaded copper ions and folic acid. The nanofibers composing of 75% pectin and 4000 kDa -PEO were chosen after morphological and mechanical characterization. Finally, the effect of MOF incorporation on the nanocomposite samples was characterized in terms of morphological, physiochemical and biological properties. The nanofibrous mats were evaluated by tensile testing, antibacterial and cytotoxicity. The release behavior of copper ions and folic acid was controlled and their burst release alleviated reducing cytotoxicity in vitro. It was found that the Young's moduli of the pectin nanofibers were improved to 19.13 MPa by the addition of Cu-based MOFs. Moreover, nanocomposite pectin nanofibers were found to be antibacterial and biocompatible. These results demonstrate that MOF-contained pectin nanofibers are promising for biomedical applications.

Fundamental Concepts of Hydrogels: Synthesis, Properties, and Their Applications

In the present review, we focused on the fundamental concepts of hydrogels-classification, the polymers involved, synthesis methods, types of hydrogels, properties, and applications of the hydrogel. Hydrogels can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and a combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical, and hybrid bonding. The bonding is formed via different routes, such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. These properties are substantial for electrochemical and biomedical applications. Furthermore, this review emphasizes flexible and self-healable hydrogels as electrolytes for energy storage and energy conversion applications. Insufficient adhesiveness (less interfacial interaction) between electrodes and electrolytes and mechanical strength pose serious challenges, such as delamination of the supercapacitors, batteries, and solar cells. Owing to smart and aqueous hydrogels, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability are the critical factors that can identify the reliability and robustness of the energy storage and conversion devices. These devices are highly efficient and convenient for smart, light-weight, foldable electronics and modern pollution-free transportation in the current decade.

Pectin polymers for colon-targeted antitumor drug delivery

The use of chemotherapeutic drugs in the treatment of malignant tumors is always associated with the severe side effects negatively affecting all organs and systems in human body. One of the approaches for reduction of the toxic influence and enhancement of the antitumor drug administration efficiency is supposed to be the use of the biopolymer delivery systems. Pectins are considered the most promising components for colon targeted drug dosage forms as they are stable in the changing gastrointestinal media and easily degraded by pectinases produced by colonic microflora. A various range of the pectin-containing delivery systems were developed contributing higher concentration of the active drug molecules in particular site inside intestine and their lower blood level resulting in lowered risk of the severe side effects. This review discusses the various forms of the pectin-based materials such as hydrogels, tablets and pellets, films, microspheres, microsponges, nanoparticles, etc. as drug delivery device and attempted to report the vast literature available on pectin biopolymers in drug delivery applications.