Synthesis and characterization of hydrogel films of carboxymethyl tamarind gum using citric acid

Fluorescent carbon dots in situ polymerized biodegradable semi-interpenetrating tough hydrogel films with antioxidant and antibacterial activity for applications in food industry

A flexible, antioxidant, biodegradable, and UV-resistant polymeric nanocomposite hydrogel with heteroatom-doped carbon dots (CDs) has been fabricated using a simple one-step in situ free radical gelation process. The hydrogel formation and their physico-mehcanical characteristics have been assessed by rheology, uniaxial tensile and compression testing. The water uptake behaviour of the hydrogels is controlled by the CDs by manipulating their internal morphology and porosity. The porous nature of the hydrogels has been found from their scanning electron microscopic images which are also supported by their anomalous diffusion-based transport mechanism. The rheological signatures of the hydrogels show delayed network rupturing due to the secondary physical crosslinking alleviated by CDs. Moreover, CDs are directly influencing the permeabilites (oxygen and moisture) by lowering the values compared to their neat hydrogel films which are essential for a packing material. The biodegradability of the hydrogel films showed gradual weight loss (<75 %) within 3 weeks. The hydrogel films also have been qualified to be acted as antibacterial and antioxidant material. The shelf-life and non-leaching of CDs from gel matrices are also performed which shows its excellent capability to be used as a potential antibacterial, biodegradable, antioxidant alternative packaging material in food sectors.

State-of-the-art progress on tamarind seed polysaccharide (Tamarindus indica) and its diverse potential applications, a review with insight

Tamarind seed polysaccharide (TSP) is a biocompatible, non-ionic polymer with antioxidant properties. Its uses include drug delivery, food industry, and wastewater treatment. TSP has various hydroxy functional groups, one of the most favorable sites for graft copolymerization of different monomers. Hence, various chemical methods for TSP modification were developed to satisfy increasing industrial demand. Of particular interest in scientific community are the methods of graft copolymerization because of their ability to alter the physicochemical properties of TSP, including pH sensitivity and the swelling index, leading to improvements in the adsorption efficiency of hazardous heavy metals and dyes from wastewater effluents. Moreover, in recent years, TSP has been used for controlled drug delivery applications due to its unique advantages of high viscosity, broad pH tolerance, non-carcinogenicity, mucoadhesive properties, biocompatibility, and high drug entrapment capacity. In light of the plethora of literature on the topic, a comprehensive review of TSP-based graft copolymers and unmodified and modified TSP important applications is necessary. Therefore, this review comprehensively highlights several synthetic strategies for TSP-grafted copolymers and discusses unmodified and modified TSP potential applications, including cutting-edge pharmaceutical, environmental applications, etc. In brief, its many advantages make TSP-based polysaccharide a promising material for applications in various industries.

Natural gums and their derivatives based hydrogels: in biomedical, environment, agriculture, and food industry

The hydrogels based on natural gums and chemically derivatized natural gums have great interest in pharmaceutical, food, cosmetics, and environmental remediation, due to their: economic viability, sustainability, nontoxicity, biodegradability, and biocompatibility. Since these natural gems are from plants, microorganisms, and seaweeds, they offer a great opportunity to chemically derivatize and modify into novel, innovative biomaterials as scaffolds for tissue engineering and drug delivery. Derivatization improves swelling properties, thereby developing interest in agriculture and separating technologies. This review highlights the work done over the past three and a half decades and the possibility of developing novel materials and technologies in a cost-effective and sustainable manner. This review has compiled various natural gums, their source, chemical composition, and chemically derivatized gums, various methods to synthesize hydrogel, and their applications in biomedical, food and agriculture, textile, cosmetics, water purification, remediation, and separation fields.

Metal ion removal using a low-cost coconut shell activated carbon bioadsorbent in the recovery of lactic acid from the fermentation broth

Downstream recovery and purification of lactic acid from the fermentation broth using locally available, low-cost materials derived from agricultural residues was demonstrated herein. Surface modification of coconut shell activated carbon (CSAC) was performed by grafting with carboxymethyl cellulose (CMC) using citric acid (CA) as the crosslinking agent. A proper ratio of CMC and CA to CSAC and grafting time improved the surface functionalization of grafted nanostructured CMC-CSAC while the specific surface area and porosity remained unchanged. Lactic acid was partially purified (78%) with the recovery percentage of lactic acid at 96% in single-stage adsorption at room temperature and pH 6 with a 10:1 ratio of cell-free broth to CMC-CSAC bioadsorbent. A thermodynamic study revealed that the adsorption was exothermic and non-spontaneous while the Langmuir isotherm model explained the adsorption phenomena. The results in this study represented the potential of waste utilization as solid adsorbents in green and low-cost adsorption technology.

Acid-induced Poria cocos alkali-soluble polysaccharide hydrogel: Gelation behaviour, characteristics, and potential application in drug delivery

Poria cocos alkali-soluble polysaccharide (PCAP), a water-insoluble β-glucan, is the main component of the total dried sclerotia of Poria cocos. However, its gelation behaviour and properties have yet to be comprehensively studied. In this study, an acid-induced physical hydrogel based on natural PCAP is fabricated. The acid-induced gelation in PCAP is explored with respect to the pH and polysaccharide concentration. PCAP hydrogels are formed in the pH range of 0.3-10.5, and the lowest gelation concentration is 0.4 wt%. Furthermore, dynamic rheological, fluorescence, and cyclic voltammetry measurements are performed to elucidate the gelation mechanism. The results reveal that hydrogen bonds and hydrophobic interactions play a dominant role in gel formation. Subsequently, the properties of the PCAP hydrogels are investigated using rheological measurements, scanning electron microscopy, gravimetric analysis, free radical scavenging, MTT assays, and enzyme-linked immunosorbent assays. The PCAP hydrogels exhibit a porous network structure and cytocompatibility, in addition to good viscoelastic, thixotropic, water-holding, swelling, antioxidant, and anti-inflammatory activities. Furthermore, using rhein as a model drug for encapsulation, it is demonstrated that its cumulative release behaviour from the PCAP hydrogel is pH dependent. These results indicate the potential of PCAP hydrogels for application in biological medicine and drug delivery.

Synthesis and characterization of citric acid crosslinked carboxymethyl tamarind gum-polyvinyl alcohol hydrogel films

The aim of present work was to synthesize and characterize carboxymethyl tamarind gum-polyvinyl alcohol (CMTG-PVA) hydrogel films using citric acid (CA) as a crosslinker. Hydrogel films were prepared by solvent casting technique. The films were evaluated for total carboxyl content (TCC), tensile strength, protein adsorption, permeability properties, hemocompatibility, swellability, moxifloxacin (MFX) loading and release, in-vivo wound healing activity and characterized using instrumental techniques. An optimal increase in amount of PVA and CA increased the TCC and tensile strength of the hydrogel films. Hydrogel films exhibited low protein adsorption and microbial permeation, good permeability to water vapour and oxygen, and sufficient hemocompatibility. The films prepared using high concentration of PVA and low concentration of CA showed good swellability in phosphate buffer and simulated wound fluids. MFX loading in the hydrogel films was found in the range of 384-440 mg/g. The hydrogel films sustained the release of MFX up to 24 h. The release followed Non-Fickian mechanism. ATR-FTIR, solid state ¹³C NMR and TGA analysis indicated formation of ester crosslinks. In-vivo study revealed good wound healing activity for hydrogel films. From the overall study, it can be concluded that the citric acid crosslinked CMTG-PVA hydrogel films can be effectively used for wound treatment.

Construction of pH-sensitive sodium alginates/sodium carboxymethyl cellulose/zeolite P composite hydrogel microspheres loaded with potassium diformate

As a substitute for feed antibiotics, potassium diformate (KDF) can effectively inhibit bacterial overgrowth in the gastrointestinal tract. To avoid the sudden release of KDF in the stomach, this article proposes a new controlled drug delivery system for controlled drug release. In this system, P-type zeolite molecular sieve (Zeolite P) and drug KDF are combined and embedded into the hydrogel microspheres of sodium alginate (ALG) and sodium carboxymethyl cellulose (CMC). In addition, ALG/CMC/Zeolite P composite hydrogel microspheres were prepared with Ca²⁺ as the crosslinking agent. The structure, composition, morphology, and thermal stability of the hydrogel microspheres were systematically characterized. The effect of the composition ratio of ALG and CMC on the swelling properties of the hydrogel microspheres was also investigated. The results revealed that ALG and CMC form a hydrogen bond and chelate with Ca²⁺ to form a double crosslinked network structure. Thus, Zeolite P can be effectively encapsulated in the hydrogel microspheres to form a dense three-dimensional network structure. Particularly, Zeolite P helps in improving the thermal stability of microspheres, balance the swelling properties, and control the release of KDF. The drug release results and release kinetics reveal that the ALG/CMC/Zeolite P composite hydrogel has higher drug release in an environment with pH 7.4. The release kinetics follow the Ritger-Peppas model and the first-order kinetic model, which indicates that the composite hydrogel has good specific pH sensitivity. In vitro antibacterial experiments revealed that the composite hydrogel microspheres have broad-spectrum antibacterial activity, and certain inhibitory effects on Escherichia coli, Staphylococcus aureus, and Bacillus subtilis.

Synthesis of cross-linked polymer based on purified Sterculia foetida L. gum as a potential hemostatic agent

A method for purifying the polysaccharides from Sterculia foetida L. gum was developed. The effects of purifying conditions were also studied. Results have shown that the conditions of pH 0.5, temperature of 80°C, and 2.5-h reaction duration gave the best polysaccharides yield. The mineral content and the molecular weight of the obtained polysaccharides were measured for characterization. The cross-linking of the polysaccharides with citric acid in order to achieve a desired polymer was performed successfully. The obtained polymers under different conditions were evaluated for the potential application as a hemostatic agent, including tests of swelling behavior in different fluids, whole-blood clotting time and enzymatic bio-degradation. Results have shown that the citric acid/polysaccharides ratio of 0.01 produced a comparative yield of polymer flakes with increased swelling properties, as well as shortened in vitro blood clotting time and gradual biodegradability in three experimental days. Therefore, the citric acid/polysaccharides ratio of 0.01 was selected for the subsequent experiment to obtain the polymer after 1.5 h of purification, which gave the best swelling properties, 20 times the initial weight, reduced the whole-blood clotting time by 50% and showed a rapid bio-degradation. The results obtained from this study provide essential knowledge on the research of the use of S. foetida gum polysaccharides as a passive hemostatic agent, thereby extending the potential pharmaceutical applications of natural polysaccharides in Vietnam.

Microwave assisted synthesis of guar gum based biopolymeric macromolecule optimized as a flocculant for mineral ore processing

The research endeavour to synthesize a novel, non-toxic, eco-friendly guar gum based biopolymeric macromolecule, [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride grafted guar gum (GG-g-P (MAETMAC)) that has been optimized as a flocculant for mineral ore processing. The synthesis was performed using non-radiation and microwave assisted technique to compare and ensure the superiority of the latter. The intended grafting of monomer[2-(methacryloyloxy) ethyl] trimethyl ammonium chloride on to the biological macromolecule (guar gum) was confirmed through standard physico-chemical characterization techniques namely X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-visible) spectroscopy, intrinsic viscosity study, etc. The flocculation efficacy of the synthesized novel graft copolymer was thoroughly investigated in kaolin, coal fine, and iron ore suspensions. We have explored a graft copolymer, [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride grafted guar gum that has not been studied yet to the best of our knowledge. To establish the superiority of the synthesized biomaterial, the flocculation study revealed that the best grade of the synthesized novel graft copolymer showed flocculation efficacy of 90 % in kaolin, 69 % in Iron ore, and 29 % in coal fine suspensions which was significantly higher than using alum as a coagulant which provided 36 % efficacy in kaolin, 29 % in iron ore and 10 % in coal fine suspensions.

Effect of Tamarind Gum on the Properties of Phase-Separated Poly(vinyl alcohol) Films

The current study aims to evaluate the effect of tamarind gum (TG) on the optical, mechanical, and drug release potential of poly(vinyl alcohol) (PVA)-based films. This involves preparing PVA-TG composite films with different concentrations of TG through a simple solvent casting method. The addition of TG has enhanced the phase separation and aggregation of PVA within the films, and it becomes greater with the increase in TG concentration. Brightfield and polarized light micrographs have revealed that aggregation is favored by forming crystalline domains at the PVA-TG interface. The interconnected network of PVA-TG aggregates influenced the swelling and drying properties of the films. Using Peleg’s analysis, the mechanical behavior of films was determined by their stress relaxation profiles. The addition of TG has made no significant changes to the firmness and viscoelastic properties of films. However, long-durational relaxation times indicated that the interconnected network might break down in films with higher TG concentration, suggesting their brittleness. The controlled release of ciprofloxacin in HCl solution (0.5% (w/v)) appears to decrease with the increase in TG concentration. In fact, TG has inversely affected the impedance and altered the ionic conductivity within the films. This seems to have directly influenced the drug release from the films as the mechanism was found to be non-Fickian diffusion (based on Korsmeyer–Peepas and Peppas–Sahlin kinetic models). The antimicrobial study using Escherichia coli was carried out to evaluate the activity of the drug-loaded films. The study proves that TG can modulate the properties of PVA films and has the potential to fine-tune the controlled release of drugs from composite films.

A review on challenges and issues with carboxymethylation of natural gums: The widely used excipients for conventional and novel dosage forms

Diverse properties of natural gums have made them quite useful for various pharmaceutical applications. However, they suffer from various problems, including unregulated hydration rates, microbial degradation, and decline in viscosity during warehousing. Among various chemical procedures for modification of gums, carboxymethylation has been widely studied due to its simplicity and efficiency. Despite the availability of numerous research articles on natural gums and their uses, a comprehensive review on carboxymethylation of natural gums and their applications in the pharmaceutical and other biomedical fields is not published until now. This review outlines the classification of gums and their derivatization methods. Further, we have discussed various techniques of carboxymethylation, process of determination of degree of substitution, and functionalization pattern of substituted gums. Detailed information about the application of carboxymethyl gums as drug delivery carriers has been described. The article also gives a brief account on tissue engineering and cell delivery potential of carboxymethylated gums.

Crosslinkers for polysaccharides and proteins: Synthesis conditions, mechanisms, and crosslinking efficiency, a review

Polysaccharides and proteins are important macromolecules for developing hydrogels devoted to biomedical applications. Chemical hydrogels offer chemical, mechanical, and dimensional stability than physical hydrogels due to the chemical bonds among the chains mediated by crosslinkers. There are many crosslinkers to synthesize polysaccharides and proteins based on hydrogels. In this review, we revisited the crosslinking reaction mechanisms between synthetic or natural crosslinkers and polysaccharides or proteins. The selected synthetic crosslinkers were glutaraldehyde, carbodiimide, boric acid, sodium trimetaphosphate, N,N'-methylene bisacrylamide, and polycarboxylic acid, whereas the selected natural crosslinkers included transglutaminase, tyrosinase, horseradish peroxidase, laccase, sortase A, genipin, vanillin, tannic acid, and phytic acid. No less important are the reactions involving click chemistry and the macromolecular crosslinkers for polysaccharides and proteins. Literature examples of polysaccharides or proteins crosslinked by the different strategies were presented along with the corresponding highlights. The general mechanism involved in chemical crosslinking mediated by gamma and UV radiation was discussed, with particular attention to materials commonly used in digital light processing. The evaluation of crosslinking efficiency by gravimetric measurements, rheology, and spectroscopic techniques was presented. Finally, we presented the challenges and opportunities to create safe chemical hydrogels for biomedical applications.

Polysaccharides as wall materials in spray-dried microencapsulation of bioactive compounds: Physicochemical properties and characterization

Natural bioactive compounds (BCs) are types of chemicals found in plants and certain foods that promote good health, however they are sensitive to processing and environmental conditions. Microencapsulation by spray drying is a widely used and cost-effective approach to create a coating layer to surround and protect BCs and control their release, enabling the production of high functional products/ingredients with extended shelf life. In this process, wall materials determine protection efficiency, and physical properties, bioavailability, and storage stability of microencapsulated products. Therefore, an understanding of physicochemical properties of wall materials is essential for the successful and effective spray-dried microencapsulation process. Typically, polysaccharide-based wall materials are generated from more sustainable sources and have a wider range of physicochemical properties and applications compared to their protein-based counterparts. In this review, we highlight the essential physicochemical properties of polysaccharide-based wall materials for spray-dried microencapsulation of BCs including solubility, thermal stability, and emulsifying properties, rheological and film forming properties. We provide further insight into possibilities for the chemical structure modification of native wall materials and their controlled release behaviors. Finally, we summarize the most recent studies involving polysaccharide biopolymers as wall materials and/or emulsifiers in spray-dried microencapsulation of BCs.

Facile synthesis of pH-responsive sodium alginate/carboxymethyl chitosan hydrogel beads promoted by hydrogen bond

In this work, a novel synthesis strategy of sodium alginate/carboxymethyl chitosan hydrogel beads promoted by hydrogen bond was described. The beads were prepared by dropping the blends of two polymers into the citric acid solution. Besides hydrogen bonding, electrostatic interactions were also involved in the formation of the hydrogel beads. The thermal stability experiments revealed that the more the content of carboxymethyl chitosan, the better the thermal stability of the beads. The beads exhibited excellent pH sensitivity, pH reversibility, and lactoferrin loading capacity. The swelling ratio of the bead and its protein releasing profile was pH-dependent, which could prevent premature protein release in the gastric environment. Also, the circular dichroism results demonstrated that lactoferrin could maintain its structure during the loading and releasing process. The obtained results revealed that the hydrogel beads prepared in this work could be used as a potential protein carrier for oral delivery.

Application or function of citric acid in drug delivery platforms

Nontoxic materials with natural origin are promising materials in the designing and preparation of the new drug delivery systems (DDSs). Today's, citric acid (CA) has attracted a great deal of attention because of its special features; green nature, biocompatibility, low price, biodegradability, and commercially available property. So, CA has been employed in the preparation of the various platforms to induce a suitable property on their structure. Recently, several research groups investigated the CA-based platforms in different forms like tablets, dendrimers, hyperbranched polymers, (co)polymer, hydrogels, and nanoparticles as efficient DDSs. By considering an increasing amount of published articles in this field, for the first time, in this review, an overview of the published works regarding CA applications in the design of various DDSs is presented with a detailed and insightful discussion.

Bio nanocomposites of graphene oxide with carboxymethyl guargum: fabrication and characterization and application for type 1 diabetes

Islet cells transplantation has limitations like low survivability, which can be overcome by using extracellular matrix mimicking three-dimensional (3D) scaffolds, which supports the growth and proliferation of seeded cells. This study was aimed to investigate the role of novel 3D carboxymethyl guargum (CMGG) nanocomposite with reduced graphene oxide (rGO) for proliferation of pancreatic islet cells (RIN-5F) and rate of insulin secretion of RIN-5F cells. Scanning electron microscope and Fourier transform infrared results have demonstrated good porosity and the chemical interactions between CMGG and rGO. Mechanical testing and thermogravimetric analysis of nanofibers have shown good tensile strength and thermal stability with rGO in the nanocomposite. These scaffolds demonstratedin vitrobiocompatibility with acceptable ranges of biodegradability and hemocompatibility. Thein vitrocell proliferation and viability of RIN-5F cells on 3D CMGG nanofibers have significantly increased compared to two-dimensional (2D) cell control. Moreover, the glucose dependent insulin secretion of RIN-5F cells on CMGG nanocomposite has significantly increased upto 4-5 folds than cells on 2D cell control. The biomaterials used in this 3D nanofiber scaffold have shown to be biodegradable and hemocompatible and can be a promising platform for the proliferation and secretion of insulin from beta cells and can be effectively used in transplantation type-1 diabetes.

Improved transdermal permeability of tanshinone IIA from cataplasms by loading onto nanocrystals and porous silica

Novel transdermal cataplasms have been designed to improve permeability of poorly soluble drugs by different pretreatments. Nanocrystal and porous silica solid dispersions were loaded with Tanshinone IIA and incorporated into a cross-linked hydrogel matrix of cataplasm. It was shown that the small particle size and improved dissolution would increase dermal bioavailability. The adhesion, rheological properties, drug release, skin permeation, skin deposition and in vivo skin absorption of the different formulations were investigated. In an in vitro experiment using mouse skin, cumulative amount of drug permeated within 24 h was 7.32 ± 0.98 μg/cm² from conventional cataplasm, 13.14 ± 0.70 μg/cm² from nanocrystal-loaded cataplasm and 11.40 ± 0.13 μg/cm² from porous silica solid dispersion-loaded cataplasm. In vitro dissolution profiles showed that drug release was 76.5% and 74.9% from two optimized cataplasms within 24 h, while conventional cataplasm was 55.0%. The cross-linking characteristics of the cataplasms were preserved after incorporation of different drug forms, while the elastic and viscous behaviors of the hydrogel layers increased. In vivo evaluation by CLSM showed the more favorable skin permeation for two optimized cataplasms. These findings suggest that applications of nanocrystal and porous silica systems on cataplasms enable effective transdermal delivery of poorly soluble drugs. The resulting drug delivery and rheological properties are desirable for transdermal application.AbbreviationAll the abbreviations that appear in this article are shown in Table 1.

Bioengineering for curcumin loaded carboxymethyl guargum/reduced graphene oxide nanocomposites for chronic wound healing applications

Biomimetic scaffolds engineering for improved collagen, epithelial cutaneous and fibrous tissue regeneration remains challenging for wound healing. To address these issues, this study aimed to report on the fabrication and characterization of electrospun of carboxymethyl guargum (CMGG), reduced graphene oxide (rGO) nanocomposite dressings loaded with curcumin for chronic wound healing applications. SEM and XRD examined the morphology of nanofibers and resulted in excellent porosity. TGA and FT-IR were done, which revealed the nanofibers' thermal and chemical interactions. CMGG, rGO nanocomposite with curcumin was investigated for in-vitro wound healing assay by scratch wound healing model using 3T3 L1 fibroblast cell lines and conducted in vitro drug-releasing studies. These nanocomposites showed 100% wound closure by the proliferation of fibroblast cell lines 3T3-L1 within 48 h and showed controlled drug release. Further, in vivo results also showed that the CMGG, rGO nanocomposite with curcumin has the potential wound healing effects. Histological studies showed that the CMGG, rGO nanocomposite with curcumin has the potential for wound healing, which indicates that the biomimetic CMGG nanofibers have an excellent healing effect on chronic wounds.

Synthesis of a PVA drug delivery system for controlled release of a Tramadol-Dexketoprofen combination

The local administration of analgesic combinations by means of degradable polymeric drug delivery systems is an alternative for the management of postoperative pain. We formulated a Tramadol-Dexketoprofen combination (TDC) loaded in poly(vinyl alcohol) (PVA) film. Films were prepared by the solvent casting method using three different molecular weights of PVA and crosslinking those films with citric acid, with the objective of controlling the drug release rate, which was evaluated by UV-vis spectrometry. Non-crosslinked PVA films were also evaluated in the experiments. Differential scanning calorimetry (DSC) analysis of samples corroborated the crosslinking of PVA by the citric acid. Blank and loaded PVA films were tested in vitro for its impact on blood coagulation prothrombin time (PT) and partial thromboplastin time (PTT). The swelling capacity was also evaluated. Crosslinked PVA films of higher-molecular weight showed a prolonged release rate compared with that of the lower-molecular-weight films tested. Non-crosslinked PVA films released 11-14% of TDC. Crosslinked PVA films released 80% of the TDC loaded (p < 0.05). This suggests that crosslinking films can modify the drug release rate. The blank and loaded PVA films induced PT and PTT in the normal range. The results showed that the polymeric films evaluated here have the appropriate properties to allow films to be placed directly on surgical wounds and have the capacity for controlled drug release to promote local analgesia for the control of postoperative pain.

Pharmaceutical applications of citric acid

Background

Citric acid (CA) is a universal plant and animal-metabolism intermediate. It is a commodity chemical processed and widely used around the world as an excellent pharmaceutical excipient. Notably, CA is offering assorted significant properties viz. biodegradability, biocompatibility, hydrophilicity, safety, etc. Therefore, CA is broadly employed in many sectors including foodstuffs, beverages, pharmaceuticals, nutraceuticals, and cosmetics as a flavoring agent, sequestering agent, buffering agent, etc. From the beginning, CA is a regular ingredient for cosmetic pH-adjustment and as a metallic ion chelator in antioxidant systems. In addition, it is used to improve the taste of pharmaceuticals such as syrups, solutions, elixirs, etc. Furthermore, free CA is also employed as an acidulant in mild astringent preparations.

Main text

In essence, it is estimated that the functionality present in CA provides excellent assets in pharmaceutical applications such as cross-linking, release-modifying capacity, interaction with molecules, capping and coating agent, branched polymer nanoconjugates, gas generating agent, etc. Mainly, the center of attention of the review is to deliver an impression of the CA-based pharmaceutical applications.

Conclusion

In conclusion, CA is reconnoitered for multiple novels pharmaceutical and biomedical/applications including as a green crosslinker, release modifier, monomer/branched polymer, capping and coating agent, novel disintegrant, absorption enhancer, etc. In the future, CA can be utilized as an excellent substitute for pharmaceutical and biomedical applications.

Graphical abstract

Synthesis, characterization and fabrication of sodium carboxymethyl-okra-gum-grafted-polymethacrylamide into sustained release tablet matrix

The objective of the present study was to modify okra gum (Abelmoschus esculentus) by carboxymethylation and subsequent graft-copolymerization, characterize and fabricate into sustained-release tablet matrix. Firstly, okra gum was carboxymethylated using sodium hydroxide and monochloroacetic acid followed by grafting with polymethacrylamide employing synergistic combination of free-radical-initiator and microwave-irradiation. The FTIR, NMR, elemental analysis and viscosity study corroborate the formation of sodium-carboxymethyl-okra gum-grafted-polymethacrylamide copolymer (SCMOG-g-PMA). The maximum degree of carboxymethyl-substitution (DCS) and % grafting (%G) were found to be 0.604 ± 0.011 and 644.1, respectively. Water-uptake-capacity was found to increase by 3.5 fold. The tablet formulation of diclofenac sodium with SCMOG-g-PMA (DCS 0.604 and 423.4% G) showed to exhibit excellent sustained-release capacity with 90% drug-release at 11.7 h and similarity-factor of 72.0. The toxicity and biodegradability study also exhibited the bio-compatible and biodegradable nature of the copolymer, which might make the copolymer suitable for sustained-release drug delivery systems as smart semi-synthetic biopolymer.

Crosslinked Carboxymethyl Sago Starch/Citric Acid Hydrogel for Sorption of Pb2+, Cu2+, Ni2+ and Zn2+ from Aqueous Solution

In the present study, CMSS (carboxymethyl sago starch)-based hydrogel was synthesized by crosslinking with citric acid via esterification and then applied as a metal sorbent to overcome excessive heavy metal pollution. The CMSS/CA (carboxymethyl sago starch/citric acid) hydrogel was characterized by Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The absorption band at 1726 cm⁻¹ was observed in the FT-IR spectrum of CMSS/CA hydrogel and indicated ester bonds formed. Further findings show that the cross-linkages in the CMSS/CA hydrogel increased the thermal stability of CMSS and various sizes of pores were also shown in the SEM micrograph. Conversely, the removal of heavy metals was analyzed using Inductively Coupled Plasma-Optic Emission Spectra (ICP-OES). The effects of the pH of the metal solution, contact time, initial concentration of the metal ions and temperature on the sorption capacity were investigated. Under optimum condition, the sorption capacity of Pb²⁺, Cu²⁺, Ni²⁺ and Zn²⁺ onto CMSS/CA hydrogel were 64.48, 36.56, 16.21, 18.45 mg/g, respectively. The experiments demonstrated that CMSS/CA hydrogel has high selectivity towards Pb²⁺ in both non-competitive and competitive conditions. In conclusion, the CMSS/CA hydrogel as a natural based heavy metal sorption material exhibited a promising performance, especially in the sorption of Pb²⁺ for wastewater treatment.

Preparation of crystalline nanocellulose/hydroxypropyl β cyclodextrin/carboxymethyl cellulose polyelectrolyte complexes and their controlled release of neohesperidin-copper (II) in vitro

A natural hydrogel film was prepared using carboxymethyl cellulose (CMC), cellulose nanocrystals (CNC), and hydroxypropyl β cyclodextrin (HP-β-CD) as reactants and citric acid as the cross-linking agent and used for the controlled release of neohesperidin-copper(II)(NH-Cu (II)). The hydrogel film was characterized by ATR-FTIR, XRD, TGA and DSC. The film showed controlled swelling behavior; the release behavior of NH-Cu(II) from the hydrogel film was also investigated in different solutions including distilled water, various salt solutions including 0.9% NaCl, and solutions having different pH values. Thiazolyl blue tetrazolium bromide assay and relative growth rates were adopted to evaluate the biocompatibility and cytotoxicity of the prepared hydrogel films. The results indicated that the expansion kinetics followed Fickian diffusion and Schott's second-order kinetics model. The hydrogel film exhibited enhanced mechanical properties and improved thermal stability at high temperatures due to the addition of CNC, with the amount of added CNC affecting the swelling ratio, salt sensitivity, and pH sensitivity of the hydrogel film in different solutions. Additionally, the CNC largely improved the loading and encapsulation efficiency of the hydrogel films, with the optimal CNC addition amount being 4% which yielded a loading amount of 753.75 mg/g and an accumulated release rate of 85.08%. The hydrogel film with proven cell compatibility and non-cytotoxicity can potentially be used as a drug delivery and controlled release material.

Fabrication and characterization of carboxymethyl guar gum nanocomposite for application of wound healing

Bio scaffolds used for cutaneous tissue regeneration is a challenging issue in the healthcare system. To help this problem, we aimed to report on fabrication and characterization of citric acid cross-linked carboxymethyl guar gum (CMGG) nanocomposite films loaded with ciprofloxacin for faster wound healing application. Differential scanning calorimeter (DSC) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy studies, dynamic light scattering (DLS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used as analytical techniques for characterization of the nanocomposite film. The morphological characters of nanocomposite film were determined by SEM. The prepared scaffolds were evaluated for the carboxyl content and swelling ratio. Ciprofloxacin was loaded into scaffold and drug release was studied at pH 7.4. The hemolysis assay was used to study the biocompatibility of scaffold films. The formation of ester cross-links between citric acid and CMGG was confirmed by DSC and ATR- FTIR. The total carboxyl content of scaffold was found to be decreased when the amount of CMGG was increased. The swelling of scaffold film was found to be decreased with increase in curing temperature and time. CMGG scaffold films showed high drug loading with non-Fickian release mechanism suggesting controlled release of drug. In vivo wound healing studies were carried out for 5 days. In this study we observed a faster wound healing effect within 5 days by incorporation of ciprofloxacin in the CMGG film and found biocompatible. Hence, these Nanocomposite films show greater potential in treating wounds.

Recent Advances in Natural Gum-Based Biomaterials for Tissue Engineering and Regenerative Medicine: A Review

The engineering of tissues under a three-dimensional (3D) microenvironment is a great challenge and needs a suitable supporting biomaterial-based scaffold that may facilitate cell attachment, spreading, proliferation, migration, and differentiation for proper tissue regeneration or organ reconstruction. Polysaccharides as natural polymers promise great potential in the preparation of a three-dimensional artificial extracellular matrix (ECM) (i.e., hydrogel) via various processing methods and conditions. Natural polymers, especially gums, based upon hydrogel systems, provide similarities largely with the native ECM and excellent biological response. Here, we review the origin and physico-chemical characteristics of potentially used natural gums. In addition, various forms of scaffolds (e.g., nanofibrous, 3D printed-constructs) based on gums and their efficacy in 3D cell culture and various tissue regenerations such as bone, osteoarthritis and cartilage, skin/wound, retinal, neural, and other tissues are discussed. Finally, the advantages and limitations of natural gums are precisely described for future perspectives in tissue engineering and regenerative medicine in the concluding remarks.

Proanthocyanidin-crosslinked collagen/konjac glucomannan hydrogel with improved mechanical properties and MRI trackable biodegradation for potential tissue engineering scaffolds

Collagen (Col) has been intensively exploited as a biomaterial for its excellent biocompatibility, biodegradation and bioactivity. However, the poor mechanical properties and rapid biodegradation of reconstituted collagen hydrogels have always been the bottlenecks for their further development especially for vascular tissue engineering. Herein, based on the self-assembly characteristics of collagen, a ternary hydrogel scaffold, comprising rigid collagen molecules, flexible konjac glucomannan (KGM) chains and biocompatible crosslinkers of proanthocyanidin (PA), has been designed to achieve a synergistic interaction for essentially optimizing the mechanical properties of the so-obtained Col/KGM/PA hydrogel, which possesses not only substantially improved strength but also good elasticity. PA endows these scaffolds with controllable biodegradation and anti-calcification and antioxidant activities. TEM discovered the co-existence of two types of fibrils with distinctly different arrangement patterns, explaining the contribution of KGM macromolecules to elasticity generation. The in vivo variations of Col/KGM/PA implants are visualized in real-time by magnetic resonance imaging (MRI). Moreover, a quantitative technique of MRI T₂-mapping combined with histology is designed to visualize the in vivo biodegradation mechanism of layer-by-layer erosion for these hydrogels. Simultaneously, three different relationships between the respective processes of in vivo degradation and in vivo dehydration of these controlled hydrogel implants were clearly revealed by this technique. Such a designed Col/KGM/PA composite hydrogel realizes the essential integration of good biocompatibility, controllable biodegradation and improved mechanical properties for developing a desired scaffold material for tissue engineering applications.

Redox-responsive blend hydrogel films based on carboxymethyl cellulose/chitosan microspheres as dual delivery carrier

A simple method to fabricate redox-responsive composite hydrogel films via incorporating chitosan (CS) microspheres into carboxymethyl cellulose (CMC) hydrogel using a di-sulphide cross-linker cystamine dihydrochloride (CYS) have done in this paper. Dual drugs, an anticancer, 5-Fluorouracil (5-FU) and an antibiotic, Tetracycline Hydrochloride (TH) were used as model drugs. The prepared composite hydrogel films were characterized using FTIR, SEM, rheology measurement, mechanical and swelling tests. Our results showed that the well dispersed spherical CS microspheres endowed hydrogel film increased mechanical properties and swellability. In vitro drug release displayed an accelerated release under weak acidic or reducing media. The in vitro cytotoxicity and cell apoptosis studies showed the drug-loaded composite film caused enhanced inhibition to HepG2 cells in presence of glutathione (GSH). Moreover, the film has exhibited excellent antimicrobial efficacy against E.coli and Staphylococcus aureus. Therefore, our simple and effective dual drug-loaded system has the potential to be used for cancer therapy in the future.

Hydrogen sulfide sensor based on tapered fiber sandwiched between two molybdenum disulfide/citric acid composite membrane coated long-period fiber gratings

In this work, a novel hydrogen sulfide detection scheme based on tapered fiber seeded in two long-period fiber gratings (LPGs) coated by a molybdenum disulfide/citric acid composite membrane is proposed and fabricated. The input light of a broadband source is coupled twice by passing through two LPGs with identical parameters, from which a Mach-Zehnder interferometer can be formed. The composite sensitive membrane was prepared with molybdenum disulfide and citric acid, which was coated on the surface of the two LPGs. The experimental results show that in the range of 0-70 ppm of hydrogen sulfide, with the increase of gas concentrations the interference spectra appear to blueshift. In addition, a high sensitivity of 16.65 pm/ppm, an excellent linear relationship (R²=0.97721), and high selectivity for hydrogen sulfide are achieved. The effect of temperature is also discussed. The sensor has the advantages of low cost and small volume, and can be used for detection applications at sites where hydrogen sulfide is produced, such as natural gas plants, areas of magmatic activity, coal mines, etc.

A facile modification to improve the biocompatibility and adsorbability of activated carbon with zwitterionic hydrogel

In this work, poly(carboxybetaine methacrylate) hydrogel (pCBMA) was employed to modify the activated carbon (AC) for improving the biocompatibility and adsorption capacity of AC in biological environments. First, size-controlled hydrogel beads and hydrogel coated AC (pCBMA-AC) were fabricated with a homemade device, and the preparation conditions were optimized. Then the physical and biological properties of pCBMA-AC with different diameters were investigated. 2 mm pCBMA-AC dispalyed excellent stability with leakage rate only 0.16% after 72 h shaking incubation, as well as remarkable biocompatibility with merely 0.13% hemolysis rate and 3.41% cell death, while 14.72% and 70.11% for the bare AC, respectively, indicating the acceptable lower hemolysis and cytotoxicity according to ISO 10993. Furthermore, the adsorption capacities of pCBMA-AC were evaluated in biological environments with methylene blue as model molecules. The pCBMA-AC displayed 93.50% and 97.32% adsorption rates in BSA solution and FBS, respectively, but only 70.33% and 40.26% for the uncoated AC. These results indicated that pCBMA endows AC remarkable biocompatibility and adsorption capacity, which could extend the applications of AC in biological environments.

Thermoresponsive nanogels with film-forming ability

A one pot semibatch method was proposed for synthesizing poly(N-vinylcaprolactam)-based nanogels with particle coalescence ability.