Journal of Controlled Release, volume 96, issue 2, pages 285-300

A novel pH-sensitive hydrogel composed of N,O-carboxymethyl chitosan and alginate cross-linked by genipin for protein drug delivery.

Sung Long Chen 1
Yung-Chun Wu 2
Fwu-Long Mi 3
Yu Lin 1
Lin Yu 2
Hsing W. Sung 2
Publication typeJournal Article
Publication date2004-04-01
scimago Q1
SJR2.157
CiteScore18.5
Impact factor10.5
ISSN01683659, 18734995
Pharmaceutical Science
Abstract
A novel pH-sensitive hydrogel system composed of a water-soluble chitosan derivative (N,O-carboxymethyl chitosan, NOCC) and alginate blended with genipin was developed for controlling protein drug delivery. Genipin, a naturally occurring cross-linking agent, is significantly less cytotoxic than glutaraldehyde and may provide a less extent of cross-linking to form a semiinterpenetrating polymeric network (semi-IPN) within the developed hydrogel system. The drug-loading process used in the study was simple and mild. All procedures used were performed in aqueous medium at neutral environment. In the study, preparation of the NOCC/alginate-based hydrogels was reported. Swelling characteristics of these hydrogels as a function of pH values were investigated. Additionally, release profiles of a model protein drug (bovine serum albumin, BSA) from test hydrogels were studied in simulated gastric and intestinal media. The semi-IPN formation of the genipin-cross-linked NOCC/alginate hydrogel was confirmed by means of the scanning electron microscopy-energy dispersive X-ray spectrometer (SEM-EDS) and the ninhydrin assays. The percentage of decrease of free amino groups and cross-linking density for the NOCC/alginate hydrogel cross-linked with 0.75 mM genipin were 18% and 26 mol/m(3), respectively. At pH 1.2, the swelling ratio of the genipin-cross-linked NOCC/alginate hydrogel was limited (2.5) due to formation of hydrogen bonds between NOCC and alginate. At pH 7.4, the carboxylic acid groups on the genipin-cross-linked NOCC/alginate hydrogel became progressively ionized. In this case, the hydrogel swelled more significantly (6.5) due to a large swelling force created by the electrostatic repulsion between the ionized acid groups. The amount of BSA released at pH 1.2 was relatively low (20%), while that released at pH 7.4 increased significantly (80%). The results clearly suggested that the genipin-cross-linked NOCC/alginate hydrogel could be a suitable polymeric carrier for site-specific protein drug delivery in the intestine.
TOUYAMA R., INOUE K., TAKEDA Y., YATSUZUKA M., IKUMOTO T., MORITOME N., SHINGU T., YOKOI T., INOUYE H.
2011-12-08 citations by CoLab: 122 Abstract  
The mechanisms of the formation of brownish-red pigments having a 2-methyl-4-carbomethoxy-2-pyrindine nucleus as a basic skeleton by reaction of genipin with methylamine under an atmosphere of inert gas are discussed based on the isolation of 5, 6-dihydro-2-methyl-4-carbomethoxy-8-hydroxymethyl-2-pyrindine as a precursor and on comparisons of the results obtained from the reactions of genipin congeners and methylamine. The origin of the extra methyl group at C-6 in the structures of some of the brownish-red pigments was clarified to be the carbon atom of the hydroxymethyl group at C-8 of genipin by using deuterium-labelled genipin.
TOUYAMA R., TAKEDA Y., INOUE K., KAWAMURA I., YATSUZUKA M., IKUMOTO T., SHINGU T., YOKOI T., INOUYE H.
2011-12-08 citations by CoLab: 186 Abstract  
During the course of studies on the blue pigment formation by the reaction of genipin with methylamine, nine red to brownish-red intermediary pigments were obtained under conditions excluding oxygen. They were identified as monomer, dimer, trimer and tetramer of 2-methyl-4-carbomethoxy-2-pyrindine derivatives on the basis of spectroscopic evidence.
AKAO T., KOBASHI K., ABURADA M.
2011-08-16 citations by CoLab: 201 Abstract  
Geniposide, a main iridoid glucoside of Gardenia fruit, is transformed to genipin, a genuine choleretic, in vivo in rats (Aburada et al., J. Pharmacobio-Dyn., 1, 81 (1978)). As geniposide was not hydrolyzed to any metabolite by rat liver homogenate, which has beta-D-glucosidase and esterase activities, beta-D-glucosidases in intestinal bacteria seem to be required for an exhibition of its choleretic action. The crude extract of Eubacterium sp. A-44, a human intestinal anaerobe, hydrolyzed geniposide, but that of Ruminococcus sp. PO1-3, another human anaerobe, did not, though both extracts had beta-D-glucosidase activities for p-nitrophenyl beta-D-glucopyranoside. Only one of three beta-D-glucosidases from E. sp. A-44 and none of two from R. sp. PO1-3 hydrolyzed geniposide to genipin. However, carboxylesterases from E. sp. A-44 and pig liver were unable to hydrolyze geniposide to geniposidic acid, but hydrolyzed genipin to an aglycone of geniposidic acid, indicating that geniposide is first hydrolyzed to genipin by beta-D-glucosidases and subsequently to the aglycone of geniposidic acid by esterases. Thus, when geniposide is orally administered, genipin seems to be effectively produced in the intestine and then absorbed to act as a genuine choleretic.
Thacharodi D., Rao K.P.
2007-04-24 citations by CoLab: 66 Abstract  
Chitosan membranes of 20 microns thickness were prepared by a solvent evaporation technique and crosslinked with different concentrations of glutaraldehyde to obtain membranes of various degrees of crosslinking. These membranes were characterized by thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) and tensile strength studies. The effect of crosslinking on the permeability of membranes to propranolol hydrochloride was evaluated by permeation studies conducted in static glass diffusion cells. A decrease in the thermal stability of chitosan membranes due to crosslinking was observed. The tensile strength of the membranes was improved by crosslinking. The introduction of crosslink points within the membrane reduced its permeability to propranolol hydrochloride as evidenced by decreased permeability and diffusion coefficients. Permeability studies revealed the operation of a pore mechanism in the transport of hydrophilic agents such as propranolol hydrochloride through chitosan and crosslinked chitosan membranes.
Sinha V.R., Trehan A.
Journal of Controlled Release scimago Q1 wos Q1
2003-07-22 citations by CoLab: 641 Abstract  
In a very short time, since their emergence, the field of controlled delivery of proteins has grown immensely. Because of their relatively large size, they have low transdermal bioavailabilities. Oral bioavailability is generally poor since they are poorly absorbed and easily degraded by proteolytic enzymes in the gastrointestinal tract. Ocular and nasal delivery is also unfavorable due to degradation by enzymes present in eye tissues and nasal mucosa. Thus parenteral delivery is currently most demanding and suitable for delivery of such molecules. In systemic delivery of proteins, biodegradable microspheres as parenteral depot formulation occupy an important place because of several aspects like protection of sensitive proteins from degradation, prolonged or modified release, pulsatile release patterns. The main objective in developing controlled release protein injectables is avoidance of regular invasive doses which in turn provide patient compliance, comfort as well as control over blood levels. This review presents the outstanding contributions in field of biodegradable microspheres as protein delivery systems, their methods of preparation, drug release, stability, interaction with immune system and regulatory considerations.
Liang H., Chang W., Lin K., Sung H.
2003-04-24 citations by CoLab: 172 Abstract  
Gelatin microspheres have been widely evaluated as a drug carrier. Nevertheless, gelatin dissolves rather rapidly in aqueous environments, making the use of the polymer difficult for the production of long-term delivery systems. This adverse aspect requires the use of a crosslinking agent in forming nonsoluble networks in microspheres. However, the use of crosslinking agents such as formaldehyde and glutaraldehyde can lead to toxic side effects owing to residual crosslinkers. In an attempt to overcome this problem, a naturally occurring crosslinking agent (genipin) was used to crosslink gelatin microspheres as a biodegradable drug-delivery system for intramuscular administration. Glutaraldehyde was used as a control. In the in vitro study, the morphology, dynamic swelling, and antienzymatic degradation of test microspheres were evaluated. In the in vivo study, the biocompatibility and degradability of test microspheres were implanted in the skeletal muscle of a rat model via intramuscular injection. The results obtained in the study suggested that crosslinking of gelatin microspheres with glutaraldehyde or genipin may produce distinct crosslinking structures. The water transport mechanism in both the glutaraldehyde- and genipin-crosslinked gelatin microspheres exhibit anomalous behavior ranging from Fickian to Case-II extremes. The increase of the swelling diameter for the genipin-crosslinked microspheres was significantly less than that observed for the glutaraldehyde-crosslinked microspheres. In the animal study, it was found that the degree in inflammatory reaction for tissues implanted with the genipin-crosslinked microspheres was significantly less than that implanted with the glutaraldehyde-crosslinked microspheres. Additionally, the degradation rate of the genipin-crosslinked microspheres was significantly slower than their glutaraldehyde-crosslinked counterparts. These results indicated that the genipin-crosslinked gelatin microspheres may be used as a long-acting drug carrier for intramuscular administration.
Mi F., Tan Y., Liang H., Sung H.
Biomaterials scimago Q1 wos Q1 Open Access
2002-01-01 citations by CoLab: 455 Abstract  
A novel injectable-chitosan-based delivery system with low cytotoxicity was fabricated in the study. The chitosan microspheres with small particle size, low crystallinity and good sphericity were prepared by a spray-drying method followed by treating with a crosslinker. In the study, a naturally occurring crosslinking reagent (genipin), which has been used in herbal medicine and in the production of food dyes, was used to crosslink the chitosan microspheres. The glutaraldehyde-crosslinked counterparts were used as a control. Histological study of the genipin-crosslinked chitosan microspheres injected intramuscularly into the skeletal muscle of a rat model showed a less inflammatory reaction than its glutaraldehyde-crosslinked counterparts. The results of the scanning electron microscopic examination indicated that the glutaraldehyde-crosslinked chitosan microspheres retrieved at 12-week postoperatively were already degraded into a loose and porous structure. However, the degradation of the genipin-crosslinked chitosan microspheres was not significant after 20 weeks of implantation. The results of the study demonstrated that the genipin-crosslinked chitosan microspheres have a superior biocompatibility and a slower degradation rate than the glutaraldehyde-crosslinked chitosan microspheres. Accordingly, the genipin-crosslinked chitosan microspheres may be a suitable polymeric carrier for long-acting injectable drug delivery.
Mi F., Tan Y., Liang H., Huang R., Sung H.
2001-01-01 citations by CoLab: 165 Abstract  
The study was to evaluate the characteristics of a chitosan membrane cross-linked with a naturally-occurring cross-linking reagent, genipin. This newly-developed genipin-cross-linked chitosan membrane may be used as an implantable drug-delivery system. The chitosan membrane without cross-linking (fresh) and the glutaraldehyde-cross-linked chitosan membrane were used as controls. The characteristics of test chitosan membranes evaluated were their cross-linking degree, swelling ratio, mechanical properties, antimicrobial activity, cytotoxicity, and degradability. It was found that cross-linking of chitosan membrane using genipin increased its ultimate tensile strength but significantly reduced its strain-at-fracture and swelling ratio. There was no significant difference in antimicrobial activity between the genipin-cross-linked chitosan membrane and its fresh counterpart. Additionally, the results showed that the genipin-cross-linked chitosan membrane had a significantly less cytotoxicity and a slower degradation rate compared to the glutaraldehyde-cross-linked membrane. These results suggested that the genipin-cross-linked chitosan membrane may be a promising carrier for fabricating an implantable drug-delivery system. The drug-release characteristics of the genipin-cross-linked chitosan membrane are currently under investigation.
Risbud M.V., Hardikar A.A., Bhat S.V., Bhonde R.R.
Journal of Controlled Release scimago Q1 wos Q1
2000-07-01 citations by CoLab: 392 Abstract  
The aim of this study was to develop a pH-sensitive chitosan/polyvinyl pyrrolidone (PVP) based controlled drug release system for antibiotic delivery. The hydrogels were synthesised by crosslinking chitosan and PVP blend with glutaraldehyde to form a semi-interpenetrating polymer network (semi-IPN). The semi-IPN formation was confirmed by Fourier transform infrared spectroscopic (FTIR) analysis. Semi-IPNs, viz, air-dried and freeze-dried, were compared for their surface morphology, wettability, swelling properties and pH-dependent swelling. Air- and freeze-dried membranes were also incorporated with amoxicillin and antibiotic release was studied. Porous freeze-dried hydrogels (pore diameter, 39.20+/-2.66 microm) exhibited superior pH-dependent swelling properties over non-porous air-dried hydrogels. A high octane contact angle (144.20+/-0.580) of hydrogel was indicative of its hydrophilic nature. Increased swelling of hydrogels, under acidic conditions, was due to the protonation of a primary amino group on chitosan, as confirmed by FTIR analysis. Freeze-dried membranes released around 73% of the amoxicillin (33% by air-dried) in 3 h at pH 1.0 and, thus, had superior drug-release properties to air-dried hydrogels. Freeze-dried membranes could serve as potent candidates for antibiotic delivery in an acidic environment.
Tsai C., Huang R., Sung H., Liang H.C.
2000-01-01 citations by CoLab: 149 Abstract  
The objective of the present study was to evaluate in vitro, using Chinese hamster ovary (CHO-K1) cells, the genotoxicity of genipin, a naturally occurring crosslinking agent. Glutaraldehyde, the most commonly used crosslinking agent for biologic tissue fixation, was employed as a reference chemical. The selected procedures for this evaluation were the micronucleus (MN) and sister chromatid exchange (SCE) assays with or without the addition of a metabolic activation system (S9 mix). Before starting the genotoxicity assays, the maximum noncytotoxic amounts of glutaraldehyde and genipin were determined using the MTT assay. The results obtained in the MTT assay revealed that the cytotoxicity of genipin was significantly lower than that of glutaraldehyde with or without S9 mix. The frequencies of MN observed in the cases drugged with varying concentrations of glutaraldehyde or genipin were not statistically different from those seen in the negative controls (blank) in the presence or absence of S9 mix. However, it was noted that glutaraldehyde significantly inhibited the cell-cycle progression while the cells drugged with genipin did not result in cell-cycle delay. In the SCE assay, the numbers of SCE per cell observed in the cases drugged with varying concentrations of glutaraldehyde were significantly greater than those found in the negative controls with or without S9 mix. Nevertheless, these numbers were still low compared to the numbers of SCE induced by the strong mutagens used as our positive control substances. This suggests that glutaraldehyde may produce a weakly clastogenic response in CHO-K1 cells. In contrast, the numbers of SCE per cell obtained in the cases drugged with genipin were comparable to those observed in the negative controls in those that were except drugged with the highest dose (50 ppm). This suggests that genipin does not cause clastogenic response in CHO-K1 cells provided its concentration is lower than 50 ppm. In conclusion, as far as cytotoxicity and genotoxicity are concerned, genipin is a promising crosslinking agent for biologic tissue fixation.
M. Ramadas, W. Paul, K. J. Dileep,
Journal of Microencapsulation scimago Q2 wos Q2
2000-01-01 citations by CoLab: 75 Abstract  
An oral formulation based on liposome encapsulated alginate-chitosan gel capsules was developed for insulin delivery for the treatment of diabetes. Liposome encapsulation helped to increase the encapsulation efficiency of insulin in alginate-chitosan capsules. This formulation delivers insulin in the neutral environment of the intestine, by-passing the acidic media in the stomach, with increased drug absorption and bioavailability. Oral administration of this formulation was found to reduce blood glucose levels when tested in diabetic rats.
Sung H., Chang Y., Liang I., Chang W., Chen Y.
2000-01-01 citations by CoLab: 94 Abstract  
In an attempt to overcome the cytotoxicity problem of the glutaraldehyde-fixed tissues, a naturally occurring crosslinking agent (genipin) was used by our group to fix biological tissues. The study was intended to investigate the rate of tissue fixation by genipin. Glutaraldehyde was used as a control. In addition, the degrees of tissue fixation by genipin at different pHs (pH 4.0, pH 7. 4, pH 8.5, or pH 10.5), temperatures (4 degrees C, 25 degrees C, 37 degrees C, or 45 degrees C), and initial fixative concentrations (0.250%, 0.625%, or 1.000%) were examined. The results obtained revealed that the rate of tissue fixation by glutaraldehyde was significantly faster than that by genipin. The degree of tissue fixation by genipin may be controlled by adjusting its fixation duration or fixation conditions. The order in degree of tissue fixation by genipin at different pHs, from high to low, was: at nearly neutral pH (pH 7.4 or pH 8.5) > at basic pH (pH 10.5) > at acidic pH (pH 4.0). The degrees of tissue fixation by genipin at different temperatures were about the same, except for that at 4 degrees C. In contrast, the initial fixative concentration did not seem to affect the degree of tissue fixation by genipin, if only the amount of genipin in the fixation solution was sufficient to complete tissue fixation. The concentrations of genipin in the aqueous solutions at different pHs, temperatures, and initial fixative concentrations tended to decrease with time with or without the occurrence of tissue fixation. This indicated that genipin was not stable in the aqueous solution. The instability of aqueous genipin was more remarkable with increasing pH or temperature. The results obtained in this study may be used to optimize the fixation process for developing bioprostheses fixed by genipin.
Sung H., Huang R., Huang L.L., Tsai C.
1999-01-01 citations by CoLab: 412 Abstract  
A recognized drawback of the currently available chemical cross-linking reagents used to fix bioprostheses is the potential toxic effects a recipient may be exposed to from the fixed tissues and/or the residues. It is, therefore, desirable to provide a cross-linking reagent which is of low cytotoxicity and may form stable and biocompatible cross-linked products. To achieve this goal, a naturally occurring cross-linking reagent -- genipin -- which has been used in herbal medicine and in the fabrication of food dyes, was used by our group to fix biological tissues. The study was to assess the cytotoxicity of genipin in vitro using 3T3 fibroblasts (BALB/3T3 C1A31-1-1). Glutaraldehyde, the most commonly used cross-linking reagent for tissue fixation, was used as a control. The cytotoxicity of the glutaraldehyde- and genipin-fixed tissues and their residues was also evaluated and compared. The observation in the light microscopic examination revealed that the cytotoxicity of genipin was significantly lower than that of glutaraldehyde. Additionally, the results obtained in the MTT assay implied that genipin was about 10000 times less cytotoxic than glutaraldehyde. Moreover, the colony forming assay suggested that the proliferative capacity of cells after exposure to genipin was approximately 5000 times greater than that after exposure to glutaraldehyde. It was noted that the cells seeded on the surface of the glutaraldehyde-fixed tissue were not able to survive. In contrast, the surface of the genipin-fixed tissue was found to be filled with 3T3 fibroblasts. Additionally, neocollagen fibrils made by these fibroblasts were observed on the genipin-fixed tissue. This fact suggested that the cellular compatibility of the genipin-fixed tissue was superior to its glutaraldehyde-fixed counterpart. Also, the residues from the glutaraldehyde-fixed tissue markedly reduced the population of the cultured cells, while those released from the genipin-fixed tissue had no toxic effect on the seeded cells. In conclusion, as far as cytotoxicity is concerned, genipin is a promising cross-linking reagent for biological tissue fixation.
Sugimoto M., Morimoto M., Sashiwa H., Saimoto H., Shigemasa Y.
Carbohydrate Polymers scimago Q1 wos Q1
1998-05-01 citations by CoLab: 299 Abstract  
Chitosan was modified with poly(ethylene glycol)-aldehyde (PEG-aldehyde) of various molecular weights under the various molar ratios of PEG-aldehyde to chitosan. Then the prepared chitosan-PEG hybrid was converted to chitin-PEG hybrid by the acetylation with acetic anhydride. The solubility of various derivatives was investigated in three buffers of various pH. Some of these derivatives were soluble in 0.01 M phosphate buffer saline (PBS, pH = 7.2). The solubility in PBS was dependent on the degree of PEG substitution, the degree of acetylation, the molecular weight of PEG, and the weight ratio of PEG in chitin/chitosan-PEG hybrid.
Farazin A., Gheisizadeh A.
2025-03-28 citations by CoLab: 0 Abstract  
ABSTRACTBone repair is a complex biological process requiring dynamic interplay between cellular mechanisms, molecular signaling, and environmental factors. The intricate stages of bone healing, including hematoma formation, inflammation, soft callus development, and hard callus remodeling, are driven by coordinated cellular responses and molecular pathways. Proinflammatory cytokines, growth factors, and the extracellular matrix play critical roles in promoting osteogenesis and angiogenesis. Factors such as age, systemic health, and mechanical stability significantly influence repair efficiency. To address limitations in natural healing, advancements in regenerative medicine have introduced innovative materials like nanocomposite hydrogels, which mimic the natural bone microenvironment and enhance cellular function. Semi‐interpenetrating network (semi‐IPN) hydrogels have emerged as a promising tool for bone tissue engineering. Combining crosslinked and non‐crosslinked polymers, these hydrogels offer a balance of mechanical stability, biological functionality, and controlled degradation. Semi‐IPN hydrogels provide structural support, facilitate cell attachment, and enable the sustained release of bioactive molecules. Their flexibility and adaptability make them suitable for encapsulating stem cells and promoting targeted bone regeneration. Moreover, nonsurgical and surgical scaffold delivery methods, ranging from injectable hydrogels to 3D‐printed and magnetically guided scaffolds, have expanded the horizons of bone repair strategies, reduced invasiveness, and improved patient outcomes. This review explores the dynamics of bone healing, the role of hydrogels in promoting regeneration, and the advanced construction strategies of semi‐IPN hydrogels for bone repair. By integrating polymer science, nanotechnology, and bioengineering, semi‐IPN hydrogels represent a transformative shift in addressing bone defects, paving the way for innovative therapeutic approaches in regenerative medicine. With ongoing advancements, these technologies hold significant potential to improve the effectiveness and accessibility of bone repair solutions.
Jang T., Yoon S., Choi J., Kim N., Park J.
Gels scimago Q1 wos Q1 Open Access
2025-03-16 citations by CoLab: 0 PDF Abstract  
Industrial textile wastewater containing both heavy metals and dyes has been massively produced. In this study, semi-interpenetrating polymer network structures of sodium alginate (SA)/polyvinyl alcohol (PVA)/κ-carrageenan (CG) aerogel beads were synthesized for their simultaneous reduction. The SA/PVA/CG aerogel beads were synthesized through a cost-effective and environmentally friendly method using naturally abundant biopolymers without toxic cross-linkers. The SA/PVA/CG aerogel beads were spheres with a size of 3.8 ± 0.1 mm, exhibiting total pore areas of 15.2 m2/g and porous structures (pore size distribution: 0.04–242.7 μm; porosity: 93.97%) with abundant hydrogen bonding, high water absorption capacity, and chemical resistance. The adsorption capacity and mechanisms of the SA/PVA/CG aerogel beads were investigated through kinetic and isotherm experiments for heavy metals (Cu(II), Pb(II)), cationic dye (methylene blue, MB), and anionic dye (acid blue 25, AB)) in both single and binary systems. The maximum adsorption capacities of the SA/PVA/CG aerogel beads based on the Langmuir model of Cu(II), Pb(II), and MB were 85.17, 265.98, and 1324.30 mg/g, respectively. Pb(II) showed higher adsorption affinity than Cu(II) based on ionic properties, such as electronegativity and hydration radius. The adsorption of Cu(II), Pb(II), and MB on the SA/PVA/CG aerogel beads was spontaneous, with heavy metals and MB exhibiting endothermic and exothermic natures, respectively.
Tang L., Xie S., Wang D., Wei Y., Ji X., Wang Y., Zhao N., Mou Z., Li B., Sun W.R., Wang P.Y., Basmadji N.P., Pedraz J.L., Vairo C., Lafuente E.G., et. al.
Carbohydrate Polymers scimago Q1 wos Q1
2025-02-01 citations by CoLab: 3
Holyavka M., Redko Y., Goncharova S., Lavlinskaya M., Sorokin A., Kondratyev M., Artyukhov V.
Polymers scimago Q1 wos Q1 Open Access
2024-11-06 citations by CoLab: 2 PDF Abstract  
Micro- and nanoparticles of chitosan and carboxymethyl chitosan were synthesized, both with and without ascorbic acid. Methods were developed to form complexes between these micro- and nanoparticles and plant proteases—ficin, papain, and bromelain. It was demonstrated that the activity of cysteine protease complexes with carboxymethyl chitosan micro- and nanoparticles was higher compared to those with chitosan micro- and nanoparticles. Additionally, the complexes of ficin, papain, and bromelain with chitosan and carboxymethyl chitosan micro- and nanoparticles synthesized in the presence of ascorbic acid exhibited greater proteolytic activity than those formed with particles prepared without ascorbic acid. Molecular docking studies revealed that the amino acid residues of ficin, papain, and bromelain primarily interact with chitosan and carboxymethyl chitosan through hydrogen bonding and hydrophobic interactions. The amino acid residues in the active sites of these enzymes participate in a complex formation, which likely contributes to the increased activity and stability of cysteine proteases in complexes with chitosan and carboxymethyl chitosan micro- and nanoparticles.
Xiao J., Liang Y., Sun T., Liu M., He X.
Scientific Reports scimago Q1 wos Q1 Open Access
2024-11-06 citations by CoLab: 1 PDF Abstract  
Within the clinical realm, the complexities of wound healing have consistently presented formidable challenges. Recent advancements, notably in hydrogel technologies, have broadened the therapeutic spectrum. This study focuses on investigating a novel dual responsive composite hydrogel for wound healing. This hydrogel is ingeniously designed to maintain an optimal moist environment, expedite healing, and combat bacterial infection during wound recovery. This study combining carboxymethyl chitosan (CMC), oxidized hyaluronic acid (OHA), and sodium alginate (SA), in addition, tobramycin (TOB) was incorporated to create a CMC/OHA/SA/TOB hydrogel. Hydrogel cross-linking was verified by infrared spectroscopy, and the microstructure was examined with scanning electron microscopy. We explored its swelling and degradation behaviors in different pH environments. The drug release profile and biocompatibility was evaluated via cytotoxicity and hemolysis assays. The antibacterial efficacy of hydrogel was tested in both solid and liquid media. Additionally, the wound models in Sprague–Dawley (SD) rat was employed to investigate the hydrogel’s wound healing capabilities in vivo. Results showed that CMCOHA/SA/TOB hydrogel was effectively cross-linked with a network structure. The hydrogel exhibited pronounced responsiveness in its swelling and degradation characteristics, which was significantly influenced by different levels of pH. In vitro results demonstrated that the CMC/OHA/SA/TOB hydrogel exhibits limited cytotoxicity and hemolysis, coupled with a drug release profile of dual responsive characteristics. Antibacterial activity of the hydrogel against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was confirmed. Furthermore, in vivo experiments underscored the hydrogel’s proficiency in promoting wound healing, highlighting its potential for clinical applications. The CMC/OHA/SA/TOB hydrogel not only fosters a moist environment essential for wound healing and enhances structural stability, but it also exhibits functional dual responsive capabilities in swelling and degradation. These distinctive abilities enable the precise release of TOB, thereby optimizing wound healing.
Khatibi N., Naimi-Jamal M.R., Balalaie S., Shokoohmand A.
2024-11-01 citations by CoLab: 2 PDF Abstract  
The development of safe and efficient delivery systems for targeted and controlled release of therapeutic agents has become a major focus in pharmacotherapy. The colon is one organ that serves as an optimal site for the absorption of protein and peptide drugs, offering significant potential for both localized and systemic therapies. However, effective drug delivery is challenged by the need to protect these drugs from premature absorption and maintain their stability across the varying pH levels of the gastrointestinal tract. In this study, we introduce, for the first time, a fully natural hydrogel system composed of N-acetylated chitosan and alginate, crosslinked using a phenylalanine-phenylalanine dipeptide. The hydrogel demonstrates a unique swelling behavior, allowing for a solvent-free drug-loading method and pH-sensitive release properties. In a colon-simulated pH environment, the hydrogel achieved a high drug release efficiency, with 77.6% of the tested drug sulfasalazine and 51% of hydrocortisone over 5 hours. These findings underscore hydrogel’s potential as a promising drug delivery carrier for targeted gastrointestinal treatments, with the capacity to enhance the efficacy of current therapeutic options.

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