Alginate/carboxymethyl chitosan composite gel beads for oral drug delivery

Preparation of pH-sensitive carboxymethyl chitosan nanoparticles loaded with ginsenoside Rb1 and evaluation of drug release in vitro

Oral absorption of ginsenoside Rb1 (Rb1) is often hindered by the gastrointestinal tract. Carboxymethyl chitosan deoxycholic acid loaded with ginsenoside Rb1 nanoparticles (CMDA@Rb1-NPs), were prepared as a delivery system using a self-assembly technique with amphipathic deoxycholic acid grafted carboxymethyl chitosan as the carrier, which improved the stability and embedding rate of Rb1. In addition, the CMDA@Rb1-NPs was encapsulated with sodium alginate by ion crosslinking method with additional layer (CMDAlg@Rb1-NPs). Scanning electron microscopy showed that the nanoparticles were spherical, evenly distributed, smooth and without obvious adhesion. By evaluating drug loading, entrapment efficiency, the encapsulation efficiency of Rb1 increased from 60.07 % to 72.14 % after grafting deoxycholic acid improvement and optimization. In vitro release results showed that the cumulative release of Rb1 by CMDAlg-NPs showed a pH dependent effect, which was <10 % in simulated gastric juice with pH 1.2, completely released with pH 7.4 for about 48 h. In addition, Rb1 and CMDAlg@Rb1-NPs had inhibitory effects on A549 cells, and the inhibitory effect of CMDAlg@Rb1-NPs was better. Therefore, all results indicated that CMDA/Alg@Rb1 nanoparticles might be a novel drug delivery system to improve the stability and embedding rate of Rb1, and has the potential to be applied in oral pharmaceutical preparations.

Formulation, Characterization and In Vitro Evaluation of Mesalamine and Bifidobacterium bifidum Loaded Hydrogel Beads in Capsule System for Colon Targeted Delivery

Mesalamine is a first-line drug for the treatment of inflammatory bowel diseases. However, its premature release associated with marketed formulations leads to adverse effects like gastric trouble, vomiting, and diarrhoea. To minimize these side effects, colon-targeted drug delivery is essential. Besides conventional pharmacotherapy, bifidogenic probiotics with anti-inflammatory activity has been reported to elicit a significant impact on the remission of ulcerative colitis. Bifidogenic probiotics being acid-labile necessitate developing a gastro-resistant formulation for enhancing the delivery of viable cells to the colon. The present study was aimed at developing a fixed-dose unit dosage form of mucoadhesive hydrogel beads loaded with mesalamine and Bifidobacterium bifidum further encapsulated in Eudragit® capsules for the targeted drug delivery at colonic pH. The hydrogel beads were prepared by ionotropic gelation, with the effect of single and dual-crosslinking approaches on various formulation characteristics studied. Standard size 00 Eudragit® gastro-resistant capsules were prepared and the dried beads were filled inside the capsule shells. The formulation was then evaluated for various parameters, including physicochemical characterization, in vitro biocompatibility and anti-inflammatory activity. No interaction was observed between the drug and the polymers, as confirmed through FTIR, XRD, and DSC analysis. The mean particle size of the beads was ~ 457-485 µm. The optimized formulation showed a drug entrapment efficiency of 95.4 ± 2.58%. The Eudragit® capsule shells disintegrated in approximately 13 min at pH 7.4. The mucoadhesive hydrogel beads sustained the drug release above 18 h, with 50% of the drug released by the end of 12 h. The optimized formulation demonstrated significant (p < 0.05) gastro-resistance, biocompatibility, sustained drug release, cell viability, and anti-inflammatory activity.

Self-triggered carboxymethyl chitosan hydrogel for the convenient sustained release of ClO2 gas with environmental stability and long-term antimicrobial effect

Challenges associated with the storage and uncontrolled release of ClO2 gas present significant hurdles to its practical application. Herein, a clever strategy for self-triggering the sustained release of chlorine dioxide (ClO2) gas is proposed by crosslinking carboxymethyl chitosan (CMCS) with Zn2+ to construct a novel CMCS-Zn@NaClO2 gel with eco-friendly, environmental stability, and convenient, long term, and efficient antibacterial activity. The precursor (NaClO2) in the CMCS solution was alkaline and triggered by the acidic Zn(NO3)2·6H2O solution to achieve sustained self-triggering ClO2 release. The ClO2 gas self-release could be sustained on demand at different temperatures for at least 20 days due to the environmental structure stability of the gel. The hydrogels showed an increase in pore size after sustained release. Molecular dynamics simulations showed the spontaneous release of ClO2 gas at room temperature and the contraction of the CMCS agglomeration, which were consistent with the macroscopic behaviour. The gel displayed a long-acting and high antibacterial efficacy, resulting in a bacteria-killing rate of over 99.9% (inhibitory concentrations of 2.5 mg mL-1 against E. coli and 0.16 mg mL-1 against S. aureus). The hydrogels could effectively extend the shelf life of fruits and demonstrated an excellent wide range of antibacterial properties. This work provides a new approach to solving the storage difficulty of ClO2 gas and offers a fresh perspective on the design of materials with convenient self-triggering release by a precursor, as well as the relationship between the material microstructure and sustained-release behaviour.

Bioprinting of alginate-carboxymethyl chitosan scaffolds for enamel tissue engineeringin vitro

Tissue engineering offers a great potential in regenerative dentistry and to this end, three dimensional (3D) bioprinting has been emerging nowadays to enable the incorporation of living cells into the biomaterials (such a mixture is referred as a bioink in the literature) to create scaffolds. However, the bioinks available for scaffold bioprinting are limited, particularly for dental tissue engineering, due to the complicated, yet compromised, printability, mechanical and biological properties simultaneously imposed on the bioinks. This paper presents our study on the development of a novel bioink from carboxymethyl chitosan (CMC) and alginate (Alg) for bioprinting scaffolds for enamel tissue regeneration. CMC was used due to its antibacterial ability and superior cell interaction properties, while Alg was added to enhance the printability and mechanical properties as well as to regulate the degradation rate. The bioinks with three mixture ratios of Alg and CMC (2-4, 3-3 and 4-2) were prepared, and then printed into the calcium chloride crosslinker solution (100 mM) to form a 3D structure of scaffolds. The printed scaffolds were characterized in terms of structural, swelling, degradation, and mechanical properties, followed by theirin vitrocharacterization for enamel tissue regeneration. The results showed that the bioinks with higher concentrations of Alg were more viscous and needed higher pressure for printing; while the printed scaffolds were highly porous and showed a high degree of printability and structural integrity. The hydrogels with higher CMC ratios had higher swelling ratios, faster degradation rates, and lower compressive modulus. Dental epithelial cell line, HAT-7, could maintain high viability in the printed constructs after 1, 7 and 14 d of culture. HAT-7 cells were also able to maintain their morphology and secrete alkaline phosphatase after 14 d of culture in the 3D printed scaffolds, suggesting the capacity of these cells for mineral deposition and enamel-like tissue formation. Among all combinations Alg4%-CMC2% and in a less degree 2%Alg-4%CMC showed the higher potential to promote ameloblast differentiation, Ca and P deposition and matrix mineralizationin vitro. Taken together, Alg-CMC has been illustrated to be suitable to print scaffolds with dental epithelial cells for enamel tissue regeneration.

Hard, Soft, and Hard-and-Soft Drug Delivery Carriers Based on CaCO3 and Alginate Biomaterials: Synthesis, Properties, Pharmaceutical Applications

Because free therapeutic drug molecules often have adverse effects on normal tissues, deliver scanty drug concentrations and exhibit a potentially low efficacy at pathological sites, various drug carriers have been developed for preclinical and clinical trials. Their physicochemical and toxicological properties are the subject of extensive research. Inorganic calcium carbonate particles are promising candidates as drug delivery carriers owning to their hardness, porous internal structure, high surface area, distinctive pH-sensitivity, low degradability, etc, while soft organic alginate hydrogels are also widely used because of their special advantages such as a high hydration, bio-adhesiveness, and non-antigenicity. Here, we review these two distinct substances as well as hybrid structures encompassing both types of carriers. Methods of their synthesis, fundamental properties and mechanisms of formation, and their respective applications are described. Furthermore, we summarize and compare similarities versus differences taking into account unique advantages and disadvantages of these drug delivery carriers. Moreover, rational combination of both carrier types due to their performance complementarity (yin-&yang properties: in general, yin is referred to for definiteness as hard, and yang is broadly taken as soft) is proposed to be used in the so-called hybrid carriers endowing them with even more advanced properties envisioned to be attractive for designing new drug delivery systems.

Preparation and characterization of magnetic nanohydrogel based on chitosan for 5-fluorouracil drug delivery and kinetic study

Chemotherapy is currently used for most cancer treatments, but one of the significant problems of this treatment is that it affects the healthy tissues of the body. Therefore, designing new systems for the intelligent and controlled release of these drugs in cancer tissues is one of the major challenges in the world. Hence, today, huge costs are spent designing appropriate new drug delivery systems (DDS) with controlled drug release. In this study, chitosan-polyacrylic acid encapsulated Fe₃O₄ magnetic nanogelic core-shell (Fe₃O₄@CS-PAA) was synthesized in the presence of glutaraldehyde used for loaded anticancer 5-fluorouracil (5-FU) drug. Also, the prepared Fe₃O₄@CS-PAA was characterized by using FT-IR, SEM, XRD, and VSM analysis. Then, drug delivery tests were carried out in the in-vitro conditions that are the simulated physiological environment and tumor tissue conditions. The drug release tests indicated that the Fe₃O₄@CS-PAA upgraded the rate of 5-FU release from nanogelic core-shell under tumor tissue conditions (pH 4.5) than physiological environments (pH 7.4). In addition, various models were used to investigate the drug release mechanism. Results of modeling studies of drug release showed the mechanism of 5-FU release from Fe₃O₄@CS-PAA controlled by Fickian diffusion.

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.

A sodium alginate-based sustained-release IPN hydrogel and its applications

Interpenetrating polymer network (IPN) hydrogels are crosslinked by two or more polymer networks, providing free volume space in the three-dimensional network structure, and providing conditions for the sustained and controlled release of drugs. The IPN hydrogels based on the natural polymer sodium alginate can form a stable porous network structure. Due to its excellent biocompatibility, the loaded drug can be sustained to the maximum extent without affecting its pharmacological effect. Sodium alginate-based IPN hydrogels have broad application prospects in the field of sustained and controlled drug release. This paper begins with an overview of the formation of alginate-based IPN hydrogels; summarizes the types of alginate-based IPN hydrogels; and discusses the pharmaceutical applications of alginate-based IPN hydrogels. We aim to give an overview of the research on IPN hydrogels based on sodium alginate in sustained and controlled drug release systems.

Biodegradable polymer scaffolds

Tissue engineering aims to repair the damaged tissue by transplantation of cells or introducing bioactive factors in a biocompatible scaffold. In recent years, biodegradable polymer scaffolds mimicking the extracellular matrix have been developed to promote the cell proliferation and extracellular matrix deposition. The biodegradable polymer scaffolds thus act as templates for tissue repair and regeneration. This article reviews the updated information regarding various types of natural and synthetic biodegradable polymers as well as their functions, physico-chemical properties, and degradation mechanisms in the development of biodegradable scaffolds for tissue engineering applications, including their combination with 3D printing.