Synthesis and characterization of a novel pH-responsive nanocomposite hydrogel based on chitosan for targeted drug release

Design and synthesis of drug hydrogels containing carboxymethylcellulose with honeycomb structure and pH-sensitivity as drug delivery systems for adriamycin, metformin, and naproxen

The aim of this research is to prepare and identify functionalized carboxymethylcellulose/mesoporous silica nanohydrogels (CMC/NH2-MCM-41) for obtaining a pH-sensitive system for the controlled release of drugs. The beads of CMC/NH2-MCM-41 nanocomposites were prepared by dispersing NH2-MCM-41 in a CMC polymer matrix and crosslinking with ferric ions (Fe3+). The SEM analysis of samples revealed enhancement in surface porosity of the functionalized nanohydrogel beads compared to the conventional beads. Swelling of the prepared functionalized nanohydrogels was evaluated at various pH values including pH = 7.35-7.45 (simulated body fluid or healthy cells), pH = 6 (simulated intestinal fluid), and pH = 1.5-3.5 (simulated gastric fluid). The swelling of CMC/MCM-41 and CMC/NH2-MCM-41 nanohydrogels at the pH values of simulated body fluid and simulated intestinal fluid is much higher than that of simulated gastric fluid, indicating successful synthesis of pH-sensitive nanohydrogels for drug delivery. The drug loading results showed that drug release in the CMC/NH2-MCM-41 system is much slower than that in the CMC/MCM-41 system. The results of the survival studies for the manufactured systems showed a very good biocompatibility of the designed drug delivery systems for biological applications. By coating the surface of functionalized mesopores with CMC hydrogel, we were able to develop a pH-sensitive intelligent drug delivery system.

A CMC-g-poly(AA-co-AMPS)/Fe3O4 hydrogel nanocomposite as a novel biopolymer-based catalyst in the synthesis of 1,4-dihydropyridines

A CMC-g-poly(AA-co-AMPS)/Fe₃O₄ hydrogel nanocomposite was successfully designed and prepared via graft copolymerization of AA and AMPS on CMC followed by the cross-linking addition of FeCl₃/FeCl₂. The synthesized hydrogel nanocomposite was characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) spectroscopy, elemental mapping, thermogravimetric analysis/differential thermal analysis (TGA/DTA), and vibrating sample magnetometry (VSM). The CMC-g-poly(AA-co-AMPS)/Fe₃O₄ hydrogel nanocomposite was employed as a biocompatible catalyst for the green synthesis of 1,4-dihydropyridine (1,4-DHP) derivatives under thermal and ultrasound-assisted reaction conditions. High efficiency, low catalyst loadings, short reaction time, frequent catalyst recovery, environmental compatibility and mild conditions were found in both methods.

Hyaluronic acid and chitosan-based injectable and self-healing hydrogel with inherent antibacterial and antioxidant bioactivities

Injectable dressings offering intrinsic antibacterial activity and antioxidation are required, because persistent bacterial infection and oxidative damage are common issues associated with chronic non-healing wounds. Herein, a versatile QCS-l-TA-l-OHA hydrogel is fabricated using ubiquitous nature derived biological macromolecules, quaternized chitosan (QCS), tannic acid (TA) and oxidant hyaluronic acid (OHA), driving by multiple dynamic interactions under physiological conditions. The hydrogel can serve as multiple functional wound dress with injectable and self-healing capabilities coupling with attractive antibacterial activity and antioxidation. The biocompatible and self-biodegradable hydrogel augments free radical scavenging capacity, antibacterial, angiogenesis, mature granulation tissue and collagen disposition, enabling fast wound healing of rat skin full-thickness incision model. This study highlights a wound dressing platform of hyaluronic acid and chitosan based injectable and self-healing hydrogel with inherent antibacterial and antioxidant bioactivities, thereby avoiding the use of antibiotics or antioxidant agents.

Targeting therapy effects of composite hyaluronic acid/chitosan nanosystems containing inclusion complexes

In order to solve the difficulties in the treatment of Staphylococcus aureus infections, a novel enrofloxacin-cyclodextrin (β-CD) inclusion complexes (IC) containing hyaluronic acid/chitosan (HA/CS) self-assemble composite nanosystems covered by poloxamer 188 was designed in our previous study. In this study, the sustained release peforemance, targeting delivery, and therapy effects of the enrofloxacin-composite nanosystems were evaluated in vivo. The enrofloxacin-composite nanosystems had uniform size and smooth surface with drug loading capacity (LC) of 9.92 ± 0.3%. Thermogravimetric analysis (TGA) showed that the material used for the preparation of the enrofloxacin-composite nanosystems did not affect the thermal stability of enrofloxacin. Compared with enrofloxacin injection and enrofloxacin polymeric nanoparticles, the enrofloxacin-composite nanosystems had excellent sustained-release performance in vivo. The enrofloxacin-composite nanosystems have specific targeting to the infection site of Staphylococcus aureus. The excellent sustained release and targeting delivery properties ensure that the anti-infective treatment effect of the enrofloxacin-composite nanosystems in vivo was higher than that of enrofloxacin injection and enrofloxacin polymeric nanoparticles. It can more effectively promote the wound healing. These results suggest that our previous designed enrofloxacin-composite nanosystems will be a promising formulation for effective targeting therapy of Staphylococcus aureus infections.

Design of Magnetic Hydrogels for Hyperthermia and Drug Delivery

Hydrogels are spatially organized hydrophilic polymeric systems that exhibit unique features in hydrated conditions. Among the hydrogel family, composite hydrogels are a special class that are defined as filler-containing systems with some tailor-made properties. The composite hydrogel family includes magnetic-nanoparticle-integrated hydrogels. Magnetic hydrogels (MHGs) show magneto-responsiveness, which is observed when they are placed in a magnetic field (static or oscillating). Because of their tunable porosity and internal morphology they can be used in several biomedical applications, especially diffusion-related smart devices. External stimuli may influence physical and chemical changes in these hydrogels, particularly in terms of volume and shape morphing. One of the most significant external stimuli for hydrogels is a magnetic field. This review embraces a brief overview of the fabrication of MHGs and two of their usages in the biomedical area: drug delivery and hyperthermia-based anti-cancer activity. As for the saturation magnetization imposed on composite MHGs, they are easily heated in the presence of an alternating magnetic field and the temperature increment is dependent on the magnetic nanoparticle concentration and exposure time. Herein, we also discuss the mode of different therapies based on non-contact hyperthermia heating.

Self-assembled biocompatible heparin-based supramolecular hydrogel for doxorubicin delivery

An array of self-assembled biocompatible doxorubicin (DOX) loaded heparin--cyclodextrin supramolecular hydrogels (DOX@HGs) with highly encapsulated efficiency was constructed using heparin-β-cyclodextrin derivatives (Hep-β-CD), α-cyclodextrin (α-CD), pluronic F-127 and DOX via the synergy of host-guest and multiple hydrogen bonding interactions. These hydrogels were characterized by GPC measurements (GPC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Size and zeta potential determinations, X-ray diffraction (XRD), and rheological characteristics; the data confirmed successful formation of the hydrogels. Furthermore, these hydrogels demonstrated distinctive thixotropy, indicating rapid self-repairing after continuously oscillatory shear stress. Variable release of DOX from DOX @HGs was obtained at various pH after 84 h depending on the strength of the hydrogels. At pH 7.4, cumulative DOX release was approximately 49.07% for DOX@HG 1, 32.15% for DOX@HG 2, and 27.12% for DOX@HG 3. While at pH 5.5, release of DOX was increased to 59.08% for DOX@HG 1 and to 43.2% for DOX@HG 3 after 84 h (P < 0.05). This information demonstrated that a higher DOX release rate was observed under a lower pH due to strong charge expansion of CDs and weakening of electrostatic interactions between heparin and DOX. Additionally, cytotoxicity of free DOX and DOX@HGs in ovarian cancer SKOV-3 cells was studied at various exposure durations. The results revealed that cytotoxicity of DOX@HG 1-3 toward ovarian cancer SKOV-3 cells was lower than that of free DOX (P < 0.05), suggesting prolonged DOX release from the hydrogels in SKOV-3 cells.

Fabrication and characterization of novel antibacterial chitosan/dialdehyde guar gum hydrogels containing pomegranate peel extract for active food packaging application

This study aimed to investigate synthesis and structural characteristics of the chitosan (CS) - modified dialdehyde guar gum (DAGG) hydrogel through the Schiff base reaction. The highest swelling capacity was achieved as about 12,000% of dry weight of the freeze-dried powder at CS: DAGG hydrogel with the mixing ratio of 30:70. The swelling ratio was not affected by changes in pH, which could be considered as an important property in the control of moisture in absorbent pad. The FTIR results indicated that the new amide groups have been formed at 1680 cm^-1, which can be attributed to the covalent bond between the amide groups of CS and the aldehyde groups of GG. Based on a SEM image, the prepared hydrogel showed the porous structure so it verified the crosslinking formation between the two polymers. Rheological analyses confirmed that formation compact and porous structure led to some noteworthy improvements in the strength of hydrogel prepared with a high ratio of DAGG. The hydrogel loaded with 5% pomegranate peel extract (PPE) showed both good antioxidant (81.13%) and antimicrobial activities. The hydrogel was observed to have a good potential to be used as an antibacterial pad.

Composite inclusion complexes containing hyaluronic acid/chitosan nanosystems for dual responsive enrofloxacin release

In order to overcome treatment difficulty of S. aureus infections, a pH/hyaluronidase dual responsive enrofloxacin-cyclodextrin (β-CD) inclusion complexes (IC) containing hyaluronic acid/chitosan (HA/CS) self-assemble composite nanosystems covered by poloxamer 188 (F68) was firstly explored for targeted "on-demand" delivery. The FTIR, DSC and PXRD showed that enrofloxacin was embedded into IC and then distributed into F68 coating nanogels formulated by electrostatic interaction between CS and HA. The optimal nanosystems of 118.8 ± 30.7 nm showed excellent stability and responsive release in the acid medium, hyaluronidase containing medium, and LB broth medium where S. aureus present. The nanosystems displayed strong surface adsorption on S. aureus and enhanced activity against S. aureus. It had stronger sustained release than the polymeric nanoparticles formulated by entrapping of IC into F68 and the single HA/CS nanogels. This study provides a promising multi-functionalized nanosystems to overcome the treatment challenge of S. aureus and other bacterial infections.

Natural Polymer-based Stimuli-responsive Hydrogels

The abilities of intelligent polymer hydrogels to change their structure and volume phase in response to external stimuli have provided new possibilities for various advanced technologies and great research and application potentials in the medical field. The natural polymer-based hydrogels have the advantages of environment-friendliness, rich sources and good biocompatibility. Based on their responsiveness to external stimuli, the natural polymer-based hydrogels can be classified into the temperature-responsive hydrogel, pH-responsive hydrogel, light-responsive hydrogel, electricresponsive hydrogel, redox-responsive hydrogel, enzyme-responsive hydrogel, magnetic-responsive hydrogel, multi-responsive hydrogel, etc. In this review, we have compiled some recent studies on natural polymer-based stimuli-responsive hydrogels, especially the hydrogels prepared from polysaccharides. The preparation methods, properties and applications of these hydrogels in the medical field are highlighted.

Chitosan-Based Nanogel Enhances Chemotherapeutic Efficacy of 10-Hydroxycamptothecin against Human Breast Cancer Cells

Chitosan (CS), the second most abundant polysaccharide in nature, has been widely developed as a nanoscopic drug delivery vehicle due to its intriguing characteristics. In this work, a positively charged CS-based nanogel was designed and synthesized to inhibit the proliferation of breast cancer cell lines. The model drug of 10-hydroxycamptothecin (HCPT) was entrapped into the core via a facile diffusion to form CS/HCPT. The characteristics of CS/HCPT were evaluated by assessing particle size, drug loading content, and drug loading efficiency. Furthermore, cell internalization, cytotoxicity, and apoptosis of CS/HCPT were also investigated in vitro. The present investigation indicated that the positively charged CS-based nanogel could be potentially used as a promising drug delivery system.

Facile Synthesis of Chitosan Based-(AMPS-co-AA) Semi-IPNs as a Potential Drug Carrier: Enzymatic Degradation, Cytotoxicity, and Preliminary Safety Evaluation

OBJECTIVE

The study describes the development of chitosan-based (AMPS-co-AA) semi-IPN hydrogels using free radical polymerization technique.

METHODS

The resulting hydrogels were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The successful crosslinking of chitosan, 2- Acrylamido-2-Methylpropane Sulfonic Acid (AMPS), and Acrylic Acid (AA) was confirmed by FT IR. Unloaded and drug-loaded hydrogels exhibited higher thermal stability after crosslinking compared to the individual components. XRD confirmed the decrease in crystallinity after hydrogel formation and molecular dispersion of Oxaliplatin (OXP) in the polymeric network. SEM showed rough, vague and nebulous surface resulting from crosslinking and loading of OXP.

RESULTS

The experimental results revealed that swelling and drug release were influenced by the pH of the medium being low at acidic pH and higher at basic pH. Increasing the concentration of chitosan and AA enhanced the swelling, drug loading and drug release while AMPS was found to act inversely.

CONCLUSION

It was confirmed that the hydrogels were degraded more by specific enzyme lysozyme as compared to the non-specific enzyme collagenase. In-vitro cytotoxicity suggested that the unloaded hydrogels were non-cytotoxic while crude drug and drug-loaded hydrogel exhibited dose-dependent cytotoxicity against HCT-116 and MCF-7. Results of acute oral toxicity on rabbits demonstrated that the hydrogels are non-toxic up to 3900 mg/kg after oral administration, as no toxicity or histopathological changes were observed in comparison to control rabbits. These pH-sensitive hydrogels appear to provide an ideal basis as a safe carrier for oral drug delivery.