Development of Chitosan/Sodium Carboxymethylcellulose Complexes to Improve the Simvastatin Release Rate: Polymer/Polymer and Drug/Polymer Interactions' Effects on Kinetic Models

Production and Characterization of Nanoparticulate Polyelectrolyte Complexes of Chitosan-Catechol, Ulvan, and Hyaluronic Acid

This work provides the first description of the synthesis and characterization of polymeric nanoparticles (NPs) obtained by polyelectrolyte complexes (PECs) of three polysaccharides: chitosan (Cs) or its catecholic derivative, ulvan, and hyaluronic acid (HA). The carbodiimide method used catechol group conjugation onto the Cs backbone using the catechol-containing compound hydrocaffeic acid. A degree of substitution of 2.98% was determined by spectroscopy in the chitosan-catechol (CsC) conjugate. DLS studies showed hydrodynamic diameter (D h) close to 300 nm for PECs of Cs and CsC with ulvan, with positive zeta potential for both complexes. HA coating was confirmed by obtaining negative zeta potential. The HA coating reduced the D h values of the materials by approximately 100 nm. This resulted in maintaining stability in water suspension for up to 8 weeks, yielding unimodal size distribution. ATR-FTIR spectra confirmed the presence of the polyelectrolytes in the PECs. FE-SEM studies demonstrated that HA-coated NPs exhibited smaller sizes than their uncoated counterparts. PECs with CsC maintained higher free radical scavenging activity than those with unmodified Cs, with the HA coating only reducing antioxidant activity by 16%. All tested NPs demonstrated biocompatibility at concentrations up to 200 μg/mL in ARPE-19 cell cultures derived from human retinal pigment epithelial cells.

Carboxymethyl cellulose/quaternized chitosan hydrogel loaded with polydopamine nanoparticles promotes spinal cord injury recovery by anti-ferroptosis and M1/M2 polarization modulation

Spinal cord injury (SCI) represents a catastrophic neurological condition resulting in long-term loss of motor, autonomic, and sensory functions. Recently, ferroptosis, an iron-regulated form of cell death distinct from apoptosis, has emerged as a potential therapeutic target for SCI. In this study, we developed an injectable hydrogel composed of carboxymethyl cellulose (CMC), and quaternized chitosan (QCS), loaded with modified polydopamine nanoparticles (PDA NPs), referred to as CQP hydrogel. This hydrogel effectively scavenged reactive oxygen species (ROS), prevented the accumulation of Fe2+ and lipid peroxidation associated with ferroptosis, and restored mitochondrial functions in primary neuronal cells. When administered to animal models (rats) with SCI, the CQP hydrogels improved motor function by regulating iron homeostasis, inhibiting ferroptosis, and mitigating oxidative stress injury. Both in vitro and in vivo studies corroborated the capacity of CQP hydrogels to promote the shift from M1 to M2 polarization of microglia/macrophages. These findings suggest that CQP hydrogels, functioning as a localized iron-chelating system, have potential as biomaterials to enhance recovery from SCI by targeting ferroptosis and modulating anti-inflammatory macrophages activity.

Development, Characterization, and Cellular Toxicity Evaluation of Solid Dispersion-Loaded Hydrogel Based on Indomethacin

Indomethacin (IND) as a non-selective cyclooxygenase 1 and 2 inhibitor administered orally causes numerous adverse effects, mostly related to the gastrointestinal tract. Moreover, when applied exogenously in topical preparations, there are obstacles to its permeation through the stratum corneum due to its low water solubility and susceptibility to photodegradation. In this work, solid dispersions (SDs) of IND with low-substituted hydroxypropyl cellulose (LHPC) were developed. The IND-SDs were incorporated into a hydroxypropyl guar (HPG) hydrogel to enhance drug solubility on the skin. The hydrogels were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), viscosity, drug release, and unspecific cytotoxicity in mammalian cells. SEM showed a highly porous structure for SD hydrogels. DSC and XRPD studies showed that amorphous IND species were formed; therefore, these hydrogels exhibited superior drug release in comparison with IND raw material hydrogels. FTIR evidenced the presence of the hydrogen bond in the SD hydrogel. The rheology parameter viscosity increased across gels formulated with SDs in comparison with hydrogels with pure IND. In addition, IND-SD hydrogels combine the advantages of a suitable viscosity for dermal use and no potentially hazardous skin irritation. This study suggests that the formulated IND-SD hydrogels represent a suitable candidate for topical administration.

Modification of a Carboxymethyl Cellulose/Poly(vinyl alcohol) Hydrogel Film with Citric Acid and Glutaraldehyde Crosslink Agents to Enhance the Anti-Inflammatory Effectiveness of Triamcinolone Acetonide in Wound Healing

Anti-inflammatory wound healing involves targeted drug delivery to the wound site using hydrogel materials to prolong drug effectiveness. In this work, hydrogel films were fabricated using carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) crosslinked with citric acid (CA) and glutaraldehyde (GA) at different concentrations. The crosslinker densities were optimized with various CA (2-10% w/v) and GA (1-5% v/v) concentrations. The optimized crosslink densities in the hydrogel exhibited additional functional group peaks in the FT-IR spectra at 1740 cm-1 for the C=O stretching of the ester linkage in CA and at 1060 cm-1 for the C-O-C stretching of the ether group in GA. Significantly, the internal porous structures of hydrogel composite films improved density, swelling capacities, solubility percentage reduction, and decreased water retention capacities with optimized crosslinker densities. Therefore, these hydrogel composite films were utilized as drug carriers for controlled drug release within 24 h during medical treatment. Moreover, the hydrogel films demonstrated increased triamcinolone acetonide (TAA) absorption with higher crosslinker density, resulting in delayed drug release and improved TAA efficiency in anti-inflammatory activity. As a result, the modified hydrogel showed the capability of being an alternative material with enhanced anti-inflammatory efficiency with hydrogel films.

Topical Meloxicam Hydroxypropyl Guar Hydrogels Based on Low-Substituted Hydroxypropyl Cellulose Solid Dispersions

Meloxicam (MX) is a poorly water-soluble drug with severe gastrointestinal side effects. Topical hydrogel of hydroxypropyl guar (HPG) was formulated using a solid dispersion (SD) of MX with hydroxypropyl cellulose (LHPC) as an alternative to oral administration. The development of a solid dispersion with an adequate MX:LHPC ratio could increase the topical delivery of meloxicam. Solid dispersions showed high MX solubility values and were related to an increase in hydrophilicity. The drug/polymer and polymer/polymer interactions of solid dispersions within the HPG hydrogels were evaluated by SEM, DSC, FTIR, and viscosity studies. A porous structure was observed in the solid dispersion hydrogel MX:LHPC (1:2.5) and its higher viscosity was related to a high increase in hydrogen bonds among the -OH groups from LHPC and HPG with water molecules. In vitro drug release studies showed increases of 3.20 and 3.97-fold for hydrogels with MX:LHPC ratios of (1:1) and (1:2.5), respectively, at 2 h compared to hydrogel with pure MX. Finally, a fitting transition from zero to first-order model was observed for these hydrogels containing solid dispersions, while the n value of Korsmeyer-Peppas model indicated that release mechanism is governed by diffusion through an important relaxation of the polymer.

Anti-Aging Properties of Chitosan-Based Hydrogels Rich in Bilberry Fruit Extract

Photoaging is a process related to an increased level of reactive oxygen species (ROS). Polyphenols can scavenge free radicals in the body, which can delay skin aging. Therefore, our work aimed to prepare a biologically active extract from dry fruits of Vaccinium myrtillus or Vaccinium corymbosum and use it for the preparation of hydrogels for topical application. Therefore, eight different extracts (using V. myrtillus and V. corymbosum and different extraction mixtures: methanol, methanol-water 1:1, water, acetone-water 1:1) were prepared and their phytochemical (total polyphenolic content, total flavonoid content, total anthocyanin content) and biological properties (antioxidant, anti-hyaluronidase, and anti-tyrosinase activity) were assessed. Cytotoxicity towards HaCaT keratinocytes was also determined. Based on the results, the acetone-water extract from V. myrtillus was selected for further study. Using the Design of Experiments approach, chitosan-based hydrogels with bilberry fruit extract were prepared. The content of extract and chitosan were selected as independent factors. The activity of hydrogels depended on the extract content; however, the enzyme-inhibiting (anti-hyaluronidase and anti-tyrosinase) activity resulted from the presence of both the extract and chitosan. Increased concentration of chitosan in the hydrogel base led to increased viscosity of the hydrogel and, consequently, a slower release of active compounds. To get optimal hydrogel characteristics, 1% extract and 2.5% MMW chitosan were utilized. The research suggests the validity of using bilberry fruit extracts in topical preparations with anti-aging properties.