Trimethyl Ammonium Chloride Chitosan Research Articles

Repair of undersea concrete using biopolymer-assisted plant urease

Concrete repair in marine environments is influenced by various factors, particularly underwater pressure and dynamic water flow. Traditional materials used for underwater concrete repair suffer from issues such as dilution, dispersion, susceptibility to erosion by moving water, and poor grout retention. In this study, a novel biopolymer-based undersea crack repair material composed of quaternized chitosan (Hydroxypropyl trimethyl ammonium chloride chitosan, HACC), sodium alginate (SA), urease, and aggregates was developed. It investigated the impact of biopolymers on urease's physiological and biochemical properties, as well as its mineralization capacity. Additionally, It conducted a comprehensive evaluation of the fluidity, rheological behavior, grout retention, mechanical properties, and anti-permeability rate of the bio-grouting material. The results showed that the optimized bio-grouting material exhibited suitable viscosity and fluidity. After injection, it rapidly formed a cohesive seal, with a grout retention rate exceeding 90 % at 48 days. The water resistance of the repaired concrete reached 93 %. Microstructural analysis using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) revealed strong electrostatic interactions between HACC and SA molecular chains. These interactions encapsulated mineralization products and sand particles, resulting in a denser microstructure.

Multifunctional double-network hydrogel with antibacterial and anti-inflammatory synergistic effects contributes to wound healing of bacterial infection

Wound infection not only hinders the time sequence of tissue repair, but also may lead to serious complications. Multifunctional wound dressings with biocompatibility, excellent mechanical properties and antibacterial properties can promote wound healing during skin infection and reduce the use of antibiotics. In this study, a multifunctional dual-network antibacterial hydrogel was constructed based on the electrostatic interaction of two polyelectrolytes, hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and sodium alginate (SA). Attributing to the suitable physical crosslinking between HACC and SA, the hydrogel not only has good biocompatibility, mechanical property, but also has broad-spectrum antibacterial properties. In vivo results showed that the hydrogel could regulate M2 polarization, promote early vascular regeneration, and create a good microenvironment for wound healing. Therefore, this hydrogel is an effective multifunctional wound dressing. Consequently, we propose a novel hydrogel with combined elements to expedite the intricate repair of wound infection.

Light-sensitive PEG hydrogel with antibacterial performance for pacemaker pocket infection prevention

Prevention of cardiovascular implantable electronic devices (CIED) infection is crucial for successful outcomes. In this study, we report an adhesive and antibacterial hydrogel coating for CIED infection treatment, by immobilizing polyethylene glycol (PEG) and 2′-O-hydroxypropyl trimethyl ammonium chloride chitosan (HAC) on Ti surface. Initial alkali and APTES treatment caused the formation of –NH2 to enhance the adhesion of the hydrogel coating to Ti implants, followed by immobilizing a photo-cross-linkable PEG/2′-O-HTACCS hydrogel on Ti/OH/NH2 surface. Surface characterization of Ti/OH/NH2 sample and adhesion testing of hydrogel on Ti/OH/NH2 surface confirm successful immobilization of hydrogel onto the Ti/OH/NH2 surface. In vitro and in vivo antimicrobial results exhibited that the photo-cross-linkable PEG/HAC composite hydrogel has excellent antimicrobial capabilities against both Grampositive (S. aureus and S. epidermidis) and Gram-negative (P. aeruginosa and E. coli) bacteria. The outcome of this study demonstrates the photo-cross linked PEG/HAC coating hydrogels can be easily formed on the Ti implants, and has great potential in preventing CIED pocket infection.

PH-responsive nanogels with enhanced antioxidant and antitumor activities on drug delivery and smart drug release

pH-responsive nanogels have played an increasingly momentous role in tumor treatment. The focus of this study is to design and develop pH-responsive benzimidazole-chitosan quaternary ammonium salt (BIMIXHAC) nanogels for the controlled release of doxorubicin hydrochloride (DOX) while enhancing its hydrophilicity. BIMIXHAC is crosslinked with carboxymethyl chitosan (CMC), hyaluronic acid sodium salt (HA), and sodium alginates (SA) using an ion crosslinking method. The chemical structure of chitosan derivatives was verified by 1H NMR and FT-IR techniques. Compared to hydroxypropyl trimethyl ammonium chloride chitosan (HACC)-based nanogels, BIMIXHAC-based nanogels exhibit better drug encapsulation efficiency and loading capacity (BIMIXHAC-D-HA 91.76 %, and 32.23 %), with pH-responsive release profiles and accelerated release in vitro. The series of nanogels formed by crosslinking with three different polyanionic crosslinkers have different particle size potentials and antioxidant properties. BIMIXHAC-HA, BIMIXHAC-SA and BIMIXHAC-CMC demonstrate favorable antioxidant capability. In addition, cytotoxicity tests showed that BIMIXHAC-based nanogels have high biocompatibility. BIMIXHAC-based nanogels exhibit preferable anticancer effects on MCF-7 and A549 cells. Furthermore, the BIMIXHAC-D-HA nanogel was 2.62 times less toxic than DOX to L929 cells. These results suggest that BIMIXHAC-based nanogels can serve as pH-responsive nanoplatforms for the delivery of anticancer drugs.

Functionalized N-hydroxypropyl trimethylammonium chloride chitosan as an ICG/DOX co-delivery nanocarriers for targeted and chemo-photothermal combination therapy

Functionalized N-hydroxypropyl trimethylammonium chloride chitosan as an ICG/DOX co-delivery nanocarriers for targeted and chemo-photothermal combination therapy

Inhibitory Potential of Chitosan Derivatives against Severe Acute Respiratory Syndrome Coronavirus 2: An In Silico Prospective

The present work was designed to investigate the antiviral potential of novel monomeric and oligomeric chitosan derivatives through in silico approaches. The goal was to identify potent broad-spectrum antiviral compounds as promising drug candidates against severe acute respiratory syndrome coronavirus 2 and understand their mode of action. Chitosan biopolymer and its derivatives were virtually screened against the spike glycoprotein and human angiotensin-converting enzyme 2 (ACE2) receptor of novel coronavirus-19. Hydroxypropyl trimethyl ammonium chloride chitosan (HTCC), a polymeric chitosan, has been reported to interact with the corona viral spike (S) protein and blocks its interaction with the ACE2 receptor. The enhancement of antiviral activity relies on better biocompatibility, structural correlations, variation in the degree of deacetylation, and molecular weight of modified chitosan derivatives. The chitosan derivatives constructively interact with viral S protein. Among the chitosan derivatives, N-carboxymethyl chitosan (NCMC) displayed efficient binding affinity. Comparing NCMC to mHTCC, monomeric chitosan, for their interaction with the S protein, receptor binding domain site, and ACE2 receptor, NCMC displayed better binding affinity of −7.9, −6.3, and −7.4 with binding energies of −6.2, −4.8, and −5.5 kcal/mol, respectively. Furthermore, through flexible docking, the interactions of the S protein with ACE2 receptor and ligand mHTCC-S protein complex and NCMC-S protein complex with ACE2 receptor were calculated, showing an efficient reduction of binding energy from −901.2 kJ/mol to −765.06 kJ/mol and −814.72 kJ/mol, respectively. This points to the decrease binding affinity of the viral S protein for the ACE2 receptor in the presence of NCMC/mHTCC. For the first time, the computational study envisages the antiviral efficiency of NCMC, mHTCC, and biocompatible chitosan derivatives as a preventive intervention against COVID-19.

The initial application of conch-shell hydroxyapatite and HACC as functional filler in PMMA bone cement

In this study, we acquired conch-shell Hydroxyapatite (cHA)with a mean size of 99.41 nm using a microwave-assisted method, and hydroxypropyl trimethyl ammonium chloride chitosan (HACC) with a molecular weight of 41 kDa was synthesized from deacetylated chitosan. These two additives were added to plain PMMA bone cement, improving its biological activity. It was shown that the addition of cHA and HACC balanced the mechanical performance and porosity of the implant, improving its biocompatibility with mouse pre-osteoblasts (MC3T3-E1). A composite cement with 30 wt% cHA and 0.5 wt% HACC significantly enhanced mineralization efficiency, protein adsorption, and alkaline phosphatase (ALP) activity.

20(R)-ginsenoside Rg3-loaded polyurethane/marine polysaccharide based nanofiber dressings improved burn wound healing potentials

The management of deep burn injuries is extremely challenging, ascribed to their delayed wound healing rate, susceptibility for bacterial infections, pain, and increased risk of hypertrophic scarring. In our current investigation, a series of composite nanofiber dressings (NFDs) based on polyurethane (PU) and marine polysaccharides (i.e., hydroxypropyl trimethyl ammonium chloride chitosan, HACC and sodium alginate, SA) were accomplished by electrospinning and freeze-drying protocols. The 20(R)-ginsenoside Rg3 (Rg3) was further loaded into these NFDs to inhibit the formation of excessive wound scars. The PU/HACC/SA/Rg3 dressings showed a sandwich-like structure. The Rg3 was encapsulated in the middle layers of these NFDs and slowly released over 30 days. The PU/HACC/SA and PU/HACC/SA/Rg3 composite dressings demonstrated superior wound healing potentials over other NFDs. These dressings also displayed favorable cytocompatibility with keratinocytes and fibroblasts and could dramatically accelerate epidermal wound closure rate following 21 days of the treatment of a deep burn wound animal model. Interestingly, the PU/HACC/SA/Rg3 obviously reduced the excessive scar formation, with a collagen type I/III ratio closer to the normal skin. Overall, this study represented PU/HACC/SA/Rg3 as a promising multifunctional wound dressing, which promoted the regeneration of burn skins and attenuated scar formation.

Preparation and Properties of Self-Cross-Linking Hydrogels Based on Chitosan Derivatives and Oxidized Sodium Alginate.

A self-cross-linking and biocompatible hydrogel has wide application potential in the field of tissue engineering. In this work, an easily available, biodegradable, and resilient hydrogel was prepared using a self-cross-linking method. This hydrogel was composed of N-2-hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and oxidized sodium alginate (OSA). A stable and reversible cross-linking network was formed by the Schiff base self-cross-linked and hydrogen bonding. The addition of a shielding agent (NaCl) may weaken the intense electrostatic effect between HACC and OSA and solve the problem of flocculation caused by the rapid formation of ionic bonds, which provided an extended time for the Schiff base self-cross-linked reaction for forming a homogeneous hydrogel. Interestingly, the shortest time for the formation of the HACC/OSA hydrogel was within 74 s and the hydrogel had a uniform porous structure and enhanced mechanical properties. The HACC/OSA hydrogel withstood large compression deformation due to improved elasticity. What's more, this hydrogel possessed favorable swelling property, biodegradation, and water retention. The HACC/OSA hydrogels have great antibacterial properties against Staphylococcus aureus and Escherichia coli and demonstrated good cytocompatibility as well. The HACC/OSA hydrogels have a good sustained release effect on rhodamine (model drug). Thus, the obtained self-cross-linked HACC/OSA hydrogels in this study have potential applications in the field of biomedical carriers.

Inhibition of Staphylococcus aureus biofilms by poly-L-aspartic acid nanoparticles loaded with Litsea cubeba essential oil

Staphylococcus aureus (S. aureus) biofilms contamination on various food-contacting surfaces is considered a significant threat in the field of food. Poly-L-aspartic acid (PASP) was proven to damage biofilm by affecting bacterial adhesion, metabolic activity, and extracellular polymeric substances in this study. Especially for eDNA, its generation was reduced by 49.4 %. After treatment with 5 mg/mL of PASP, the number of S. aureus in the biofilm at different growth stages decreased by 1.20–1.68 log CFU/mL. The nanoparticles prepared by PASP and hydroxypropyl trimethyl ammonium chloride chitosan were used to embed LC-EO (EO@PASP/HACCNPs). The results indicated that the particle size of the optimized nanoparticles was 209.84 nm with an encapsulation rate of 70.28 %. Compared to LC-EO alone, EO@PASP/HACCNPs had more significant permeation and dispersion effects on biofilms and possessed long-lasting anti-biofilm activity. For the biofilm grown for 72 h, the population of S. aureus in the EO@PASP/HACCNPs-treated biofilm was additionally reduced by 0.63 log CFU/mL compared with the LC-EO-treated group. EO@PASP/HACCNPs were also applied to different food-contacting materials. The lowest inhibition rate of EO@PASP/HACCNPs on S. aureus biofilm still reached 97.35 %. The sensory properties of the chicken breast were not affected by EO@PASP/HACCNPs.

Adjuvanted quaternized chitosan composite aluminum nanoparticles-based vaccine formulation promotes immune responses in chickens.

Aluminum adjuvant is a typical adjuvant that can promote humoral immune response, but it lacks the ability to effectively induce cellular immune response. The water-soluble N-2-Hydroxypropyl trimethyl ammonium chloride chitosan nanoparticles (N-2-HACC NPs) can enhance humoral and cellular immune responses of vaccines. To enable aluminum adjuvant to induce cellular immunity, the composite nano adjuvant N-2-HACC-Al NPs were synthesized by the N-2-HACC and aluminum sulfate (Al2(SO4)3). The particle size and zeta potential of the N-2-HACC-Al NPs were 300.70±24.90nm and 32.28±0.52mV, respectively. The N-2-HACC-Al NPs have good thermal stability and biodegradability and lower cytotoxicity. In addition, to investigate the immunogenicity of the composite nano adjuvant, the combined inactivated vaccine against Newcastle disease (ND) and H9N2 avian influenza (AI) was prepared with the N-2-HACC-Al NPs as a vaccine adjuvant. The immune effect of the vaccine (N-2-HACC-Al/NDV-AIV) was evaluated by chicken in vivo immunization. The vaccine induced higher levels of serum IgG, IL-4, and IFN-γ than those of the commercial combined inactivated vaccine against ND and H9N2 AI. The levels of IFN-γ were more than twice those of the commercial vaccine at 7days post the immunization. The N-2-HACC-Al NPs could be used as an efficient nano adjuvant to enhance the effectiveness of vaccine and have immense application potential.

Palmitic acid- and cysteine-functionalized nanoparticles overcome mucus and epithelial barrier for oral delivery of drug.

Nanoparticles (NPs) used for oral administration have greatly improved drug bioavailability and therapeutic efficacy. Nevertheless, NPs are limited by biological barriers, such as gastrointestinal degradation, mucus barrier, and epithelial barrier. To solve these problems, we developed the PA-N-2-HACC-Cys NPs loaded with anti-inflammatory hydrophobic drug curcumin (CUR) (CUR@PA-N-2-HACC-Cys NPs) by self-assembled amphiphilic polymer, composed of the N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC), hydrophobic palmitic acid (PA), and cysteine (Cys). After oral administration, the CUR@PA-N-2-HACC-Cys NPs had good stability and sustained release under gastrointestinal conditions, followed by adhering to the intestine to achieve drug mucosal delivery. Additionally, the NPs could penetrate mucus and epithelial barriers to promote cellular uptake. The CUR@PA-N-2-HACC-Cys NPs could open tight junctions between cells for transepithelial transport while striking a balance between mucus interaction and diffusion through mucus. Notably, the CUR@PA-N-2-HACC-Cys NPs improved the oral bioavailability of CUR, which remarkably relieved colitis symptoms and promoted mucosal epithelial repair. Our findings proved that the CUR@PA-N-2-HACC-Cys NPs had excellent biocompatibility, could overcome mucus and epithelial barriers, and had significant application prospects for oral delivery of the hydrophobic drugs.

Chitosan modification and its synergism with clay to mitigate harmful algal blooms

Chitosan is a natural and eco-friendly material, often used as a flocculant in water purification; however, due to the influences of high salinity and pH, the application of chitosan in seawater has been greatly limited. In this paper, a modified chitosan (3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CTA) chitosan, denoted as CTC) was prepared by chemical modification. This greatly increased the solubility of chitosan both in deionized water and seawater, and solved the technical difficulty of applying chitosan in seawater. The structure of CTC and its solubilization on chitosan in seawater were analyzed by Zeta potential, FTIR, 13C NMR, XRD and SEM. On this basis, CTC modified clay (CTCMC) was further prepared based on the principle of mitigating harmful algal blooms with modified clay. At a CTCMC dosage of 20 mg/L, the removal efficiency of Prorocentrum donghaiense was approximately 80%, while the dosage of traditional modified clay (MCI) was 200 mg/L for the same removal efficiency. The dosage was nearly an order of magnitude less than that of the MCI, suggesting that the novel CTCMC is promising in the mitigation of harmful algal blooms. Further, the flocculation mechanism was determined based upon surface properties, and mechanical and flocculation characteristics.

Protective Effect of Composite Hydrogel Based on Hydroxypropyl Trimethylammonium Chloride Chitosan on Skin Photodamage

Long-term or excessive exposure to UV light can lead to sunburn, erythema, melanin deposition, inflammation, and even skin cancer. This study used composite hydrogels with N-2-hydroxypropyl trimethylammonium chloride chitosan (N-2-HACC) and hyaluronic acid (HA) as carriers. In addition, ellagic acid (EA) and proanthocyanidins (PC) as functionalized materials were prepared. The infrared results show that the N-2-HACC/HA/EA/PC hydrogel is formed by N-2-HACC connecting with HA by electrostatic interaction, and HA forms hydrogen bonds between EA and PC. The in vitro antioxidant results show that EA and PC have different clearance efficiency of DPPH and superoxide anion radicals at different pH values. Thus, they have complementary effects on antioxidant properties. The cumulative release results demonstrate that the hydrogels had an excellent slow-release rate at different pHs. The animal experiments reveal that N-2-HACC/HA/EA/PC could restore the consumption of antioxidant enzymes induced by UVB irradiation and inhibit matrix metalloproteinase 1. N-2-HACC/HA/EA/PC can inhibit UVB-induced histological damage, such as epidermal thickening, collagen fiber, and elastic fiber destruction. N-2-HACC/HA/EA/PC has a significant photoprotective effect by protecting the activities of superoxide dismutase, catalase, and glutathione peroxidase and inhibiting the activity of inflammatory factors. N-2-HACC/HA/EA/PC composite hydrogel system shows comprehensive performance. Its ability to scavenge free radicals may act as an antioxidant to protect mice from skin cancer.

An injectable, self-healing composite hydrogel with enhanced near-infrared photo-antibacterial therapeutic effects for accelerated wound healing

Antibacterial hydrogels with injectable and self-healing properties have attracted much attention in the field of wound dressings because they not only can prevent bacterial infections, but also meet the basic needs for wound healing. However, how to achieve high antibacterial efficacy and low drug resistance for hydrogels is still a challenge. Herein, an injectable, self-healing, near-infrared (NIR) photosensitive antibacterial hydrogel composed of CuS-grafted-curcumin (CuS@C) and carboxymethyl cellulose modified with aldehyde groups and hydroxypropyl trimethyl ammonium chloride chitosan is prepared for wound dressings. The p-n junction formed between curcumin and CuS promotes separation of electron-hole pairs, enhances the mobility of photogenerated charges, and destroys the conjugated structure of curcumin simultaneously consequently increasing the photocatalytic activity. CuS@C is immobilized and distributed uniformly in the hydrogel via the π-π conjugation ring. The hybrid hydrogel exhibits excellent antibacterial activity after irradiation with 808 NIR light for 10 min due to the enhanced photodynamic and photothermal antibacterial effects. In addition, the hybrid structure improves the biocompatibility of CuS and expedites infected-wound healing at a mild temperature of 45 ℃. This organic/inorganic hybrid is shown to be an excellent wound dressing for the treatment of bacterial-infected wounds.

N‐2‐hydroxypropyl trimethyl ammonium chloride chitosan‐glycerol complex temperature‐sensitive hydrogel for wound dressing

AbstractWith the development of the times, it becomes difficult or even impossible for traditional wound dressings to meet people's needs for high‐quality wound repair and management. Therefore, there is an urgent need for new biomedical dressings that can accelerate wound healing in clinical practice. In this study, N‐2‐hydroxypropyl trimethylammonium chloride chitosan (N‐2‐HACC), a derivative of chitosan, was used as raw material to sprepare N‐2‐HACC temperature sensitive hydrogel. The structure, thermal stability and water content of N‐2‐HACC temperature sensitive hydrogel were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. The safety of N‐2‐HACC temperature sensitive hydrogel was evaluated by in vitro cell assay and in vitro degradation assay, and the effect of N‐2‐HACC temperature sensitive hydrogel on wound healing was evaluated by wound healing experiment in SD rats. The results show that N‐2‐HACC hydrogel, as a wound dressing, has the characteristics of good biocompatibility, good biodegradation, non‐toxic, anti‐inflammatory and so on. It plays a barrier role in the process of wound healing, provides a moist environment for the wound and accelerates wound healing. Therefore, N‐2‐HACC hydrogel has a broad application prospect in promoting wound healing as a wound dressing.

Amoxicillin encapsulated in the N-2-hydroxypropyl trimethyl ammonium chloride chitosan and N,O-carboxymethyl chitosan nanoparticles: Preparation, characterization, and antibacterial activity

This is a report on the encapsulation amoxicillin (AMX) in the N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC) and N,O-carboxymethyl chitosan (CMCS) nanoparticles (NPs) for biomedical applications. The N-2-HACC/CMCS NPs have broad-spectrum antibacterial properties. In order to achieve sustained and slow drug release, improve drug transport efficiency and bioavailability, prolong drug residence time, and reduce pollution, we synthesized highly efficient, easily absorbed and rapidly degradable nano-formulation veterinary antibiotics in this study. The N-2-HACC/CMCS NPs were used for the encapsulation of AMX, and the cytocompatibility, in vitro release, in vivo drug release kinetics and antimicrobial activity of N-2-HACC/CMCS/AMX NPs were investigated. The NPs displayed a round shape and smooth surface, and the NPs allowed the sustained release of AMX at a much slower rate than that of non-coated AMX. The NPs exhibited excellent cytocompatibility and the antimicrobial activity against Escherichia coli, Acinetobacter baumannii, Streptococcus pneumoniae and Staphylococcus aureus. Moreover, the NPs could store at 4 °C, −20 °C and 25 ± 5 °C for 30 d. These results suggested that the N-2-HACC/CMCS NPs could be availed as a candidate for drug delivery carrier to achieve sustained and slow release, improve bioavailability, prolong residence time at the target site, and reduce the dosage of drug.

Tannic acid/polyvinyl alcohol/2-hydroxypropyl trimethyl ammonium chloride chitosan double-network hydrogel with adhesive, antibacterial and biocompatible properties

Hydrogels have great potential for biomedical applications. However, there are still significant challenges in preparing biomass-based hydrogels with excellent adhesive, antibacterial and biocompatible properties. In this study, pure physically cross-linked tannic acid (TA)/polyvinyl alcohol (PVA)/2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) double-network (PVA/HACC-TA) hydrogels are prepared by a combination approach of cyclic freeze-thaw and soaking method. The prepared PVA/HACC-TA hydrogels are formed by hydrogen bond cross-linking and do not use any toxic and harmful cross-linking agents. Meanwhile, the prepared PVA/HACC-TA hydrogels have excellent mechanical properties, the maximum tensile strength can reach 4.13 MPa and the maximum tensile strain can attain 830%. In addition, PVA/HACC-TA hydrogels display good adhesion to different materials. At the same time, the PVA/HACC-TA hydrogels also show favorable antibacterial activities. Therefore, the excellent mechanical, adhesive, antibacterial and cytocompatible biomass hydrogels showed promising potential applications in the biomedicine field, especially as the skin wound dressings.

Rhodojaponin III-Loaded Chitosan Derivatives-Modified Solid Lipid Nanoparticles for Multimodal Antinociceptive Effects in vivo.

BackgroundRhodojaponin III (RJ-III) is a bioactive diterpenoid, which is mainly found in Rhododendron molle G. Don (Ericaceae), a potent analgesia in traditional Chinese medicine with several years of clinical applications in the country. However, its clinical use is limited by its acute toxicity and poor pharmacokinetic profiles. To reduce such limitations, the current study incorporated RJ-III into the colloidal drug delivery system of hydroxypropyl trimethyl ammonium chloride chitosan (HACC)-modified solid lipid nanoparticles (SLNs) to improve its sustained release and antinociceptive effects in vivo for oral delivery.ResultsThe optimized RJ-III@HACC-SLNs were close to spherical, approximately 134 nm in size, and with a positive zeta potential. In vitro experiments showed that RJ-III@HACC-SLNs were stable in the simulated gastric fluid and had a prolonged release in PBS (pH = 6.8). Pharmacokinetic results showed that after intragastric administration in mice, the relative bioavailability of RJ-III@HACC-SLNs was 87.9%. Further, it was evident that the peak time, half-time, and mean retention time of RJ-III@HACC-SLNs were improved than RJ-III after the administration. In addition, pharmacodynamic studies revealed that RJ-III@HACC-SLNs markedly reduced the acetic acid, hot, and formalin-induced nociceptive responses in mice (P < 0.001), and notably increased the analgesic time (P < 0.01). Moreover, RJ-III@HACC-SLNs not only showed good biocompatibility with Caco-2 cells in vitro but its LD50 value was also increased by 1.8-fold as compared with that of RJ-III in vivo.ConclusionThese results demonstrated that RJ-III@HACC-SLNs improved the pharmacokinetic characteristics of the RJ-III, thereby exhibiting toxicity-attenuating potential and antinociceptive enhancing properties. Consequently, HACC-SLNs loaded with RJ-III could become a promising oral formulation for pain management that deserves further investigation in the future.

Structural characteristics and rheological properties of hydroxypropyl trimethyl ammonium chloride chitosan

Hydroxypropyl trimethyl ammonium chloride chitosan (HACC) was synthesized by reacting chitosan with glycidyl trimethylammonium chloride. Atomic force microscopy showed that HACC exhibited disorderly coils in dilute solution and formed a three-dimensional network. Flow, thixotropy, and dynamic viscoelasticity tests were conducted using an MCR301 rheometer. The HACC solution was a non-Newtonian pseudoplastic fluid, and the shear behavior of different concentrations (2–6 %, w/v) was evaluated by the Williamson model fitting. Furthermore, the thixotropy was highly dependent on concentration changes: the high-concentration solution structure was difficult to recover in a short time. The dynamic viscoelasticity test indicated that the viscoelasticity of the HACC solution not only exhibited a viscous behavior similar to that of a fluid, but also exhibited elastic properties of weak gel. HACC exhibited high-strength solid-like gel characteristics at high temperature.