Development of novel pH-sensitive thiolated chitosan/PMLA nanoparticles for amoxicillin delivery to treat Helicobacter pylori

Ureido-modified carboxymethyl chitosan-graft-stearic acid polymeric nano-micelles as a targeted delivering carrier of clarithromycin for Helicobacter pylori: Preparation and in vitro evaluation

The effect of antibiotics in the stomach for curing Helicobacter pylori infection is hampered by the adverse gastric environment and low bioavailability of the administered drugs. Concerning these challenges, a polymeric nano-micelle was developed. Initially, carboxymethyl chitosan (CMCS) was hydrophobically modified with stearic acid (SA), and the obtained CMCS-g-SA co-polymers was further conjugated with urea to acquire U-CMCS-g-SA co-polymers. Sphere-shaped nano-micelles (UCS-NMs) with the particle sizes of approximately 200nm were obtained with the U-CMCS-g-SA co-polymers. It was specified that this nano-micelle had no cell toxicity to AGS cells, and it could maintain a stable particle size for 6h in simulated gastric fluid and for 24h in 1×PBS. Attractively, the CMCS backbones granted this nano-micelle an excellent retention time in the stomach, almost 24h; meanwhile, the grafted ureido groups conferred effective targeting to H. pylori. This nano-micelle could load clarithromycin with high efficiency and exhibited slow release of this antibiotic in a slightly alkaline environment. In vitro inhibitory assay also indicated that a significantly enhanced anti-H. pylori activity was achieved by using this nano-micelle. This work demonstrated that the U-CMCS-g-SA nano-micelle is a proper carrier for targeted delivery of clarithromycin to H. pylori under the gastric mucus layer.

Delivering amoxicillin at the infection site - a rational design through lipid nanoparticles

Purpose

Amoxicillin is a commonly used antibiotic, although degraded by the acidic pH of the stomach. This is an important limitation for the treatment of Helicobacter pylori infections. The purpose of this work was to encapsulate amoxicillin in lipid nanoparticles, increasing the retention time at the site of infection (gastric mucosa), while protecting the drug from the harsh conditions of the stomach lumen.

Materials and methods

The nanoparticles were produced by the double emulsion technique and optimized by a three-level Box-Behnken design. Tween 80 and linolenic acid were used as potential therapeutic adjuvants and dioleoylphosphatidylethanolamine as a targeting agent to Helicobacter pylori. Nanoparticles were characterized regarding their physico-chemical features, their storage stability, and their usability for oral administration (assessment of in vitro release, in vitro cell viability, permeability, and interaction with mucins).

Results

The nanoparticles were stable for at least 6 months at 4°C. In vitro release studies revealed a high resistance to harsh conditions, including acidic pH and physiologic temperature. The nanoparticles have a low cytotoxicity effect in both fibroblasts and gastric cell lines, and they have the potential to be retained at the gastric mucosa.

Conclusion

Overall, the designed formulations present suitable physico-chemical features for being henceforward used by oral administration to treat Helicobacter pylori infections.

Unveiling the potentials of biocompatible silver nanoparticles on human lung carcinoma A549 cells and Helicobacter pylori

Silver nanoparticles (AgNPs) are gaining importance in health and environment. This study synthesized AgNPs using the bark extract of a plant, Toxicodendron vernicifluum (Tv) as confirmed by a absorption peak at 420 nm corresponding to the Plasmon resonance of AgNPs. The AgNPs were spherical, oval-shaped with size range of 2–40 nm as evident by field emission transmission electron microscopy (FE-TEM) and particle size analysis (PSA). The particles formed were crystalline by the presence of (111), (220) and (200) planes, as revealed by X ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The presence of amine, amide, phenolic, and alcoholic aromatics derived from Tv extract was found to be capping and or reducing agents as evident by Fourier-transform infrared spectroscopy (FTIR) spectra. The Tv-AgNPs were observed to be biocompatible to chick embryonic and NIH3T3 cells at various concentrations. Interestingly, Tv-AgNPs at the concentration of 320 µg. mL⁻¹ induced 82.5% of cell death in human lung cancer, A549 cells and further 95% of cell death with annexin V FITC/PI based apoptosis. The Tv-AgNPs selectively targeted and damaged the cancer cells through ROS generation. The Tv-AgNPs displayed minimal inhibitory concentration (MIC) of 8.12 µg.mL⁻¹ and 18.14 µg.mL⁻¹ against STEC and H. pylori respectively. This multi-potent property of Tv-AgNPs was due to shape and size specific property that facilitated easy penetration into the bacterial and cancer cells for targeted therapy.

Brazilian red propolis reduces orange-complex periodontopathogens growing in multispecies biofilms

This study investigated the antimicrobial effects of the ethanolic extract of Brazilian red propolis (BRP) on multispecies biofilms. A seven-day-old subgingival biofilm with 32 species was grown in a Calgary device. Biofilms were treated with BRP (1,600, 800, 400 and 200 μg ml^-1) twice a day for 1 min, starting from day 3. Chlorhexidine (0.12%) and dilution-vehicle were used as positive and negative controls, respectively. On day 7, metabolic activity and the microbial composition of the biofilms by DNA-DNA hybridization were determined. The viability data were analyzed by one-way ANOVA followed by Tukey's post hoc, whereas the microbial composition data were transformed via BOX-COX and analyzed using Dunnett's post hoc. BRP (1,600 μg ml^-1) decreased biofilm metabolic activity by 45%, with no significant difference from chlorhexidine-treated samples. BRP (1,600 μg ml^-1) and chlorhexidine significantly reduced levels of 14 bacterial species compared to the vehicle control. Taken together, BRP showed promising antimicrobial properties which may be useful in periodontal disease control.

Pharmaceutical applications of chitosan

Chitosan (CS) is a linear polysaccharide which is achieved by deacetylation of chitin, which is the second most plentiful compound in nature, after cellulose. It is a linear copolymer of β-(1 → 4)-linked 2-acetamido-2-deoxy-β-d-glucopyranose and 2-amino-2-deoxy-β-d-glucopyranose. It has appreciated properties such as biocompatibility, biodegradability, hydrophilicity, nontoxicity, high bioavailability, simplicity of modification, favorable permselectivity of water, outstanding chemical resistance, capability to form films, gels, nanoparticles, microparticles and beads as well as affinity to metals, proteins and dyes. Also, the biodegradable CS is broken down in the human body to safe compounds (amino sugars) which are easily absorbed. At present, CS and its derivatives are broadly investigated in numerous pharmaceutical and medical applications including drug/gene delivery, wound dressings, implants, contact lenses, tissue engineering and cell encapsulation. Besides, CS has several OH and NH₂ functional groups which allow protein binding. CS with a deacetylation degree of ~50% is soluble in aqueous acidic environment. While CS is dissolved in acidic medium, its amino groups in the polymeric chains are protonated and it becomes cationic which allows its strong interaction with different kinds of molecules. It is believed that this positive charge is responsible for the antimicrobial activity of CS through the interaction with the negatively charged cell membranes of microorganisms. This review presents properties and numerous applications of chitosan-based compounds in drug delivery, gene delivery, cell encapsulation, protein binding, tissue engineering, preparation of implants and contact lenses, wound healing, bioimaging, antimicrobial food additives, antibacterial food packaging materials and antibacterial textiles. Moreover, some recent molecular dynamics simulations accomplished on the pharmaceutical applications of chitosan were presented.

Morphological, Release and Antibacterial Performances of Amoxicillin-Loaded Cellulose Aerogels

Cellulose has been widely used in the biomedical field. In this study, novel cellulose aerogels were firstly prepared in a NaOH-based solvent system by a facile casting method. Then amoxicillin was successfully loaded into cellulose aerogels with different loadings. The morphology and structure of the cellulose aerogels were characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The drug release and antibacterial activities were also evaluated. The drug release results showed that cellulose aerogels have controlled amoxicillin release performance. In vitro antibacterial assay demonstrated that the cellulose aerogels exhibited excellent antibacterial activity with the amoxicillin dose-dependent activity. Therefore, the developed cellulose aerogels display controlled release behavior and efficient antibacterial performance, thus confirming their potential for biomedical applications.

Anti-Helicobacterpylori effectiveness and targeted delivery performance of amoxicillin-UCCs-2/TPP nanoparticles based on ureido-modified chitosan derivative

The amoxicillin-UCCs-2/TPP nanoparticles constructed with ureido-modified chitosan derivative UCCs-2 and sodium tripolyphosphate (TPP) played an important role to deliver drug to achieve more efficacious and specific eradication of Helicobacterpylori (H. pylori) in vitro. In this study, the anti-H. pylori effectiveness in vivo and uptake mechanism was investigated in details, including the effect of temperature, pH values and the addition of competitive substrate urea on uptake. Compared with unmodified nanoparticles, a more efficacious and specific anti-H. pylori activities were obtained in vivo by using this biological chitosan derivative UCCs-2. Histological staining and immunological analysis verified that the amoxicillin-UCCs-2/TPP nanoparticles could diminish the proinflammatory cytokines levels and alleviate the inflammatory damages caused by H. pylori infection. The uredio-modified nanoparticles also have favorable gastric retention property, which is beneficial for the oral drug delivery to targeted eradicate H. pylori infection in stomach. These findings suggest that this targeted drug delivery system may serve for specific treatment of H. pylori infection both in vitro and in vivo, which can also be used as promising nanocarriers for other therapeutic reagents to target H. pylori.