Preparation and Characterization of Chitosan-Based Nanoparticles as Protein Delivery System

Bioactive-Loaded Hydrogels Based on Bacterial Nanocellulose, Chitosan, and Poloxamer for Rebalancing Vaginal Microbiota

Biocompatible drug-delivery systems for soft tissue applications are of high interest for the medical and pharmaceutical fields. The subject of this research is the development of hydrogels loaded with bioactive compounds (inulin, thyme essential oil, hydro-glycero-alcoholic extract of Vitis vinifera, Opuntia ficus-indica powder, lactic acid, citric acid) in order to support the vaginal microbiota homeostasis. The nanofibrillar phyto-hydrogel systems developed using the biocompatible polymers chitosan (CS), never-dried bacterial nanocellulose (NDBNC), and Poloxamer 407 (PX) incorporated the water-soluble bioactive components in the NDBNC hydrophilic fraction and the hydrophobic components in the hydrophobic core of the PX fraction. Two NDBNC-PX hydrogels and one NDBNC-PX-CS hydrogel were structurally and physical-chemically characterized using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and rheology. The hydrogels were also evaluated in terms of thermo-responsive properties, mucoadhesion, biocompatibility, and prebiotic and antimicrobial effects. The mucin binding efficiency of hydrogel base systems was determined by the periodic acid/Schiff base (PAS) assay. Biocompatibility of hydrogel systems was determined by the MTT test using mouse fibroblasts. The prebiotic activity was determined using the probiotic strains Limosilactobacillus reuteri and Lactiplantibacillus plantarum subsp. plantarum. Antimicrobial activity was also assessed using relevant microbial strains, respectively, E. coli and C. albicans. TEM evidenced PX micelles of around 20 nm on NDBNC nanofibrils. The FTIR and XRD analyses revealed that the binary hydrogels are dominated by PX signals, and that the ternary hydrogel is dominated by CS, with additional particular fingerprints for the biocompounds and the hydrogel interaction with mucin. Rheology evidenced the gel transition temperatures of 18-22 °C for the binary hydrogels with thixotropic behavior and, respectively, no gel transition, with rheopectic behavior for the ternary hydrogel. The adhesion energies of the binary and ternary hydrogels were evaluated to be around 1.2 J/m2 and 9.1 J/m2, respectively. The hydrogels exhibited a high degree of biocompatibility, with the potential to support cell proliferation and also to promote the growth of lactobacilli. The hydrogel systems also presented significant antimicrobial and antibiofilm activity.

Characterisation of products from EDC-mediated PEG substitution of chitosan allows optimisation of reaction conditions

PEGylation is a common method use to modify the physiochemical properties and increase the solubility of chitosan (CHI). Knowledge of optimal reaction conditions for PEGylation of CHI underpins its ongoing use in nanomedicine. This study synthesised methoxy polyethylene glycol grafted CHI (mPEG-CHI) using carbodiimide-mediated coupling. The effect of reagent concentrations and pH on the degree of substitution (DS) and the PEGylation yield (conversion of free PEG to conjugated PEG) was evaluated through detailed chemical characterisation. Within the parameter space investigated, optimised reaction conditions (NH₂: COOH:NHS:EDC of 3.5:1:1:10, pH = 5) resulted in a DS of 24 % and a PEGylation yield of 84 %. An EDC-derived adduct formed at pH ≥ 5.5 and a at 15-fold excess of EDC relative to COOH. The adduct was evaluated to be a guanidine derivative formed by the reaction of the amine group of CHI directly with EDC. DS ≥ 12 imparted water solubility to CHI at physiological pH and mPEG-CHI (0.2-1.0 mg/mL) was not cytotoxic against the breast cancer cell lines MCF-7 and MDA-MB-231, indicating its suitability for medical applications.

Synthesis of Eudragit® L100-coated chitosan-based nanoparticles for oral enoxaparin delivery

Enoxaparin is an effective biological molecule for prevention and treatment of coagulation disorders. However, it is poorly absorbed in the gastrointestinal tract. In this study, we developed an Eudragit® L100 coated chitosan core shell nanoparticles for enoxaparin oral delivery (Eud/CS/Enox NPs) through a completely eco-friendly method without employing any high-energy homogenizer technique and any organic solvents. Spherical nanocarriers were successfully prepared with particle size lower than 300 nm, polydispersity index about 0.12 and zeta potential higher than +25 mV, entrapment efficiency greater than 95% and the in vitro release behavior confirms the good colloidal stability and the successful Eudragit® L100 coating process demonstrated by negligible cumulative enoxaparin release (<10%) when the particles are submitted to simulated gastric fluid conditions. Finally, we demonstrated that the core-shell structure of the particle influenced the drug release mechanism of the formulations, indicating the presence of the Eudragit® L100 on the surface of the particles. These results suggested that enteric-coating approach and drug delivery nanotechnology can be successfully explored as potential tools for oral delivery of enoxaparin.

Emergence of Polymeric Material Utilising Sustainable Radiation Curable Palm Oil-Based Products for Advanced Technology Applications

In countries that are rich with oil palm, the use of palm oil to produce bio-based acrylates and polyol can be the most eminent raw materials used for developing new and advanced natural polymeric materials involving radiation technique, like coating resins, nanoparticles, scaffold, nanocomposites, and lithography for different branches of the industry. The presence of hydrocarbon chains, carbon double bonds, and ester bonds in palm oil allows it to open up the possibility of fine-tuning its unique structures in the development of novel materials. Cross-linking, reversible addition-fragmentation chain transfer (RAFT), polymerization, grafting, and degradation are among the radiation mechanisms triggered by gamma, electron beam, ultraviolet, or laser irradiation sources. These radiation techniques are widely used in the development of polymeric materials because they are considered as the most versatile, inexpensive, easy, and effective methods. Therefore, this review summarized and emphasized on several recent studies that have reported on emerging radiation processing technologies for the production of radiation curable palm oil-based polymeric materials with a promising future in certain industries and biomedical applications. This review also discusses the rich potential of biopolymeric materials for advanced technology applications.

Biodegradable polyelectrolyte complexes of chitosan and partially crosslinked dextran phosphate with potential for biomedical applications

Polyelectrolyte complexes (PECs) are spontaneously formed by mixing oppositely charged polyelectrolyte solutions without the use of organic solvents and chemical crosslinkers are great candidate carriers for drug delivery. Herein, biodegradable antimicrobial polyelectrolyte complexes of chitosan - dextran phosphate (DPCS) containing cefazolin were developed and characterized in order to assess their suitability for biomedical applications. For this purpose, the simultaneous partial crosslinking and functionalization of dextran with phosphoric acid in a urea melt under reduced pressure were studied. The functional group content and molecular weight of dextran phosphate were varied in order to establish their influence on gel fraction yield, thermal properties and morphologies of the hydrogels. The stoichiometric PECs of DPCS showed good in vitro biocompatibility, pH sensitivity and biodegradability depending on the hydrogel composition. The release of drug from cefazolin-loaded DPCS hydrogels was through non-Fickian diffusion and displayed long sustained-release time. The drug-loaded hydrogels showed antimicrobial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. The tunable degradation behavior under physiological conditions in combination with biocompatibility of the pristine DPCS and high antibacterial efficacy drug-loaded hydrogels may render the presented materials interesting for biomedical applications.

Comparison and process optimization of PLGA, chitosan and silica nanoparticles for potential oral vaccine delivery

Aim: The study compared performance of nanoparticles prepared from synthetic organic, natural organic and inorganic materials as vaccine delivery platforms. Materials & methods: Various formulation (concentration, polymer/silica:surfactant ratio, solvent) and process parameters (homogenization speed and time, ultrasonication) affecting functional performance characteristics of poly(lactic-co-glycolic acid) (PLGA), chitosan and silica-based nanoparticles containing bovine serum albumin were investigated. Nanoparticles were characterized using dynamic light scattering, x-ray diffraction, scanning/transmission electron microscopy, Fourier transform infrared spectroscopy and in vitro protein release. Results: Critical formulation parameters were surfactant concentration (PLGA, silica) and polymer concentration (chitosan). Optimized nanoparticles were spherical in shape with narrow size distribution and size ranges of 100-300 nm (blank) and 150-400 nm (protein loaded). Protein encapsulation efficiency was 26-75% and released within 48 h in a sustained manner. Conclusion: Critical formulation and process parameters affected size of PLGA, chitosan and silica nanoparticles and protein encapsulation, while silica produced the smallest and most stable nanoparticles.

Multiplatform Protein Detection and Quantification Using Glutaraldehyde-Induced Fluorescence for 3D Systems

Glutaraldehyde (GTA) is a dialdehyde used as biological fixative and its interaction with proteins like bovine serum albumin (BSA) has been well described. Additionally, GTA is known to induce fluorescence when interacting with BSA molecules. In this work, it is developed a new sensitive and reproducible method for BSA quantification using GTA crosslinking to endow fluorescence to BSA molecules. This method can be used with standard lab equipment, providing a low cost, fast-tracking and straightforward approach for BSA quantification. Techniques such as confocal laser scanning microscopy (CLSM) and spectrofluorometry are applied for quantitative assessment, and widefield fluorescence microscopy for qualitative assessment. Qualitative and quantitative correlations between BSA content and GTA-induced fluorescence are verified. BSA concentrations as low as 62.5 μg/mL are detected using CLSM. This method can be highly advantageous for protein quantification in three-dimensional hydrogel systems, specially to evaluate protein loading/release in protein delivery or molecular imprinting systems. Graphical Abstract Preparation and analysis of glutaraldehyde-induced protein-fluorescence in 3D hydrogels. Alginate-methacrylate hydrogels containing varying amounts of bovine serum albumin (BSA) are prepared by photopolymerization and then incubated in glutaraldehyde solutions. Samples observation is performed using confocal laser scanning microscopy, spectrofluorometry and widefield fluorescence microscopy. Data is processed and retrieves a quantitative correlation between protein content and fluorescence levels.

In vitro and in vivo investigation of chitosan–polylysine polymeric nanoparticles for ovalbumin and CpG co-delivery

A simple and powerful vaccine delivery system was developed by electrostatic binding of chitosan-based polycation methoxy poly(ethylene glycol)–chitosan–poly(l-lysine) (mPEG–CS–PLL) with ovalbumin (OVA) and cytosine–phosphate–guanine (CpG).