Synthesis and characterization of water-soluble chitosan grafted with hydrophilic aliphatic polyester

A novel water-soluble chitosan grafted with nerol: Synthesis, characterization and biological activity

In order to improve the antibacterial activity of chitosan and change its solubility, a novel water-soluble chitosan (CS)-nerol (N) derivative (CS-N) was prepared via Schiff base reaction and grafting reaction. FT-IR, NMR, XRD, TGA and SEM were used to characterize the structure and physicochemical properties, and in vitro antibacterial, antioxidant, and cellular assays were used to test for bioactivity and safety. The results revealed that the C6 hydroxyl group of CS was substituted with N, with a degree of substitution of 38 % for CS-N. Furthermore, compared to CS, CS-N demonstrated superior antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as significant DPPH and ABTS free radical scavenging activity. Most importantly, CS-N did not harm HaCaT cells. In conclusion, this study provides a promising strategy for the design of chitosan derivatives with significant potential for application in pharmaceutical, food and cosmetic applications.

Chitosan grafted/cross-linked with biodegradable polymers: A review

Public perception of polymers has been drastically changed with the improved plastic management at the end of their life. However, it is widely recognised the need of developing biodegradable polymers, as an alternative to traditional petrochemical polymers. Chitosan (CH), a biodegradable biopolymer with excellent physiological and structural properties, together with its immunostimulatory and antibacterial activity, is a good candidate to replace other polymers, mainly in biomedical applications. However, CH has also several drawbacks, which can be solved by chemical modifications to improve some of its characteristics such as solubility, biological activity, and mechanical properties. Many chemical modifications have been studied in the last decade to improve the properties of CH. This review focussed on a critical analysis of the state of the art of chemical modifications by cross-linking and graft polymerization, between CH or CH derivatives and other biodegradable polymers (polysaccharides or proteins, obtained from microorganisms, synthetized from biomonomers, or from petrochemical products). Both techniques offer the option of including a wide variety of functional groups into the CH chain. Thus, enhanced and new properties can be obtained in accordance with the requirements for different applications, such as the release of drugs, the improvement of antimicrobial properties of fabrics, the removal of dyes, or as scaffolds to develop bone tissues.

Solid-State Synthesis of Water-Soluble Chitosan-g-Hydroxyethyl Cellulose Copolymers

Graft copolymers of chitosan with cellulose ether have been obtained by the solid-state reactive mixing of chitin, sodium hydroxide and hydroxyethyl cellulose under shear deformation in a pilot twin-screw extruder. The structure and composition of the products were determined by elemental analysis and IR spectroscopy. The physicochemical properties of aqueous solutions of copolymers were studied as a function of the composition, and were correlated to the mechanical characteristics of the resulting films to assess the performance of new copolymers as coating materials, non-woven fibrous materials or emulsifiers for interface stabilization during the microparticle fabrication process.

Self-assembled nanoparticles for cellular delivery of peptide nucleic acid using amphiphilic N,N,N-trimethyl-O-alkyl chitosan derivatives

Peptide nucleic acid (PNA) holds enormous potentials as antisense/antigenic drug due to its specific binding ability and biostability with DNA or RNA. However, the poor cellular delivery is the key obstacle in development of PNA therapy. To overcome this difficulty, we developed self-assembled nanoparticles (NPs) for delivery of PNA to living cells using amphiphilic CS derivatives. A series of N,N,N-trimethyl-O-alkyl chitosans (TMACs) with different lengths of alkyl chains were synthesized. The structures of these synthesized chemicals were characterized with FT-IR and ¹H NMR. We found that the TMACs were all able to self-assemble in aqueous condition to form nano-size NPs. These nano-size NPs are spherical shape with a size range of around 100 nm and a zeta potential above +30 mV. PNA was easily encapsulated into chitosan derivative NPs by an ultrasonic method with entrapment efficiency up to 75%. The PNA-loaded TMAC NPs released the drug in a sustained manner in PBS (pH 7.4) at 37 °C. N,N,N-trimethyl-O-cetyl chitosan (TMCC) showed the best in vitro hemocompatibility and cell viability. These TMCC based NPs were able to dramatically increase the cellular uptake of PNA, specifically, 66-fold higher compared to without using these nanoparticles. The results suggest that the designed TMCC NPs might be a promising solution for improving cellular delivery of PNA.

Fabrication and Characterization of Polyphosphazene/Calcium Phosphate Scaffolds Containing Chitosan Microspheres for Sustained Release of Bone Morphogenetic Protein 2 in Bone Tissue Engineering

Bone morphogenetic protein 2 has a major role in promoting bone regeneration in tissue engineering scaffolds. Growth factor release rate is a remaining crucial problem in these systems. The aim of this study was to fabricate and characterize a novel calcium phosphate/polyphosphazenes porous scaffold for the sustained release of bone morphogenetic protein 2 in bone tissue engineering. Polyphosphazenes were substituted with 2-dimethylaminoethanol and evaluated by GPC, NMR, and in vitro degradation. Calcium phosphate porous samples were prepared from hydroxyapatite nanoparticles and naphthalene using the sintering method at 1250 °C before being composited with poly(dimethylaminoethanol)phosphazenes containing chitosan microspheres loaded with bone morphogenetic protein 2. The characteristics and biodegradability of the product were evaluated by SEM, XRD, and in vitro degradation. Moreover, the release rate and mechanical properties of the scaffolds were investigated. The release behavior was found to be sustained since the scaffolds had been fabricated from polyphosphazenes with a low degradation rate. The release rates of the scaffolds were observed to increase with increasing chitosan microspheres content from 10 to 30%. The bioactivity of the scaffolds depended on the release rate of growth factor while bone morphogenetic protein 2 was able to induce an osteoblast proliferation. The results of cell adhesion and cell viability tests showed that scaffolds displayed a non-toxic behavior and western blot analyses confirmed that the scaffolds loaded with growth factor increased the osteogenic differentiation potential of cells when compared with scaffolds alone. These results demonstrate that these scaffolds can be successfully utilized in bone tissue engineering.

Hydrophilic Finishing of Polyester Fiber with Finishing Agents Based on Poly(γ-glutamic acid)

The work is aimed to investigate the suitability of poly (γ-glutamic acid) (γ-PGA) for the hydrophilic finishing of polyester fiber. γ-PGA hydrogel was successfully synthesized by a simple mixture process in the aqueous solution. A novel hydrophilic finishing agent was prepared by γ-PGA hydrogel. The rheology behavior study indicated that γ-PGA solution and hydrophilic finishing agent performed pseudoplastic fluid and approximately Newtonian behavior, respectively. The particle diameter determined that particles in hydrophilic finishing agent reached micro-nanograde. Furthermore, polyester fiber was treated with γ-PGA solution and hydrophilic finishing agent. Moisture regain was evaluated as a key performance, results shown the hydrophilicity of polyester fiber was greatly enhanced by γ-PGA finishing.