Chitosan/starch based unoxidized tannic acid modified microparticles for rapid hemostasis with broad spectrum antibacterial activity

The development of a rapid hemostat through a facile method with co-existing antibacterial activity and minimum erythrocyte lysis property stands as a major requirement in the field of hemostasis. Herein, a series of novel microparticle hemostats were synthesized using chitosan, different hydrothermally-treated starches, and cross-linked with tannic acid (TA) simultaneously in an unoxidized environment via ionotropic gelation method. Hemostats' comparative functional properties, such as adjustable antibacterial and erythrocyte compatibility upon various starch additions were evaluated. The in vivo hemostatic study revealed that the developed hemostats for mouse liver laceration and rat tail amputation had clotting times (13 s and 38 s, respectively) and blood loss (51 mg and 62 mg, respectively) similar to those of Celox™. The erythrocyte adhesion test suggested that erythrocyte distortion can be lowered by modifying the antibacterial hemostats with different starches. The broad-spectrum antibacterial efficacy of the hemostats remained intact against S. aureus (>90 %), E. coli (>80 %), and P. mirabilis bacteria upon starch modification. They also demonstrated high hemocompatibility (<3 % hemolysis ratio), moderate cell viability (>81 %), in vivo biodegradation, and angiogenesis indicating adequate biocompatibility and wound healing. The developed hemostats hold significant promise to be employed as rapid hemostatic agents for preventing major bleeding and bacterial infection in emergencies.

Effect of hydrophobic modification of chitin nanocrystals on role as anti-nucleator in the crystallization of poly(ε-caprolactone)/polylactide blend

Biodegradable polymer blends filled with rod-like polysaccharide nanocrystals have attracted much attention because each component in this type of ternary composites is biodegradable, and the final properties are more easily tailored comparing to those of binary composites. In this work, chitin nanocrystals (ChNCs) were used as nanofiller for the biodegradable poly(ε-caprolactone) (PCL)/polylactide (PLA) immiscible blend to prepare ternary composites for a crystallization study. The results revealed that the crystallization behavior of PCL/PLA blend matrices strongly depended on the surface properties of ChNCs. Non-modified ChNCs and modified ChNCs played completely different roles during crystallization of the ternary systems: the former was inert filler, while the latter acted as anti-nucleator to the PCL phase. This alteration was resulted from the improved ChNC-PCL affinity after modification of ChNCs, which was due to the 'interfacial dilution effect' and the preferential dispersion of ChNCs. This work presents a unique perspective on the nucleation role of ChNCs in the crystallization of immiscible PCL/PLA blends, and opens up a new application scenario for ChNCs as anti-nucleator.

Biomimetic Growth of Hydroxyapatite in Hybrid Polycaprolactone/Graphene Oxide Ultra-Porous Scaffolds

This paper reports the preparation and characterization of hybrid scaffolds composed of polycaprolactone (PCL) and different graphene oxide (GO) amounts, intending to incorporate the intrinsic characteristics of their constituents, such as bioactivity and biocidal effect. These materials were fabricated by a solvent-casting/particulate leaching technique showing a bimodal porosity (macro and micro) that was around 90%. The highly interconnected scaffolds were immersed in a simulated body fluid, promoting the growth of a hydroxyapatite (HAp) layer, making them ideal candidates for bone tissue engineering. The growth kinetics of the HAp layer was influenced by the GO content, a remarkable result. Furthermore, as expected, the addition of GO neither significantly improves nor reduces the compressive modulus of PCL scaffolds. The thermal behavior of composites was investigated by differential scanning calorimetry, showing an increase in crystallinity as the addition of GO raised, which implies that GO nanosheets can act as seeds to induce the crystallization of PCL. The improved bioactivity was demonstrated by the deposition of an HAp layer on the surface of the scaffold with GO, especially with a 0.1% GO content.

Polysaccharides for Biodegradable Packaging Materials: Past, Present, and Future (Brief Review)

The ecological problems emerging due to accumulation of non-biodegradable plastics are becoming more and more urgent. This problem can be solved by the development of biodegradable materials which will replace the non-biodegradable ones. Among numerous approaches in this field, there is one proposing the use of polysaccharide-based materials. These polymers are biodegradable, non-toxic, and obtained from renewable resources. This review opens discussion about the application of polysaccharides for the creation of biodegradable packaging materials. There are numerous investigations developing new formulations using cross-linking of polymers, mixing with inorganic (metals, metal oxides, clays) and organic (dyes, essential oils, extracts) compounds. The main emphasis in the present work is made on development of the polymer blends consisting of cellulose, starch, chitin, chitosan, pectin, alginate, carrageenan with some synthetic polymers, polymers of natural origin, and essential oils.

Blood-Vessel-Inspired Hierarchical Trilayer Scaffolds: PCL/Gelatin-Driven Protein Adsorption and Cellular Interaction

Fabrication of scaffolds with hierarchical structures exhibiting the blood vessel topological and biochemical features of the native extracellular matrix that maintain long-term patency remains a major challenge. Within this context, scaffold assembly using biodegradable synthetic polymers (BSPs) via electrospinning had led to soft-tissue-resembling microstructures that allow cell infiltration. However, BSPs fail to exhibit the sufficient surface reactivity, limiting protein adsorption and/or cell adhesion and jeopardizing the overall graft performance. Here, we present a methodology for the fabrication of three-layered polycaprolactone (PCL)-based tubular structures with biochemical cues to improve protein adsorption and cell adhesion. For this purpose, PCL was backbone-oxidized (O-PCL) and cast over a photolithography-manufactured microgrooved mold to obtain a bioactive surface as demonstrated using a protein adsorption assay (BSA), Fourier transform infrared spectroscopy (FTIR) and calorimetric analyses. Then, two layers of PCL:gelatin (75:25 and 95:5 w/w), obtained using a novel single-desolvation method, were electrospun over the casted O-PCL to mimic a vascular wall with a physicochemical gradient to guide cell adhesion. Furthermore, tensile properties were shown to withstand the physiological mechanical stresses and strains. In vitro characterization, using L929 mouse fibroblasts, demonstrated that the multilayered scaffold is a suitable platform for cell infiltration and proliferation from the innermost to the outermost layer as is needed for vascular wall regeneration. Our work holds promise as a strategy for the low-cost manufacture of next-generation polymer-based hierarchical scaffolds with high bioactivity and resemblance of ECM’s microstructure to accurately guide cell attachment and proliferation.

Innovative electrospun PCL/fibroin/l-dopa scaffolds scaffolds supporting bone tissue regeneration

Poly-caprolactone is one of the most promising biocompatible polymers on the market, in particular for temporary devices that are not subjected to high physiological loads. Even if completely resorbable in various biological environments, poly-caprolactione does not play any specific biological role in supporting tissue regeneration and for this reason has a limited range of possible applications. In this preliminary work, for the first time l-dopa and fibroin have been combined with electrospun poly-caprolactone fibers in order to induce bioactive effects and, in particular, stimulate the proliferation, adhesion and osteoconduction of the polymeric fibers. Results showed that addition of low-molecular weight fibroin reduces the mechanical strength of the fibers while promoting the formation of mineralized deposits, when tested in vitro with KUSA-A1 mesenchymal cells. l-dopa, on the other hand, improved the mechanical properties and stimulated the formation of agglomerates of mineralized deposits containing calcium and phosphorous with high specific volume. The combination of the two substances resulted in good mechanical properties and higher amounts of mineralized deposits formed in vitro.

Chitosan-based blends for biomedical applications

Polysaccharides are the most abundant naturally available carbohydrate polymers; composed of monosaccharide units covalently connected together. Chitosan is the most widely used polysaccharides because of its exceptional biocompatibility, mucoadhesion, and chemical versatility. However, it suffers from a few drawbacks, e.g. poor mechanical properties and antibacterial activity for biomedical applications. Blending chitosan with natural or synthetic polymers may not merely improve its physicochemical and mechanical properties, but may also improve its bioactivity-induced properties. This review paper summarizes progress in chitosan blends with biodegradable polymers and polysaccharides and their biomedical applications. Blends of chitosan with alginate, starch, cellulose, pectin and dextran and their applications were particularly addressed. The critical and challenging aspects as well as the future ahead of the use of chitosan-based blends were eventually enlightened.

The effect of diameter of fibre on formation of hydrogen bonds and mechanical properties of 3D-printed PCL

Fused Deposition Modelling (FDM) technique has been widely utilized in fabrication of 3D porous scaffolds for tissue engineering (TE) applications. Surprisingly, although there are many publications devoted to the architectural features of the 3D scaffolds fabricated by the FDM, none of them give us evident information about the impact of the diameter of the fibres on material properties. Therefore, the aim of this study was to investigate, for the first time, the effect of the diameter of 3D-printed PCL fibres on variations in their microstructure and resulting mechanical behaviour. The fibres made of poly(ε-caprolactone) (PCL) were extruded through commonly used types of nozzles (inner diameter ranging from 0.18 mm to 1.07 mm) by means of FDM technique. Static tensile test and atomic force microscopy working in force spectroscopy mode revealed strong decrease in the Young's modulus and yield strength with increasing fibre diameter in the investigated range. To explain this phenomenon, we conducted differential scanning calorimetry, wide-angle X-ray-scattering, Fourier-transform infrared spectroscopy, infrared and polarized light microscopy imaging. The obtained results clearly showed that the most prominent effect on the obtained microstructures and mechanical properties had different cooling and shear rates during fabrication process causing changes in supramolecular interactions of PCL. The observed fibre size-dependent formation of hydrogen bonds affected the crystalline structure and its stability. Summarising, this study clearly demonstrates that the diameter of 3D-printed fibres has a strong effect on obtained microstructure and mechanical properties, therefore should be taken into consideration during design of the 3D TE scaffolds.

Development and Characterization of a Fucoidan-Based Drug Delivery System by Using Hydrophilic Anticancer Polysaccharides to Simultaneously Deliver Hydrophobic Anticancer Drugs

Fucoidan, a natural sulfated polysaccharide, which can activate the immune response and lessen adverse effects, is expected to be an adjuvant agent in combination with chemotherapy. Using natural hydrophilic anticancer polysaccharides to simultaneously encapsulate hydrophobic anticancer drugs is feasible, and a reduced side effect can be achieved to amplify the therapeutic efficacy. In this study, a novel type of fucoidan-PLGA nanocarrier (FPN-DTX) was developed for the encapsulation of the hydrophobic anticancer drug, docetaxel (DTX), as a drug delivery system. From the comparison between FPN-DTX and the PLGA particles without fucoidan (PLGA-DTX), FPNs-DTX with fucoidan were highly stable with smaller sizes and dispersed well without aggregations in an aqueous environment. The drug loading and release can be further modified by modulating relative ratios of Fucoidan (Fu) to PLGA. The (FPN 3-DTX) nanoparticles with a 10:3 ratio of Fu:PLGA displayed uniform particle size with higher encapsulation efficiency than PLGA NPs and sustained drug release ability. The biocompatible fucoidan-PLGA nanoparticles displayed low cytotoxicity without drug loading after incubation with MDA-MB-231 triple-negative breast cancer cells. Despite lower cellular uptake than that of PLGA-DTX due to a higher degree of negative zeta potential and hydrophilicity, FPN 3-DTX effectively exerted better anticancer ability, so FPN 3-DTX can serve as a competent drug delivery system.

Tensile Properties of Composite Reinforced with Three-Dimensional Printed Fibers

This study used melt-electrospinning writing to fabricate three-dimensional fiber constructs by embedding them in a polyvinyl alcohol (PVA) matrix to obtain thin composite films. Fourier transform infrared spectroscopy (FTIR) and dynamic scanning calorimetry (DSC) were used to demonstrate an interaction between the polycaprolactone (PCL) fibrous phase and the PVA matrix phase. Following this, the mechanical deformation behavior of the composite was investigated, and the effect of reinforcement with three-dimensional fibrous constructs was illustrated. The specific strength of the composite was found to be five times higher than the specific strength of the neat PVA matrix. Additionally, the specific toughness of the composite was determined to be roughly four times higher than the specific toughness determined for the neat PVA matrix. These results demonstrate the potential of using melt-electrospinning writing for producing three-dimensional fibrous constructs for composite reinforcement purposes.

Insoluble and Thermostable Polyhydroxyesters From a Renewable Natural Occurring Polyhydroxylated Fatty Acid

To explore the potential of long chain polyhydroxyalkanoates as non-toxic food packaging materials, the characterization of polyesters prepared from a natural occurring polyhydroxylated C16 carboxylic acid (9,10,16-trihydroxyhexadecanoic or aleuritic acid) has been addressed. Such monomer has been selected to elucidate the reactivity of primary and secondary hydroxyl groups and their contribution to the structure and properties of the polyester. Resulting polyaleuritate films have been produced using an open mold in one-step, solvent-free self-polycondensation in melt state and directly in air to evaluate the effect of oxygen in their final physical and chemical properties. These polymers are amorphous, insoluble, and thermostable, being therefore suitable for solvent, and heat resistant barrier materials. Structurally, most of primary hydroxyls are involved in ester bonds, but there is some branching arising from the partial participation of secondary O-H groups. The oxidative cleavage of the vicinal diol moiety and a subsequent secondary esterification had a noticeable effect on the amorphization and stiffening of the polyester by branching and densification of the ester bond network. A derivation of such structural modification was the surface compaction and the reduction of permeability to water molecules. The addition of Ti(OiPr)₄ as a catalyst had a moderate effect, likely because of a poor diffusion within the melt, but noticeably accelerated both the secondary esterification and the oxidative processes. Primary esterification was a high conversion bulk reaction while oxidation and secondary esterification was restricted to nearby regions of the air exposed side of cast films. The reason was a progressive hindering of oxygen diffusion as the reaction progresses and a self-regulation of the altered layer growth. Despite such a reduced extent, the oxidized layer noticeably increased the UV-vis light blockage capacity. In general, characterized physical properties suggest a high potential of these polyaleuritate polyesters as food preserving materials.

Morphology, Crystallinity, and Molecular Weight of Poly(ε-caprolactone)/Graphene Oxide Hybrids

A study was carried out to determine the effects of graphene oxide (GO) filler on the properties of poly(ε-caprolactone) (PCL) films. A series of nanocomposites were prepared, incorporating different graphene oxide filler contents (0.1, 0.2, and 0.5 wt%) by the solution mixing method, and an in-depth study was made of the morphological changes, crystallization, infrared absorbance, molecular weight, thermal properties, and biocompatibility as a function of GO content to determine their suitability for use in biomedical applications. The infrared absorbance showed the existence of intermolecular hydrogen bonds between the PCL’s carbonyl groups and the GO’s hydrogen-donating groups, which is in line with the apparent reduction in molecular weight at higher GO contents, indicated by the results of the gel permeation chromatography (GPC), and the thermal property analysis. Polarized optical microscopy (POM) showed that GO acts as a nucleating point for PCL crystals, increasing crystallinity and crystallization temperature. The biological properties of the composites studied indicate that adding only 0.1 wt% of GO can improve cellular viability and that the composite shows promise for use in biomedical applications.

Synthesis, Nanomechanical Characterization and Biocompatibility of a Chitosan-Graft-Poly(ε-caprolactone) Copolymer for Soft Tissue Regeneration

Tissue regeneration necessitates the development of appropriate scaffolds that facilitate cell growth and tissue development by providing a suitable substrate for cell attachment, proliferation, and differentiation. The optimized scaffolds should be biocompatible, biodegradable, and exhibit proper mechanical behavior. In the present study, the nanomechanical behavior of a chitosan-graft-poly(ε-caprolactone) copolymer, in hydrated and dry state, was investigated and compared to those of the individual homopolymers, chitosan (CS) and poly(ε-caprolactone) (PCL). Hardness and elastic modulus values were calculated, and the time-dependent behavior of the samples was studied. Submersion of PCL and the graft copolymer in α-MEM suggested the deterioration of the measured mechanical properties as a result of the samples’ degradation. However, even after three days of degradation, the graft copolymer presented sufficient mechanical strength and elastic properties, which resemble those reported for soft tissues. The in vitro biological evaluation of the material clearly demonstrated that the CS-g-PCL copolymer supports the growth of Wharton’s jelly mesenchymal stem cells and tissue formation with a simultaneous material degradation. Both the mechanical and biological data render the CS-g-PCL copolymer appropriate as a scaffold in a cell-laden construct for soft tissue engineering.

Three-dimensional printed polycaprolactone-microcrystalline cellulose scaffolds

Microcrystalline cellulose (MCC) is proposed in this study as an additive in polycaprolactone (PCL) matrices to obtain three-dimensional (3D) printed scaffolds with improved mechanical and biological properties. Improving the mechanical behavior and the biological performance of polycaprolactone-based scaffolds allows to increase the potential of these structures for bone tissue engineering. Different groups of samples were evaluated in order to analyze the effect of the additive in the properties of the PCL matrix. The concentrations of MCC in the groups of samples were 0, 2, 5, and 10% (w/w). These combinations were subjected to a thermogravimetric analysis in order to evaluate the influence of the additive in the thermal properties of the composites. 3D printed scaffolds were manufactured with a commercial 3D printer based on fused deposition modelling. The operation conditions have been established in order to obtain scaffolds with a 0/90° pattern with pore sizes between 450 and 500 µm and porosity values between 50 and 60%. The mechanical properties of these structures were measured in the compression and flexural modes. The scaffolds containing 2 and 5% MCC have higher flexural and compression elastic modulus, although those containing 10% do not show this reinforcement effect. On the other hand, the proliferation of sheep bone marrow cells on the proposed scaffolds was evaluated over 8 days. The results show that the proliferation is significantly better (p < 0.05) on the group of samples containing 2% MCC. Therefore, these scaffolds (PCL:MCC 98:2) have suitable properties to be further evaluated for bone tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 521-528, 2019.

Injectable Chitin-Poly(ε-caprolactone)/Nanohydroxyapatite Composite Microgels Prepared by Simple Regeneration Technique for Bone Tissue Engineering

Injectable gel systems, for the purpose of bone defect reconstruction, have many advantages, such as controlled flowability, adaptability to the defect site, and increased handling properties when compared to the conventionally used autologous graft, scaffolds, hydroxyapatite blocks, etc. In this work, nanohydroxyapatite (nHAp) incorporated chitin-poly(ε-caprolactone) (PCL) based injectable composite microgels has been developed by a simple regeneration technique for bone defect repair. The prepared microgel systems were characterized using scanning electron microscope (SEM), Fourier transformed infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The composite microgel, with the incorporation of nHAp, showed an increased elastic modulus and thermal stability and had shear-thinning behavior proving the injectability of the system. The protein adsorption, cytocompatibility, and migration of rabbit adipose derived mesenchymal stem cells (rASCs) were also studied. Chitin-PCL-nHAp microgel elicited an early osteogenic differentiation compared to control gel. The immunofluorescence studies confirmed the elevated expression of osteogenic-specific markers such as alkaline phosphatase, osteopontin, and osteocalcin in chitin-PCL-nHAp microgels. Thus, chitin-PCL-nHAp microgel could be a promising injectable system for regeneration of bone defects which are, even in deeper planes, irregularly shaped and complex in nature.

Fabrication of chitosan/poly(ε-caprolactone) composite hydrogels for tissue engineering applications

The aim of this study was to fabricate three-dimensional (3D) porous chitosan/poly(ε-caprolactone) (PCL) hydrogels with improved mechanical properties for tissue engineering applications. A modified emulsion lyophilisation technique was developed to produce 3D chitosan/PCL hydrogels. The addition of 25 and 50 wt% of PCL into chitosan substantially enhanced the compressive strength of composite hydrogel 160 and 290%, respectively, compared to pure chitosan hydrogel. The result of ATR-FTIR imaging corroborated that PCL and chitosan were well mixed and physically co-existed in the composite structures. The composite hydrogels were constructed of homogenous structure with average pore size of 59.7 ± 14 μm and finer pores with average size of 4.4 ± 2 μm on the wall of these larger pores. The SEM and confocal laser scanning microscopy images confirmed that fibroblast cells were attached and proliferated on the 3D structure of these composite hydrogels. The composite hydrogels acquired in this study possessed homogeneous porous structure with improved mechanical strength and integrity. They may have a high potential for the production of 3D hydrogels for tissue engineering applications.

Chitosan/poly(epsilon-caprolactone) blend scaffolds for cartilage repair

Chitosan (CHT)/poly(ɛ-caprolactone) (PCL) blend 3D fiber-mesh scaffolds were studied as possible support structures for articular cartilage tissue (ACT) repair. Micro-fibers were obtained by wet-spinning of three different polymeric solutions: 100:0 (100CHT), 75:25 (75CHT) and 50:50 (50CHT) wt.% CHT/PCL, using a common solvent solution of 100 vol.% of formic acid. Scanning electron microscopy (SEM) analysis showed a homogeneous surface distribution of PCL. PCL was well dispersed throughout the CHT phase as analyzed by differential scanning calorimetry and Fourier transform infrared spectroscopy. The fibers were folded into cylindrical moulds and underwent a thermal treatment to obtain the scaffolds. μCT analysis revealed an adequate porosity, pore size and interconnectivity for tissue engineering applications. The PCL component led to a higher fiber surface roughness, decreased the scaffolds swelling ratio and increased their compressive mechanical properties. Biological assays were performed after culturing bovine articular chondrocytes up to 21 days. SEM analysis, live-dead and metabolic activity assays showed that cells attached, proliferated, and were metabolically active over all scaffolds formulations. Cartilaginous extracellular matrix (ECM) formation was observed in all formulations. The 75CHT scaffolds supported the most neo-cartilage formation, as demonstrated by an increase in glycosaminoglycan production. In contrast to 100CHT scaffolds, ECM was homogenously deposited on the 75CHT and 50CHT scaffolds. Although mechanical properties of the 50CHT scaffold were better, the 75CHT scaffold facilitated better neo-cartilage formation.

Chitin Fiber and Chitosan 3D Composite Rods

Chitin fiber (CHF) and chitosan (CS) 3D composite rods with layer-by-layer structure were constructed by in situ precipitation method. CHF could not be dissolved in acetic acid aqueous solution, but CS could be dissolved due to the different deacetylation degree (D.D) between CHF and CS. CHF with undulate surfaces could be observed using SEM to demonstrate that the sufficiently rough surfaces and edges of the fiber could enhance the mechanical combining stress between fiber and matrix. XRD indicated that the crystallinity of CHF/CS composites decreased and CS crystal plane d-spacing of CHF/CS composites became larger than that of pure CS rod. TG analysis showed that mixing a little amount of CHF could enhance thermal stability of CS rod, but when the content of CHF was higher than the optimum amount, its thermal stability decreased. When 0.5% CHF was added into CS matrix, the bending strength and bending modulus of the composite rods arrived at 114.2 MPa and 5.2 GPa, respectively, increased by 23.6% and 26.8% compared with pure CS rods, indicating that CHF/CS composite rods could be a better candidate for bone fracture internal fixation.

Development of polycaprolactone/chitosan blend porous scaffolds

Polycaprolactone (PCL) and chitosan were blended to fabricate porous scaffolds for tissue-engineering applications by employing a concentrated acetic acid solution as solvent and salt particles as porogen. These scaffolds showed well-controlled and interconnected porous structures. The pore size and porosity of the scaffolds could be effectively modulated by selecting appropriate amounts and sizes of porogen. The results obtained from compressive mechanical measurements indicated that PCL/chitosan could basically retain their strength in their dry state compared to individual components. In a hydrated state, their compressive stress and modulus could be still well maintained even though the weight ratio of chitosan reached around 50 wt%.

Poly(ɛ-Caprolactone)/Chitin and Poly(ɛ-Caprolactone)/Chitosan Blend Films With Compositional Gradients: Fabrication and Their Biodegradability

Poly(epsilon-caprolactone) (PCL)/chitin and PCL/chitosan blend films with compositional gradients were successfully fabricated by a dissolution/diffusion method; that is, repeatedly pouring the PCL/chitin (or PCL/chitosan) blend solutions, with variable composition, onto polysaccharide layers. The compositional gradient structure in the resulting films was characterized by polarized optic microscopy, ATR-FT-IR and trans-FT-IR microscopic spectroscopy. Enzymatic degradability of the PCL/chitin and PCL/chitosan blend films with compositional gradients in the presence of lysozyme was compared with those of homogeneous films and two-layer films. It was found that the degradation rate of PCL/chitin blend films with a compositional gradient was far lower than that of the neat chitin film, whereas the degradation rate of PCL/chitosan blend films with a compositional gradient was close to that of the neat chitosan film. The suppression of the chitosan crystallization, which accelerates the enzymatic degradation, at the surface of PCL/chitosan films with a compositional gradient was much more severe than that for PCL/chitin films with a compositional gradient.

Facile preparation of biodegradable chitosan derivative having poly(butylene glycol adipate) side chains

Various modes are being explored for the construction of functional materials from nanoparticles. Despite these efforts, the assembly of nanoparticles remains challenging with respect to the requirement of multiple component organization on varying dimensions and length scales. The graft copolymers of chitosan with poly(butylene glycol adipate) (PBGA) were prepared due to the esterification reaction between PBGA and 6-O-succinate-N-phthaloyl-chitosan (PHCSSA) in the presence of toluene as a swelling agent. The graft copolymers are nanoparticles with the size of few hundred nanometers as observed from TEM. It is a potential method to combine chitosan with the hydrophobic synthetic polymers. The grafting reactions were conducted with various PBGA/PHCSSA feed ratios to obtain chitosan-g-PBGA copolymers with various PBGA contents. FT-IR, NMR, XRD, spectrofluorophotometer, and TEM were detected to characterize the copolymers.