Evaluation of cytotoxicity, hemocompatibility and spectral studies of chitosan assisted polyurethanes prepared with various diisocyanates

Synthesis and optimization of molecular weight of chitosan and carboxymethyl cellulose based polyurethanes

For the first time in this research, using a mixture design approach, polyurethanes (PUs) based on chitosan (CSN) and carboxymethyl cellulose (CMC) were synthesized to develop a high molecular weight polymer. In the synthesis process, a reaction between isophorone diisocyanate (IPDI) and hydroxyl-terminated polybutadiene was carried out to synthesize a prepolymer containing free NCO groups at the corners. This prepolymer was further reacted with changing moles ratio of CSN and CMC following the principles of statistical mixture design. The structural confirmation of the developed PUs was carried out through spectroscopic techniques (FTIR and NMR). The molecular weights of the PU specimens were characterized using gel permeation chromatography. The findings demonstrated that the interaction between CMC and CSN led to a notable increase in the molecular weights of the samples, supported by a significant p-value of 0.006. Additionally, the analysis of variance (ANOVA) disclosed that the employed mixture design and the resulting interaction model effectively account for 98 % of the total variation observed in the molecular weights. The sample labeled as PUS-3 (CMC0.50:CSN0.50) emerged as the most significant formulation, exhibiting a noteworthy 27.9 % improvement in the polymer molecular weight compared to the base sample, denoted as PUS-1 (CMC1.00:CSN0.00).

Tenebrio Molitor breeding rejects as a high source of pure chitin and chitosan: Role of the processes, influence of the life cycle stages and comparison with Hermetia illucens

This work valorizes rejects from Tenebrio Molitor TM breeding through the production of chitin and chitosan. Two processes are proposed for extracting chitin from larval exuviae and adult. The first process P1 provides chitin with high contents compared to literature data but the characterization shows the presence of impurities in the exuviae chitin responsible for the shifts in the values of the physicochemical characteristics towards those presented by γ chitin. These impurities are removed by delipidation and pure α chitin is obtained. The effective delipidation of this chitin would be linked to its fibrous surface structure. The analysis of the results of P1 led us to develop a second extraction process P2 which provides pure chitin with improved yields using delipidation followed by deproteinization. The N-deacetylation of chitin according to Kurita or Broussignac process makes possible the preparation of pure, highly deacetylated chitosan samples (2 % < DA < 12 %) with high yields and controlled molar masses (Mv). A kinetic study of molecular degradation during deacetylation is carried out. A comparison with Hermetia illucens allows to extend the use of insects as a potential source of chitin and chitosan and confirms the role of the source and the processes in the determination of their characteristics.

Modulating alginate-polyurethane elastomer properties: Influence of NCO/OH ratio with aliphatic diisocyanate

This research addresses the need for enhanced biomaterials by investigating the influence of the NCO/OH ratio on sodium alginate-based polyurethane elastomers(Al-PUEs), offering novel insights into their structural, thermal, mechanical and swelling behavior. Al-PUEs were prepared by blending the chain extenders with key ingredients in a specific molar ratio using aliphatic HMDI and HTPB monomers. The chemical linkages, crystalline behavior, homogeneity, and surface morphology of PUEs were evaluated by FT-IR, XRD, SEM, and EDX analysis. Thermo-mechanical studies were performed using TGA, DSC and tensile testing. Swelling behavior and absorption analysis were analyzed in DMSO and water. The analysis indicated that the hydrophilicity and swelling behavior of the prepared PUEs were affected by the addition of sodium alginate content. The results exhibit the tailor-made network structure of Al-PUEs, resulting in better thermal stability, elasticity of materials via stress-strain behavior and marvelous characteristic features than traditional high-tech yields. Furthermore, the resulting Al-PUEs are potential candidates for biomedical implants.

Exploring the therapeutic applications of nano-therapy of encapsulated cisplatin and anthocyanin-loaded multiwalled carbon nanotubes coated with chitosan-conjugated folic acid in targeting breast and liver cancers

This study aimed to assess the targeted nano-therapy of encapsulated cisplatin (Cis) and anthocyanin (Ant)-loaded multiwalled carbon nanotubes (CNT) coated with chitosan conjugated folic acid on breast MCF7 and liver HepG2 cancer cells. Zeta potential, UV-spectroscopy, FTIR, TEM, and SEM were used to evaluate CNT, its modified form (CNT Mod), CNT-loaded Cis NPs, CNT-loaded Ant NPs, and CNT- Cis + Ant NPs. All treatments induced apoptosis-dependent cytotoxicity in both cell lines as revealed functionally by the MTT assay, morphologically (DNA degradation) by acridine orange/ethidium bromide (AO/EB) double staining, and molecularly (Bax upregulation and Bcl2 downregulation) by real-time PCR, with best effect for the combined treatment (CNT- Cis + Ant NPs). This combined treatment also significantly reduced inflammation (low TNFα), migration (low MMP9 and high TIMP1), and angiogenesis (low VEGF), while significantly increasing antioxidant status (high Nrf2 and OH-1) in MCF7 and HepG2 cells compared to other treatments. Interestingly, cells treated with CNT Mod exhibited higher cytotoxic, apoptotic, anti-migratory, and anti-angiogenic potentials relative to CNT-treated cells. In conclusion, targeted nano-therapy of encapsulated cisplatin and anthocyanin-loaded carbon nanotubes coated with chitosan conjugated folic acid can efficiently combat breast and liver cancers by sustained release, in addition to its apoptotic, antioxidant, anti-inflammatory, anti-metastatic, and anti-angiogenic effects.

Injectable and in situ foaming shape-adaptive porous Bio-based polyurethane scaffold used for cartilage regeneration

Irregular articular cartilage injury is a common type of joint trauma, often resulting from intense impacts and other factors that lead to irregularly shaped wounds, the limited regenerative capacity of cartilage and the mismatched shape of the scaffods have contributed to unsatisfactory therapeutic outcomes. While injectable materials are a traditional solution to adapt to irregular cartilage defects, they have limitations, and injectable materials often lack the porous microstructures favorable for the rapid proliferation of cartilage cells. In this study, an injectable porous polyurethane scaffold named PU-BDO-Gelatin-Foam (PUBGF) was prepared. After injection into cartilage defects, PUBGF forms in situ at the site of the defect and exhibits a dynamic microstructure during the initial two weeks. This dynamic microstructure endows the scaffold with the ability to retain substances within its interior, thereby enhancing its capacity to promote chondrogenesis. Furthermore, the chondral repair efficacy of PUBGF was validated by directly injecting it into rat articular cartilage injury sites. The injectable PUBGF scaffold demonstrates a superior potential for promoting the repair of cartilage defects when compared to traditional porous polyurethane scaffolds. The substance retention ability of this injectable porous scaffold makes it a promising option for clinical applications.

A review of nanotechnology in enzyme cascade to address challenges in pre-treating biomass

Nanotechnology has become a revolutionary technique for improving the preliminary treatment of lignocellulosic biomass in the production of biofuels. Traditional methods of pre-treatment have encountered difficulties in effectively degrading the intricate lignocellulosic composition, thereby impeding the conversion of biomass into fermentable sugars. Nanotechnology has enabled the development of enzyme cascade processes that present a potential solution for addressing the limitations. The focus of this review article is to delve into the utilization of nanotechnology in the pretreatment of lignocellulosic biomass through enzyme cascade processes. The review commences with an analysis of the composition and structure of lignocellulosic biomass, followed by a discussion on the drawbacks associated with conventional pre-treatment techniques. The subsequent analysis explores the importance of efficient pre-treatment methods in the context of biofuel production. We thoroughly investigate the utilization of nanotechnology in the pre-treatment of enzyme cascades across three distinct sections. Nanomaterials for enzyme immobilization, enhanced enzyme stability and activity through nanotechnology, and nanocarriers for controlled enzyme delivery. Moreover, the techniques used to analyse nanomaterials and the interactions between enzymes and nanomaterials are introduced. This review emphasizes the significance of comprehending the mechanisms underlying the synergy between nanotechnology and enzymes establishing sustainable and environmentally friendly nanotechnology applications.

Exploring the synergistic effect of carboxymethyl cellulose and chitosan in enhancing thermal stability of polyurethanes through statistical mixture design approach

The thermal stability of polyurethanes, known for its limitations, was addressed in this research by seeking improvement through the introduction of carbohydrate-based chain extenders. In this research paper, we systematically sought to improve the thermal resistance of polyurethanes by incorporating carboxymethyl cellulose and chitosan, representing a pioneering application of the mixture design approach in their preparation. In this synthesis, hydroxyl-terminated polybutadiene and isophorone diisocyanate (IPDI) were reacted to prepare -NCO terminated prepolymer, which was subsequently reacted with varying mole ratios of CMC and CSN to develop a series of five PU samples. The prepared PU samples were characterized using the Fourier-transformed infrared spectroscopic technique. Thermal pyrolysis of PU samples was examined using thermal gravimetric analysis (TGA). It was observed that, among all the samples, PUS-3 showed remarkable thermal stability over a wide temperature range. A comprehensive statistical analysis was conducted to substantiate the experimental findings. It was estimated that CMC and CSN significantly enhance the thermal stability of the samples when involved in an interaction fashion. The ANOVA Table for the mixture design demonstrates that over 90 % of the total variation in thermal stability is explained by the mixture model across a wide temperature range. Moreover, PSU-3 exhibited 4 % more thermal stability over a wide range of temperatures on average, as compared to contemporary samples.

Development of lactic acid based chain extender and soybean oil-derived polyurethanes for ecofriendly sustained drug delivery systems

In the present study, a range of sustainable, biocompatible and biodegradable polyurethanes (PU-1 to PU-4) were synthesized using different combinations of biobased polyol (obtained through the epoxidation of soybean oil, followed by ring opening with ethanol) and polyethylene glycol (PEG) and isophorone diisocyanate. The sustainable chain extender used in this study was synthesized by the esterification of lactic acid with ethylene glycol (EG). The synthesized PU samples were characterized through scanning electron microscopy (SEM), Fourier transformed infrared (FTIR) and nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopy. Wetting ability and thermal degradation analysis (TGA) of the samples were also studied. Subsequently, these PUs were examined as potential drug delivery systems using Gabapentin as a model drug, which was loaded in the polymer matrix using the solvent evaporation method. The drug release studies were carried out in 0.06 N HCl as a release medium according to the method outlined in the United States Pharmacopeia. The maximum drug release was observed for sample PU-P1, which was found to be 53.0 % after 6 h. Moreover, a comparison of different PU samples revealed a trend wherein the values of drug release were decreased with an increase in the PEG content.

Investigation of the in vitro biological activities of polyethylene glycol-based thermally stable polyurethane elastomers

The intense urge to replace conventional polymers with ecofriendly monomers is a step towards green products. The novelty of this study is the extraction of starch from the biowaste of wheat bran (WB) and banana peel (BP) for use as a monomer in the form of chain extenders. For the synthesis of polyurethane (PU) elastomers, polyethylene glycol (PEG) bearing an average molecular weight Mn = 1000 g mol-1 was used as a macrodiol, which was reacted with isophorone diisocyanate (IPDI) to develop NCO-terminated prepolymer chains. These prepolymer chains were terminated with chain extenders. Two series of linear PU elastomers were prepared by varying the concentration of chain extenders (0.5-2.5 mol%), inducing a variation of 40 to 70 wt% in the hard segment (HS). Fourier-transform infrared (FTIR) spectroscopy confirmed the formation of urethane linkages. Thermal gravimetric analysis (TGA) showed a thermal stability of up to 250 °C. Dynamic mechanical analysis (DMA) revealed a storage modulus (E') of up to 140 MPa. Furthermore, the hemolytic activities of up to 8.97 ± 0.1% were recorded. The inhibition of biofilm formation was investigated against E. coli and S. aureus (%), which was supported by phase contrast microscopy.

Development of biocompatible aqueous polyurethane dispersions using chitosan and curcumin to improve physicochemical properties of textile surfaces

The present research work aims to synthesize a blend of chitosan (CSN) and curcumin (CRN) based aqueous polyurethane dispersions (CSN-CRN APUDs) for the modification of textile surfaces. A series of anionic CSN-CRN APUDs were prepared by the reaction of isophorone diisocyanate (IPDI) with polyethylene glycol (PEG) and extended with chain extenders (CSN and CRN). Structural characterizations of prepared materials were examined through a fourier transformed infrared (FTIR) spectrophotometer. The performances of coated CSN-CRN APUDs on the colorfastness properties (washing, rubbing and perspiration) and the mechanical properties like tensile strength and tearing strength of plain weaved poly/cellulosic textiles (dyed, printed and white) were examined before and after the application of CSN-CRN APUDs. The findings showed that the mechanical and colorfastness properties of all the CSN-CRN APUDs treated poly/cellulosic textile samples were improved significantly as compared with untreated poly/cellulosic textile samples. The newly synthesized CSN-CRN APUD coating materials are sustainable and greener products, particularly derivatized from bio-resources. These coating materials can be utilized as outstanding eco-friendly substitutes for poly/cellulosic textile coatings for surface modifications.

Incorporation of Chitosan in Polyurethanes Based on Modified Castor Oil for Cardiovascular Applications

The increased demand for vascular grafts for the treatment of cardiovascular diseases has led to the search for novel biomaterials that can achieve the properties of the tissue. According to this, the investigation of polyurethanes has been a promising approach to overcome the present limitations. However, some biological properties remain to be overcome, such as thrombogenicity and hemocompatibility, among others. This paper aims to synthesize polyurethanes based on castor oil and castor oil transesterified with triethanolamine (TEA) and pentaerythritol (PE) and with the incorporation of 1% chitosan. Analysis of the wettability, enzymatic degradation, mechanical properties (tensile strength and elongation at break), and thermal stability was performed. Along with the evaluation of the cytotoxicity against mouse fibroblast (L929) and human dermal fibroblast (HDFa) cells, the hemolysis rate and platelet adhesion were determined. The castor-oil-based polyurethanes with and without 1% chitosan posed hydrophobic surfaces and water absorptions of less than 2% and enzymatic degradation below 0.5%. Also, they were thermally stable until 300 °C, with tensile strength like cardiovascular tissues. The synthesized castor oil/chitosan polyurethanes are non-cytotoxic (cell viabilities above 80%) to L929 and HDFa cells and non-thrombogenic and non-hemolytic (less than 2%); therefore, they are suitable for cardiovascular applications.

Development of amylopectin based polyurethanes for sustained drug release studies

In this research work, the crosslinked structure of polyurethane has been exploited for sustained drug delivery. Polyurethane composites have been prepared by the reaction of isophorone diisocyanate (IPDI) and polycaprolactone diol (PCL), which were further extended by varying the mole ratios of amylopectin (AMP) and 1,4-butane diol (1,4-BDO) chain extenders. The progress and completion of the reaction of polyurethane (PU) were confirmed using Fourier Transform infrared (FTIR) and nuclear magnetic resonance (¹H NMR) spectroscopic techniques. Gel permeation chromatography (GPC) analysis showed that the molecular weights of prepared polymers were increased with the addition of amylopectin into the PU matrix. The molecular weight of AS-4 (M_w ≈ 99,367) was found threefold as compared to amylopectin-free PU (M_w ≈ 37,968). Thermal degradation analysis was done using thermal gravimetric analysis (TGA) and inferred that AS-5 showed stability up to 600 °C which was the maximum among all PUs because AMP has a large number of -OH units for linking with prepolymer resulting in a more cross-linked structure which improved the thermal stability of the AS-5 sample. The samples prepared with AMP showed less drug release (<53 %) as compared to the PU sample prepared without AMP (AS-1).

Biocompatibility and Hemolytic Activity Studies of Synthesized Alginate-Based Polyurethanes

Many investigators have focused on the development of biocompatible polyurethanes by chemical reaction of functional groups contained in a spacer and introduced in the PU backbone or by a grafting method on graft polymerization of functional groups. In this study, alginate-based polyurethane (PU) composites were synthesized via step-growth polymerization by the reaction of hydroxyl-terminated polybutadiene (HTPB) and hexamethylene diisocyanate (HMDI). The polymer chains were further extended with blends of 1,4-butanediol (1,4-BDO) and alginate (ALG) with different mole ratios. The structures of the prepared PU samples were elucidated with FTIR and 1H NMR spectroscopy. The crystallinity of the prepared samples was evaluated with the help of X-ray diffraction (XRD). The XRD results reveal that the crystallinity of the PU samples increases when the concentration of alginate increases. Thermogravimetric (TGA) results show that samples containing a higher amount of alginate possess higher thermal stability. ALG-based PU composite samples show more biocompatibility and less hemolytic activity. Mechanical properties, contact angle, and water absorption (%) were also greatly affected.

Biodegradable and Biocompatible Thermoplastic Poly(Ester-Urethane)s Based on Poly(ε-Caprolactone) and Novel 1,3-Propanediol Bis(4-Isocyanatobenzoate) Diisocyanate: Synthesis and Characterization

A series of non-toxic biodegradable and biocompatible polyurethanes bearing p-aminobenzoate moieties are presented. The introduction of this attractive motif was carried out by the synthesis of a novel isocyanate. These biodegradable polymers were chemically and physically characterized by several techniques and methods including bioassay and water uptake measurements. The molecular weight of the soft segment (poly-ε-caprolactone, PCL) and hard segment crystallinity dictated the mechanical behavior and water uptake. The behavior of short PCL-based polyurethanes was elastomeric, whilst increasing the molecular weight of the soft segment led to plastic polyurethanes. Water uptake was hindered for long PCL due to the crystallization of the soft segment within the polyurethane matrix. Furthermore, two different types of chain extender, hydrolyzable and non-hydrolyzable, were also evaluated: polyurethanes based on hydrolyzable chain extenders reached higher molecular weights, thus leading to a better performance than their unhydrolyzable counterparts. The good cell adhesion and cytotoxicity results demonstrated the cell viability of human osteoblasts on the surfaces of these non-toxic biodegradable polyurethanes.

Preparation and characterization of guar gum based polyurethanes

Guar gum (plant-based polysaccharide) is a promising candidate with immense potential. It is used as emulsifier, thickener, stabilizer, and as binding agent in many industries. In the present project, it was planned to synthesize guar gum based polyurethanes by varying the amount of guar gum. Guar gum (GG) was used along with hydroxyl-terminated polybutadiene (HTPB) as soft segment, which was then reacted with isophorone diisocyanate (IPDI) to form PU pre-polymers. In last step, these -NCO terminated pre-polymers were extended with 1,4 butane diol as chain extender. The prepared polyurethane samples were then characterized by using FTIR, solid-state ¹HNMR and X-ray diffraction (XRD). Thermal behavior of the samples was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Results indicated that the incorporation of guar gum in PU backbone improved its thermal behavior and crystallinity.

Synthesis and molecular characterization of chitosan/alginate blends based polyurethanes biocomposites

The present work aims to examine the structural properties of polyurethanes bio-composites with mole ratios of alginate and chitosan. For this concern, a two-step reaction mechanism was carried out; in the first step isocyanate (-NCO) terminated pre-polymer was synthesized by the reaction of hexamethylene diisocyanate (HMDI) and hydroxyl-terminated polybutadiene (HTPB). The pre-polymer was further extended with 1,4-butanediol (BDO), chitosan (CS) and alginate (ALG) in the second step. Structural and functional group elucidation was done by using Fourier Transform Infra-red (FT-IR) and proton nuclear magnetic resonance (¹H NMR) spectroscopy. The crystallinity of the prepared samples was investigated by using X-ray diffraction (XRD) method, the maximum observed intensity was 7704 a.u. The thermal properties of polyurethane composites were carried out using thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The TGA results showed that thermal stability of RPU-5 was 20 °C more than RPU-1 at each corresponding degradation temperature. It is observed all physical parameters like crystallinity, glass transition temperature, melting point are much dependent on ratio of chain extenders. Overall, CS based samples along with small amount of ALG showed better thermal properties.

Gamma radiation-induced grafting of poly(2-aminoethyl methacrylate) onto chitosan: A comprehensive study of a polyurethane scaffold intended for skin tissue engineering

A novel brush-like poly(2-aminoethyl methacrylate) (PAEMA) was grafted onto chitosan (CS) through gamma radiation-induced polymerization. The copolymer (CS-g-PAEMA) was used to prepare a sodium acetate leached poly(urethane-urea) scaffold. The above derivatives were developed, synthesized, and characterized to meet the specific characteristics of biomaterials. The results revealed that this method is an easy and successful route for grafting PAEMA onto CS. The feasibility of preparing a CS-g-PAEMA polyurethane foam was confirmed by mechanical, morphometric, spectroscopic, and cytotoxic studies. The scaffold showed high biocompatibility both in vitro and in vivo. The first experiment proved that CS-based polyurethane efficiently allows the dynamic culturing of human fibroblast cells. Additionally, an in vivo study in a murine model indicated a complete integration of the scaffold to surrounding subcutaneous tissue as supported by the histological and histochemical assessments. The aforementioned results support the use of CS-g-PAEMA poly(saccharide-urethane) as a model of in vitro-engineered skin.

Design and Performance of Polyurethane Elastomers Composed with Different Soft Segments

Thermoplastic polyurethane elastomers (TPUs) are widely used in a variety of applications as a result of flexible and superior performance. However, few scholars pay close attention on the design and synthesis of TPUs through the self-determined laboratory process, especially on definite of chemical structures and upon the influence on properties. To investigate the properties of synthesized modifier based on chemical structure, firstly each kind of unknown structure and composition ratio of TPUs was determined by using a new method. Furthermore, the thermal characteristics and mechanical properties of modifiers were exposed by thermal characteristics and mechanics performance tests. The experimental results indicate that TPUs for use as an asphalt modifier can successfully be synthesized with the aid of semi-prepolymer method. The linear backbone structure of TPUs with different hard segment contents were determined by micro test methods. The polyester-based TPUs had thermal behavior better than the polyether-based TPUs; conversely, the low temperature performance of polyether-based TPUs was superior. Most importantly, it was found that the relative molecular mass of TPUs exhibited a weak effect on the mechanical properties, whereas the crystallinity of hard segment showed a significant influence on the properties of TPUs.

Synthesis and molecular characterization of chitosan/starch blends based polyurethanes

Starch/chitosan modified polyurethanes (PUs) were synthesized by step growth polymerization reaction between -NCO terminated prepolymer and chain extenders (1,4-Butanediol/starch/chitosan). Isophorone diisocyanate (IPDI) was reacted with hydroxyl-terminated polybutadiene (HTPB) to synthesize prepolymer and was further reacted with different moles ratio of starch/chitosan to produced five samples of polyurethane (PU). These samples were characterized by Fourier transformed infrared (FTIR) and Proton nuclear magnetic resonance (¹H NMR) spectroscopy. The surface characterizations of PUs were done by scanning electron microscope (SEM). Thermogravimetric analysis showed that the thermal stability of PUs was higher when the mixture of both natural materials was used at equal amounts. It is concluded that combination of both starch and chitosan are efficient for the synthesis of PUs.