Synthesis of Novel Triazine-Based Chalcones and 8,9-dihydro-7H-pyrimido[4,5-b][1,4]diazepines as Potential Leads in the Search of Anticancer, Antibacterial and Antifungal Agents.

This study presents the synthesis of four series of novel hybrid chalcones (20,21)a-g and (23,24)a-g and six series of 1,3,5-triazine-based pyrimido[4,5-b][1,4]diazepines (28-33)a-g and the evaluation of their anticancer, antibacterial, antifungal, and cytotoxic properties. Chalcones 20b,d, 21a,b,d, 23a,d-g, 24a-g and the pyrimido[4,5-b][1,4]diazepines 29e,g, 30g, 31a,b,e-g, 33a,b,e-g exhibited outstanding anticancer activity against a panel of 60 cancer cell lines with GI50 values between 0.01 and 100 µM and LC50 values in the range of 4.09 µM to >100 µM, several of such derivatives showing higher activity than the standard drug 5-fluorouracil (5-FU). On the other hand, among the synthesized compounds, the best antibacterial properties against N. gonorrhoeae, S. aureus (ATCC 43300), and M. tuberculosis were exhibited by the pyrimido[4,5-b][1,4]diazepines (MICs: 0.25-62.5 µg/mL). The antifungal activity studies showed that triazinylamino-chalcone 29e and triazinyloxy-chalcone 31g were the most active compounds against T. rubrum and T. mentagrophytes and A. fumigatus, respectively (MICs = 62.5 µg/mL). Hemolytic activity studies and in silico toxicity analysis demonstrated that most of the compounds are safe.

All-Natural Plant-Derived Polyurethane as a Substitute of a Petroleum-Based Polymer Coating Material.

The development of efficient, biobased polyurethane controlled-release fertilizers from sustainable and eco-friendly biomaterials has received increased research attention, owing to concerns regarding global food security and environmental sustainability. Most previous studies focused on replacing petroleum-based polyols with biopolyols; however, the other main raw material, isocyanate, remained a petrochemical product. Herein, all-natural, plant-derived polyurethane-coated urea was successfully developed using castor oil and biobased isocyanate, and the performance of the coating shell before and after modification was compared. The results showed that the incorporation of a low dose of lauric acid copper into the coating material simultaneously enhanced the hydrophobicity and elasticity of the all-biobased polyurethane membrane, which prolonged the nitrogen release longevity from 3 to 112 days. In addition, the modified membrane showed excellent biodegradability in a soil environment. The novel all-biobased polyurethane coating material and modification technique provide insight for developing sustainable and eco-friendly controlled-release fertilizers.

Synthesis of sydnonimines from sydnones and their use for bioorthogonal release of isocyanates in cells.

In this article, we report the synthesis of sydnonimines from sydnones and their use as dipoles for fast click-and-release reactions. The process relies on nucleophilic aromatic substitution of aliphatic and aromatic amines with triflated sydnones. This new methodology allowed the preparation of functionalised sydnonimine probes that are otherwise difficult to prepare. These probes were then used to release a drug and a fluorescent aromatic isocyanate inside living cells.

Lung Gene Expression Suggests Roles for Interferon-Stimulated Genes and Adenosine Deaminase Acting against RNA-1 in Pathologic Responses to Diisocyanate.

Mechanisms underlying methylene diphenyl diisocyanate (MDI) and other low molecular weight chemical-induced asthma are unclear and appear distinct from those of high molecular weight (HMW) allergen-induced asthma. We sought to elucidate molecular pathways that differentiate asthma-like pathogenic vs nonpathogenic responses to respiratory tract MDI exposure in a murine model. Lung gene expression differences in MDI exposed immune-sensitized and nonsensitized mice vs unexposed controls were measured by microarrays, and associated molecular pathways were identified through bioinformatic analyses and further compared with published studies of a prototypic HMW asthmagen (ovalbumin). Respiratory tract MDI exposure significantly altered lung gene expression in both nonsensitized and immune-sensitized mice, vs controls. Fifty-three gene transcripts were altered in all MDI exposed lung tissue vs controls, with levels up to 10-fold higher in immune-sensitized vs nonsensitized mice. Gene transcripts selectively increased in MDI exposed immune-sensitized animals were dominated by chitinases and chemokines and showed substantial overlap with those increased in ovalbumin-induced asthma. In contrast, MDI exposure of nonsensitized mice increased type I interferon stimulated genes (ISGs) in a pattern reflecting deficiency in adenosine deaminase acting against RNA (ADAR-1), an important regulator of innate, as well as "sterile" or autoimmunity triggered by tissue damage. Thus, MDI-induced changes in lung gene expression were identified that differentiate nonpathogenic innate responses in nonsensitized hosts from pathologic adaptive responses in immune-sensitized hosts. The data suggest that MDI alters unique biological pathways involving ISGs and ADAR-1, potentially explaining its unique immunogenicity/allergenicity.

[An epidemiological and evolutionary profile of occupational asthma of Tunisian workers]. / Profil épidémiologique et évolutif de l'asthme professionnel des travailleurs tunisiens.

INTRODUCTION: This study aims to identify the epidemiological and occupational characteristics of patients with occupational asthma (OA) and to assess their clinical evolution and occupational outcomes. METHODS: We carried out a descriptive epidemiological study over a period of five years (from 2012 to 2016) about the OA cases in the private sector reported in the Tunisian region of Zaghouan. RESULTS: All in all, 165 OA cases were reported during the study period, representing an annual incidence of 733.3 cases per 1,000,000 workers in the private sector. Our study population was composed predominantly (85.5%) of women, whose mean age was 41.5±6.8years. More than three quarters of the affected persons were working in the automobile industry, and most illnesses (77%) were attributable to isocyanates. The mean time to onset of the respiratory symptoms was longer for low molecular weight agents (13.6±3.1years) compared to high molecular weight agents (12.0±3.9years) (P=0.0006). The majority of OA cases (66.7%) lost their jobs. Job loss was significantly more frequent among asthmatic women and workers with OA due to isocyanates. Among the 62 cases of OA for whom risk factors were eliminated, 45 nonetheless remained symptomatic. CONCLUSION: Effective prevention strategies involving the various actors need to be implemented in work environments so as to reduce the frequency and the medico-legal repercussions of a disabling condition.

Design, manufacturing and testing of a green non-isocyanate polyurethane prosthetic heart valve.

The sole effective treatment for most patients with heart valve disease is valve replacement by implantation of mechanical or biological prostheses. However, mechanical valves represent high risk of thromboembolism, and biological prostheses are prone to early degeneration. In this work, we aim to determine the potential of novel environmentally-friendly non-isocyanate polyurethanes (NIPUs) for manufacturing synthetic prosthetic heart valves. Polyhydroxyurethane (PHU) NIPUs are synthesized via an isocyanate-free route, tested in vitro, and used to produce aortic valves. PHU elastomers reinforced with a polyester mesh show mechanical properties similar to native valve leaflets. These NIPUs do not cause hemolysis. Interestingly, both platelet adhesion and contact activation-induced coagulation are strongly reduced on NIPU surfaces, indicating low thrombogenicity. Fibroblasts and endothelial cells maintain normal growth and shape after indirect contact with NIPUs. Fluid-structure interaction (FSI) allows modeling of the ideal valve design, with minimal shear stress on the leaflets. Injection-molded valves are tested in a pulse duplicator and show ISO-compliant hydrodynamic performance, comparable to clinically-used bioprostheses. Poly(tetrahydrofuran) (PTHF)-NIPU patches do not show any evidence of calcification over a period of 8 weeks. NIPUs are promising sustainable biomaterials for the manufacturing of improved prosthetic valves with low thrombogenicity.

Linezolid brain penetration in neurointensive care patients.

BACKGROUND: Linezolid exposure in critically ill patients is associated with high inter-individual variability, potentially resulting in subtherapeutic antibiotic exposure. Linezolid exhibits good penetration into the CSF, but its penetration into cerebral interstitial fluid (ISF) is unknown. OBJECTIVES: To determine linezolid penetration into CSF and cerebral ISF of neurointensive care patients. PATIENTS AND METHODS: Five neurocritical care patients received 600 mg of linezolid IV twice daily for treatment of extracerebral infections. At steady state, blood and CSF samples were collected from arterial and ventricular catheters, and microdialysate was obtained from a cerebral intraparenchymal probe. RESULTS: The median fAUC0-24 was 57.6 (24.9-365) mg·h/L in plasma, 64.1 (43.5-306.1) mg·h/L in CSF, and 27.0 (10.7-217.6) mg·h/L in cerebral ISF. The median penetration ratio (fAUCbrain_or_CSF/fAUCplasma) was 0.5 (0.25-0.81) for cerebral ISF and 0.92 (0.79-1) for CSF. Cerebral ISF concentrations correlated well with plasma (R = 0.93, P < 0.001) and CSF levels (R = 0.93, P < 0.001).The median fAUC0-24/MIC ratio was ≥100 in plasma and CSF for MICs of ≤0.5 mg/L, and in cerebral ISF for MICs of ≤0.25 mg/L. The median fT>MIC was ≥80% of the dosing interval in CSF for MICs of ≤0.5 mg/L, and in plasma and cerebral ISF for MICs of ≤0.25 mg/L. CONCLUSIONS: Linezolid demonstrates a high degree of cerebral penetration, and brain concentrations correlate well with plasma and CSF levels. However, substantial variability in plasma levels, and thus cerebral concentrations, may result in subtherapeutic tissue concentrations in critically ill patients with standard dosing, necessitating therapeutic drug monitoring.

Recent developments in occupational asthma.

PURPOSE OF REVIEW: Occupational asthma (OA) is a complex condition that can be difficult to diagnose. The purpose of this review is to describe some recent findings regarding the epidemiology of OA, the occupational sensitizing agents, the prognosis of OA, and its primary prevention. RECENT FINDINGS: The risk of developing OA varies according to the geographic localization of the worker, the type of industry and the type of sensitizing agents. New findings have been reported for several known sensitizing agents, such as isocyanates, seafood & cleaning agents, and their related industries, such as hairdressing salons and schools. Moreover, a few new sensitizing agents, such as cannabis, have been identified in the past few years. The prognosis of OA seems worse than that of nonwork-related asthma. It is mainly determined by the duration and the level of exposure. Primary prevention is crucial to reduce the number of new cases of OA. Complete avoidance of exposure to the causal agent remains the optimal treatment of sensitizer-induced OA. SUMMARY: Improving our knowledge regarding OA and its causative agents is key to enable an early recognition of this condition and improve its prognosis. Further research is still needed to improve primary prevention.

Thermoplastic polyurethane/POSS nanohybrids: Synthesis, morphology, and biological properties.

Recent studies show good osteoinductive properties of polyurethanes modified with polyhedral oligomeric silsesquioxanes (POSS). In this work, three types of POSS; propanediolisobutyl-POSS (PHI-POSS), disilanolisobutyl-POSS (DSI-POSS), and octahydroxybutyl-POSS (OCTA-POSS) were chemically incorporated into linear polyurethane based on an aliphatic isocyanate, hexamethylene diisocyanate (HDI), to obtain new nanohybrid PU-POSS materials. The full conversion of POSS was confirmed by Fourier transform infrared spectroscopy (FTIR-ATR) spectra of the model reactions with pure HDI. The materials obtained were investigated by FTIR, SEM-EDS, and DSC. The DSC studies showed the thermoplasticity of the obtained materials and apparently good recovery. 30-day immersion in SBF (simulated body fluid) revealed an increase in the rate of deposition of hydroxyapatite (HAp) for the highest POSS loadings, resulting in thick layers of hydroxyapatite (~60-40 µm), and the Ca/P ratio 1.67 (even 1.785). The structure and properties of the inorganic layer depend on the type of POSS, the number of hard segments, and those containing POSS, which can be tailored by changing the HDI/poly(tetramethylene glycol) (PTMG) ratio. Furthermore, the obtained composites revealed good biocompatibility, as confirmed by cytotoxicity tests conducted on two cell lines; normal human dermal fibroblasts (NHDF) and primary human osteoblasts (HOB). Adherent cells seeded on the tested materials showed viability even after a 48-h incubation. After this time, the population of viable, and proliferating cells exceeded 90%. Bioimaging studies have shown the fibroblast and osteoblast cells were well attached to the surface of the tested materials.

Design of 3D-Photoprintable, Bio-, and Hemocompatible Nonisocyanate Polyurethane Elastomers for Biomedical Implants.

Polyurethanes (PUs) have adjustable mechanical properties, making them suitable for a wide range of applications, including in the biomedical field. Historically, these PUs have been synthesized from isocyanates, which are toxic compounds to handle. This has encouraged the search for safer and more environmentally friendly synthetic routes, leading today to the production of nonisocyanate polyurethanes (NIPUs). Among these NIPUs, polyhydroxyurethanes (PHUs) bear additional hydroxyl groups, which are particularly attractive for derivatizing and adjusting their physicochemical properties. In this paper, polyether-based NIPU elastomers with variable stiffness are designed by functionalizing the hydroxyl groups of a poly(propylene glycol)-PHU by a cyclic carbonate carrying a pendant unsaturation, enabling them to be post-photo-cross-linked with polythiols (thiol-ene). Elastomers with remarkable mechanical properties whose stiffness can be adjusted are obtained. Thanks to the unique viscous properties of these PHU derivatives and their short gel times observed by rheology experiments, formulations for light-based three-dimensional (3D) printing have been developed. Objects were 3D-printed by digital light processing with a resolution down to the micrometer scale, demonstrating their ability to target various designs of prime importance for personalized medicine. In vitro biocompatibility tests have confirmed the noncytotoxicity of these materials for human fibroblasts. In vitro hemocompatibility tests have revealed that they do not induce hemolytic effects, they do not increase platelet adhesion, nor activate coagulation, demonstrating their potential for future applications in the cardiovascular field.

Direct ink writing of biocompatible chitosan/non-isocyanate polyurethane/cellulose nanofiber hydrogels for wound-healing applications.

The demand for new biocompatible and 3D printable materials for biomedical applications is on the rise. Ideally, such materials should exhibit either biodegradability or recyclability, possess antibacterial properties, and demonstrate remarkable biocompatibility with no cytotoxic effects. In this research, we synthesized biocompatible and 3D printable hydrogels tailored for biomedical applications, such as wound healing films, by combining antibacterial double-quaternized chitosan (DQC) with cystamine-based non-isocyanate polyurethane (NIPU-Cys) - a material renowned for enhancing both the flexibility and mechanical properties of the hydrogels. To improve the rheological behavior, swelling attributes, and printability, cellulose nanofibrils were introduced into the matrix. We investigated the impact of DQC on degradability, swelling capacity, rheological behavior, printability, and cell biocompatibility. The slightly cytotoxic nature associated with quaternary chitosan was evaluated, and the optimal concentration of DQC in the hydrogel was determined to ensure biocompatibility. The resulting hydrogels were found to be suitable materials for 3D printing via a direct ink writing technique (DIW), producing porous, biocompatible hydrogels endowed with valuable attributes suitable for various wound-healing applications.

A Novel Hydrophobic Polyimide Film with Sag Structure Derived from Multi-Hybrid Strategy.

Polyimide (PI) film with hydrophilic greatly limits their application in the field of microelectronic device packaging. A novel hydrophobic PI film with sag structure and improved mechanical properties is prepared relying on the reaction between anhydride-terminated isocyanate-based polyimide (PIY) containing a seven-membered ring structure and the amino-terminated polyamide acid (PAA) via multi-hybrid strategy, this work named it as hybrid PI film and marked it as PI-PIY-X. PI-PIY-30 showed excellent hydrophobic properties, and the water contact angle could reach to 102°, which is 20% and 55% higher than simply PI film and PIY film, respectively. The water absorption is only 1.02%, with a decrease of 49% and 53% compared with PI and PIY. Due to that the degradation of seven-membered ring and generation of carbon dioxide led to the formation of sag structure, the size of sag structures is ≈16.84 and 534.55 nm for in-plane and out-plane direction, which are observed on surface of PI-PIY-30. Meanwhile, PI-PIY-30 possessed improved mechanical properties, and the tensile strength is 109.08 MPa, with 5% and more than 56% higher than that of pure PI and PIY film, showing greatly application prospects in the field of integrated circuit.

Preparation and fire resistance modification on tannin-based non-isocyanate polyurethane (NIPU) rigid foams.

Non-isocyanate polyurethane (NIPU) as a new type of polyurethane material has become a hot research topic in the polyurethane industry due to its no utilization of toxic isocyanates during the synthesis process. And the developing on recyclable biomass materials has also much attention in the industrial sector, hence the preparation and application of bio-based NIPU has also become a very meaningful study work. So, in this paper, tannin as a biomass material was used to synthesize tannin based non-isocyanate polyurethanes (TNIPU) resin, and then successfully prepared a self-blowing TNIPU foam at room temperature by using formic acid as initiator and glutaraldehyde as cross-linking agent. The compressive strength of this foam as high as 0.8 MPa, which is an excellent compressive performance. Meanwhile it will return to the state before compression when removing the pressure. This indicating that the foam has good toughness. In addition, formic acid can react with the amino groups in TNIPU to form amide substances, and generated enough heat to initiate the foaming process. Glutaraldehyde, as a crosslinking agent, reacts with the amino group in TNIPU to form a network structure system. By scanning electron microscope (SEM) observation of the cell shapes, it can be seen that the foam cells were uniform in size and shape, and the cell pores showed open and closed cells. The limiting oxygen index (LOI) tested value of this TNIPU foam is 24.45 % without any flame retardant added, but compared to the LOI value of polyurethane foam (17 %-19 %), TNIPU foam reveal a better fire resistance. It has a wider application prospect.

Efficient recycling pathway of bio-based composite polyurethane foams via sustainable diamine.

Aminolysis is widely recognized as a valuable chemical route for depolymerizing polymeric materials containing ester, amide, or urethane functional groups, including polyurethane foams. Bio-based polyurethane foams, pristine and reinforced with 40 wt% of sustainable fillers, were depolymerized in the presence of bio-derived butane-1,4-diamine, BDA. A process comparison was made using fossil-derived ethane-1,2-diamine, EDA, by varying amine/polyurethane ratio (F/A, 1:1 and 1:0.6). The obtained depolymerized systems were analyzed by FTIR and NMR characterizations to understand the effect of both diamines on the degradation pathway. The use of bio-based BDA seemed to be more effective with respect to conventional EDA, owing to its stronger basicity (and thus higher nucleophilicity), corresponding to faster depolymerization rates. BDA-based depolymerized systems were then employed to prepare second-generation bio-based composite polyurethane foams by partial replacement of isocyanate components (20 wt%). The morphological, mechanical, and thermal conductivity properties of the second-generation polyurethane foams were evaluated. The best performances (σ10 %=71 ± 9 kPa, λ = 0.042 ± 0.015 W∙ m-1 ∙K-1) were attained by employing the lowest F/A ratio (1:0.6); this demonstrates their potential application in different sectors such as packaging or construction, fulfilling the paradigm of the circular economy.

A Versatile Isocyanate-Mediated Strategy for Appending Chemical Tags onto Drug-Like Small Molecules.

Target identification studies are a major hurdle in probe and drug discovery pipelines due to the need to chemically modify small molecules of interest, which can be time intensive and have low throughput. Here, we describe a versatile and scalable method for attaching chemical moieties to a small molecule, isocyanate-mediated chemical tagging (IMCT). By preparation of a template resin with an isocyanate capture group and a cleavable linker, nucleophilic groups on small molecules can be modified with an enforced one-to-one stoichiometry. We demonstrate a small molecule substrate scope that includes primary and secondary amines, thiols, phenols, benzyl alcohols, and primary alcohols. Cheminformatic analyses predict that IMCT is reactive with more than 25% of lead-like compounds in publicly available databases. To demonstrate that the method can produce biologically active molecules, we generated FKBP12 photoaffinity labeling (PAL) compounds with a wide range of affinities and showed that purified and crude cleavage products can bind to and label FKBP12. This method could be used to rapidly modify small molecules for many applications, including the synthesis of PAL probes, fluorescence polarization probes, pull-down probes, and degraders.

Reconstruction of exposure to methylene diphenyl-4,4'-diisocyanate (MDI) aerosol using computational fluid dynamics, physiologically based toxicokinetics and statistical modeling.

OBJECTIVES: This study employed computational fluid dynamics (CFD), physiologically based toxicokinetics (PBTK), and statistical modeling to reconstruct exposure to methylene diphenyl-4,4'-diisocyanate (MDI) aerosol. By utilizing a validated CFD model, human respiratory deposition of MDI aerosol in different workload conditions was investigated, while a PBTK model was calibrated using experimental rat data. Biomonitoring data and Markov Chain Monte Carlo (MCMC) simulation were utilized for exposure assessment. RESULTS: Deposition fraction of MDI in the respiratory tract at the light, moderate, and heavy activity were 0.038, 0.079, and 0.153, respectively. Converged MCMC results as the posterior means and prior values were obtained for several PBTK model parameters. In our study, we calibrated a rat model to investigate the transport, absorption, and elimination of 4,4'-MDI via inhalation exposure. The calibration process successfully captured experimental data in the lungs, liver, blood, and kidneys, allowing for a reasonable representation of MDI distribution within the rat model. Our calibrated model also represents MDI dynamics in the bloodstream, facilitating the assessment of bioavailability. For human exposure, we validated the model for recent and long-term MDI exposure using data from relevant studies. CONCLUSION: Our computational models provide reasonable insights into MDI exposure, contributing to informed risk assessment and the development of effective exposure reduction strategies.

4,4'-Methylene diphenyl diisocyanate exposure induces expression of alternatively activated macrophage-associated markers and chemokines partially through Krüppel-like factor 4 mediated signaling in macrophages.

Occupational exposure to the most widely used monomeric diisocyanate (dNCO), 4,4'-methylene diphenyl diisocyanate (MDI), may lead to the development of occupational asthma (OA). Alveolar macrophages with alternatively activated (M2) phenotype have been implicated in allergic airway responses and the pathogenesis of asthma. Recent in vivo studies demonstrate that M2 macrophage-associated markers and chemokines are induced by MDI-exposure, however, the underlying molecular mechanism(s) by which this proceeds is unclear.Following MDI exposure (in vivo and in vitro) M2 macrophage-associated transcription factors (TFs), markers, and chemokines were determined by RT-qPCR, western blots, and ELISA.Expression of M2 macrophage-associated TFs and markers including Klf4/KLF4, Cd206/CD206, Tgm2/TGM2, Ccl17/CCL17, Ccl22/CCL22, and CCL24 were induced by MDI/MDI-GSH exposure in bronchoalveolar lavage cells (BALCs)/THP-1 macrophages. The expression of CD206, TGM2, CCL17, CCL22, and CCL24 are upregulated by 3.83-, 7.69-, 6.22-, 6.08-, and 1.90-fold in KLF4-overexpressed macrophages, respectively. Endogenous CD206 and TGM2 were downregulated by 1.65-5.17-fold, and 1.15-1.78-fold, whereas CCL17, CCL22, and CCL24 remain unchanged in KLF4-knockdown macrophages. Finally, MDI-glutathione (GSH) conjugate-treated macrophages show increased chemotactic ability to T-cells and eosinophils, which may be attenuated by KLF4 knockdown.Our data suggest that MDI exposure may induce M2 macrophage-associated markers partially through induction of KLF4.

Innovations in applications and prospects of non-isocyanate polyurethane bioplastics.

Currently, conventional plastics are necessary for a variety of aspects of modern daily life, including applications in the fields of healthcare, technology, and construction. However, they could also contain potentially hazardous compounds like isocyanates, whose degradation has a negative impact on both the environment and human health. Therefore, researchers are exploring alternatives to plastic which is sustainable and environmentally friendly without compromising its mechanical and physical features. This review study highlights the production of highly eco-friendly bioplastic as an efficient alternative to non-biodegradable conventional plastic. Bioplastics are produced from various renewable biomass sources such as plant debris, fatty acids, and oils. Poly-addition of di-isocyanates and polyols is a technique employed over decades to produce polyurethanes (PUs) bioplastics from renewable biomass feedstock. The toxicity of isocyanates is a major concern with the above-mentioned approach. Novel green synthetic approaches for polyurethanes without using isocyanates have been attracting greater interest in recent years to overcome the toxicity of isocyanate-containing raw materials. The polyaddition of cyclic carbonates (CCs) and polyfunctional amines appears to be the most promising method to obtain non-isocyanate polyurethanes (NIPUs). This method results in the creation of polymeric materials with distinctive and adaptable features with the elimination of harmful compounds. Consequently, non-isocyanate polyurethanes represent a new class of green polymeric materials. In this review study, we have discussed the possibility of creating novel NIPUs from renewable feedstocks in the context of the growing demand for efficient and ecologically friendly plastic products.

Improvement of the mechanical and shape memory properties in polylactide/polyethylene glycol blends by reactive graphene oxide.

The widespread application of biodegradable polylactide (PLA) is hindered by its brittleness. Polyethylene glycol (PEG) is commonly utilized as a plasticizer because of its favorable compatibility with PLA. However, the incorporation of PEG considerably diminishes the tensile strength of PLA. To address this issue, reactive isocyanate-modified graphene oxide (mGO) was synthesized and used as an enhancer in PLA/PEG blends. By virtue of the reaction between the isocyanate group in mGO and the terminal hydroxyl groups of PLA and PEG, graphene-based polyurethane (PU) in-situ formed and enhanced the interface between GO and the matrix. Consequently, the PLA/PEG/mGO composites exhibit simultaneously improved tensile and impact strengths, achieving an increase of 20.6% and 29.4%, respectively, compared to PLA/PEG blends. Moreover, the in situ formed PU reduces the relaxation time of the molecule motion and improved the entanglement density, thereby improving the shape-memory recovery rate and final recovery degree of the composites. This work provides a facile method to simultaneously improve the dispersion of GO and enhance its interface with polymer, thereby supplying well comprehensive properties of PLA and extending the applications of biodegradable polymers.

Preparation of light-colored bio-based particles by isocyanate-modified lignins and its application for tetracycline adsorption.

A practical method for the preparation of lignin derivatives-light-colored bio-based particles (LC-BP) via the modification of hexamethylene diisocyanate (HDI) is presented in this work. In the mixed EtOH/H2O system, the change of solvent polarity induced the self-assembly of the lignosulfonate (LS) with the hydrophobic chromophores encapsulated inside the particles. The color of LS was reduced by the polymerization between the isocyanate groups (-N=C=O) of HDI and hydroxy groups of LS. Compared with the typical lignin-based adsorbent preparation process in the past, this is a simple, direct, and efficient preparation method and the synthetic LC-BP has good chemical stability and resistance to heat, acid and alkali. This effectively solves the problem that LS has high water solubility and is difficult to use directly for wastewater treatment. To investigate the properties, the synthetic LC-BP was characterized by SEM, specific surface area, L*a*b* (CIELAB) color space, FT-IR, XPS, and TGA. The results showed that the LC-BP exhibited obvious advantages in color reduction with a low CIE-L* value. The LC-BP exhibits a scale-like intercalation structure, which makes it a promising candidate for adsorbing tetracycline (TC) from wastewater. The conditions of pH, adsorbent dosages, adsorption time, and initial TC concentration were investigated, and the adsorption performance of LC-BP for TC was significantly better than that of conventional polyurethane particles (PP). The adsorption fitted the Langmuir model and there were hydrogen bonding, π-π conjugated binding, and electrostatic attraction during the absorption process. The adsorption capacity was up to 53.1 mg/g, and the removal rate was 67 %. The utilization of LC-BP, a low-cost, effective, and renewable resource derived from natural biomass, holds immense practical and economic potential in wastewater treatment.