Chitosan Microspheres Research Articles

Nanostructured chitosan-palygorskite hybrid microspheres for controlled delivery of thymol

Hybrid microspheres from palygorskite (PAL) nanoclay and crosslinked chitosan (QS) were prepared with the emulsion method to trap and control the release of thymol (TIM). The morphology of the microspheres was characterized by scanning electron microscopy and x-ray diffraction. The size of the microspheres, the swelling rate, the encapsulation efficiency and thymol release rate were characterized. Compared to pristine chitosan microspheres, hybrid microspheres showed the highest encapsulation efficiency. The average particle sizes of the QS and QS-PAL microspheres are in a range of 20 to 50 μm, with a size distribution of the hybrid microspheres showing less size polydispersity. The QS-PAL microspheres have a higher swelling rate than the QS microspheres. The lowest swelling degree, 88%, was from the microspheres without PAL cross-linked with 950 μl of glutaraldehyde (GL), and the highest swelling degree, 146%, was from the microspheres with 10% PAL crosslinked with 630 μl of GL. The thymol release kinetics was modified by the palygorskite content of the chitosan hybrid microspheres.

Synergistic DFT-guided design and microfluidic synthesis of high-performance ion-imprinted biosorbents for selective heavy metal removal

International water security has become unprecedentedly complicated, therefore, effective and selective removal of hazardous materials, especially toxic heavy metal ions, are significant for effluent purification. In this regard, ion-imprinted polymers with special recognition cavities have received much attention. However, configuration screening and performance optimization of functional materials by trial-and-error design method is undoubtedly time- and money-consuming. In this study, high-performance ion-imprinted chitosan microspheres (ICSMs) were successfully designed via density functional theory (DFT) calculation and synthesized via facile microfluidic technology. As-synthesized ICSMs exhibited highly uniform morphology ( D av = 420.6 µm, CV = 3.6%) and ultra-high adsorption capacity ( q max = 107.12 mg g −1 ). The adsorption isotherm was best fitted to the Langmuir model while the kinetic data followed the pseudo-second order model, indicating a dominant role of chemisorptions. Also, ICSMs displayed satisfactory stability and reusability (95.34 mg g −1 , after 5 cycles). Moreover, the selective adsorption mechanism was quantitative revealed by electronegativity, electrophilicity index, adsorption energy ( E a ) and bond length. This study is expected to lay a foundation for high-performance biosorbents design and synthesis for future water remediation. • High-performance ICSMs were obtained by DFT-guided design and microfluidic synthesis. • Ultra-high adsorption property for targeted metal ions (107.12 mg g −1 ) was proved. • Target ions selective removal from mono- and multi-component systems was achieved. • Selectivity mechanism was quantitative revealed by adsorption energy and bond length. • Superior and stable re-adsorption efficiency (> 95 mg g −1 after 5 cycles) was verified.

Jawbones Scaffold Constructed by TGF-β1 and BMP-2 Loaded Chitosan Microsphere Combining with Alg/HA/ICol for Osteogenic-Induced Differentiation.

Bone scaffolds based on multi-components are the leading trend to address the multifaceted prerequisites to repair various bone defects. Chitosan is the most useable biopolymer, having excellent biological applications. Therefore, in the present study, the chitosan microsphere was prepared by the ion–gel method; transforming growth factor β (TGF-β1) and bone morphogenetic protein 2 (BMP-2) were loaded onto it and then combined with alginate/hyaluronic acid/collagen (Alg/HA/ICol) to construct a jawbones scaffold. The Alg/HA/ICol scaffolds were characterized by FTIR and SEM, and the water content, porosity, tensile properties, biocompatibility, and osteogenic-induced differentiation ability of the Alg/HA/ICol jawbones scaffolds were studied. The results indicate that a three-dimensional porous jawbone scaffold was successfully constructed having 100–250 μm of pore size and >90% of porosity without cytotoxicity against adipose-derived stem cells (ADSCs). Its ALP quantification, osteocalcin expression, and Von Kossamineralized nodule staining was higher than the control group. The jawbones scaffold constructed by TGF-β1 and BMP-2 loaded chitosan microsphere combining with Alg/HA/ICol has potential biomedical application in the future.

Toluidine blue-immobilized macroporous chitosan microspheres for highly efficient purification of fucoidan

Advanced adsorbents offer possible solutions to the challenge of isolation and purification of fucoidan. In this work, a toluidine blue-immobilized macroporous chitosan microsphere (TMCM) is prepared by surfactant micelle swelling strategy followed by modification with toluidine blue for efficiently purification of fucoidan. The macroporous structure of TMCM provides wide channels and allows fast mass transfer of adsorbates, thereby affording fast adsorption rate and high desorption efficiency; Toluidine blue, a high-affinity ligand that is immobilized on the pore surface, renders high adsorption capacity and selectivity for fucoidan. Adsorption experiments demonstrated that TMCM has superior adsorption performances, including fast adsorption rate with the adsorption amount 164.10 mg/g within 15 h, high desorption efficiency with over 93.6%, high adsorption capacity with 187.69 mg/g, and good selectivity, indicating a very appealing application prospect.

A new strategy to prepare fully bio-based poly(lactic acid) composite with high flame retardancy, UV resistance, and rapid degradation in soil

Despite the advantages of biological compatibility and high transparency, there are still some drawbacks for Poly(lactic acid) (PLA) such as highly flammability and poor ultraviolet resistance. Herein, a fully bio-based additive (PA@CHTM) with a core–shell structure is synthesized by chitosan microspheres and phytic acids. The introduction of PA@CHTM simultaneously improves the mechanical properties, flame retardancy, and UV-blocking performance of PLA, accompanied by an accelerated degradation capacity in soil. By the presence of 9 wt% PA@CHTM in the PLA composite sample, the limiting oxygen index value is increased from 18.2% to 29.6%, and the UL-94 test grade is improved to V-0. The tensile strength is well maintained and Young's modulus is sharply increased for PLA/PA@CHTM composites. Moreover, the photoaging process of PLA can be significantly delayed due to the excellent free radical quenching capacity of PA@CHTM. Only less than 10% UV light can be penetrated for the PLA/9%PA@CHTM sample, and the ultraviolet protection factor is increased from 0.77 of control PLA to 30.07. More importantly, the addition of PA@CHTM can accelerate the degradation of PLA, which is of significance for biodegradable materials. This work firstly provides a green strategy to fabricate fully bio-based polymer composites with high performance, long service life, and rapid degradation in soil.

Preparation of chitosan microspheres as carrier material to controlled release of urea fertilizer

This study aimed to investigate the effects of volume ratio in the continuous phase and the dispersed phase (CP/DP) and stirring speed on yield, water absorption, particle size, morphology surface, and cumulative release of nitrogen from the chitosan microsphere. The chitosan microsphere preparation method was emulsion cross-linking with glutaraldehyde saturated toluene (GST) as the cross-linking agent. Urea was mixed with chitosan solution and put into the oil. It was then stirred to form an emulsion. Glutaraldehyde saturated toluene (GST) was added slowly, followed by 2 ml glutaraldehyde, stirred continuously for 2 h. The formed chitosan microsphere was eventually washed and dried to be analyzed. The yield obtained was about 87.01%-96.71%, the water absorption was 79.77%–89.25%, and the diameter size of chitosan microspheres was from 153.66 ± 26.35 μm to 179.39 ± 34.95 μm. The chitosan microspheres morphology were good sphericity even though there were irregular size. Cumulative release analysis was obtained from 32.38%–37.69% by release mechanism such as anomalous behavior (non-Fickian kinetics)

Design, Formulation and Characterization of Microspheres containing Mesalamine for the Treatment of Ulcerative Colitis

The purpose of the present study was to prepare, characterize and evaluate the colon-targeted microspheres of mesalamine for the treatment and management of ulcerative colitis (UC). Microspheres were prepared by the ionic-gelation emulsification method using tripolyphosphate (TPP) as cross linking agent. The microspheres were coated with Eudragit S-100 by the solvent evaporation technique to prevent drug release in the stomach. The prepared microspheres were evaluated for surface morphology, entrapment efficiency, drug loading, micromeritic properties and in-vitro drug release. The microspheres formed had rough surface as observed in scanning electron microscopy. The entrapment efficiency of microspheres ranged from 43.72% - 82.27%, drug loading from 20.28% - 33.26%. The size of the prepared microspheres ranged between 61.22-90.41μm which was found to increase with increase in polymer concentration. All values are statistically significant as p<0.05. The release profile of mesalamine from eudragit-coated chitosan micro-spheres was found to be pH dependent. It was observed that Eudragit S100 coated chitosan microspheres gave no release in the simulated gastric fluid, negligible release in the simulated intestinal fluid and maximum release in the colonic environment. It was concluded from the study that Eudragit-coated chitosan microspheres were promising carriers for colon-targeted delivery of Mesalamine.

Tenofovir Alafenamide Fumarate Microspheres, Process Parameters for Enhanced Permeability and Liver Targeting

Aims: Chronic hepatitis B (CHB) infection is a serious global health problem and one of the main causes of chronic liver disease, cirrhosis. Tenofovir Alafenamide Fumarate (TAF) is a prodrug of Tenofovir, a nucleotide analogue with limited oral bioavailability. TAF is considered to be a BCS Class III substance (high solubility, low permeability). The aim of the study was to develop the Tenofovir Alafenamide Fumarate (TAF) microspheres to improve permeability.
 Study design: Preparation and Evaluation of Microspheres.
 Place and Duration of Study: Department of pharmaceutics, Mallareddy Institute of Pharmaceutical Sciences, Affiliated to JNTUH, Hyderabad, Telangana, India, between January 2018 and June 2019.
 Methodology: TAF loaded chitosan microspheres were prepared by emulsion cross linking method using glutaraldehyde as cross-linking agent. The prepared microspheres were characterized by morphology, size distribution, encapsulation efficiency. The permeability study was evaluated by Ex-vivo permeation studies. The optimized formulation was subjected to FTIR studies to examine the Drug Excipient Compatibility.
 Results: Scanning Electron Microscopy (SEM) studies indicated that the microspheres are spherical in shape. The optimized formulation has average particle size of 11.00 ± 0.05 µm, the encapsulation efficiency 68
 ± 0.04% and the percentage (%) yield of 94%. FTIR studies indicated that the drug and polymer are compatable with each other. In Ex-vivo permeation studies of optimized formulation 80% of drug was permeated with in 60 min.
 Conclusion: TAF microspheres could improve the absorption by increasing the permeability.

Formulation, Characterisation and In vitro Cytotoxic Effect of Lens culinaris Medikus Seeds Extract Loaded Chitosan Microspheres.

The aim of present study was to formulate chitosan microspheres loaded with ethanolic extract of Lens culinaris Medikus (L.culinaris) seeds (ME) and to explore its anticancer potential against lung cancer (A549) cell line. Central composite design was applied to prepare and optimise the chitosan microspheres. The prepared microspheres were evaluated for its physicochemical characterisation, in vitro drug release and anti-cancer potential in vitro. L.culinaris loaded chitosan microspheres were prepared successfully with suitable particle size, entrapment efficiency and drug release. The developed ME were spherical shaped with the particle size of 2.08 μm. The drug entrapment efficiency and cumulative drug release was found 1.58±0.02% and 81.95±0.35%, respectively. Differential scanning calorimetry studies revealed no interaction between drugs and polymers used. The cytotoxic effect of the optimised formulation revealed a significant response as compared to the ethanolic extract of L.culinaris seeds (IC50: 22.56 μg/ml vs. 63.58 μg/ml), which was comparable to that of reference drug, doxorubicin (22 μg/ml). These observations demonstrate that the optimised microspheres are effective against lung cancer (A549) cells. The significant cytotoxic response of the developed microspheres may be attributed due to its low particle size, high entrapment efficiency and prolonged drug release profile.

Degradation-Dependent Controlled Delivery of Doxorubicin by Glyoxal Cross-Linked Magnetic and Porous Chitosan Microspheres.

Glyoxal cross-linked porous magnetic chitosan microspheres, GMS (∼170 μm size), with a tunable degradation profile were synthesized by a water-in-oil emulsion technique to accomplish controlled delivery of doxorubicin (DOX), a chemotherapeutic drug, to ensure prolonged chemotherapeutic effects. The GMS exhibit superparamagnetism with saturation magnetization, Ms = 7.2 emu g–1. The in vitro swelling and degradation results demonstrate that a swelling plateau of GMS is reached at 24 h, while degradation can be modulated to begin at 96–120 h by formulating the cross-linked network using glyoxal. MTT assay, live/dead staining, and F-actin staining (actin/DAPI) validated the cytocompatibility of GMS, which further assured good drug loading capacity (35.8%). The release mechanism has two stages, initiated by diffusion-inspired release of DOX through the swollen polymer network (72 h), which is followed by a disintegration-tuned release profile (>96 h) conferring GMS a potential candidate for DOX delivery.

Preparation and characterization of chitosan/polyvinyl porous alcohol aerogel microspheres with stable physicochemical properties

Chitosan/polyvinyl alcohol (CS/PVA) porous aerogel microspheres with stable physicochemical properties were obtained by gelation and freeze-drying process, and modified by adding different content of polyvinyl alcohol (PVA) into the microspheres. The physicochemical properties of porous aerogel microspheres, including porosity, swelling degree, acid-base resistance and compression performance were compared with chitosan (CS) microspheres. The microspheres were characterized by scanning electronic microscopy, Fourier transform infrared spectra, X-ray diffraction and compression test. The results showed that the structure of hybrid aerogel microspheres could be controlled by adjusting the content of PVA. The increase of PVA content reduced the pore size of CS/PVA porous aerogel microspheres, promoted the roughness of the surface and formed more orderly pore distribution. The higher PVA content was, the greater the swelling degree of the CS/PVA porous microspheres was. Adding proper amount of PVA into the CS/PVA microspheres could improve their acid resistance, but reduce their alkali resistance. Furthermore, the porosity of CS/PVA microspheres containing 33.3% PVA was the highest (78.3%) and the best compression strength (0.0505 MPa) when compression depth was 60% of the maximum height.

Facile synthesis of magnetic CS-g-SPSS microspheres via electron beam radiation for efficient removal of methylene blue

Efficient adsorption and separation of organic dyes in the wastewater is highly desirable for environmental protection. A facile synthesis of magnetic bio-based chitosan (CS) microspheres grafted with sodium polystyrene sulfonate (SPSS) via electron beam radiation is described. The obtained microspheres were characterized by FTIR, SEM, TG and VSM, which demonstrated millimetric magnetic CS-g-SPSS microspheres were obtained with enhanced thermal stability. Experimental parameters such as absorbed dosage, mass ratio, initial pH, initial concentration and contact time for the adsorption were thoroughly investigated. To investigate the adsorption rate and recyclability, evaluation of adsorption kinetic model and adsorption/desorption experiment were conducted.

Superhydrophobic Surface for Enhancing the Bioavailability of Salbutamol Sulfate from Cross-Linked Microspheres: Formulation, Characterization, and in vivo Evaluation.

IntroductionThe aim of the work was to formulate salbutamol sulfate (SB) microspheres by using superhydrophobic surface (SHS) under different processing factors for improving its encapsulation efficiency, controling its release rate, and hence enhancing its bioavailability.MethodsCross-linked microspheres of chitosan (CN) and carrageenan (KN) were made on a SHS under a glutaraldehyde-saturated atmosphere. The formulations were designed and optimized based on 42 factorial design. Percentage encapsulation efficiency (%EE), particle size, swelling ratio, and in vitro release rate were characterized, and the in vivo performance of optimized formula was investigated in beagle dogs.ResultsThe results showed that the prepared microspheres have a high %EE (97.11±0.78%) for F13. The swelling ratio was 4.2 at the end of the 8 hours for the optimized formula, and the in vitro release rate was controlled for 12 hours. In vivo study verified that there was a 1.61-fold enhancement in SB bioavailability from optimized formula (F13) compared to market tablet.ConclusionThe study suggested that microspheres prepared from CN/KN crosslinking on an SHS using glutaraldehyde atmosphere is a promising technique that can encapsulate and sustain the release of water-soluble drugs such as SB in addition to improving its in vivo pharmacokinetic profile.

Synthesis of chitosan-lysozyme microspheres, physicochemical characterization, enzymatic and antimicrobial activity

Chitosan microspheres (CMS) by the emulsion-chemical cross-linking method with and without lysozyme immobilization were synthesized and characterized. The technique conditions were adjusted, and spherical particles with approximate diameters of 3.74 ± 1.08 μm and 0. 29 ± 0.029 μm to CMS and chitosan-lysozyme microspheres (C-LMS), respectively, were obtained. The microspheres were characterized by scanning electron microscopy (FESEM), Spectroscopy Fourier Transform Spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and zeta potential. Particle size was identified by laser light scattering (DLS) and the thermal properties by Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA) were determined. By the lysis of Micrococcus lysodeikticus, the activity of the microspheres was determined, and the results correlated with the amount of lysozyme used in the immobilization process and the enzyme loading efficiency was 67%. Finally, release tests pointed out the amount of enzyme immobilized on the microsphere surface. These results showed that chitosan microspheres could be used as material for lysozyme immobilization by cross-linking technique. The antimicrobial activity was tested by inhibition percent determination, and it evidenced both chitosan microspheres (CMS) and chitosan-lysozyme microspheres (C-LMS) positive antimicrobial activity to Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa.

A new pH-sensitive CS/Zn-MOF@GO ternary hybrid compound as a biofriendly and implantable platform for prolonged 5-Fluorouracil delivery to human breast cancer cells

In the current work, we investigated and compared the capability of the monodispersed chitosan (CS) microspheres, CS coated zinc-based metal-organic framework (CS/Zn-MOF) microspheres, and CS coated the hybrid of Zn-MOF with graphene oxide (CS/Zn-MOF@GO) microspheres as an anticancer drug carrier. The prepared samples were characterized through the common characterization techniques. The morphologies, sizes, and drug loading efficiency of the prepared compounds respectively were well-characterized, obtained, and compared with each other. The scanning electron microscopy (SEM) analysis displayed the particle size of the prepared microspheres in the range of 20–40 µm. The highest amount of 5-fluorouracil (5-Fu) loading was found for the ternary hybrid of CS/Zn-MOF@GO microspheres; ~45%. The 5-Fu loaded CS microspheres (5-Fu@CS/Zn-MOF@GO microspheres) with rough surfaces exhibited a pH-sensitive and sustained release pattern for loaded 5-Fu. So, the cumulative drug release amount at pH 5.0 was relatively two times greater than pH 7.4. Eventually, CS/Zn-MOF@GO microspheres exhibited acceptable enzymatic biodegradability and also good biocompatibility toward MDA-MB 231 cells line as an epithelial, human breast cancer cell. 41.2% cell viability after 48 treatment with 5-Fu@CS/Zn-MOF@GO microspheres confirmed the capability of 5-Fu loaded CS/Zn-MOF@GO microspheres in the tumor cell treatment. Based on the founded interesting results the CS/Zn-MOF@GO ternary hybrid microspheres could be proposed as a promising and hopeful candidate to applied in the localized anticancer delivery.

Synthesis of 3D calcium-modified microspheres for fast purification of simulated phosphate wastewater

Adsorption is one of the most promising techniques for large-scale application in phosphate-containing wastewater treatment and the synthesis of efficient adsorbents is the core of the process. High efficiency adsorbent include inorganic adsorbents and organic adsorbents, and the chitosan performs better adsorption capacity because of readily biodegradable and abundant amino functional groups. In this work, a kind of calcium-modified chitosan microspheres (Ca-CTS gel) has been gained through in-situ precipitation for absorbing phosphate from simulation wastewater. The influence factors of the synthesis conditions including crosslinking agent addition, mental ions types, and Ca2+ loading amount, etc., on the adsorption efficiency have been researched. The results showed that the metal ions modified chitosan represented by La3+ modified chitosan was significantly different from Ca2+ modified chitosan in loading principle. The characterization results indicated that the adsorption mechanism belonged to the precipitation conversion between Ca(OH)2 and CaHPO4·2H2O. The adsorption kinetics and thermodynamics results showed that the adsorption reaction was endothermic and spontaneous, and the Langmuir-fitted maximum adsorption capacity was 23.7 mg/g at 25 °C. The adsorption experiment results also showed that the other anions, i.e., SO42− and CO32− have a negative influence on phosphate removal, attributing to the smaller Ksp values of their calcium salts. In addition, the dynamic phosphate-adsorption curves have been obtained under different operating conditions for evaluating the industrial application prospect of the as-prepared Ca-CTS gel.

Immobilizing of palladium on melamine functionalized magnetic chitosan beads: A versatile catalyst for p-nitrophenol reduction and Suzuki reaction in aqueous medium

In this study, an environmental-friendly palladium catalyst with high efficiency, magnetic, recoverability, reusability, and excellent stability was prepared and thoroughly characterized by the Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), X-ray diffraction (XRD), Elemental mapping, Thermogravimetric analysis (TGA) and Energy-dispersive X-ray spectroscopy (EDX). Results demonstrates that melamine provides a coordination point on the surface of chitosan microspheres, which provides a platform for the uniform distribution of palladium (II) and combines with palladium (II) firmly to avoid unnecessary leaching of nanoparticles. Besides, Fe3O4/CS-Me@Pd microcapsules exhibited high catalytic performance in reducing p-NP in water at room temperature (150–300 s). This composite was also effective in the Suzuki-Miyaura coupling reaction under mild conditions with high catalytic performance (TON = 3.8 × 104, TOF = 7.6 × 104). Reproducibility experiments also showed that Fe3O4/CS-Me@Pd microcapsules have high recovery efficiency and can work at least six times during these two catalytic reactions. The hot filtration test indicated that the catalyst has heterogeneous nature.

High specific immobilization of His-tagged recombinant Microbacterium esterase by Ni-NTA magnetic chitosan microspheres for efficient synthesis of key chiral intermediate of d-biotin.

The novel Ni-NTA-functionalized magnetic chitosan microspheres (MCS-NTA-Ni) were prepared via amino functionalization of MCS with epichlorohydrin and ethylenediamine, followed by the introduction of the aldehyde groups and NTA in turn, and nickel (II) ions were chelated in the end. MCS-NTA-Ni contained numerous long-armed NTA-Ni surface groups, ensuring high enzyme loading and providing more space and flexibility to attach enzymes and maintain their activity. This microsphere can have highly selective adsorption of his-tagged recombinant protein. The his-tagged recombinant Microbacterium esterase of E. coli BL21 (DE3)/pET21a-EstSIT01 was first immobilized on MCS-NTA-Ni by affinity fixation, giving high immobilization yield (90.1%) and enzyme loading (120mg/g). Compared with free esterase, the immobilized esterase was found to exhibit higher pH stability and thermal stability. In addition, the immobilized esterase had excellent reusability for the synthesis of key chiral intermediate of d-biotin and the substrate conversion could still keep 100% after 8 cycles continuously.

Preparation of Freeze-Dried Porous Chitosan Microspheres for the Removal of Hexavalent Chromium

Novel porous chitosan microspheres were successfully produced by a freezing–lyophilization drying method in this study and were then used as adsorbents to remove a toxic iron metal, hexavalent chromium (Cr(VI)). The effects of the concentration of the chitosan solution, syringe diameter, and freezing time on the morphologies of porous chitosan microspheres were characterized. The metal ion adsorption for Cr(VI) was also studied. Results showed that freezing chitosan hydrogel beads at a temperature of −20 °C and subsequently lyophilizing the frozen structure allowed to easily obtain the porous chitosan microspheres with rough surfaces and large pores, which were more suitable for adsorption materials to remove metal ions. A chitosan solution concentration of 3% (w/v) and a syringe diameter of 500 μm allowed the porous microspheres to have a good sphericity, thinner pore walls, and small pore sizes. The adsorption capacity of porous chitosan microspheres for Cr(VI) increased with the increase in freezing time. The pH of the initial adsorption solution ranged from 3.0 to 5.0 and was beneficial to the maximum adsorption efficiency for Cr(VI). The porous chitosan microspheres prepared with 3% (w/v) chitosan solution at −20 °C for a freezing time of 72 h had a higher adsorption capacity of 945.2 mg/g for Cr(VI) than the those at 24-h and 48-h freezing times. Kinetic study showed that the adsorption process could be described by a pseudo-second order (PSO) kinetic model. The equilibrium adsorption rate constant and the adsorption amount at equilibrium for the porous chitosan microspheres increased with an increase in the freezing time, and those for the porous microspheres prepared with 3% chitosan solution at −20 °C for a 72-h freezing time were 1.83 × 10−5 g mg−1 min−1 and 1070.5 mg g−1, respectively. The porous chitosan microspheres have good potential to facilitate the separation and recycling of expensive and toxic Cr(VI) from wastewater.

Highly thermally conductive and eco-friendly OH-h-BN/chitosan nanocomposites by constructing a honeycomb thermal network

More than 110,000,000 tons of mismanaged plastics were to be produced in 2020. Polymers are favored in the preparation of thermally conductive materials due to their excellent comprehensive properties. However, most polymers fabricated for thermally conductive materials are difficult to degrade in the natural environment. To alleviate the increasingly severe environmental problems, we reported a novel eco-friendly material with high thermal conductivity, which was composited of chitosan microspheres (CSM) and hydroxyl-functionalized hexagonal boron nitride (OH-h-BN) nanoplatelets. Utilizing their significant difference in scales, the OH-h-BN nanoplatelets were arranged between each CSM. Their overall structure was similar to the honeycomb: CSM were honeycomb cores, and OH-h-BN nanoplatelets were honeycomb network. The routine-structure OH-h-BN/CS nanocomposites were only 0.94 ± 0.02 W·m−1·K−1 at 50 wt% in thermal conductivity. However, the OH-h-BN/CSM nanocomposites with honeycomb structure can reach 5.66 ± 0.32 W·m−1·K−1 in the same loading, for enhancement of 502% and 1914% than OH-h-BN/CS nanocomposites and pure CS, respectively.