Investigating the synergistic effects of various amine groups on Zeolite-Y for CO2 capture.

Growing concern about global warming and greenhouse effects has led to persistent demands for increased energy efficiency and reduced carbon dioxide emissions. As a result, energy-intensive processing of carbon dioxide separation became imperative. Accordingly, energy-efficient, economically viable carbon dioxide separation technologies are sought as carbon dioxide capture options for future industrial process schemes. The article provides an overview of current technology for the separation of carbon dioxide, specifically focusing on adsorption. In this study, amine-loaded Zeolite-Y adsorbents were evaluated to enhance carbon dioxide adsorption capacity through synthesis, characterization, and the adsorption of carbon dioxide, within the context of current trends in separation technology. This study aims to study the ability of amine-loaded Zeolite-Y to adsorb carbon dioxide using three different loadings ethanolamine, diethanolamine, and triethanolamine. The amine-loaded materials were characterized by various technologies, including X-ray diffraction pattern (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and field emission scanning electron microscope (FESEM) studies. The study suggests that monoethanolamine-loaded Zeolite-Y is a promising and cost-effective adsorbent for carbon dioxide adsorption in comparison to other synthesized amine-loaded adsorbents. The adsorbent has been able to adsorb carbon dioxide in the range of 1.14-2.26 mmol g-1 at 303 K and 1 bar for a loading of 1, 5, and 10 wt.% amine groups.

Synergistic enhancement of CO2/N2 separation performance via Ce-MOF-infused chitosan mixed matrix membrane.

Reticular chemistry, exemplified by metal-organic frameworks (MOFs), has proven invaluable in creating porous materials with finely tuned structures to address critical global energy and environmental challenges. In this context, the need for efficient carbon dioxide (CO2) capture and utilization has taken center stage. One promising approach involves the integration of MOFs into polymer matrix to develop mixed matrix membranes (MMMs). In this work, cerium-based MOFs (Ce-MOF) were selected due to their robust CO2 capture capabilities, while chitosan (CS) was chosen as the polymer matrix due to its reasonably good selectivity and balanced CO2 permeance for the development of MMMs for CO2/N2 (20/80 vol%) separation. A comprehensive suite of analytical techniques, including FTIR, XRD, FESEM, XPS, TGA, EDX, FETEM, and BET, was applied for precise characterization of both the MOF and MMMs. Various operational parameters, such as Ce-MOF content and temperature, were systematically explored to investigate the CO2 capture efficiency of the synthesized MMMs. The results revealed that the optimized Ce-MOF-embedded CS MMMs consistently outperformed the bare CS membranes.

New generation mixed matrix membrane for CO2 separation: Transition from binary to quaternary mixed matrix membrane.

Contemporary advances in material development associated with membrane gas separation refer to the cost-effective fabrication of high-performance, defect-free mixed matrix membranes (MMMs). For clean energy production, natural gas purification, and CO2 capture from flue gas systems, constituting a functional integration of polymer matrix and inorganic filler materials find huge applications. The broad domain of research and development of MMMs focused on the selection of appropriate materials, inexpensive membrane fabrication, and comparative study with other gas separation membranes for real-world applications. This study addressed a comprehensive review of the advanced MMMs wrapping various facets of membrane material selection; polymer and filler particle morphology and compatibility between the phases and the relevance of several fillers in the assembly of MMMs are analyzed. Further, the research on binary MMMs, their problems, and solutions to overcome these challenges have also been discussed. Finally, the future directions and scope of work on quaternary MMM are scrutinized in the article.

A Strategical Improvement in the Performance of CO2/N2 Gas Permeation via Conjugation of L-Tyrosine onto Chitosan Membrane.

Rubbery polymeric membranes, containing amine carriers, have received much attention in CO2 separation because of their easy fabrication, low cost, and excellent separation performance. The present study focuses on the versatile aspects of covalent conjugation of L-tyrosine (Tyr) onto the high molecular weight chitosan (CS) accomplished by using carbodiimide as a coupling agent for CO2/N2 separation. The fabricated membrane was subjected to FTIR, XRD, TGA, AFM, FESEM, and moisture retention tests to examine the thermal and physicochemical properties. The defect-free dense layer of tyrosine-conjugated-chitosan, with active layer thickness within the range of ~600 nm, was cast and employed for mixed gas (CO2/N2) separation study in the temperature range of 25-115 °C in both dry and swollen conditions and compared to that of a neat CS membrane. An enhancement in the thermal stability and amorphousness was displayed by TGA and XRD spectra, respectively, for the prepared membranes. The fabricated membrane showed reasonably good CO2 permeance of around 103 GPU and CO2/N2 selectivity of 32 by maintaining a sweep/feed moisture flow rate of 0.05/0.03 mL/min, respectively, an operating temperature of 85 °C, and a feed pressure of 32 psi. The composite membrane demonstrated high permeance because of the chemical grafting compared to the bare chitosan. Additionally, the excellent moisture retention capacity of the fabricated membrane accelerates high CO2 uptake by amine carriers, owing to the reversible zwitterion reaction. All the features make this membrane a potential membrane material for CO2 capture.

Mixed Matrix Membranes for Carbon Capture and Sequestration: Challenges and Scope.

Carbon dioxide (CO2) is a major greenhouse gas responsible for the increase in global temperature, making carbon capture and sequestration (CCS) crucial for controlling global warming. Traditional CCS methods such as absorption, adsorption, and cryogenic distillation are energy-intensive and expensive. In recent years, researchers have focused on CCS using membranes, specifically solution-diffusion, glassy, and polymeric membranes, due to their favorable properties for CCS applications. However, existing polymeric membranes have limitations in terms of permeability and selectivity trade-off, despite efforts to modify their structure. Mixed matrix membranes (MMMs) offer advantages in terms of energy usage, cost, and operation for CCS, as they can overcome the limitations of polymeric membranes by incorporating inorganic fillers, such as graphene oxide, zeolite, silica, carbon nanotubes, and metal-organic frameworks. MMMs have shown superior gas separation performance compared to polymeric membranes. However, challenges with MMMs include interfacial defects between the polymeric and inorganic phases, as well as agglomeration with increasing filler content, which can decrease selectivity. Additionally, there is a need for renewable and naturally occurring polymeric materials for the industrial-scale production of MMMs for CCS applications, which poses fabrication and reproducibility challenges. Therefore, this research focuses on different methodologies for carbon capture and sequestration techniques, discusses their merits and demerits, and elaborates on the most efficient method. Factors to consider in developing MMMs for gas separation, such as matrix and filler properties, and their synergistic effect are also explained in this Review.

Synthesis of lignin from waste leaves and its potential application for bread packaging: A waste valorization approach.

In this study, lignin was synthesized from the waste leaves of Ficus auriculata obtained after the extraction of gallic acid. The synthesized lignin was incorporated into PVA films, and the neat and blended films were characterized using different techniques. Lignin addition improved the UV-shielding, thermal, antioxidant, and mechanical properties of PVA films. The water solubility decreased from 31.86 % to 7.14 ± 1.94 %, while the water vapor permeability increased from 3.85 ± 0.21 × 10-7 g.m.h-1 Pa-1 to 7.84 ± 0.64 × 10-7 g.m.h-1 Pa-1 for pure PVA film and the film containing 5 % lignin, respectively. The prepared films showed a much better performance than commercial packaging films in inhibiting mold growth during the storage of preservative-free bread. The bread samples packed with commercial packaging showed signs of mold growth on the 3rd day, while the growth was inhibited entirely till the 15th day for PVA film containing 1 % lignin. The pure PVA film and the ones containing 3 % and 5 % of lignin inhibited growth till the 12th and 9th day, respectively. Findings from the current study show that safe, cheap, and eco-friendly biomaterials can hinder the growth of spoilage microorganisms and potentially be used in food packaging.

Antioxidant-Incorporated Poly(vinyl alcohol) Coating: Preparation, Characterization, and Influence on Ripening of Green Bananas.

In this study, the gallic acid (antioxidant)-rich leaf extract of Ficus auriculata was incorporated into poly(vinyl alcohol) (PVA) and utilized as a coating to delay the ripening of green bananas. The films exhibited low opacity of 0.86 ± 0.014 for pure PVA (PP) and 0.92 ± 0.019, 0.99 ± 0.020, and 1.18 ± 0.029 for PVA + 1% extract (PE1), PVA + 5% extract (PE5), and PVA + 10% extract (PE10), respectively, indicating excellent transparency. The weight loss was higher in the uncoated group than in any coated fruits. The reduction in titratable acidity and the increase in total soluble sugars were slower in all of the coated samples as compared to the uncoated ones. The fruits without any treatment attained complete maturity on the ninth day where the ion leakage was 85.61 ± 2.33% while that of PP was 56.36 ± 2.95% and those of PE1, PE5, and PE10 remained below 30%. The coated samples showed better retention and consequently slower degradation of chlorophyll. The fruits coated with pure PVA as well as 10% extract-incorporated PVA remained acceptable till day 15, while the ones with 1 and 5% of extract reached full ripeness on day 18. Results of the present investigation suggest that safe, low-cost, and environmentally friendly coatings can improve the shelf life of perishable produces like bananas.

Enrichment in CO2 Absorption by 2-Methyl Piperazine-Activated Tertiary Amines, Physical Solvents, and Ionic Liquid Systems.

One of the ever-demanding research fields is the development of new solvents with better properties for mitigation of CO2 compared to existing solvents. This work reports the measurement and modeling of CO2 solubility in newly proposed aqueous solvent blends of 2-methyl piperazine with N-methyldiethanolamine (MDEA), sulfolane (TMSO2), and 1-butyl-3-methyl-imidazolium acetate ([bmim] [Ac]). The operating temperature and CO2 partial pressure conditions chosen were 303.2-323.2 K and 2-370 kPa, respectively. Along with this, qualitative 13C NMR and FTIR analysis were also performed to consider the proposed reaction scheme. The experimental vapor-liquid equilibrium data were modeled by a modified Kent-Eisenberg equilibrium model. The equilibrium constants associated with 2-methyl piperazine (2-MPZ) and [bmim] [Ac] deprotonation and carbamate formation reactions were regressed to fit the experimental CO2 solubility data. In addition, the CO2 cyclic capacity and heat of absorption were evaluated for the aq (MDEA + 2-MPZ) blend.

Composite Scaffolds Based on Bacterial Cellulose for Wound Dressing Application.

Wound dressing materials fabricated using biocompatible polymers have become quite relevant in medical applications, and one such material is bacterial cellulose (BC) with exceptional properties in terms of biocompatibility, high purity, crystallinity (∼88%), and high water holding capacity. However, the lack of antibacterial activity slightly restricts its application as a wound dressing material. In this work, polycaprolactone (PCL) was first impregnated into the BC matrix to fabricate flexible bacterial cellulose-based PCL membranes (BCP), which was further functionalized with antibiotics gentamicin (GEN) and streptomycin (SM) separately, to form wound dressing composite scaffolds to aid infectious wound healing. Fourier transform infrared spectroscopy (FT-IR) results confirmed the presence of characteristic PCL and cellulose peaks in the composite scaffolds at 1720 cm-1, 3400 cm-1, and 2895 cm-1, respectively, explaining the successful interaction of PCL with the BC matrix, which is further corroborated by scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies revealed the formation of highly crystalline BCP films (∼86%). In vitro studies of the BC and BCP scaffolds against baby hamster kidney (BHK-21) cells revealed their cytocompatible nature; also the wettability studies indicated the hydrophilicity of the developed scaffolds, qualifying the main criterion in wound dressing applications. Energy dispersive X-ray analysis (EDX) of the drug loaded scaffolds showed the presence of sulfur in the composites. The prepared scaffolds also exhibited excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. The release profiles initially indicated a burst release (6 h) followed by controlled release of GEN (∼42%) and SM (∼58%) from the prepared scaffolds within 48 h. Hence, these results interpret that the prepared drug-functionalized cellulosic scaffolds have great potential as a wound dressing material in biomedical applications.

Engineering of graphene quantum dots by varying the properties of graphene oxide for fluorescence detection of picric acid.

The study examines the effect of different forms of graphene oxide (GO) on the synthesis of graphene quantum dots (GQD). GO synthesized at various temperatures i.e. 30, 50, 110 °C possessed different structural and functional properties and was used as a substrate for GQD preparation. Thorough characterization of the GQDs in terms of their structural, morphological, functional, and optical properties was performed. The GQDs exhibited variation in their size and fluorescence properties depending upon the type of GO used. Hydrothermal reduction of GO, prepared at an oxidation temperature of 50 °C (GO-50), minimized the particle size (3.6 nm) and maximized the photoluminescence (PL) intensity and quantum yield (64.8%) of the GQD (GQD-50). GQD-50 was found to detect picric acid (PA) in an aqueous solution via 'turn-off' fluorescence quenching, unlike the other GQDs where the initial precursor is synthesized at 30, 110 °C. Experimental studies summarize that interaction between the fluorophore-quencher resulted in static quenching. The limit of detection was estimated to be 1.2 µM with a detection range of 0-200 µM. The work concludes that optimization of the substrate i.e. GO can result in the development of a simple, non-toxic, cost-effective GQD based sensor for PA detection. The study eliminates the need for doping/functionalization of GQDs as reported previously, and hence finds a promising impact on the development of sensors.

Advancements in visible light responsive MOF composites for photocatalytic decontamination of textile wastewater: A review.

Heterogeneous photocatalysis using metal-organic frameworks (MOFs) is expected to provide a pivotal solution for the remediation of toxic dyes and heavy metals from textile wastewater. However, MOFs often suffer from a low removal efficiency, due to the rapid recombination between holes and electrons, generated upon photoexcitation. Additionally, the MOFs exhibit poor water stability, which restricts their large-scale application. In this regard, various approaches (i.e. doping of metal nanoparticle, semiconductor, quantum dot, and ligand functionalization) have been adopted for the formation of multifunctional composites. The MOF-composites possess suitable photochemical, surface, optical, and electronic properties, resulting in enhanced water stability, visible light absorption, and reduced recombination between photogenerated species. This comprehensive review targets to provide an insight into the synthesis and subsequent application of various MOF composites for photocatalytic removal of organic contaminants (dyes) and inorganic (Cr(VI)) contaminants from water. MOFs/graphene oxide composites possess improved surface area and reusability whereas noble metal incorporated MOFs composites suffer from photocorrosion and are relatively costly. Zr and Ti based MOFs exhibit tuning from UV to visible light response and surpass the poor water stability upon binary/ternary composite formation. The role of the dopants in enhancing the efficiency of the composites; the effect of influencing factors such as solution pH, pollutant concentration; the mechanism, and the kinetics of reactions have been outlined. In spite of many advancements, the article also summarizes some roadblocks that need to be unraveled to achieve the energy-water-environment nexus and scope for future breakthrough research in this field.

Synthesis of highly fluorescent, amine-functionalized carbon dots from biotin-modified chitosan and silk-fibroin blend for target-specific delivery of antitumor agents.

Carbon dots (CDs) have been a promising theranostic tool with high biocompatibility and a tailorable fluorescence profile. Herein, we report the synthesis of highly fluorescent amine-functionalized CDs from low molecular weight chitosan (LMWC) and silk-fibroin (SF) blends. The synthesized CDs were quasi-spherical in shape with a size of 3 ± 1.5 nm. A significant increase in fluorescent intensity and quantum yield was achieved upon increasing the SF content due to nitrogen doping. For inducing target specificity to cancer cells, biotin was covalently conjugated to the CDs, and the conjugation was determined by FTIR spectroscopy. The conjugate was further loaded with 5-fluorouracil (5-FU) as a model anti-cancer drug. The MTT assay showed increased cytotoxicity of the conjugated CDs in cancer cells compared to normal cells. The live-cell imaging in MCF-7 cell lines showed bright blue-colored fluorescence and increased internalization of the conjugated CDs than the non-conjugate ones due to receptor-mediated endocytosis.

A review on chitosan-based membranes for sustainable CO2 separation applications: Mechanism, issues, and the way forward.

Effective carbon dioxide (CO2) separation by nominal energy utilization is the factual attempt in the present era of energy scarcity and environmental calamity. In this perspective, the membrane- based gas separation technology is a budding endeavour owing to its cost -effectiveness, ease of operational maintenance and compact modular design. Among various membrane materials, bio-based polymers are of interest as they are abundant and can be obtained from renewable resources, and can also reduce our dependency on exhaustible fossil fuel-based sources. In this review, the structure-property relationship of chitosan and some of its film-forming derivatives has been critically studied for the first time in view of the fundamental properties required for gas separation applications. Various factors affecting the gas permeation performance of chitosan-based membranes have been highlighted along with prospects and propositions for the design of a few novel bio-based membranes based on the exhaustive analyses.

Engineering of Interfacial Energy Bands for Synthesis of Photoluminescent 0D/2D Coupled MOF Heterostructure with Enhanced Selectivity toward the Proton-Exchange Membrane.

Engineering of the interface for tuning the structural, functional, and electronic properties of materials via the formation of heterostructure composites exhibits immense potential in the current research scenario. This study reports a novel ternary composite synthesized by decoration of zero-dimensional Pd nanoparticles (NPs) and two-dimensional (2D) graphite oxide (GO) sheets in the UiO-66 metal-organic framework (MOF). A mixed matrix membrane was fabricated by incorporating this composite in the SPEEK polymer matrix, which exhibited higher selectivity compared to commercial Nafion 117. The synthesized composite and fabricated membranes were thoroughly characterized in terms of their chemical structures, microstructural morphologies, physicochemical, thermal, photo-electrochemical, and optical properties, ion-exchange capacity, proton conductivity, and methanol permeability. As per our knowledge, this is the first study which explores the effect of noble metal NPs and carbon 2D material simultaneously on the electronic structure of the MOF, resulting in improved selectivity. The electron-accepting nature of GO and surface plasmon resonance effect of Pd alter the energy band positions and scavenge the electrons, improving the proton conduction of the composite. The introduction of oxygen vacancies in lattice leads to efficient charge separation. The formation of a Schottky junction results in the localized electric field effect due to electron density fluctuation which aids in ion transport. The current study opens up a new route to overcome the major challenge associated with direct methanol fuel cells (DMFCs), that is, high/low methanol crossover by improving the proton conduction.

Synthesis of functionalized silk-coated chitosan-gold nanoparticles and microparticles for target-directed delivery of antitumor agents.

Chemically modified biopolymers derived nanomaterials have shown great potential in drug delivery and live-cell imaging. We have developed two materials, doxorubicin-loaded chitosan-gold nanoparticles and beads, both embedded with functionalized silk fibroin. Nanoparticles with size 8 ± 3 nm were synthesized using chitosan as reducing and stabilizing agent. Beads with 900-1000 µm size were formulated by the ionic gelation technique. Both the materials were coated with functionalized silk fibroin for targeted and sustained drug release properties. The coated materials showed retarded drug release compared to the uncoated ones. The cytotoxicity was assessed in HeLa cell lines, which demonstrated a maximum dose-dependent decrease in cell viability for the cells treated with folate conjugated silk fibroin coated nanoparticles. The live-cell imaging of the nanoparticles unveiled the increased cellular uptake of the coated materials by seven folds than the uncoated ones. Thus, functionalized silk coated materials can be effective drug delivery tools for targeted and sustained drug release.

Fabrication and Performance Evaluation of Industrial Alumina Based Graded Ceramic Substrate for CO2 Selective Amino Silicate Membrane.

The present study mainly focuses on the careful design of an amino-silicate membrane integrated on an asymmetric graded membrane substrate, comprised of a cost-effective macroporous industrial alumina based ceramic support with a systematic graded assemblage of sol-gel derived γ-alumina intermediate and silica-CTAB sublayer-based multilayered interface, specifically dedicated for the separation of CO2 gas from the binary gas mixture (CO2/N2) under nearly identical flue gas atmospheric conditions. The tailor-made industrial α-alumina-based porous ceramic support has been characterized in terms of apparent porosity, bulk density, flexural strength, microstructural feature, pore size, and its distribution to demonstrate its application feasibility toward the evolution of the subsequent membrane structure. The near surface morphology of the subsequent intermediate and submembrane layer has been carefully controlled via precisely scheming the colloidal chemistry and consequently implementing it during the deposition process of the respective γ-alumina and silica-CTAB precursor sols, whereas the potentiality of the quarantined amine groups in the final amino-silicate membrane has been methodically optimized by the appropriate heat treatment process. Finally, the real-time applicability of the hybrid amino-silicate membrane has been evaluated in terms of systematic analysis of the binary gas (CO2/N2) separation performance under variable operating conditions. The investigated ceramic membrane exhibited optimum CO2 permeance of 46.44 GPU with a CO2/N2 selectivity of 12.5 at 80 °C under a trans-membrane pressure drop of 0.8 bar having a feed and sweep side water flow rate of 0.03 mL/min, which shows its performance reliability at nearly identical flue gas operating conditions.

pH Responsive Carboxymethyl Chitosan/Poly(amidoamine) Molecular Gate Membrane for CO2/N2 Separation.

Efficient carbon dioxide separation is an emerging field of interest in the era of energy scarcity and environmental calamity. The present study focuses on the versatile aspects of carboxymethyl chitosan and dendrimer in terms of CO2 separation. A comprehensive study has been accomplished to inspect the physicochemical properties of the prepared membrane. The mixed gas (CO2/N2) separation performances have been measured varying the temperature (60-110 °C) and sweep/feedwater flow ratio (0.33-3). The blend membrane containing 10 weight (wt.)% dendrimer presented highest CO2 permeance of ∼100 GPU and CO2/N2 selectivity ∼149 on maintenance of sweep/feedwater flow ratio 2.33 and 1.67, respectively, at an operating temperature of 90 °C. The remarkable performance displayed by the membrane has been explained with reference to the dendrimer molecular gate mechanism and the salting out effect offered by carboxymethyl chitosan matrix.

Thermally induced characterization and modeling of physicochemical, acoustic, rheological, and thermodynamic properties of novel blends of (HEF + AEP) and (HEF + AMP) for CO2/H2S absorption.

CO2 and H2S removal from flue gases is indispensable to be done for protection of environment with respect to global warming as well as clean air. Chemical absorption is one of the most developed and capable techniques for the removal of these sour gases. Among the many solvents, ionic liquids (ILs) are more capable due to their desirable green solvent properties. However, ILs being usually costlier, the blends of ILs and amines are more suggestive for absorption. In the present work, various essential characterization properties such as density, viscosity, sound velocity, and refractive index of two ionic liquid-amine blend systems viz. (1) 2-Hydroxy ethyl ammonium formate (HEF) + 1-(2-aminoethyl) piperazine (AEP) and (2) 2-Hydroxy ethyl ammonium formate (HEF) + 2-Amino-2-methyl-1-propanol (AMP) are reported. The temperature range for which all the measurements were conducted is 298.15 to 333.15 K. For both systems of (HEF + AEP) and (HEF + AMP), HEF mass fractions were varied from 0.2 to 0.8.The density and viscosity results were correlated as a function of temperature and concentration of ionic liquid and amine with Redlich-Kister and Grunberg-Nissan models, respectively. Moreover, feed forward neural network model (ANN) is explored for correlating experimentally determined sound velocity and refractive index data. The measured properties are further analyzed to estimate various thermodynamic as well as transport properties such as diffusivity of CO2/H2S in the (HEF + AEP) and (HEF + AMP), thermal expansion coefficients, and isentropic compressibility, ΔG0, ΔS0, ΔH0, using the available models in the literature.

Graphene Quantum Dots-Doped Thin Film Nanocomposite Polyimide Membranes with Enhanced Solvent Resistance for Solvent-Resistant Nanofiltration.

The core of the organic solvent nanofiltration (OSN) technology is solvent-resistant nanofiltration (SRNF) membranes. Till now, relative poor performance of solvent resistance is still the bottleneck of industrial application of SRNF membranes. This work reports a novel polyimide (PI)-based thin-film nanocomposite (TFN) membrane which was embedded with graphene quantum dots (GQDs) and showed an improved solvent resistance for OSN application. This kind of SRNF membrane, termed (PI-GQDs/PI)XA, was synthesized via serial processes of interfacial polymerization (IP), imidization, cross-linking, and solvent activation. The IP process was performed between an aqueous m-phenylenediamine solution doped with GQDs, having an average size of 1.9 nm, and an 1,2,4,5-benzenetetracarboxylic acyl chloride n-hexane solution on the PI substrate surface. The prepared (PI-GQDs-50/PI)X SRNF membranes without organic solvent activation achieved an ethanol permeance of nearly 50% higher than those of the GQD-free membranes under the same preparation conditions, while no compromise of the dye rejection was observed. Further, after the solvent activation using N, N-dimethylformamide (DMF) at 80 °C for 30 min, the ethanol permeance achieved about an 8-folds increment, from 2.84 to 22.6 L m-2 h-1 MPa-1. Interestingly, the rejection of rhodamine B also increased from 97.8 to 98.6%. A long-term permeation test of more than 100 h using rose bengal (RB, 1017 Da)/DMF solution at room temperature demonstrated that the synthesized (PI-GQDs-50/PI)XA membranes could maintain the DMF permeance and the RB rejection as high as 18.3 L m-2 h-1 MPa-1 and 99.9%, respectively. Moreover, the immersion test of the prepared (PI-GQDs-50/PI)XA SRNF membranes in both DMF and ethanol at room temperature for about one year also demonstrated the long-term organic solvent stability, indicating their good potential for OSN application.

Development of a photoresponsive chitosan conjugated prodrug nano-carrier for controlled delivery of antitumor drug 5-fluorouracil.

Controlled drug delivery offers improved therapeutic efficacy of the drugs while minimizing side effects. Biocompatible polymers and nanomaterials have emerged as effective carriers for the controlled delivery of drugs. We have synthesized a prodrug of 5-fluorouracil (5FU) covalently conjugated to low molecular weight chitosan (LMWC) via a photocleavable linker. The conjugate was designed to be cleaved under 365 nm UV-A radiations, which is regarded as relatively safe for the cells and release 5FU in a dose-dependent manner. The conjugate showed enhanced water solubility compared to LMWC and forms hydrogel and DMSO gel. The conjugate polymer was also fabricated into nanoparticles by ionic gelation technique. The size of the nanoparticles was found to be in the range 70-90 nm, thus should have the ability to penetrate into living cells. In vitro release study of 5FU from the conjugate showed controlled release of the antitumor drug over time. The synthesized nanoparticles and the gel, therefore, could be a good model for controlled release of antitumor drugs.