Cellulose is an important raw material used for the preparation of aerogel materials in life sciences. Cellulose aerogel's excellent biocompatibility, biodegradability, and nontoxicity combined with ...its multiple chemical functions make it an ideal carrier for drug delivery. Cellulose aerogels offer high porosity, large specific surface area, and ultra-light density. They can be used as drug carriers to improve bioavailability and drug loading. We reviewed the methods used to prepare cellulose aerogels with nanocellulose, renewable cellulose, and cellulose derivatives as raw materials. In addition, we described cellulose aerogels as a drug delivery carrier to inspire work in new drug delivery systems that intelligently use cellulose aerogels. Finally, we described the application prospects of intelligent and responsive cellulose aerogels in drug delivery systems.
Display omitted
•Kraft lignin was cationized with glycidyl-trimethylammonium chloride.•Reaction was optimized based on charge density and solubility of the product.•Cationic lignin was analyzed by ...FTIR, TGA, NMR, GPC and elemental analyzer.•Cationic lignin was used as a flocculant for dye removal from model wastewater.
The cationization of polymers was regarded as an effective method to improve their performance for various applications. In this work, the cationization of kraft lignin was investigated using glycidyl-trimethylammonium chloride (GTMAC) with kraft lignin in an aqueous solution under altered conditions. The conditions investigated were temperature, time, pH, GTMAC to lignin molar ratio, and lignin concentration. The optimized conditions based on charge density and solubility of cationic lignin were found to be 70°C, 1h, 12.5 pH, 2/1 GTMAC/lignin molar ratio, and 1.0wt.% lignin concentration. The solubility of the resulting cationic lignin reached 90% in 1wt.% lignin concentration and the charge density reached 1.10meq/g under the optimized conditions. The cationic lignin was characterized and compared with unmodified kraft lignin using elemental analysis, Fourier Transform Infrared (FTIR) spectrophotometer, proton nuclear magnetic resonance (1H NMR) and thermogravimetry (TGA) analysis in order to confirm the success of the grafting reaction. The cationic lignin was used as a flocculant for dye removal (Remazol Brilliant Violet, Reactive Black, and Direct Yellow) from model wastewater.
Temperature-responsive aerogels from hydroxypropyl methylcellulose (HPMC)-grafted N-isopropylacrylamide (NIPAM) were developed for the first time as a novel drug delivery system. The morphology and ...structure of temperature-responsive HPMC-NIPAM aerogels were characterized with scanning electron microscopy, Fourier-transform infrared, X-ray diffraction, and X-ray photoelectron spectroscopic analyses. Water-soluble 5-fluorouracil was used as a model drug to study drug loading and release. Drug release experiments demonstrated a sustained and controlled release behavior of the HPMC-NIPAM aerogels that were highly dependent on temperature. Meanwhile, the first-order kinetic model, Higuchi model, and Korsmyer–Peppas model were used to fit the sustained-release curve of drug-loaded aerogel revealing a sustained-release mechanism.
The presence of dyes in wastewater effluents made from the textile industry is a major environmental problem due to their complex structure and poor biodegradability. In this study, a cationic lignin ...polymer was synthesized via the free radical polymerization of lignin with 2-(methacryloyloxy) ethyl trimethyl ammonium chloride (METAC) and used to remove anionic azo-dyes (reactive black 5, RB5, and reactive orange 16, RO16) from simulated wastewater. The effects of pH, salt, and concentration of dyes, as well as the charge density and molecular weight of lignin-METAC polymer on dye removal were examined. Results demonstrated that lignin-METAC was an effective flocculant for the removal of dye via charge neutralization and bridging mechanisms. The dye removal efficiency of lignin-METAC polymer was independent of pH. The dosage of the lignin polymer required for reaching the maximum removal had a linear relationship with the dye concentration. The presence of inorganic salts including NaCl, NaNO₃, and Na₂SO₄ had a marginal effect on the dye removal. Under the optimized conditions, greater than 98% of RB5 and 94% of RO16 were removed at lignin-METAC concentrations of 120 mg/L and 105 mg/L in the dye solutions, respectively.
The application of natural polymers to hydrogel materials with stretchable and compressible properties has attracted more and more attention. However, hydrogel materials made of pure natural polymers ...are not only poor in mechanical properties, but also lack in stability and sensitivity in strain sensors. Herein, the ionic conductive lignin hydrogels with highly stretchable (tensile strain ∼525.1%) and compressible (compression strain ∼95%) performance were formulated by a simple solution blending method. The lignin-based hydrogel with ultra-self-adhesive properties was able to adhere to various hydrophobic or hydrophilic surfaces. The adhesion measured on stainless steel, plexiglass, and paper reached 307 kPa, 301 kPa, and 174 kPa, respectively. Moreover, lignin-based hydrogels can be used as reliable and stable strain sensors to respond to environmental stimuli. Good adhesion can make hydrogels closer to the skin, so as to more accurately detect human signals, and excellent ion conduction ability can meet the needs of monitoring wrist bending activities. Significantly, the various properties of lignin-based hydrogel can be controlled through rationally adjusting the chemical composition of the hydrogel. It was proved that lignin-based hydrogel with natural-based formulation, high mechanical properties, and adhesion performance has great application potential in flexible equipment.
•A facile strategy of designing lignin hydrogel is presented.•The ionic conductive lignin hydrogel has highly stretchable and compressible performance.•The hydrogel strain sensor with ultra-self-adhesive properties has high sensitivity in monitoring human motion.
Display omitted
•CMCh-based pH-responsive HBCC and H2ECC were synthesized.•Optimum reaction conditions: reaction time 4 h, nepoxy/n-NH2 3/1, temperature 80 °C.•Self-aggregate properties of HBCC and ...H2ECC are pH-responsive.•HBCC and H2ECC have non-cytotoxicity but show antibacterial activity.
Chitosan has attracted much attention in drug delivery, however, carboxymethyl chitosan (CMC)-based self-aggregated nanocarriers are seldom reported. In this paper, two kinds of CMC-based pH-responsive amphiphilic chitosan derivatives, N-2-hydroxylpropyl-3-butyl ether-O-carboxymethyl chitosan (HBCC) and N-2-hydroxylpropyl-3-(2-ethylhexyl glycidyl ether)-O-carboxymethyl chitosan (H2ECC), have been synthesized by the homogeneous reaction. The molecular structures were characterized by FTIR, 1H NMR and 13C NMR. The optimum reaction condition was obtained based on the data of 1H NMR spectrum: reaction time of 4 h, reaction temperature of 80 °C and nepoxyn-NH2 of 3/1, respectively. The XRD patterns showed the crystallinity of HBCC and H2ECC decreased due to the introduction of hydrophobic segments. The thermostability of HBCC and H2ECC was improved for the formation of heat-resistant stereo-complexed structures. The intermolecular hydrophobic interaction hindered the intermolecular mobility by increasing glass transition temperature of ca. 10 °C. Both HBCC and H2ECC have very low critical aggregation concentrations (HBCC: 0.66–1.56 g/L, H2ECC: 0.57–1.07 g/L) and moderate aggregate particle size, which is advantageous for utilization as a drug carrier. The curcumin loaded HBCC and H2ECC aggregates showed nontoxicity, meanwhile, HBCC and H2ECC showed good antibacterial activity against Staphylococcus aureus and Escherichia coli. As a result of these two favorable properties, HBCC and H2ECC could be used as curcumin nanocarriers as well as antibacterial agents.
Nanocellulose is a renewable material with excellent properties. At present, nanocellulose powder is mainly prepared by high-cost spray drying, which severely limits its output and quality. In this ...paper, we propose an innovative method to prepare dispersible nanocellulose powder by simple precipitation and conventional evaporation. Potassium acetate was added to CNC (a kind of nanocellulose) suspension to precipitate and purify CNC. The added potassium acetate was dissolved in ethanol and removed. Then dispersible nanocellulose powder can be obtained by simple evaporation. In CNC purification, we discussed the combination of different electrolytes and CNCs. It was found that although the monovalent electrolytes lead to weak aggregation with CNC, the resulting dry CNC powder had the best dispersion. In CNC drying, we discussed the effects of different dispersants and different drying methods on the forming of dry CNC powder. It is revealed that ethanol is the best dispersant tested in this paper because it can only form a single hydrogen bond with CNC and is easy to evaporate. In the evaporation of CNC and ethanol mixture, it will not lead to the aggregation of CNC fibers. It is hopeful that the new method may greatly reduce the cost of the preparation of nanocellulose powder.
A type of zwitterionic chitosan derivative, N-2-hydroxylpropyl-3-trimethylammonium-O-carboxymethyl chitosan (HTCMCh), was synthesized and introduced into carboxymethyl cellulose (CMC)-based films as ...a film strength enhancer and antibacterial agent. The influencing factors include degree of substitution (DS) and mHTCMCh/mCMC. Their influences on mechanical properties, thermal stability, antibacterial activities, microstructures, transmittance, and wettability of the CMC-based films were studied. It was found that HTCMCh improves the tensile strength (by 9.0–130.9%), Young's modulus (47.8–351.6%), and elongation at break (90.8–280.8%) of CMC/HTCMCh films simultaneously, depending on the DS and mass content of HTCMCh. However, the HTCMCh shows little influence on microstructure and thermal stability of CMC/HTCMCh films. Satisfactorily, CMC/HTCMCh films show strong antibacterial activities against E. coli and S. aureus and are nontoxic to fibroblast HFF-1 cells. Pork packaging experiments demonstrated that CMC/HTCMCh10%,0,58 film could significantly inhibit bacterial growth, indicating that the HTCMCh-doped CMC films could be used as food packaging materials.
•HTCMCh enhances tensile strength, elongation at break and Young's modulus of CMC films simultaneously.•Interactions between CMC and HTCMCh play a key role in enhanced mechanical properties.•CMC/HTCMCh film inhibits bacterial growth on pork surface significantly.
Temperature/pH-responsive carboxymethyl cellulose/poly (
-isopropyl acrylamide) interpenetrating polymer network (IPN) aerogels (CMC/Ca
/PNIPAM aerogels) were developed as a novel drug delivery ...system. The aerogel has a highly open network structure with a porosity of more than 90%, which provides convenient conditions for drug release. The morphology and structure of the CMC/Ca
/PNIPAM aerogels were characterized via scanning electron microscopy (SEM), Micro-CT, X-ray photoelectron spectroscopy (XPS), pore size analysis, and cytotoxicity analysis. The analysis results demonstrate that the aerogel is non-toxic and has more active sites, temperatures, and pH response performances. The anticancer drug 5-fluorouracil (5-FU) was successfully loaded into aerogels through physical entrapment and hydrogen bonding. The drug loading and sustained-release model of aerogels are used to fit the drug loading and sustained-release curve, revealing the drug loading and sustained-release mechanism, and providing a theoretical basis for the efficient drug loading and sustained release.
This work was aimed to beneficiate biomass waste (lignin) to prepare a low-cost, ultralight, and high absorbent lignin-based aerogel via a facile and environmentally-friendly method that entailed ...blending of modified lignin with amine (LA) under high shear with polyvinyl alcohol (PVA) solution and followed by a freeze-drying process. Methyltriethoxy silicon (MTMS) was used as a silanization agent to improve the hydrophobicity of LA-PVA aerogel via chemical vapor deposition (CVD) reaction. The chemical and physical properties of the aerogel were then investigated using several characterization techniques such as Fourier transform infrared (FTIR) spectroscopy, elemental analysis, proton nuclear magnetic resonance (HNMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and thermogravimetric analysis. The hydrophobicity of the aerogels was satisfactory due to the formation of polysiloxane on the surface. The absorption capacity of oil and the organic solvent was varied between 2 and 12 times. The recycling experiments showed that after ten consecutive cycles, the separation efficiency was still above 90%, indicating a high recoverability. This was in addition to its other unique properties such as low density (0.1150 g/cm
3
), high porosity (88%), and satisfactory hydrophobicity (143°). Therefore, and based on the exceptional properties of the aerogel in terms of its reusability, oil/water separation efficiency, and mechanical properties render them ideal materials for application in oily wastewater treatment.
PDF
