Zhongxin Lin,Renliang Huang,Jiangjiexing Wu,Anastasia Penkova,Wei Qi,Zhimin He,Rongxin Su
With excellent biocompatibility and unique physiochemical properties, nanocelluloses including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are promising candidates for preparing biomedical hydrogels. CNCs and CNFs are different in morphology and surface charges. Herein, CNCs and two CNFs (CNFs-C, Carboxylated CNFs; CNFs-P, Phosphorylated CNFs) were synthesized and applied to fabricate hydrogels through metal crosslinking. Aluminum crosslinking was found to be the best choice for enhancing the strength. This study systematically compared the morphologies, storage modulus, loss factor, continuous shear ramp, self-healing, swelling, in vitro degradation and injectable properties of the fabricated hydrogels. Further, a radar chart is summarized as guidelines to direct the rational selection to meet the specific requirements of further biomedical applications. At the same nanocellulose concentration and after Al 3+ crosslinking, CNCs hydrogels had strong water holding capacity twice as much as that of CNFs hydrogels. While CNFs hydrogels showed higher hardness and stronger resistance to degradation than that of CNCs. These results provide detailed insights into nanocellulose hydrogels, making it possible to use these guidelines to select hydrogels for desired performance.
Wenjuan Chen,Qingwen Lin,Suli Cheng,Min Wu,Yayu Tian,Kaiyu Ni,Yunshan Bai,Hongzhu Ma
Novel amphoteric microspheres adsorbents (HA x /CMC-yAl), based on carboxymethyl cellulose (CMC) modified with various amount of humic acid (HA) and cross-linker aluminum nitrate (Al(NO 3 ) 3 ), were synthesized facilely under mild conditions. Its adsorption properties toward representative cationic and anionic dyes were studied. The optimized adsorbent HA 1.0 /CMC-3Al was characterized and analyzed by fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, thermogravimetric analysis and Zeta potentials. The effects of types of dye substrates, contact time, initial dye concentration, pH of the solution, and adsorbent dosage, on cationic methylene blue (MB) and anionic orange II (ORII) removal were systematically investigated. The HA 1.0 /CMC-3Al showed pH-sensitive and the maximum adsorption capacities toward MB and ORII were 76.92 and 71.43 mg g −1 , respectively, within 300 min at pH 3 and 295 K. The swelling rate and the recylcing properties were also studied. The pseudo-second-order kinetic model and Langmuir isotherm provided better correlation with the experimental data for the adsorption of dyes onto HA 1.0 /CMC-3Al. The effects of coexistent NaCl and sodium dodecylbenzenesulfonate (SDBS) surfactant on a binary dye system (MB/ORII) were also investigated. The results indicated that the adsorption of dyes was inhibited by NaCl, while the adsorption of cationic dye was promoted by SDBS at given concentrations. In addition, the possible mechanism of adsorption process was proposed.
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