Nanocellulose has the advantages of high strength,good biocompatibility and biodegradability.It is widely used in adsorption,drug loading,photoelectric sensing and other fields.At present,the preparation and application of nanocellulose based gel materials have attracted extensive attention.Physically crosslinked nanocellulose gel materials usually have the characteristics of good biocompatibility,green and environmental protection,but there is also a problem of poor strength,which limits their application.In this paper,it is mainly focuses on the design of nanocellulose based functional gel materials to improve their mechanical properties and apply to the fields of dye removal and drug delivery.(1)Cellulose nanofibril(CNF)based composite aerogels with high strength and high adsorption properties were fabricated using mussel biomimetic strategy.Firstly,the composite hydrogel material with stable three-dimensional structure was prepared by physical crosslinking method.Secondly,the obtained CNF hydrogel was modified by mussel-inspired modification method.Finally,polydopamine(PDA)modified nanocellulose composite aerogel(PCNF)was prepared by freeze-drying method.The results demonstrated that the PCNF composite aerogels had large surface areas(368.15 m~2/g)and low bulk density(27.2 mg/cm~3).The composite aerogels exhibited improved mechanical properties(375 k Pa),which were almost three times compared with pure CNF aerogel.Moreover,PCNF composite aerogel had good resilience under wet state.Due to the highly porous structure and the presence of a large number of amino groups,the adsorption capacity of the composite aerogels to methylene blue(MB)was significantly enhanced.The maximum adsorption of MB was 208 mg/g at an initial dye concentration of 50 mg/L.The adsorption isotherm and kinetic behaviors of the composite aerogel were consistent with Langmuir and pseudo-second-order model.In addition,the PCNF composite aerogels had a high adsorption capacity over a wide p H range.Finally,the reuse experiment showed that the removal ratio of the composite aerogel remained higher than 85%after 5 cycles.(2)ZIF-8@PCNF composite hydrogels with encapsulated structure were successfully prepared by one-pot method,and the drug loading capacity and drug release properties of the composite hydrogels were further investigated.Firstly,PCNF composite hydrogels were prepared using mussel biomimetic method.Then,the metal-organic-framework(ZIF-8)was grown in situ in the PCNF composite hydrogel structure(ZIF-8@PCNF composite hydrogel),while the hydrophobic drug curcumin(Cur)was loaded into the network framework of the gel.The experimental results showed that the maximum drug encapsulation efficiency and drug loading rate of composite hydrogel were 82 wt%and 4.5 wt%,respectively.The mechanical strength of the ZIF-8@PCNF composite hydrogel(58 k Pa)was 2.75 times greater than that of the PCNF hydrogel.Moreover,the drug delivery behavior could be accelerated by lower p H value and NIR light irradiation.In acid p H environment,the release time of ZIF-8@PCNF composite hydrogel was 3.57 times and 5.35 times of that of PCNF composite hydrogel and CNF hydrogel.Meanwhile,the drug delivery mechanism was verified as anomalous transport.More importantly,in vitro cytotoxicity experiment found that the ZIF-8@PCNF composite hydrogel had good biocompatibility toward normal BRL cells,while it had anticancer activity toward Hep G2 cells.Therefore,the as-fabricated ZIF8@PCNF composite hydrogel has potential application in cancer treatment. |