Preparation And Application Of Orgnanic-inorganic Hybrid Multifunctional Biomaterials Based On Nanocellulose Crystals

Gold nanoparticles have a wide range of applications in imaging,therapy,electrochemistry,diagnostics,and catalysis owing to its unique optical,electromagnetic,and catalytic properties.However,the high specific surface area and high surface energy of gold nanoparticles make them very easy to agglomerate,a variety of surfactants are usually used to protect them,but most surfactants are biologically toxic.Efficiently loading gold nanoparticles on some substrate materials is an effective solution.Cellulose is a rich polymer resource in nature which is also renewable,the nanocellulose crystals（CNC）made by removing the amorphous region is a nanometer scale material with rigid rod structure,high aspect ratio,low toxicity,and biodegradability.CNC is often used as template material and medical material in various fields,but CNC is very easy to agglomerate too due to the presence of a large number of ions in a physiological environment,which also limits its partial application.Polydopamine（PDA）,as a material with high biocompatibility and easy surface chemical modification,has been used as a coating material for various substrate materials.Using CNC as the substrate material,PDA as the coupling material,and then loading gold nanoparticles supplemented by related molecular modification to improve salt tolerance,a multifunctional organic-inorganic hybrid nanomaterials with excellent performance can be prepared.In this study,bleached softwood pulp was used as the raw material to produce CNC by TEMPO oxidation.PDA was wrapped on the surface of CNC by stirring method and ultrasonic method,and these two products were characterized and compared.The results show that ultrasonic method has obvious advantages.CNC@PDA prepared by ultrasonic method was used to prepare organic-inorganic hybrid nanoparticles loaded with different gold nanoparticles by electrostatic adsorption method and in-situ growth method,respectively.CNC@PDA@Au NPs prepared by adsorption method have a unique structure similar to gold nanoclusters,shows excellent photothermal effect in the near infrared region.The photothermal effect of CNC@PDA@Au NSs@PEG prepared by in-situ growth method in the near infrared region are more prominent,at the same time,it has a good photoacoustic signal response in the near infrared region,and also has a good ability to chelate Cu²⁺and Fe³⁺.