Research On Pulping Of Recycling Waste Cotton Textiles,the Fluorescent Functional Modification And Application

Waste cotton textiles are produced in large quantities,and the traditional treatment method will cause environmental pollution and resource waste.It is an effective way to construct functional materials of reclaimed fibers to prepare waste cotton fabrics into cotton fibers by chemical pulping process and to modify the reclaimed cotton fibers by functional modification.The regenerated fiber has good biocompatibility,biodegradability and low toxicity,and can be used in the fields of biology,medicine and materials.Fluorescent probe is an important tool in the field of biological detection,which can be used to trace and detect specific substances in organisms.In this paper,a series of fluorescence detection materials based on reclaimed cotton fibers and chitosan from waste cotton textiles were constructed in combination with fluorescence detection,which were applied to the fluorescence imaging detection of active species such as formaldehyde,hydrogen peroxide and carbon monoxide in the environment and in the body.（1）The traditional method of burning or burying waste cotton fabrics directly causes environmental pollution and resource waste.Therefore,after recycling waste cotton textiles,they are processed by cooking,grinding and bleaching.The influence of different conditions on the polymerization degree and whiteness of cotton pulp or cotton fiber was studied by changing the conditions.The effect of different grinding time on the broomization of cotton fibers was observed by scanning electron microscope and biological microscope.Finally,the cotton fiber with certain degree of polymerization and whiteness is obtained,which provides a good foundation for further modification application.（2）Formaldehyde as an indoor air pollutant poses a serious threat to human health owing to its high toxicity,wide distribution,and long release time.Therefore,the development of methods for the sensitive detection and removal of indoor formaldehyde is crucial.Based on reclaimed cotton pulp,a visual formaldehyde detection and removal method with high sensitivity to formaldehyde was constructed based on cotton cellulose（CC）.Owing to the presence of a highly sensitive ratiometric fluorescent probe RP,aerogel exhibited up to 600-fold fluorescence enhancement(F₅₄₀/F₄₅₀)in a formaldehyde-containing atmosphere.Moreover,the composition of aerogel was optimized,and the physical and formaldehyde response properties were examined via texture analysis,X-ray diffraction,scanning electron microscopy,and X-ray photoelectron spectroscopy（XPS）.Aerogel exhibited excellent formaldehyde adsorption capacity,and over 70%of the NH₂ group in the aerogel was consumed by formaldehyde,as indicated by the XPS and Fouriertransform infrared spectra.Additionally,RP exhibited a rapid fluorescence response and high selectivity toward formaldehyde in solusion.RP could successfully detect formaldehyde in live zebrafish with remarkable fluorescence changes.（3）Carbon monoxide（CO）is one of the most significant signal molecules and plays an important role in regulating human physiological and pathological processes.In this study,a novel Pd-based complex（Pd-BNP-OH）was developed for endogenous CO detection.The structure and morphology of Pd-BNP-OH was characterized by SEM,XPS,and NMR analyses.When Pd-BNP-OH was reacted with CO,a strong fluorescence enhancement at 510 nm was observed.In addition,Pd-BNP-OH exhibited high stability and selectivity toward CO in PBS buffer.Therefore,we prepared Pd-BNP-OH loaded cotton fiber paper based material to detect CO in the air.Moreover,In biological experiments,Pd-BNP-OH exhibited little cytotoxicity in cellular environment,and a bright fluorescence turn on was observed in the presence of exogenous CO and endogenous generated CO.The probe was then applied for CO detection in live zebrafish by both one-photon and two-photon excitation.Significantly,Pd-BNP-OH has excellent two-photon property,controllable structure and high biocompatibility.These features enable the probe to detect endogenously generated carbon monoxide in live organisms successfully.（4）Hydrogen peroxide（H₂O₂）acts as an important reactive oxygen species（ROS）and maintains the redox equilibrium in organisms.Imbalance of H₂O₂ concentration is associated with the development of many diseases.Traditional small molecular based fluorescent probes often show drawbacks of cytotoxicity and easily metabolic clearance.Herein,a chitosan-based two-photon fluorescent nanoprobe（DC-BI）was constructed and applied for H₂O₂ detection in live organisms.DC-BI was composed by chitosan nanoparticles and a two-photon fluorophore of naphthalimide analogues（BI）with H₂O₂-responsive property.The structure of DC-BI was characterized by NMR,FTIR,XPS,XRD,DLS and MLS analyses.As study shown,the nanoprobe DC-BI exhibited improved distribution stability and smaller cytotoxicity.In the presence of H₂O₂,both the absorption and emission spectra show dramatic changes,the fluorescence intensity at 580nm obviously enhanced.Furthermore,fluorescence imaging results indicate that DC-BI is capable of imaging endogenous H₂O₂in cells and zebrafish.The design and development of chitosan-based nanoprobe DC-BI has provided a general example of nanoprobe construction with excellent distribution stability,two-photon property,and biocompatibility.