Functional Design Of Cellulose Membranes And Its Application In Biosensor Field

With the development of society and times,the energy crisis and environmental protection pressure have become the two major constraints on the current social development.The depletion of non-renewable energy and environmental pollution caused by petroleum-based polymers has stimulated the demand for renewable resources.Natural polymers are considered to be an excellent alternative to petroleum-based products because of its reproducibility and biodegradability,etc.Among them,cellulose,as a natural polymer with the most abundant reserves in the natural world,has abroad applications in the field of biosensing and has attracted wide attention due to its properties of renewable,safe and non-toxic,low cost and biodegradability,etc.In this paper,cellulose was used as a matrix,and a series of functional modifications are made to cellulose through molecular design and synthesis strategies to prepare a series of functional cellulose composite membranes.The main contents are as follows:(1)Here,cellulose was used as a carrier,and the regenerated cellulose membrane(CM)was prepared from a cellulose solution dissolved in a sodium hydroxide/urea aqueous solution system.Then,the hydroxyl group on the cellulose membrane was modified by selective oxidation method to obtain the dialdehyde cellulose membrane,and glucose oxidase(GO_X)and horseradish peroxidase(HRP)were immobilized on the oxidized cellulose membrane by Schiff-base reaction.The morphology structure and physicochemical properties of composite membrane were analyzed by scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS),Fourier-transform infrared spectroscopy(FT-IR)and X-ray photoelectron spectroscopy(XPS),etc.The detection performance of the prepared cellulose-based composite membrane for low concentration of glucose in aqueous phase was systematically studied.The results showed that the prepared cellulose-based composite membrane had a good three-dimensional network porous structure,which could achieve rapid detection of lower concentrations of glucose in the aqueous phase,and the fastest response time was only 5 minutes.In addition,the cellulose-based composite membrane was also applied to the detection of glucose in real urine samples.The color on the cellulose-based composite membrane could be recorded and picked up by a mobile phone,which could achieve the semi-quantitative detection of glucose to a certain extent.(2)The cobalt nanoflakes synthesized by a simple redox method were chosen as the functional fillers,then,blended with the cellulose solution dissolved in the sodium hydroxide/urea aqueous solution system to prepare the cobalt nanoflakes/cellulose composite membrane(CCM)by the casting method.The morphology structure and physicochemical properties of the composite membrane were analyzed by SEM,FT-IR and X-ray diffraction(XRD),etc.The detection performance of the prepared cobalt nanoflakes/cellulose composite membrane for low concentration of ascorbic acid in aqueous phase was systematically studied.The results showed that the prepared composite membrane had a good three-dimensional network porous structure,lower detection limit and response time.It could achieve rapid detection of ascorbic acid at a lower concentration in the water phase,and ccould be applied to the ascorbic acid detection in real samples.(3)The quaternized cellulose solution was prepared through the principle that poxy groups of quaternary reagents reacted with the hydroxyl groups of the cellulose under alkaline conditions.And the quaternized cellulose membrane(QCM)was fabricated by the casting method.The gold nanoparticles nanoparticles(Au NPs)was synthesized by the citrate reduction method,and the gold nanoparticles were attached to the quaternized cellulose membrane by electrostatic interaction to obtain the gold nanoparticles/cellulose composite membrane(Au-QCM).The morphology structure and physicochemical properties of composite membrane were analyzed by SEM,FT-IR and XRD,etc.The detection performance of the prepared gold nanoparticles/cellulose composite membrane for low concentration of glucose in aqueous phase was systematically studied.The results showed that the prepared composite membrane had a good three-dimensional network porous structure,which could achieve rapid detection of lower concentrations of glucose in the aqueous phase.In addition,the gold nanoparticles/cellulose composite membrane had also been applied to the detection of glucose in real fruit samples.In summary,a series of functionalized cellulose composite membranes were designed with good stability,easy operability and practicality in this paper,it has a broad application prospects in the field of biosensors.