Development Of Functionalized Hydrogel Materials And Their Application In The Field Of Analysis And Detection

Hydrogel is a new type of material with a three-dimensional network structure that combines flexibility,stretchability and conductivity.Unlike rigid materials,hydrogels generally have a water content of more than 80%,have similar mechanical properties to human skin,and have excellent biocompatibility.Hydrogel has been widely used in food detection,flexible sensing,biomedicine,artificial intelligence,wastewater treatment and other fields,and is a very potential material.In recent years,food safety problems have occurred frequently,and there is a higher demand for rapid detection.In this study,three different functionalized hydrogels were developed based on the sodium alginate-acrylamide hydrogel system,from the selective enrichment of the analyte to the construction of an in situ real-time monitoring platform,to the research of functional sensors.Layer by layer,in order to achieve in-situ enrichment of the analyte and rapid detection.Firstly,metal-organic framework materials were encapsulated in a hydrogel system to prepare a portable pretreatment method for enrichment of malachite green in samples;then,by compounding with liquid metal materials,a novel method with both good stretchability and conductivity was prepared.The flexible strain sensor can be attached to the surface of the object to be tested to realize in situ real-time monitoring of the movement of human body and aquatic organisms.Finally,taking the detection of glucose as an example,a selective functional sensor is developed.Phenylboronic Acid（PBA）,combined with a quartz crystal microbalance to achieve rapid quantification of glucose in food.The research content and results of this paper are as follows:（1）Metal organic frameworks（MOF）materials were prepared,and malachite green（MG）was adsorbed by hydrogel PAAM-SA/MOF doped with MOF nanomaterials.MOF,PAAM-SA and PAAM-SA/MOF were characterized by a series of characterization methods,which showed that the adsorbent was successfully synthesized.By optimizing the amount of adsorbent,adsorption time,malachite green p H,adsorption temperature and initial malachite green concentration,the malachite green was completely absorbed in the hydrogel.Under the optimal conditions,the adsorption efficiency was up to 97%.In addition,the adsorbed malachite green was eluted with organic solvents of different polarity.The volume of eluent was optimized,and the desorption rate was up to 99%.This method simplifies the pretreatment process,combines the advantages of MOF and hydrogel,and improves the adsorption efficiency and recovery of two.The actual sample test shows that the new hydrogel adsorption material can be used for rapid extraction and detection of malachite green in aquaculture waters.It is a new,fast and convenient pretreatment method,and has great potential in food detection field.（2）A polyacrylamide（PAAM）-sodium alginate（SA）double network hydrogel was prepared,and a suitable doping method was found to incorporate the liquid metal gallium indium alloy（EGa In）into the double network structure,keeping the It has high electrical conductivity under the condition of good mechanical properties.The liquid metal particles release free radicals and partially polymerize acrylamide by means of ultrasound,thereby preparing a hydrogel with a denser network structure.The synthesized hydrogel microstructure,mechanical properties,electrical properties,water content,swelling ratio,sensing properties were studied in detail,and they were assembled into a flexible strain sensor sensitive to fine deformation,which can be used for human motion（e.g.Large-scale movement:finger,wrist bending and subtle movement:swallowing,coughing）real-time monitoring,and can monitor the movement of aquatic organisms,it is expected to be used to identify the quality of aquatic products in the future,and has great application potential in the field of food quality and safety.It was found that the prepared PAAM-SA/EGa In hydrogel has excellent mechanical properties,the maximum strain can reach 1500%,and it has extraordinary durable fatigue resistance,which can be stretched 12,000 times under 80%strain.The application range and service life of the flexible hydrogel-based strain sensor are greatly improved.In addition,it also takes into account the good electrical properties,the conductivity can reach up to 22.43 S·m^-1,and the sensitivity is high（GF=3.86）,which is higher than that of ordinary hydrogel materials.The hydrogel wearable sensor based on PAAM-SA/EGa In has good application potential in the future.（3）A method was developed for the rapid quantification of glucose in foodstuffs using a flexible hydrogel containing phenylboronic acid as the recognition module,a quartz chip as the carrier and a quartz crystal microbalance（QCM）as the detection system.The doping method of phenylboronic acid with the hydrogel and the solid fixation on the quartz chip were investigated to verify the specific recognition principle of phenylboronic acid and glucose,and the anti-interference and long-term stability of the hydrogel-based glucose sensor were tested.The results showed that phenylboronic acid was successfully doped in the hydrogel system and the designed QCM sensor showed a low detection limit(0.15 mg·L^-1)among the reported glucose sensors,which was approximately 20 times lower than previously reported.The limit of quantification reached 0.5 mg·L^-1 with a linear range of 0.5～120 mg·L^-1.The response time of the PBA hydrogel-based QCM sensor was 32 s and showed excellent stability after 40 days.Finally,six actual samples were tested for glucose content and the results were in general agreement with traditional HPLC method.This sensor overcomes the problems of improper storage conditions for biosensors using enzymes as recognition elements which are prone to deactivation,is simple to assay,enables continuous testing and has great potential for market applications.