Preparation Of Hyperbrache Cellulose-based Sensor And Its Capture And Visual Detection For Copper Ions

Copper ions is an essential nutrient for life,but excess of copper ions in the human body can cause various neurodegenerative diseases,including Wilson's and Menkes diseases.In addition,exposure of copper ions in the environment can also cause pollution to the atmosphere,soil and water resources,causing serious damage to the ecological environment and food safety,and eventually enrichment through the food chain into the human body and causing harm to the human body.Therefore,it is necessary to develop a convenient,sensitive and real-time sensor for copper ion detection.In this paper,the green and environmentally friendly cellulose is used as raw material,which is oxidated grafting of polyethyleneimine?PEI?and then using ethanol extraction and dialysis to obtain the solids?Sensor-D?and the liquid?Sensor-S?sensor,respectively.The sensitivity,selectivity and detection limit of hyperbranched cellulose-based sensors for exogenous copper ions in aqueous solution,artificial urine and bovine serum were systematically investigated.The mechanism of sensor for Cu²⁺capture and visualization was also discussed.Further,based the Sensor-S,a test strip is prepared by a cyclic impregnation method for semi-quantitative detection of Cu²⁺.The specific research results are as follows:?1?Preparation of hyperbranched cellulose-based sensor:cellulose was oxidized and grafted with PEI,and the supernatant is obtained by centrifugation.The hyperbranched cellulose bases of solid?Sensor-D?and liquid?Sensor-S?sensors were obtained by ethanol extraction and dialysis respectively.The preparation process was optimized by adjusting the amount of PEI and reaction time.When the amount of PEI was 2 g and the reaction time was 7 h,the hyperbranched cellulose-based sensor have the highest grafting efficiency and capture efficiency for Cu²⁺.The amino contents reached 10 mmol/g and the capture capacity reached 94.2%.?2?Capture and detection of copper ions by hyperbranched cellulose-based solid-state sensors:Aqueous solution,artificial urine and bovine serum by adding exogenous Cu²⁺were selected to investigated the selectivity,sensitivity and detection limit of Sensor-D for Cu²⁺.The results showed that Sensor-D can detect Cu²⁺in aqueous solution within 30 s and from its own pale yellow to green,the detection limit?LOD?was 1.054 ppm;and the maximum capture efficiency for Cu²⁺aqueous solution is 94.2%.In addition,Sensor-D detected exogenous Cu²⁺in artificial urine and bovine serum at 60 s and 5 min,respectively,with LODs of 1.996 ppm and1.154 ppm,respectively.The mechanism of capture and visual detection of Cu²⁺by Sensor-D was determined as follows:The capture of Cu²⁺by the amino group of Sensor-D belongs to chemisorption,and Sensor-D and Cu²⁺chelated to form a Sensor-D/Cu²⁺complexs,due to the presence of the electron transfer inside the structure of the base?C=N?of Sensor-D undergoes a color change.?3?Visual detection of hyperbranched cellulose-based liquid sensors and semi-quantitative analysis:Sensor-S exhibited a good visual inspection of Cu²⁺.Compared to Sensor-D,Sensor-S had higher sensitivity and can detect exogenous Cu²⁺in aqueous solution,artificial urine and bovine serum within 10 s,with LODs of 1.185 ppm,1.9309 ppm and 1.9154 ppm,respectively.On this basis,the test strips were prepared by cyclic impregnation for 100 times,and Cu²⁺in the aqueous solution could be quickly identified and displayed in green within 70 s.At the same time,the standard colorimetric card and linear equation corresponding to Cu²⁺aqueous solution,artificial urine and bovine serum were established respectively,and the semi-quantitative detection of Cu²⁺in water system showed good results.In this paper,hyper-branched cellulose-based sensors in both solid and liquid forms were prepared,in which the solid state sensor has both capture and detection properties;the liquid state exhibits excellent rapid detection capability.The development of a highly accurate test strip can be used for semi-quantitative analysis of Cu²⁺.Therefore,hyperbranched cellulose-based sensors have great potential for real-time detection of copper ions in real samples.