Preparation Of Modified Gelatin Hydrogel And Application In In-vitro Glucose Detection Chip

Compared with liquid diagnostic reagents,in-vitro diagnostic detection chip has the advantages of rapid detection,simple operation,easy to carry,and its application range is extremely wide.In order to realize POCT real-time detection,detection chip needs to have the characteristics of high accuracy and sensitivity,and the composition and structure of reagent layer have a significant influence on accuracy and sensitivity.The reagent layer of detection chip is prepared with uncrosslinked gelatin,and when the sample to be tested is added to react under the human body temperature of 37℃,the gelatin of reagent layer will be dissolved by water in sample and the detection chip will be deformed,which will affect the repeatability and accuracy of test results.In order to improve the detection accuracy of in-vitro diagnostic detection chip,it is necessary to improve the thermal stability of reagent layer which based on the modification of gelatin without affecting the speed,sensitivity and response value of the color reaction of reagent layer.In this study,gelatin is used as raw material,the effects of glutaraldehyde,genipin and bis（vinylsulfone）methane on reaction rate,color sensitivity and detection response value of modified gelatin hydrogel system containing enzyme are investigated by chemical crosslinking method.The results show that bis（vinylsulfone）methane has the least effect on the system.And with bis（vinylsulfone）methane as crosslinking agent,the influence of crosslinking agent mass fraction,gelatin mass fraction,stirring speed,reaction time,crosslinking reaction temperature,standing time,type and mass fraction of plasticizer are investigated respectively.By studying the influence law and mechanism of above factors on the dissolution rate of modified gelatin hydrogel,reduce the dissolution rate of gelatin hydrogel at 37℃.The optimal conditions for preparing modified gelatin hydrogel are obtained:crosslinking agent is bis（vinylsulfone）methane,and its mass fraction and addition amount are 5%and 0.25 mL respectively;the mass fraction of gelatin is 15%;the crosslinking reaction temperature is 38℃;the reaction time is 22 min;the stirring rate is 300 r/min;the standing time is45 min;plasticizer is glycerin,and its mass fraction and addition amount are 3%and 0.25 mL,respectively.Under the optimal conditions,modified gelatin hydrogel is characterized by SEM,FTIR and DSC,which shows the crosslinking effect between crosslinking agent and gelatin is good.The structure of three-dimensional network is compact;the surface of hydrogel is uniform and smooth.At the same time,its flexibility and thermal stability are also significantly improved.Reagent layer is prepared based on the above modified gelatin hydrogel,and combined with TiO₂ multi-functional layer and support layer PET film to construct a self-made glucose detection chip.The relationship between coating thickness of modified gelatin hydrogel reagent layer with the penetration rate,the relationship between coating thickness of TiO₂ multi-functional layer with the penetration rate,and the effect of plasma treatment on liquid-solid contact angle are investigated.The self-made glucose detection chip is evaluated from five aspects:concentration range,same group repeatability,different group repeatability,accuracy and stability.The results show that:self-made glucose detection chip has sensitive response changes to different concentrations of glucose solution.The standard deviation of reflectivity between and within groups is less than 1%,which has good repeatability.The coefficient of variation CV is less than 4%of the specified value of this item.The accuracy of self-made glucose detection chip is within the range of specified target value,which has good accuracy.The self-made glucose detection chip has good stability within two months under the conditions of sealing and freezing.Therefore,modified gelatin hydrogel reagent layer has good application potential in in-vitro diagnostic detection chip.