Photonic-crystal Sensors For Visual Detection Of Glucose And Organic Phosphorus Pollutant

Photonic crystal is a kind of artificial periodic dielectric structure with the characteristic of photonic band-gap,which can combine with other materials and apply in biological/chemical field.For example,photonic crystals and responsive polymers can be combined to form photonic crystal sensing materials.These materials can generate special structural colors that can be observed by the naked eyes and emerge corresponding optical signals that can be recorded by the related spectrometer under external stimulation,so they have gradually become the research hotspots of biochemical sensing field.In this paper,we developed two simple and convenient techniques based on 3D photonic crystal hydrogel Materials for glucose and paraoxon detecting.The main contents are as follows:(1)By combining the three-dimensional photonic crystal with glucose oxidase-modified responsive hydrogel containing disulfide bonds,a 3D photonic crystal hydrogel material for glucose detection with naked eyes was developed.When the reducing agent dithiothreitol(DTT)is present,it can break the disulfide bonds in the photonic crystal hydrogel material,and have a 54 nm red-shift of the diffraction wavelength,resulting in thiols exposed in the hydrogel skeleton.An enzymatic reaction occurs to produce hydrogen peroxide and gluconic acid under the existence of glucose.Hydrogen peroxide oxidizes the sulfhydryl groups on the hydrogel skeleton to re-form disulfide bonds,resulting in a certain degree of shrinkage of the hydrogel;glucose acid lowers the pH value of the hydrogel environment,which causes the pH-sensitive hydrogel material to shrink and the diffraction wavelength emerges a blue-shift.The combined response of the two effects causes the hydrogel to shrink to a certain degree and the lead to a 140 nm blue-shift in the diffraction wavelength,and the detection limit of glucose is 0.3mM.Owing to the stable structure of hydrogel material and the high specificity of enzyme,the photonic crystal response material has excellent reversibility and selectivity.(2)In order to further develop the application of densely packed 3D photonic crystal materials,an AChE modified three-dimensional photonic crystal hydrogel sensing material was prepared for rapid detection of organic phosphorus pesticide.When the inhibitor of AChE is existing,it will affect the electrostatic environment of the system by inhibiting the reaction of AChE hydrolyzing acetylcholine,and then cause a change of the diffraction wavelength of the photonic crystal material.Based on this principle,the purpose of detecting paraoxon pesticide can be achieved,and the detection limit was as low as 10 ng·mL-1.In addition,because the photonic crystal hydrogel material has a stable structural performance,the sensor has good resistance to external interference and reversibility,which is expected to be used for the detection of paraoxon pesticide in the environments.