Photonic Crystal Sensing Technology For Rapid Detection Of Calcium In Blood

Purpose Calcium ions in the blood have important physiological significance,reflecting the nutritional status of the human body.The total calcium content in the blood is usually detected in the clinic,including the combination of calcium and ionized calcium,resulting in inaccurate detection of ionized calcium.In recent years,the detection of calcium ions in blood mainly uses large-scale instruments,etc.These technologies have the advantages of high sensitivity and specificity,and also have the disadvantages of high cost,complicated pre-treatment of target materials,and cumbersome operation techniques.Photonic crystal materials can be self-expressed by the characteristics of their own structural colors.There is no need to add a color developer,and the reaction principle is relatively simple.There is a huge space for development in the field of rapid screening.In this study,photonic crystals are used as a sensing platform,and calcium ions（Ca2+）in blood are used as detection targets.Combined with precious metal nanoparticles and biometric technology,a simple,rapid and sensitive technique can be constructed for epidemics.The large sample in the survey was quickly collected.Method 1.Synthesize silica nanoparticles with uniform particle size and regular shape,and synthesize gold nanoparticles with different sizes by using different reducing agents and protective agents of sodium citrate.The surface of the SiO₂ microspheres was modified with amino groups.The AuNPs of different sizes was modified by electrostatic adsorption.The modified products were subjected to vertical sedimentation and self-assembly under constant temperature and humidity conditions,and the composites were prepared into composite opal photonic crystal materials.Compared with traditional opal photonic crystal materials,the performance of this composite material is significantly improved,and the application field is more extensive.2.The ordered arrangement of opal photonic crystals determines the intensity of the characteristic peaks of the reflection spectrum.Therefore,if the closely packed six-sided structure is destroyed,the reflection spectrum will change.According to this property,we use composite PC materials.The surface-linked AuNPs are negatively charged,and the protein that specifically recognizes Ca²⁺（guinea pig liver transglutaminase）is modified on the PC material.When Ca²⁺binds to it,the spatial conformation of the protein changes and destroys.The protein causes the lattice spacing of the photonic crystals to cause a change in the reflection peak of the PC material for detection purposes.Result 1.Regular spherical SiO₂ nanoparticles were successfully prepared by precisely controlling the amount of ammonia added during the reaction and the reaction time.The SiO₂ microspheres with a particle size of about 280 nm were obtained by centrifugal screening at different rotation speeds.AuNPs was prepared by sodium citrate reduction method,and AuNPs of about 13 nm and 3 to 5 nm was obtained by applying different protective agents.2.The silane coupling agent APTES is used to modify the surface amino group of SiO₂ microspheres,which has a strengthening effect and its properties is more active.Due to electrostatic adsorption,AuNPs can be uniformly modified on the surface,and the product is stacked into the PC material.According to the reflection spectrum of the prepared PC material,the volume of AuNPs prepared using sodium borohydride-sodium citrate is finally selected.The composite PC was prepared by modifying the amino-modified SiO₂ microspheres in a ratio of 1:1.3.Further study the practical application of the composite PC.By optimizing the conditions,the TG enzyme was selected to modify the composite PC at a concentration of 1.25 mg/mL,and the Ca²⁺was detected under the condition that the detection environment was pH=7.4.The working curve is y=-0.315+109.86x,R²=0.9885,the detection limit is 0.003,the detection range is 0.08².56mmol/L,and it is stored in 4°C environment.Conclusion The photonic crystal sensing technology has the advantages of simple synthesis of raw materials,rapid response of sensors,simple and clear reading results,and can be combined with various other technologies to have great potential in the fields of environmental monitoring,food and drug safety,and auxiliary diagnosis.