Growth Mechanism And Fluorescence Biodetection Of ZnO Nanorods In Confined Microchannels

Cardiovascular disease is a serious threat to human health in modern society and how to implement the early diagnosis of cardiovascular disease is the focus of attention.Due to the low concentration of biomarkers in early stage,high specificity and sensitivity are required for biosensors.Among them,immunofluorescence detection is widely used in biodetection due to its facile operation and high sensitivity.At the same time,point-of-care testing(POCT)of low cost and fast response is headed in the future.Therefore,highly sensitive real-time detection of biomarker can be achieved by microfluidic chips with the advantages of small volume,high throughput and high integration.ZnO nanorods have been widely used in fluorescence biodetection due to their high electric point and unique optical properties.As the detection performance is significantly affected by the shape and morphology of nanorods,it is essential to optimize the biodetection by ameliorating the synthesis conditions.In this paper,a geometry confined microenvironment was constructed in a microfluidic chip.The morphology of ZnO nanorods was regulated by the introduction of Al and Mg complex ions,and the biomarker C-reactive protein(CRP)of cardiovascular disease was detected by immunoassays.The main research contents are as follows:1.A four-parallel microchannels was designed and fabricated for the synthesis of ZnO nanorods.Initially,ZnO nanorods were synthesized in the microchannels with different widths on ZnO seed layer as a substrate.The results show that the largest surface area of the ZnO nanorods can be obtained in the microchannels with the width of 300?m.Afterward,different concentrations of non-zinc ions(Al,Mg)were introduced into the growth solution to synthesize ZnO nanorods with different lengths and diameters in 300-?m microchannels.It is revealed that the diameter of ZnO nanorods decreased with the addition of negatively charged Al complex ions,whereas the diameter of ZnO nanorods increased with the addition of positively charged Mg complex ions.2.The fluorescence biodetection of ZnO nanorods regulated by Al and Mg complex ions was demonstrated by FITC anti-bovine Ig G.It was found that the ZnO nanorods synthesized in growth solution of 1 m M Al³⁺and 1.5 m M Mg²⁺exhibited optimal performance.These two growth conditions were used to synthesize ZnO nanorods for sandwich immunoassay of CRP.The results show that the detection limit can be as low as 10 fg/m L.Finally,two interfering proteins myoglobin and bovine serum albumin(BSA)were used to evaluate the selectivity for CRP detection.In the presence of interfering proteins,the fluorescence intensity did not decrease significantly,thus CRP can be selectively detected by ZnO nanorods and this platform is promising for practical applications.