| Early diagnosis of cancer plays a significant role in the treatment and prognosis of diseascs.Due to the anomalous concentration of cancer markers in patients,cancer marker detection is an effective method for early detection.However,commonly used detection methods may not achieve high sensitivity due to the low concentration of cancer biomarkers in the patient’s body in the early stages of the disease.Immunofluorescence detection,which quantifies the concentration of cancer biomankers by fluorescence intensity,is a highly sensitive method for cancer biomarker detection,ZnO nanomaterials can be applied to immunofluorescence detection due to their good biocompatibility,high isoelectric point,and unique fluorescence enhancement properties.Microfluidic chips have the advantages of mass and heat transfer,low reagent consumption,and ease of operation,which are widely used in biochemical analysis and detection research.By combining microfluidic technology with ZnO nanorods and applying it to fluorescence immunoassay,it is possible to develop high-sensitivity and high-throughput portable biosensors.In this study,two modes of droplet array were established based on the flow channel design of microfluidic chips,and the in-situ growth of ZnO nanorod arrays was achieved.The synthesized ZnO nanorod arrays were used as substrates for the fluorescence biodetection of cancer biomarkers.Growth and detection chips have been designed and prepared for in situ synthesis and fluorescence biodetection of ZnO nanorod arrays.Firstly,different methods were studied for establishing a two-dimensional(2D)droplet array,and the effect of fluid dynamics on droplet capture efficiency was investigated.Then,various synthesis conditions were explored for their effects on the morphology of ZnO nanorods.Finally,the fluorescence enhancement performance of the ZnO nanorod array was tested and analyzed,and it was applied to the fluorescence biodetection of cancer biomarkers.The main work is as follows:1.The droplet capture structure was optimized to establish a high-throughput droplet array.The size of the capture structure on chip was optimized through flow resistance analysis and experimental investigation for capturing droplets.The mechanism of different modes of droplet capture and droplet generation was analyzed according to fluid poperties and interacial effects.The effects of aqueous phase flow rate and oil phase flow rate on droplet capture efficiency were also studied and the conditions for obtaining stable droplet arrays were determined.The results indicated that a high ratio of flow resistance between the necking and the microchamber,and similar flow resistance between the capture channel and the bypass channel,are necessary for successful establishment of a droplet array.Herein,stable droplet arrays can be established by using the optimized droplet capture structure with a resistance ratio of 82,16 between the necking and the microchamber and a resistance ratio of 3.31 between the capture channel and the bypass channel,respectively.It is also revealed that droplet arrays can be successfully established within the range of 12.5μL/h-800 μL/h of oil phase flow rate.400 μL/h and 150 μL/h were slected as the flow rate of oil phase and aqueoes phase in our study,respectively.2.The effects of substance replenishement and growth time in the droplet array on the diameter and density of synthesized ZnO nanorods was explored.And FITC labeled goat anti-bovine IgG was used to detect the fluorescence enhancenent performance of ZnO nanorods and screen for the optimal conditions for synthesizing ZnO nanorods.The results showed that the ZnO nanorods synthesized with a replenishing interval of 10 min and a growth time of 2 h had the largest diameter,The fluorescence enhancement performance was optimized when the incident light wave was transmitted to the vicinity of the ZnO nanorods and met the conditions for the fluorescence group to be excited by the evanescent wave of single-mode waveguide.Furthermore,ZnO nanorod array synthesized with areplenishing interval of 10 min and a growth time of 2 h was used to detect cancer markers AFP and CEA.The results indicated that the detection limit of CEA and AFP can be as low as 1 pg/mL,with a dynamic detection range from 1pg/mL to 1 μg/mL,showing good specificity in the assays.In conclusion,a microfluidic chip for high-throughput droplet arrays that enables the in-situ growth of ZnO nanorod arrays was presented in this work.The microfluid chip extends the approach for in-situ synthesis of materials and the application of high-throughput detection for cancer biomarkers. |
