Research On Optofluidic Chip For Biochemical Sample Analysis Based On Total Internal Reflection Technology

Optofluidics can realize thehighly efficient screening and analysis of biochemical samples atmicro-nano scalebased on the principles of theinteraction of light-fluid or light-substances in the fluid.The interaction of light-fluid and the interaction of light-substances in fluid are key scientific issues in the research of optofluidics.Among them,the interaction of light and fluid has been demonstrated.Such as,using the gradient refractive index distribution or the step index distribution of the fluid to manipulate the light and make it focus,corner and split,etc.,so as to the development and application of on-chip micro-nano optical devices can be realized.Besides,the interaction of light and substances(including micro-nanoparticles,cells and biomacromolecules,etc.)in fluidhas been also reported,for example,the evanescent field with high sensitivity and high signal-to-noise ratio formed by total internal reflection of the light is used for cell analysis.These do not only expand the practicality of the optofluidics,but also provide more technical platforms for biochemical sample analysis at the micro-nano scale.Compared with traditional technology,optofuidics has the advantages of low loss,fast,accurate and efficient detection or analysis.In recent years,with these advantages,more and more studies have been carried out on the detection of biochemical samples(including nanoparticles and single cells).Among them,for nanoparticles,not only synthetic nanoparticles but also natural biological nanoparticles(such as biomacromolecules,bacteria,viruses and organelles)have been continuously researched in recent decades to promote the development of sciences including physics,chemistry,biomedicine,and materials.Furthermore,single cells are another important substance in fluids and one of the basic components of organisms.The analysis of single cells not only plays an important role in the classification,diagnosis and treatment of cancer,but also highlights its specificity in life activities.Recently,a series of analysis and research at single cell level based on optofluidics have been reported,which has made exciting progress in understanding cancer occurrence,progression,metastasis and drug resistance.Especially in terms of drug resistance,various techniques have been used in single cell analysis.Different from clinical trials,single-cell analysis based on optofluidics is more time-sensitive and targeted,so it plays an important role in the development of cancer specific drugs.In this paper,based on the above-mentioned advantages of optofluidics,combined with total internal reflection technology and other operated technologies,with microfluidic system and optofluidic chip as the operating platform,and taking substances in fluid such as nanoparticles and cancer cells as the main research object,the corresponding research on nanoparticles recognition,detection and cancer cell analysis are carried out.The research works of this paper are as follows:1.Based on Dean flow,an optofluidic chip of three-dimensional liquid-liquid lens is designed to improve the imaging effect of single cells of tumor in low magnification.Asymmetrical arc-shaped microfluidic channel is used to be form a three-dimensional liquid-liquid lens.In the experiment,the three-dimensional structure of the liquid-liquid lens in the optotofluidic chip,the formation conditions and the feasible range are all demonstrated.At the same time,we have studied the focusing of the optical path under the liquid-liquid lens and explored its related optical properties.Thus,under optimal conditions and at the same magnification,we have also compared this lens with a conventional lens.2.Based on total internal reflection technology,combined with the high throughput advantage of flow cytometry,an optofluidic flow cytometer has been designed and applied to the detection of nanoparticles,especially for the identification of gold nanoparticles below 100 nanometers.We use the ideal natural smooth interface of two-phase flow to provide physical conditions for the formation of total internal reflection.Through the experimental study,the effective liquid material is selected as the detection environment.The three-dimensional distribution of liquid in the micro-channel is also studied.The specific distribution of the evanescent field of optical detection is verified by the experiment.Under this condition,50 nm and 100 nm gold particles and 200 nm fluorescent polystyrene microspheres can be distinguished and counted by restricted imaging and scattering spectra of nanoparticles in dark field.3.Based on the total internal reflection technology and the convective-diffusion mechanism of drug concentration,an optofluidic chip is designed and used to research on the toxicity of azelaic acid for single cells of acute myeloid leukemia.Here,through simulation and experimentation,we havestudied and determined the basic trends and distribution of fluid flow and drug diffusion in optofluidic chips.In the bright field,the morphology and response time of single cells affected by drugs are explored.In the dark field,the total internal reflection fluorescence microscope is used to monitor the concentration of the drug,and at the same time,the activity of the single cell is detected.Thus,the drug resistance response of the acute myeloid leukemia cells is obtained.