Study Of Sensing Method Based On 3D Printing Microfluidic Technology For Point-of-care Testing

With the innovation of technology and the rise of portable home testing instruments,the role of point-of-care testing in the early screening,accurate diagnosis and active treatment of diseases is becoming more and more obvious.Compared with traditional laboratory testing,point-of-care testing allows patients to self-diagnose and obtain test results in a short time to make treatment decisions.Microfluidics has the advantages of high throughput,low reagent requirements,and integration,enabling fluid conditioning and diagnostic detection in a single component,improving sensitivity and specificity for trace target analytes.Therefore,instant detection based on microfluidic chips is a general trend to replace traditional detection schemes.However,the traditional processing steps of microfluidic chips are cumbersome,the production cycle is long,and the flexibility is poor,which can no longer meet the production requirements of its integration and polymorphism.In addition,commercial point-of-care detection technologies and detection methods have limited capabilities,and there is an urgent need to develop rapid,sensitive,and reliable point-of-care detection methods for disease markers.In order to improve the shortcomings of chip fabrication and detection methods,a sensing method based on 3D printed microfluidic chips for instant detection was constructed in this paper.The specific research includes four aspects:(1)The performance and mechanism of four 3D printing methods including photocuring molding,selective laser sintering,fused deposition and digital light processing were studied.Using their respective commercial typical 3D printers to print test samples containing different microchannels,it was concluded that the photocured UnionTech 3D Lite 600 and the digital light processed AccFab-L4K met the fabrication accuracy of microfluidic chips.(2)In view of the problem that the resin mold makes PDMS difficult to cure in the digital light processing printing method,TMCS silanization treatment,calcium/iron-based phosphorus removal agent treatment,varnish immersion and plasma cleaning are used for surface treatment of the small samples.From the perspective of curing effect,time and light transmittance,it is concluded that the effect of 30 min iron-based phosphorus removal agent on the surface is the best.This successfully solves the phenomenon of resin material inhibiting PDMS curing or sticking firmly to the mold in digital light processing.(3)A microfluidic hybrid chip based on chemiluminescence instant detection was designed to realize the rapid detection of procalcitonin in the microchannel.Theoretically,the simulation software is used to explore and explain the relationship that the smaller the eccentricity of the hyperbola,the better the solution mixing efficiency.Using digital light processing printer,PDMS pouring,reagent storage,capture antibody pre-coating and micromixer pre-mixing methods,the detection results can be obtained within 15 minutes,and the detection signal ΔCL has a good linear relationship with the concentration:y=18959.69x43922.21,R2=0.975,LOD=0.17 ng/mL.This has great potential for commercialization of point-of-care detection of procalcitonin.(4)An enzyme-amplified magnetic relaxation switch immunosensing method was constructed to realize low-cost,high-sensitivity,and immediate detection of tumor markers such as alpha-fetoprotein.Based on an enzyme-triggered cascade reaction,it amplifies the longitudinal magnetic relaxation signal of water protons and improves the detection sensitivity.Using the microfluidic chip to simplify the complicated experimental operation,optimize the parameters of the reaction reagents to obtain the optimal linear relationship between alphafetoprotein and the magnetic relaxation signal:y=0.646x+1.019,R2=0.97,LOD=0.56 ng/mL.Finally,the clinical detection of alpha-fetoprotein in actual samples showed excellent consistency with the results measured by traditional ELISA,with a correlation coefficient of 0.97,which greatly promoted the real-time detection of targets in human whole blood process.