| Liquid biopsy is a crucial branch of in vitro diagnostic technology.It is a non-invasive diagnostic technique that can diagnose diseases by testing free biomolecules(such as nucleic acid fragments and proteins),cells or vesicles,and other markers that reflect disease information in body fluids.Despite the absence of symptoms in the early stages of several diseases,patients’bodily fluids already contain specific biomarkers formed from sick cells or tissues.Liquid biopsy can identify these marks,enabling early disease identification.In addition,monitoring of disease progression in patients can also be achieved through liquid biopsy.In-vitro diagnostic devices,crucial platforms for realizing liquid biopsy,have drawn increasing interest due to the broad application prospect of liquid biopsy in disease screening and monitoring.Nevertheless,the use of liquid biopsy has been severely constrained by the large size,complicated operation,high cost,and limited testing areas of conventional in-vitro diagnostic instruments.Therefore,point-of-care testing(POCT)is becoming increasingly popular due to the sharp rise in that demand.Many characteristics of POCT include its quick detection time,cheap detection expense,and limitless detection area.The development of this technology will have significant positive social and economic effects.The primary trend in in-vitro diagnostic technology is POCT,and many in-vitro diagnostic products are transitioning to POCT products.Several POCT products now available on the market partially satisfy demand while compromising detection sensitivity.In this thesis,a portable microfluidic in-vitro diagnostic device based on the optical properties of gold nanoparticles and photoelectric colorimetric analysis technology is proposed to meet the requirements of POCT,such as low cost,miniaturization,easy operation,fast detection speed,and higher detection sensitivity.The detection sensitivity is significantly increased by employing a high-efficiency cascade amplification reaction.This cascade amplification reaction is due to the ability of hydrogen peroxide to oxidize individual silver nanoparticles into tens of thousands of silver ions.These silver ions promote the aggregation of the terminal alkyne-functionalized gold nanoparticles,resulting in the absorption wavelength of the terminal alkyne-functionalized colloidal gold solution becoming longer and longer,resulting in a change in color from red to blue(the color of the solution is a complementary color of the absorption color).The device is approximately 8 cm in height,9 cm in width,and 10 cm in length.And an adult can hold it with one hand.It is composed of two components:a microfluidic colorimetric chip and a photoelectric sensing system.Microfluidic colorimetric chips can be divided into marker capture and labeling functional areas and colorimetric analysis functional areas.The photoelectric detection equipment can be divided into hardware parts(each electronic component,optical device,and shell)and software parts(running program based on Python language).The hardware part of the shell was made using 3D printing technology.To evaluate the performance of the device,N protein was employed as a marker and added to PBS,serum,and plasma.N protein’s limit of detection(LOD)in PBS was less than 0.04 ng/m L and in serum and plasma than 0.05 ng/m L.Moreover,the three samples’N protein concentrations had a strong linear relationship with the detection data,with R~2values of 0.9964(0.04–14 ng/m L),0.99435(0.05–14 ng/m L),and 0.98901(0.05–13ng/m L),respectively.These indicate that the device has the potential to be applied in clinical testing,offering a means of addressing the demand for high-efficiency,affordable,portable diagnostic tools.Additionally,the labeled antibodies on the surface of silver nanomaterials and the capturing antibodies on the microfluidic chip channel surface can be flexibly replaced following various protein markers,offering the possibility of using the device in the detection and analysis of additional biomarkers. |
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