Point-of-Care Testing Based On Color And Temperature Signal

Point-of-care testing（POCT）is a technology that can employ portable devices to obtain test results in a very short time.POCT can be kept beside to achieve diagnosis performing next to or near the patient without time and space restrictions,which is conducive to pooling resources,experts and analysis.Such chain-line diagnosis also makes the testing process more convenient and beneficial to the people.With its advantages of convenience,speed and no need for complex instruments,POCT has been increasingly favored by researchers and has made vital progress in the fields of medical diagnosis,environmental monitoring,food safety and biological detection.However,the existing signal readout can not eliminate the gaps of resources and technology in unbalanced and underdeveloped areas to a greater extent,nor can the specialized knowledge about detection cover more people.Hence,in order to exploit more simple signal readout methods with POCT and expand the application of POCT in visual analysis and temperature sensing,this paper designed POCT detection strategies based on simple color and temperature readout and applied it into the analysis of life-related substances and enzymes.Chapter 1:The concept,characteristics and development prospect of POCT are discussed.It also provides a detailed review on the introduction,classification and development trend of color-based signal readout and temperature-based signal readout.Chapter 2:Fenton-like reaction as a typical advanced oxidation technology has made great progress in the degradation of organic substances.But its in-depth application of Fenton-like reaction in the field of colorimetric and temperature sensing events always be restricted due to its low reactivity.To accelerate the rate of Fenton-like reaction,dopamine（DA）was introduced to induce the enhancement of the conversion rate of Fe³⁺to Fe²⁺as well as the decomposition rate of H₂O₂in Fenton-like reaction system.As a result,more hydroxyl radicals（·OH）and superoxide radicals（·O₂^-）with strong oxidation properties could be dramatically generated,finally enhacing reactivity of Fenton-like reaction and resulting in the generation of chromogenic substrate 3,3’,5,5’-tetramethylbenzidine（3,3’,5,5’-tetramethylbenzidine,TMB）to its blue colored oxidation producti（TMBox）.Based on this,a real-time colorimetric and photothermal detection strategy for dopamine was successfully explored.With the increase of DA concentration,the color of reaction solution from colorless to blue changes significantly,resulting in the corresponding colorimetric analysis of DA with a LOD of 47 n M.Additionally,taking the advantage of good photothermal effect of TMBox,photothermometric sensing of DA with a LOD of 91n M was also achieved by using a common thermometer as a reader.Chapter 3:By using the benefit of the in situ generation reaction of prussian blue nanocubes（PB NCs）between ascorbic acid（AA）and Fe₃O₄magnetic nanoparticles（Fe₃O₄MNPs）,we successfully developed a colorimetric and photothermometric sensor for the detection of ascorbic acid oxidase（AOX）.When AA was introduced into the solution of Fe₃O₄MNPs,Fe³⁺existed on the Fe₃O₄MNPs surface would be reduced by AA to generate Fe²⁺,which subsequently react with potassium ferricyanide to produce PB NCs along with an obvious blue color.However,with the increase of AOX content,AA in the reaction system was gradually oxidized to dehydroascorbic acid（DHAA）by AOX,resulting in the less production of PB NCs.As a result,we successfully established a new colorimetric and photothermometric sensor of AOX with a LOD of 1.83 U/L and 0.82 U/L,respectively.Chapter 4:The advantages and benefits of the developed sensing platform in this paper were summarized and discussed.And the corresponding outlook on this direction in future was provided.