Colorimetric And Photothermal Dual Mode Detection Of MicroRNA And Choline

MicroRNA（miRNA）serves as a biomarker for cancer,neurodegenerative diseases,diabetes and other ailments.Choline is a crucial food additive and an early indicator of various illnesses.Therefore,the development of efficient,precise and portable methods for detecting mi RNA and choline holds immense significance in disease diagnosis,treatment and the food industry.A dual-mode sensing mechanism based on colorimetric and photothermal principles is utilized to develop a point-of-care test for mi RNA and choline,using oxidized 3,3’,5,5’-tetramethylbenzidine（ox TMB）as a probe.The main contents are arranged as follows:Firstly,the colorimetric and photothermal dual-mode sensing of mi RNA is established using ox TMB as a probe.The detection signal of mi RNA on magnetic microspheres is amplified by two enzyme-free amplification techniques triggered by let-7a,namely catalytic hairpin assembly（CHA）and hybrid chain reaction（HCR）.In addition,HRP-labeled hairpin nucleic acid is introduced in the HCR process to closely correlate the content of let-7a with the enrichment of horseradish peroxidase.The TMB-H₂O₂ system is catalyzed by HRP to generate ox TMB,which enables the indirect quantitative analysis of let-7a through dual-mode detection via colorimetry and photothermal methods.The results indicate that both sensing modes have a linear detection range of 0.010 n M-1.0 n M for let-7a,with corresponding detection limits of2.8 p M and 3.4 p M,respectively.The impact of several other mi RNA sequences related to cancer on the detection of let-7a was investigated,and the results demonstrate that this method exhibits good anti-interference ability.The measurement of let-7a content in total mi RNA of He La cells and the spiking recovery yielded satisfactory results,indicating the suitability of this method for detecting let-7a content in complex sample systems.Secondly,the colorimetric and photothermal dual-mode sensing of choline is established using ox TMB as a probe.Choline oxidase（Ch Ox）is utilized as a catalyst for the production of H₂O₂ from choline.HRP catalyzes the oxidation of TMB by H₂O₂,resulting in ox TMB formation,and the quantity of ox TMB produced is proportional to the amount of H₂O₂generated by choline.Therefore,a point-of-care choline test can be accomplished by utilizing colorimetric and photothermal measurements of ox TMB.The results indicate that the linear range of choline in both colorimetric sensing mode and photothermal sensing mode is 10.0μM-300μM.The detection limits are 2.54μM and 3.32μM,respectively.The impact of certain amino acids and metal cations on this experiment was investigated,revealing that the method exhibits excellent specificity.This method is utilized for the determination of choline content in infant formula and compared with the declared value on product packaging.The obtained results are satisfactory,indicating that this method holds certain potential for application in measuring choline levels in complex sample systems.The strategies outlined in this article possess the following notable characteristics:firstly,the photothermal biosensor requires only a household thermometer to achieve precise quantification of target molecules,presenting novel possibilities for real-time detection of mi RNA and choline beyond laboratory settings;secondly,the results obtained from colorimetric and photothermal dual sensing modes can be cross-validated,thereby enhancing accuracy in detecting target molecules.These characteristics make this method highly promising for detecting mi RNA and choline,while also providing new insights into point-of-care testing of other substances.