| Cancer is a deadly disease threatening human health.Most cancers do not show any symptoms at an early stage,so many patients are already at an advanced stage once they are diagnosed with cancer.It is difficult to cure advanced cancer,which not only brings pain to patients,but also brings a heavy burden to the family due to the huge treatment costs.Therefore,the development and application of non-invasive or minimally invasive biomarkers to achieve early cancer diagnosis is of great significance for improving the survival rate of cancer patients and reducing family and social burdens.MiRNA is a kind of small non-coding RNA that participates in a variety of human physiological activities.Studies have found that a variety of miRNAs are abnormally expressed in cancer,and circulating miRNAs can exist stably in body fluids and are not easily decomposed by RNase.Therefore,miRNA is considered as a potential biomarker for early cancer diagnosis.Highly specific and sensitive detection of miRNA is conducive to clinical cancer detection and treatment status judgment.However,the short strands,low abundance and high sequence similarity of miRNAs pose challenges for accurate and efficient detection.Among many detection methods,photoelectrochemical（PEC）detection is considered to be an effective means to achieve high-sensitivity detection of miRNA due to its advantages of low cost,low background noise,and high sensitivity.However,PEC biosensors still have some technical problems such as low photo-harvesting efficiency and fast electron-hole recombination,which greatly limit its performance improvement.Exploring the detection mechanism of PEC detection and exploring efficient photoactive materials are both challenges and opportunities for the construction of high-performance biosensors.Therefore,in this paper,a high-performance PEC biosensor based on Titanium Carbide@Risulfide Rhenium（Ti3C2@Re S2）was constructed to realize the highly sensitivity,highly specificity and highly stability detection of cancer biomarker miRNA-141.First of all,in order to improve the photo-harvesting efficiency and to avoid the ultraviolet light region that is likely to cause damage to biomolecules,Re S2 was selected and prepared as the photoactive material.Re S2 is an emerging transition metal disulfide（TMDs）with unique layer-independent characteristics and narrow band gap,which enables it to be excited in the visible light range to generate sufficient photogenerated carriers.Secondly,in order to further improve the performance of the PEC biosensor and inhibit the electron-hole recombination,this paper introduces Ti3C2into the preparation of the electrode substrate,and prepares a PEC biosensor based on Ti3C2@Re S2 for the detection of miRNA-141.Experiments show that Ti3C2@Re S2 not only has higher light absorption capacity and lower electron transfer resistance,but the introduction of Ti3C2 is beneficial to inhibit the recombination of electron-hole pairs.Essentially,these advantages are mainly due to the synergistic effect of Ti3C2 and Re S2 on photoactivity and conductivity.Ti3C2 not only has excellent conductivity,but the Schottky junction formed between Ti3C2 and Re S2 can capture the photogenerated electrons generated by Re S2,thereby fully suppressing the recombination of photogenerated carriers.At the same time,in order to obtain the optimal PEC biosensor,this paper also studies the optimal mass ratio of Re S2 in Ti3C2@Re S2.The results show that Ti3C2@Re S2 with 45%mass ratio of Re S2 can generate a photocurrent of 2.48 times that of Re S2,which is much larger than that of Ti3C2@Re S2 with other mass ratios,so it was selected as the photoactive substrate of PEC biosensor.In addition,other parameters of the electrode were also optimized,and the optimized PEC biosensor was applied to detect miRNA-141.The test results show that the highly sensitive PEC detection platform based on the above method can offer a log-linear detection window from 0.1 f M to 1 n M with an estimated detection limit of 2.4 a M（S/N=3）for cancer-related miRNA-141 without any other amplification.and still maintain excellent specificity and stability. |
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