Objective To construct an immunosensor for detecting CD4+ T lymphocytes without labeling .Methods The staphy-lococcus protein A(SPA) method was adopted to conduct the oriented immobilization of CD4 monoclonal antibodies on the gold in-terdigitated microelectrode surface for capturing CD4+ T lymphocytes .Then cyclic voltammetry(CV) method was used to conduct the representation of modification situation on the gold interdigitated microelectrode surface .Finally the electrochemical impedance spectroscopy(EIS) was used to detect the impedance of CD4+ T lymphocytes captured by the immunosensor .The standard curve was drawn by the impedance values change obtained by the equivalent electric circuit fitting .Results The linear range of this im-munosensor for detecting CD4+ T lymphocytes was (5 × 103 -5 .0 × 106 )/mL ,with lower detection limit of 5 .0 × 102/mL .Conclu-sion The constructed immunosensor has accurate and reliable detection results uhidn is simple to operate accurate ,convenient and cheap ,which might be expected to be used in the real-time detection system ,and offers help for realizing rapid ,accurate and inex-pensive CD4+ T lymphocyte count .

Objective To investigate the relationship between the expression level of miRNA Let-7 and the deletion of DNA mismatch repair(dMMR)proteins in endometrial carcinoma(EC).Methods A total of 74 patients with EC who underwent radical surgery at Lianyungang Maternal and Child Health Hospital in Jiangsu Province from May 2016 to December 2022 were selected.Immunohistochemistry was used to detect the expression of dMMR proteins(including MLH1,PMS2,MSH2,and MSH6),while real-time fluorescence quantitative polymerase chain reaction(qRT-PCR)was performed to measure the relative expression levelof miRNA Let-7.According to the expression of dMMR proteins,EC patients were divided into the complete expression group(n=43)and the absent expression group(n=31).Logistic multivariate regression analysis was conducted to identify risk factors associated with dMMR protein deficiency,and receiver operating characteristic(ROC)curve was plotted to evaluate the predictive value of relevant factors.Results In 74 cases of EC,the expression level of miRNA Let-7 was higher in the myographic infiltration＜1/2 group than in the myographic infiltration ≥ 1/2 group,and the difference was significant(t=1.79,P=0.04).The deletion rate of dMMR protein expression was 41.89％,the deletion rate in patients aged＜55 years and miRNA Let-7 low expression group(＜0.715)were higher than those in ≥ 55 years and miRNA Let-7 high expression group(≥ 0.715),with significant differences(x2=3.92,4.50,all P＜0.05).Logistic regression analysis revealed that miRNA Let-7 expression level was an independent risk factor for dMMR expression deletion(P=0.012).Spearman correlation analysis demonstrated a negative correlation between miRNA Let-7 expression level and dMMR protein deletion(r=-0.247,P=0.034).ROC curve analysis indicated that the expression level of miRNA Let-7 had a certain predictive value for dMMR protein deletion in EC patients,with an AUC of 0.737,an optimal critical value of 0.77,a sensitivity and a specificity of 0.651 and 0.806,respectively.Conclusion The expression level of miRNA Let-7 was correlated with the deletion of dMMR proteins in patients diagnosed with EC.Moreover,it served as a potential risk factor for dMMR protein deficiency.It may offer valuable insights into predicting dMMR expression deletion.