半胱氨酸蛋白酶Cathepsin B被认为是癌症和炎症性肠病早期诊断的潜在生物标志物。因此，更可行、更有效的诊断方法可能有助于监测癌症或相关疾病。我们利用缀合生物素的Cathepsin B筛选噬菌体库，并找到了一个高亲和力的肽段序列为WDMWPSMDWKAE。我们采用酶联免疫吸附试验（ELISA）和电化学分析（阻抗谱、循环伏安和方波伏安）来表征已鉴定的肽段展示噬菌体克隆和无噬菌体的合成肽段。我们评估了噬菌体-传感器、肽段-传感器和肽段-金纳米颗粒/ MXene 传感器的可行性。肽段-金纳米颗粒/ MXene传感器接口的检测限和结合亲和力值比另外两个传感器低两到四倍，表明肽段-金纳米颗粒/ MXene 传感器对Cathepsin B更加特异（良好的恢复率（86-102%）和%RSD（<11%）与临床样品一致，并能够区分Crohn病的不同阶段。此外，我们传感器测得的Cathepsin B浓度与商用ELISA试剂盒估测的浓度存在很好的相关性。综上所述，本研究首次报道了筛选和合理设计高亲和力的肽段特异于Cathepsin B用于开发肽基电化学生物传感器。该研究将促进开发替代无抗体检测方法用于临床检测炎症性肠病和其他疾病。© 2023. The Author(s)。

Cathepsin B, a cysteine protease, is considered a potential biomarker for early diagnosis of cancer and inflammatory bowel diseases. Therefore, more feasible and effective diagnostic method may be beneficial for monitoring of cancer or related diseases.A phage-display library was biopanned against biotinylated cathepsin B to identify a high-affinity peptide with the sequence WDMWPSMDWKAE. The identified peptide-displaying phage clones and phage-free synthetic peptides were characterized using enzyme-linked immunosorbent assays (ELISAs) and electrochemical analyses (impedance spectroscopy, cyclic voltammetry, and square wave voltammetry). Feasibilities of phage-on-a-sensor, peptide-on-a-sensor, and peptide-on-a-AuNPs/MXene sensor were evaluated. The limit of detection and binding affinity values of the peptide-on-a-AuNPs/MXene sensor interface were two to four times lower than those of the two other sensors, indicating that the peptide-on-a-AuNPs/MXene sensor is more specific for cathepsin B (good recovery (86-102%) and %RSD (< 11%) with clinical samples, and can distinguish different stages of Crohn's disease. Furthermore, the concentration of cathepsin B measured by our sensor showed a good correlation with those estimated by the commercially available ELISA kit.In summary, screening and rational design of high-affinity peptides specific to cathepsin B for developing peptide-based electrochemical biosensors is reported for the first time. This study could promote the development of alternative antibody-free detection methods for clinical assays to test inflammatory bowel disease and other diseases.© 2023. The Author(s).