Abstract：
The accurate and rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) holds significant clinical importance. This work presents a new method for detecting methicillin-resistant Staphylococcus aureus (S. aureus) in clinical samples. The method uses an aptamer-based colorimetric assay that combines a recognizing probe to identify the target and split DNAzyme to amplify the signal, resulting in a highly sensitive and direct analysis of methicillin-resistance. The identification of the PBP2a protein on the membrane of S. aureus in clinical samples leads to the allosterism of the recognizing probe, and thus provides a template for the proximity ligation of split DNAzyme. The proximity ligation of split DNAzyme forms an intact DNAzyme to identify the loop section in the L probe and generates a nicking site to release the loop sequence (\"3\" and \"4\" fragments). The \"3\" and \"4\" fragments forms an intact sequence to induce the catalytic hairpin assembly, exposing the G-rich section. The released the G-rich sequence of LR probe induces the formation of G-quadruplex-hemin DNAzyme as a colorimetric signal readout. The absorption intensity demonstrated a strong linear association with the logarithm of the S. aureus concentration across a wide range of 5 orders of magnitude dynamic range under the optimized experimental parameters. The limit of detection was calculated to be 23 CFU/ml and the method showed high selectivity for MRSA.
摘要：
准确、快速检测耐甲氧西林金黄色葡萄球菌(MRSA)具有重要的临床意义。这项工作提出了一种检测耐甲氧西林金黄色葡萄球菌的新方法(S.临床样品中的金黄色葡萄球菌)。该方法使用基于适体的比色测定法，该测定法结合识别探针来识别靶标并分裂DNA酶以放大信号，导致对甲氧西林耐药性的高度敏感和直接分析。临床样品中金黄色葡萄球菌膜上PBP2a蛋白的鉴定导致识别探针的变构,并因此为分裂DNA酶的邻近连接提供了模板。分裂的DNA酶的邻近连接形成完整的DNA酶，以识别L探针中的环部分，并产生切口位点以释放环序列（\“3\”和\“4\”片段）。\"3\"和\"4\"片段形成完整的序列，以诱导催化发夹组装，暴露富含G的部分。释放的LR探针的富含G的序列诱导G-四链体-血红素DNA酶的形成作为比色信号读出。在优化的实验参数下,在5个数量级的动态范围的宽范围内,吸收强度显示出与金黄色葡萄球菌浓度的对数的强线性关联。计算的检出限为23CFU/ml，该方法对MRSA显示出高选择性。
