The demand for rapid and sensitive bacterial detection is continuously increasing due to the significant requirements of various applications. In this study, a terahertz (THz) biosensor based on rolling circle amplification (RCA) was developed for the isothermal detection of bacterial DNA. The synthetic bacterium-specific sequence of 16S rDNA hybridized with a padlock probe (PLP) that contains a sequence fully complementary to the target sequence at the 5′ and 3′ ends. The linear PLP was circularized by ligation to form a circular PLP upon recognition of the target sequence; then the capture probe (CP) immobilized on magnetic beads (MBs) acted as a primer to initialize RCA. As DNA molecules are much less absorptive than water molecules in the THz range, the RCA products on the surface of the MBs cause a significant decrease in THz absorption, which can be sensitively probed by THz spectroscopy. Our results showed that 0.12 fmol of synthetic bacterial DNA and 0.05 ng μL⁻¹ of genomic DNA could be effectively detected using this assay. In addition, the specificity of this strategy was demonstrated by its low signal response to interfering bacteria. The proposed strategy not only represents a new method for the isothermal detection of the target bacterial DNA but also provides a general methodology for sensitive and specific DNA biosensing using THz spectroscopy.

中文翻译：

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太赫兹光谱通过基于磁珠的滚环扩增等温检测细菌DNA

由于各种应用的重大需求，对快速，灵敏的细菌检测的需求不断增长。在这项研究中，开发了基于滚环扩增（RCA）的太赫兹（THz）生物传感器，用于细菌DNA的等温检测。与挂锁探针（PLP）杂交的16S rDNA合成细菌特异性序列，该序列在5'和3'端含有与靶序列完全互补的序列。通过识别靶序列，通过连接使线性PLP环化以形成环状PLP；然后将固定在磁珠（MBs）上的捕获探针（CP）用作引发RCA的引物。由于在THz范围内，DNA分子的吸收性远不如水分子，因此MBs表面的RCA产物会导致THz吸收的显着降低，可以通过太赫兹光​​谱法灵敏地进行探测。我们的结果表明合成细菌DNA的0.12 fmol和0.05 ngμL使用该测定法可以有效地检测到^-1的基因组DNA。另外，该策略的特异性通过其对干扰细菌的低信号响应得到证明。提出的策略不仅代表了等温检测目标细菌DNA的新方法，而且还提供了使用THz光谱技术进行敏感和特异DNA生物传感的通用方法。