Zibaii Mohammad Ismail, Latifi Hamid, Saeedian Zahra, Chenari Zinab
Laser & Plasma Research Institute, Shahid Beheshti University, Evin, Tehran, Iran.
Laser & Plasma Research Institute, Shahid Beheshti University, Evin, Tehran, Iran.
J Photochem Photobiol B. 2014 Jun 5;135:55-64. doi: 10.1016/j.jphotobiol.2014.03.017. Epub 2014 Apr 21.
Silver nanoparticles (SNPs) exhibit antibacterial properties via bacterial inactivation and growth inhibition but the mechanism is not yet completely understood. In this study a label free and rapid detection method for study of antimicrobial activity of the SNP against Escherichia coli (E. coli K-12) is investigated using a nonadiabtic tapered fiber optic (NATOF) biosensor. The results show that SNPs interact with bacteria either by anchoring to or penetrating into the bacterial cell layer. These mechanism changes the refractive index (RI) of the tapered region, which in turn lead to the changes in the optical characteristics of the tapered fiber and output signals. With similar conditions for bacteria, the inhibition rate of the E. coli growth was measured by colony counting method as an experimental control and the results were compared with those obtained from the fiber sensor measurements. For SNP concentrations ranging from 0 to 50 μg ml(-1) the inhibition rates of the E. coli growth were measured to be from 1.27 h(-1) to -0.69 h(-1) and from -3.00×10(-3) h(-1) to -1.98×10(-2) h(-1) for colony counting and optical fiber biosensor, respectively. The results demonstrate the potential of the proposed NATOF biosensor as a label free and rapid sensing platform for understanding the mechanism of antibacterial effects of SNPs.
银纳米颗粒（SNPs）通过使细菌失活和抑制生长来展现抗菌特性，但其机制尚未完全明确。在本研究中，使用非绝热锥形光纤（NATOF）生物传感器研究了一种用于研究SNP对大肠杆菌（E. coli K-12）抗菌活性的无标记快速检测方法。结果表明，SNP与细菌相互作用的方式是要么锚定在细菌细胞层上，要么穿透进入细菌细胞层。这些机制改变了锥形区域的折射率（RI），进而导致锥形光纤的光学特性和输出信号发生变化。在细菌条件相似的情况下，通过菌落计数法测量大肠杆菌生长的抑制率作为实验对照，并将结果与光纤传感器测量结果进行比较。对于浓度范围为0至50 μg ml(-1)的SNP，通过菌落计数法测得的大肠杆菌生长抑制率为1.27 h(-1)至 -0.69 h(-1)，而通过光纤生物传感器测得的抑制率分别为 -3.00×10(-3) h(-1)至 -1.98×10(-2) h(-1)。结果证明了所提出的NATOF生物传感器作为一种无标记快速传感平台用于理解SNP抗菌作用机制的潜力。
