Institute of Microanalytical System, Zhejiang University, Hangzhou, 310058, China.
Anal Chem. 2013 Mar 5;85(5):2787-94. doi: 10.1021/ac303282j. Epub 2013 Feb 8.
For appropriate selection of antibiotics in the treatment of pathogen infection, rapid antibiotic susceptibility testing (AST) is urgently needed in clinical practice. This study reports the utilization of a microfluidic pH sensor for monitoring bacterial growth rate in culture media spiked with different kinds of antibiotics. The microfluidic pH sensor was fabricated by integration of pH-sensitive chitosan hydrogel with poly(dimethylsiloxane) (PDMS) microfluidic channels. For facilitating the reflectometric interference spectroscopic measurements, the chitosan hydrogel was coated on an electrochemically etched porous silicon chip, which was used as the substrate of the microfluidic channel. Real-time observation of the pH change in the microchannel can be realized by Fourier transform reflectometric interference spectroscopy (FT-RIFS), in which the effective optical thickness (EOT) was selected as the optical signal for indicating the reversible swelling process of chitosan hydrogel stimulated by pH change. With this microfluidic pH sensor, we demonstrate that confinement of bacterial cells in a nanoliter size channel allows rapid accumulation of metabolic products and eliminates the need for long-time preincubation, thus reducing the whole detection time. On the basis of this technology, the whole bacterial growth curve can be obtained in less than 2 h, and consequently rapid AST can be realized. Compared with conventional methods, the AST data acquired from the bacterial growth curve can provide more detailed information for studying the antimicrobial behavior of antibiotics during different stages. Furthermore, the new technology also provides a convenient method for rapid minimal inhibition concentration (MIC) determination of individual antibiotics or the combinations of antibiotics against human pathogens that will find application in clinical and point-of-care medicine.
为了在治疗病原体感染时选择合适的抗生素，临床实践中急需快速抗生素药敏试验（AST）。本研究报告了一种利用微流控 pH 传感器监测含有不同种类抗生素的培养基中细菌生长率的方法。微流控 pH 传感器通过将 pH 敏感壳聚糖水凝胶与聚二甲基硅氧烷（PDMS）微流道集成来制备。为了便于反射干涉光谱测量，将壳聚糖水凝胶涂覆在电化学蚀刻的多孔硅芯片上，该芯片用作微流道的基底。通过傅里叶变换反射干涉光谱（FT-RIFS）可以实时观察微通道中 pH 值的变化，其中有效光学厚度（EOT）被选为光学信号，用于指示壳聚糖水凝胶在 pH 值变化刺激下的可逆溶胀过程。使用这种微流控 pH 传感器，我们证明了将细菌细胞限制在纳升级大小的通道中可以快速积累代谢产物，并且不需要长时间的预孵育，从而减少了整个检测时间。在此技术的基础上，不到 2 小时即可获得整个细菌生长曲线，从而可以实现快速 AST。与传统方法相比，从细菌生长曲线获得的 AST 数据可以为研究抗生素在不同阶段的抗菌行为提供更详细的信息。此外，这项新技术还为快速测定个体抗生素或抗生素组合对人体病原体的最小抑制浓度（MIC）提供了一种方便的方法，将在临床和即时医疗中得到应用。
