Nematic liquid crystal alignment based biosensor for plant pathogen detection

¹ Department of General Science, Faculty of Science and Engineering, Kasetsart University, Chalermphrakiat Sakon Nakhon Province Campus, Sakon Nakhon 47000, Thailand
² Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
³ Department of Microbiology, School of Science, RK University, Rajkot 360020, Gujarat, India
⁴ Plant Genome and Disease Research Unit, Department of Agriculture and Resources, Faculty of Natural Resources and Agro-Industry, Kasetsart University, Chalermphrakiat, Sakon Nakhon Province Campus, Sakon Nakhon 47000, Thailand

^* Corresponding Author: pemika.hi@ku.ac.th

Abstract

The orientational mechanism of liquid crystal (LC) molecules in biosensors, optical equipment and other applications relies on its sensitivity, real-time detection and response at a specific location. In our study, we used nematic LC (5CB) for the rapid detection of specific DNA from plant pathogenic bacteria; Pectobacterium carotovorum, Xanthomonas citri subsp. citri, and Ralstonia solanacearum. Optical images of genomic DNA mixed with 5CB exhibited a changing anchoring transition. The speed of the planar-homeotropic configuration for R. solanacearum is faster perfect dynamic than X. citri subsp. citri. Conversely, in the case of P. carotovorum, an unchanged mechanism was observed. It can detect the DNA from plant pathogenic bacteria. Moreover, voltage can drive the reorientation of molecules into ITO glass cells. We found distinct responses at different voltages. The charge transfer was measured in an ITO glass cell between 5CB and DNA. We successfully identified the presence of the plant pathogenic bacteria by analyzing the genomic DNA and PCR products, partial 16S rRNA gene, of the pathogenic sensing. These results affirm that the LC based biosensor presents a simple, reliable, and accurate detection method.