Development of retroreflection-based optical biosensing platform using retroreflective Janus particle as a signaling probe

일반대학원 분자과학기술학과
The Graduate School, Ajou University
Publication Year
Alternative Abstract
We developed a nonspectroscopic optical biosensing platform by employing the principle of retroreflection. Retroreflection is the phenomenon of light rays striking a surface and being redirected back to the light source. Retroreflection is not related to the type of light source, but rather to the condition and structure of the reflecting surface and material. Since all conventional light sources can induce retroreflection, if retroreflection is introduced to optical biosensing, the optical system can be simplified and miniaturized. Based on these features, in order to overcome the limitations in conventional optical biosensors that require a sophisticated optics system, including a precisely aligned filter, mirror, and wavelength-tunable light source, we sought to implement a retroreflection-based optical biosensor that can be operated under a simplified optics configuration based on the general white light. To employ the retroreflection as a signaling principle, half-coated Janus particles that can induce interior retroreflection were developed and used as an optical signaling probe. First, to assess the applicability of the developed reflective Janus particles (RJPs) as an optical signaling probe, quantitative analysis for a disease biomarker was performed. As a model biomarker, cardiac troponin I (cTnI), which is a biomarker for the diagnosis of acute myocardial infarction, was selected. The RJPs were observed under a simple optics configuration and general light conditions such as a white light emitting diode (LED) and a complementary metal oxide semiconductor (CMOS) camera. Using this platform, the quantitative analysis of the cTnI ranging from 0 to 100 ng/mL was successfully performed with a low sensitivity and a good reproducibility. Based on these results, we confirmed that the RJPs can be used as a novel optical signaling probe. Second, to confirm the applicability of the RJPs for molecular diagnosis, the Salmonella Typhimurium (S. Typhimurium) was analyzed as a target molecule. To effectively amplify the S. Typhimurium, the loop-mediated isothermal amplification (LAMP) technique was employed. Due to the property of the LAMP technique where the amplified gene was generated dumbbell-shaped DNA structure containing a single-stranded loop region with two different sequences, the amplified gene could be measured in a manner similar to the sandwich-type immunoassay. Using the developed biosensing platform, a highly sensitive and selective quantification of S. Typhimurium (102 to 107 CFU) was successfully accomplished with the detection limit of 102 CFU. Based on the results, we proved that the developed RJPs could be applied for the molecular diagnostic field including pathogen. Third, to prove the possibility of RJPs utilization, the RJPs were applied to environmental monitoring. The water-soluble mercury ion was selected as the target model. To detect the mercury ion present in the water, Hg2+-mediated thymine-thymine (T-T) base-stabilization principle was integrated with a RJP-based optical sensing strategy. Using this system, various concentrations of Hg2+ (0 to 100 nM) could be quantitatively analyzed with the LOD of 0.027 nM. In addition, our results not only showed that the developed sensing system had a high selectivity, but also confirmed that it could be applied to a real sample. Based on these findings, we propose a retroreflection-based optical biosensing platform using RJPs as a novel optical signaling probe which can be adapted to various biosensing fields.

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Graduate School of Ajou University > Department of Molecular Science and Technology > 4. Theses(Ph.D)
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