Detection of anthrax lef with DNA-based photonic crystal sensors

Abstract

Bacillus anthracis has posed a threat of becoming biological weapons of mass destruction due to its virulence factors encoded by the plasmid-borne genes, such as lef for lethal factor. We report the development of a fast and sensitive anthrax DNA biosensor based on a photonic crystal structure used in a total-internal-reflection configuration. For the detection of the lef gene, a single-stranded DNA lef probe was biotinylated and immobilized onto the sensor via biotin-streptavidin interactions. A positive control, lef-com, was the complementary strand of the probe, while a negative control was an unrelated single-stranded DNA fragment from the 16S rRNA gene of Acinetobacter baumannii. After addition of the biotinylated lef probe onto the sensor, significant changes in the resonance wavelength of the sensor were observed, resulting from binding of the probe to streptavidin on the sensor. The addition of lef-com led to another significant increase as a result of hybridization between the two DNA strands. The detection sensitivity for the target DNA reached as low as 0.1 nM. In contrast, adding the unrelated DNAs did not cause an obvious shift in the resonant wavelength. These results demonstrate that detection of the anthrax lef by the photonic crystal structure in a total-internal-reflection sensor is highly specific and sensitive.

Nanopore Biosensor for Label-Free and Real-Time Detection of Anthrax Lethal Factor

“…Although the sensitivity of our nanopore aLF sensor has the potential to be significantly improved by utilizing a PNA probe 51,52 instead of the c DNA probe and/or replacing the (M113F) 7 protein pore with another engineered αHL nanopore (e.g., K131D 7 /K147D 7 ), 53 which could catalyze the translocation of biomolecules, the detection limit of our present unoptimized sensor is still comparable with those (ranging from 1 pM to 10 nM) of most of the other c DNA-based approaches to detect gene sequences. 7,11,47,54 …”

Label-free detection of cardiac troponin I with a photonic crystal biosensor

“…B. et al 2008, Ye and Ishikawa 2008, Zhang B. et al 2013, Zhang B. L. et al 2011). Basically, the sensor is composed of a PC structure of five alternating layers of two different dielectric materials (titania and silica), and a cavity layer on the top.…”

“…For that, a broadband white light source was coupled to a single-mode optical fiber and the output light from the fiber was collimated with an aspherical lens and passed through a linear polarizer to select s-polarization (Zhang B. L. et al 2011). The light had an incident angle of 64° to a PC-TIR sensor and the spectra of the beam reflected from the sensor were measured with a high-resolution spectrometer (HR4000, Ocean Optics) to monitor the resonant wavelength.…”

“…The PC-TIR configuration creates a unique open sensing surface, which allows easy immobilization of analyte-recognition molecules on the surface and direct exposure of the functionalized sensor surface to analyte molecules in real-time bioassays (Dallo et al 2012, Guo Y. et al 2010, Guo Y. B. et al 2008, Ye and Ishikawa 2008, Ye et al 2009, Zhang B. et al 2013, Zhang B. L. et al 2011). Compared to the conventional analytical methods such as ELISA, PCR and HPLC, the PC-TIR biosensor has the advantages of label-free detection, rapid response time, and the potential for continuous in vivo monitoring.…”

Sensitivity enhancement of an open-cavity-based optoacoustic sensor

“…Several design configurations utilizing photonic crystal (PC) structures for ultrasound detection have been explored which use two surfaces acting as high quality mirrors sandwiching a cavity layer. In contrast to the closed cavity optical resonators, we recently demonstrated a novel open-cavity optoacoustic sensor using a PC structure in a total-internal-reflection (TIR) configuration [10,11]. The PC-TIR sensor has an open cavity layer that is directly exposed to outside media, and as such, requires no coating on top of the cavity layer.…”