A Label-Free Photoluminescence Genosensor Using Nanostructured Magnesium Oxide for Cholera Detection.

Manoj Kumar Patel,H Fouad,Abdulaziz A Al Kheraif,Z A Ansari,Md Azahar Ali,S G Ansari,Ved Varun Agrawal,Sadagopan Krishnan,Bansi D Malhotra

doi:10.1038/srep17384

Abstract

Nanomaterial-based photoluminescence (PL) diagnostic devices offer fast and highly sensitive detection of pesticides, DNA, and toxic agents. Here we report a label-free PL genosensor for sensitive detection of Vibrio cholerae that is based on a DNA hybridization strategy utilizing nanostructured magnesium oxide (nMgO; size >30 nm) particles. The morphology and size of the synthesized nMgO were determined by transmission electron microscopic (TEM) studies. The probe DNA (pDNA) was conjugated with nMgO and characterized by X-ray photoelectron and Fourier transform infrared spectroscopic techniques. The target complementary genomic DNA (cDNA) isolated from clinical samples of V. cholerae was subjected to DNA hybridization studies using the pDNA-nMgO complex and detection of the cDNA was accomplished by measuring changes in PL intensity. The PL peak intensity measured at 700 nm (red emission) increases with the increase in cDNA concentration. A linear range of response in the developed PL genosensor was observed from 100 to 500 ng/μL with a sensitivity of 1.306 emi/ng, detection limit of 3.133 ng/μL and a regression coefficient (R2) of 0.987. These results show that this ultrasensitive PL genosensor has the potential for applications in the clinical diagnosis of cholera.

Highlights

Nanostructured materials are useful building blocks of photoluminescence (PL)-based nano-electronic devices for investigating immunocytochemistry, immunohistochemistry, and protein-protein and DNA-DNA interactions[1,2]
The high crystallinity of the MgO NPs was confirmed by X-ray diffraction (XRD), and the particle size and morphological shape of the synthesized NPs were determined using transmission electron microscopic (TEM) studies
The PL response of the fabricated genosensor was measured as a function of complementary genomic DNA (cDNA) concentration ranging from 100 to 500 ng/μ L

Summary

Results

Implies that the majority of the grains are oriented along the (200) direction. The average crystallite size (d200) of the nMgO is estimated as ~16 nm based on the Scherrer equation for the dominant (200) plane. Due to the negatively charged DNA backbone electrostatically attached to the positively charged MgO NPs. Table 1 shows the relative atomic percentage (%) of different peaks observed in the nMgO/ITO and pDNA-nMgO/ITO films. Indicates interaction of DNA with the nMgO surface and formation of a DNA-nMgO complex (Fig. 4B) This increase may be due to the strong binding tendency of the negatively charged DNA molecules with positively charged nMgO through electrostatic bound to the nMgO surface and forms a pDNA-nMgO complex. It appears that the oxygen defects and various F and F+ centres in nMgO are responsible for the observed PL27, indicating that nMgO is a suitable nanoprobe for detection of the oligonucleotide hybridization. When the cDNA is present in the added sample solution, DNA hybridization occurs between the cDNA and the surface captured pDNA and displays a cDNA concentration-dependent PL intensity increase (Fig. 4C)

Discussion

Findings

Methods