Browsing by Author "Park, Enoch Y."

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Femtomolar Detection of Dengue Virus DNA with Serotype Identification Ability
(2018-11-06)
Chowdhury, Ankan Dutta
;
Ganganboina, Akhilesh Babu
;
Nasrin, Fahmida
;
Takemura, Kenshin
;
Doong, Ruey-an
Dengue surveillance trusts only on reverse transcription-polymerase chain reaction (RT-PCR) type methodologies for confirmation of dengue virus serotypes; however, its real time application is restricted due to the expensive, complicated, and time-consuming process. In search of a new sensing system, here, we have reported a two-way-detection method for Dengue virus (DENV) serotype identification along with DNA quantification by using a new class of nanocomposite of gold nanoparticles (AuNP) and nitrogen, sulfur codoped graphene quantum dots (N,S-GQDs). The N,S-GQDs@AuNP has been used for serotype detection via a simple fluorescence technique using four dyecombined probe DNAs which is further validated by confocal microscopy. The quantification of the DNA has been measured by the differential pulse voltammetric (DPV) technique using methyelene blue as a redox indicator. Results obtained in this study, clearly demonstrate that the N,S-GQDs@AuNP can efficiently detect the four serotypes of DENV individually in the concentration range of 10(-14 )to 10(-6 )M with the LOD of 9.4 fM. In addition, to confirm its applicability in long chained complex DNA system, the sensor was also applied to the clinically isolated DENV DNA and showed satisfactory performances for serotype identification as well as quantification. We hope this simple and reliable method can pave an avenue for the development of sensitive and robust sensing probes in biomedical applications.
Impedimetric biosensor for detection of cancer cells employing carbohydrate targeting ability of Concanavalin A
(2018-12-30)
Chowdhury, Ankan Dutta
;
Ganganboina, Akhilesh Babu
;
Park, Enoch Y.
;
Doong, Ruey-an
;
環境工程研究所
The successful development of selective detection of cancer cells from normal cells is a highly demanded but challenging task. Herein, we have developed a rapid and label-free impedimetric biosensor for quantitative determination of cancer cells with high glycoprotein expression. Homogenously distributed 2-9 nm graphene quantum dots (GQDs) was anchored on the surface Fe3O4 through covalent bonding. Concovalin A (ConA) was then adhered onto GQDs by physical mixing to fabricate ConA-GQD@Fe3O4 nanosensing probe. A good dynamic range in the cell concentration of 5 x 10(2)-1 x 105 cells mL(-1) with LOD values of 246 and 367 cells mL(-1) for HeLa and MCF-7, respectively, is obtained. The impedimetric responses to the cancerous HeLa and MCF-7 cells are 16.7 and 13.1 times higher than those of their original sensor electrodes. However, the interaction between sensing probe and normal MCF-10 and bEnd.3 cells is negligible, confirming the specific selectivity toward cancer cells. Cellular uptake images as well as in-vitro cytotoxicity corroborates the electrochemical results. In addition, the successful detection of cancer cells in human serum and circulating tumor cells in blood sample envisions the feasibility of using ConA-GQD@Fe3O4 as the nanosensing probe for clinically early diagnosis of cancer cells with high glycoprotein expression.