Browsing by Author "Chowdhury, Ankan Dutta"

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Femtomolar Detection of Dengue Virus DNA with Serotype Identification Ability
(2018-11-06)
Chowdhury, Ankan Dutta
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Ganganboina, Akhilesh Babu
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Nasrin, Fahmida
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Takemura, Kenshin
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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.
Highly sensitive and selective detection of mercury ions using N, S-codoped graphene quantum dots and its paper strip based sensing application in wastewater
(2017-11-01)
Nguyen Thi Ngoc Anh
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Chowdhury, Ankan Dutta
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
The development of robust and low-cost sensing materials with superior selectivity and sensitivity for rapid detection of analytes in a wide variety of samples has attracted much attention. Herein, the N, S-codoped graphene quantum dots (N, S-GQDs) with high quantum yield were fabricated by one-pot hydrothermal method for highly sensitive and selective detection of nanomolar level of mercury ions (Hg2+) in water and wastewater. The as-prepared N, S-GQDs are uniform in size with mean particle size of 3.5 +/- 0.5 nm. The doping of nitrogen atoms increases the quantum yield to 41.9%, while the introduction of sulfur atoms enhances the selectivity of Hg2+ via strong coordination interaction. The fluorescence intensity of N, S-GQDs is quenched proportionally after adding Hg2+ and a dynamic range of 4 orders of magnitude with limit of detection of 0.14nM is obtained in deionized water. The N, S-GQDs nanosensing probes can be successfully applied to the sewage and dye wastewater samples and a linear range of 0.1-15 mu M with recovery of 96-116% is obtained. In addition, the coating of N, S-GQDs onto paper strip provides an excellently rapid screening and highly selective technique for Hg2+ detection in real wastewater. Results obtained in this study clearly indicate that the N, S-GQDs are promising nanomaterials which can open an new avenue to design the GQD based sensing probe for highly sensitive and selective detection of metal ions and other analytes in environmental and biological fluid samples. (C) 2017 Elsevier B.V. All rights reserved.
Highly Sensitive and Selective Detection of Nanomolar Ferric Ions Using Dopamine Functionalized Graphene Quantum Dots
(2016-08-17)
Chowdhury, Ankan Dutta
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
The good stability, low cytotoxicity, and excellent photoluminescence property of graphene quantum dots (GQDs) make them an emerging class of promising materials in various application fields ranging from sensor to drug delivery. In the present work, the dopamine-functionalized GQDs (DA-GQDs) with stably bright blue fluorescence were successfully synthesized for low level Fe3+-ions detection. The as-synthesized GQDs are uniform in size with narrow-distributed particle size of 4.5 +/- 0.6 nm and high quantum yield of 10.2%. The amide linkage of GQDs with dopamine, confirmed by using XPS and FTIR spectra, results in the specific interaction between Fe3+ and catechol moiety of dopamine at the interfaces for highly sensitive and selective detection of Fe3+. A linear range of 20 nM to 2 mu M with a detection limit of 7.6 nM is obtained for Fe3+ detection by DA-GQDs. The selectivity of DA-GQDs sensing probe is significantly excellent in the presence of other interfering metal ions. In addition, the reaction mechanism for Fe3+ detection based on the complexation and oxidation of dopamine has been proposed and validated. Results obtained in this study clearly demonstrate the superiority of surface functionalized GQDs to Fe3+ detection, which can pave an avenue for the development of high performance and robust sensing probes for detection of metal ions and other organic metabolites in environmental and biomedical applications.
Impedimetric biosensor for detection of cancer cells employing carbohydrate targeting ability of Concanavalin A
(2018-12-30)
Chowdhury, Ankan Dutta
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Ganganboina, Akhilesh Babu
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Park, Enoch Y.
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Doong, Ruey-an
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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.
Label-Free and Nondestructive Separation Technique for Isolation of Targeted DNA from DNA-Protein Mixture Using Magnetic Au-Fe3O4 Nanoprobes
(2017-11-21)
Chowdhury, Ankan Dutta
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Agnihotri, Nidhi
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Doong, Ruey-an
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De, Amitabha
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環境工程研究所
The interest in DNAprotein-based diagnostics has recently been growing enormously, which makes the separation process of DNA or protein from a cell extract extremely important. Unlike the traditional separation process, a novel approach is in demand which can nondestructively isolate the target biomolecules without sacrificing the other components in the mixture. In this study, we have demonstrated a new and simple separation technique by using well-established bifunctional AuFe3O4 nanocomposites as the separation nanoprobes to efficiently isolate the specifically targeted nanomolar concentrated DNA over 70% from its associate DNAprotein mixture in the presence of a magnetic field. The sensing accuracy of both as-separated DNA and protein are quantitatively examined by UVvis spectroscopy, and then qualitatively validated by gel analysis. Results obtained in this study clearly demonstrated that this newly developed separation procedure not only provides the efficient separation for the targeted DNA but can also maintain the bioactivity of as-separated protein and DNA solutions. The superiority of this technique can open an avenue to establish a label-free and nondestructive platform for a wide variety of biomolecule separation applications.
Multifunctional GQDs-Concanavalin A@Fe3O4 nanocomposites for cancer cells detection and targeted drug delivery
(2018-10-16)
Chowdhury, Ankan Dutta
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Ganganboina, Akhilesh Babu
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Tsai, Yuan-chung
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Chiu, Hsin-cheng
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Doong, Ruey-an
Multifunctional nanocomposites containing intrinsic property for serving as the sensing elements as well as targeted nanoconjugates are highly preferred in various therapeutic applications. In this work, nanocomposites of graphene quantum dots (GQDs) and Fe3O4 with conjugation of lectin protein, concanavalin A, to form GQD-ConA@ Fe3O4 nanocomposites are developed for both detection of cancer cell and release of drugs to HeLa cells. The GQD-ConA@ Fe3O4 nanocomposites deposited on Pt electrode can detect cancerous HeLa cells over normal endothelial cells with a dynamic linear range of 5 x 10(2) to 1 x 10(5) cells mL(-1) with a detection limit of 273 cell mL(-1). The GQD-ConA@ Fe3O4 also can serve as nanocarriers for loading and delivering doxorubicin (Dox). The in vitro cell images show that the Dox concentration in HeLa cells is enhanced more than double in the presence of external magnetic field due to the incorporation of Fe3O4 in the nanocarrier. The cytotoxicity assay indicates that the susceptibility of cancerous HeLa cells to Dox is 13% higher than that of normal cells, confirming the selective role of ConA in nanocarriers. Results clearly indicate the GQD-ConA@ Fe3O4 nanocomposites as a promising material for cancer cell detection and targeted Dox release toward HeLa cells which can serve as the multifunctional platform for novel cancer cell diagnostic and therapeutic applications. (C) 2018 Elsevier B.V. All rights reserved.
N-Doped Graphene Quantum Dots-Decorated V2O5 Nanosheet for Fluorescence Turn Off-On Detection of Cysteine
(2018-01-10)
Ganganboina, Akhilesh Babu
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Chowdhury, Ankan Dutta
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Doong, Ruey-An
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環境工程研究所
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Institute of Environmental Engineering
The development of a fast-response sensing technique for detection of cysteine can provide an analytical platform for prescreening of disease. Herein, we have developed a fluorescence turn off-on fluorescence sensing platform by combining nitrogen-doped graphene quantum dots (N-GQDs) with V2O5 nanosheets for the sensitive and selective detection of cysteine in human serum samples. V2O5 nanosheets with 2-4 layers are successfully synthesized via a simple and scalable liquid exfoliation method and then deposited with 2-8 nm of N-GQDs as the fluorescence turn off-on nanoprobe for effective detection of cysteine in human serum samples. The V2O5 nanosheets serve as both fluorescence quencher and cysteine recognizer in the sensing platform. The fluorescence intensity of N-GQDs with quantum yield of 0.34 can be quenched after attachment onto V2O5 nanosheets. The addition of cysteine triggers the reduction of V2O5 to V4+ as well as the release of N-GQDs within 4 min, resulting in the recovery of fluorescence intensity for the turn off-on detection of cysteine. The sensing platform exhibits a two-stage linear response to cysteine in the concentration range of 0.1-15 and 15-125 mu M at pH 6.5, and the limit of detection is 50 nM. The fluorescence response of N-GQD@V2O5 exhibits high selectivity toward cysteine over other 22 electrolytes and biomolecules. Moreover, this promising platform is successfully applied in detection of cysteine in human serum samples with excellent recovery of (95 +/- 3.8) - (108 +/- 2.4)%. These results clearly demonstrate a newly developed redox reaction-based nanosensing platform using N-GQD@V2O5 nanocomposites as the sensing probe for cysteine-associated disease monitoring and diagnosis in biomedical applications, which can open an avenue for the development of high performance and robust sensing probes to detect organic metabolites.
Nano assembly of N-doped graphene quantum dots anchored Fe3O4/halloysite nanotubes for high performance supercapacitor
(2017-08-10)
Ganganboina, Akhilesh Babu
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Chowdhury, Ankan Dutta
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
The development of robust and low cost electrode materials with superior electrochemical properties has been a subject of focus on energy storage devices. Herein, the development of N-doped graphene quantum dots (N-GQDs) deposited on Fe3O4-halloysite nanotubes (Fe3O4-HNTs) as active anode materials has been established for supercapacitor applications. The Fe3O4 nanoparticles synthesised by coprecipitation have been in-situ deposited on HNT surfaces following by the coating of (3-aminopropyl)-triexthoxysilane to anchor 4-10 nm N-GQDs via the formation of amide linkage. The N-GQD@Fe3O4-HNTs exhibits a high specific capacitance of 418 F g(-1) and maintains good rate capability in neutral electrolyte solutions. In addition, the anode materials show excellent electrochemical performance with energy and power densities of 10.4-29 W h kg(-1) and 0.25-5.2 kW kg(-1), respectively. Such excellent electrochemical features can be attributed to the synergistic contribution from individual components. The Fe3O4-HNTs provide 1-dimensional matrix to shorten the diffusion path of electrons and electrolyte ions as well as to absorb the mechanical stress during cycling along with excess sites for charge storage, while N-GQDs offer abundantly accessible electroactive sites for rapid electrons and electrolyte ions transport as well as enhance electrical conductivity of Fe3O4-HNTs. Results obtained in this study clearly demonstrate that metal oxide-HNTs are promising support to anchor N-GQDs nanomaterials as the high performance anode materials for next generation of energy storage devices with high energy and power densities. (C) 2017 Elsevier Ltd. All rights reserved.
New Avenue for Appendage of Graphene Quantum Dots on Halloysite Nanotubes as Anode Materials for High Performance Supercapacitors
(2017-06-01)
Ganganboina, Akhilesh Babu
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Chowdhury, Ankan Dutta
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Doong, Ruey-an
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環境工程研究所
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Institute of Environmental Engineering
Graphene quantum dots (GQDs) are a newly developed graphene family with good electrical conductivity and high theoretical capacitance, while halloysite nanotubes (HNTs) are naturally occurring layered mineral materials containing high active sites for energy storage support. The combination of HNTs and GQDs can offer a new strategy on the fabrication of eco-friendly electrode materials for high performance supercapacitor applications. Herein, an environmentally friendly GQD-HNT nanocomposite is fabricated in the presence of (3aminopropyl)-triethoxysilane to provide increased charge storage sites as well as to allow for the fast charge transport for supercapacitor application. Morphological and surface analytical results show that 5-10 nm GQDs are homogeneously distributed on the surface of APTES-coated HNTs via amide linkage. This new and novel layered nanocomposite can provide accessible electroactive sites and low resistance to accelerate the electrons and electrolyte ion transport, resulting in excellent specific capacitance and high energy density. The specific capacitances of 363-216 F/g at current densities of 0.5-20 A/g are obtained. In addition, the GQD-HNTs exhibit excellent energy density of 30-50 Wh/kg. Results obtained in this study clearly demonstrate the feasibility of using GQD-HNTs as alternative energy storage materials with increased charge storage sites and fast charge transport for high energy density supercapacitor applications.