Browsing by Author "Kumar, Priyank V."

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Enhanced Cell Capture on Functionalized Graphene Oxide Nanosheets through Oxygen Clustering
(2017-02)
Bardhan, Neelkanth M.
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Kumar, Priyank V.
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Li, Zeyang
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Ploegh, Hidde L.
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Grossman, Jeffrey C.
With the global rise in incidence of cancer and infectious diseases, there is a need for the development of techniques to diagnose, treat, and monitor these conditions. The ability to efficiently capture and isolate cells and other bio-molecules from peripheral whole blood for downstream analyses is a necessary requirement. Graphene oxide (GO) is an attractive template nanomaterial for such biosensing applications. Favorable properties include its two-dimensional architecture and wide range of functionalization chemistries, offering significant potential to tailor affinity toward aromatic functional groups expressed in biomolecules of interest. However, a limitation of current techniques is that as-synthesized GO nanosheets are used directly in sensing applications, and the benefits of their structural modification on the device performance have remained unexplored. Here, we report a microfluidic-free, sensitive, planar device on treated GO substrates to enable quick and efficient capture of Class-II MHC-positive cells from murine whole blood. We achieve this by using a mild thermal annealing treatment on the GO substrates, which drives a phase transformation through oxygen clustering. Using a combination of experimental observations and MD simulations, we demonstrate that this process leads to improved reactivity and density of functionalization of cell capture agents, resulting in an enhanced cell capture efficiency of 92 +/- 7% at room temperature, almost double the efficiency afforded by devices made using as-synthesized GO (54 +/- 3%). Our work highlights a scalable, cost-effective, general approach to improve the functionalization of GO, which creates diverse opportunities for various next-generation device applications.
Enhanced Osteogenic Differentiation of Stem Cells on Phase-Engineered Graphene Oxide
(2018-04-18)
Yang, Jia-Wei
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Hsieh, Kuan Yu
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Kumar, Priyank V.
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Cheng, Sheng-Jen
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Lin, You-Rong
Graphene oxide (GO) has attracted significant interest as a template material for multiple applications due to its two-dimensional nature and established functionalization chemistries. However, for applications toward stem cell culture and differentiation, GO is often reduced to form reduced graphene oxide, resulting in a loss of oxygen content. Here, we induce a phase transformation in GO and demonstrate its benefits for enhanced stem cell culture and differentiation while conserving the oxygen content. The transformation results in the clustering of oxygen atoms on the GO surface, which greatly improves its ability toward substance adherence and results in enhanced differentiation of human mesenchymal stem cells toward the osteogenic lineage. Moreover, the conjugating ability of modified GO strengthened, which was examined by auxiliary osteogenic growth peptide conjugation. Overall, our work demonstrates GO's potential for stem cell applications while maintaining its oxygen content, which could enable further functionalization and fabrication of novel nano-biointerfaces.
Graphene- and Graphene Oxide-Based Nanocomposite Platforms for Electrochemical Biosensing Applications
(2019-06-02)
Thangamuthu, Madasamy
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Hsieh, Kuan Yu
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Kumar, Priyank V.
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Chen, Guan-Yu
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交大名義發表
Graphene and its derivatives such as graphene oxide (GO) and reduced GO (rGO) offer excellent electrical, mechanical and electrochemical properties. Further, due to the presence of high surface area, and a rich oxygen and defect framework, they are able to form nanocomposites with metal/semiconductor nanoparticles, metal oxides, quantum dots and polymers. Such nanocomposites are becoming increasingly useful as electrochemical biosensing platforms. In this review, we present a brief introduction on the aforementioned graphene derivatives, and discuss their synthetic strategies and structure-property relationships important for biosensing. We then highlight different nanocomposite platforms that have been developed for electrochemical biosensing, introducing enzymatic biosensors, followed by non-enzymatic biosensors and immunosensors. Additionally, we briefly discuss their role in the emerging field of biomedical cell capture. Finally, a brief outlook on these topics is presented.
Microfluidics and Nanomaterial-based Technologies for Circulating Tumor Cell Isolation and Detection
(2020-04-01)
Cheng, Sheng-Jen
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Hsieh, Kuan Yu
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Chen, Shiue-Luen
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Chen, Chong-You
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Huang, Chien-Yu
Cancer has been one of the leading causes of death globally, with metastases and recurrences contributing to this result. The detection of circulating tumor cells (CTCs), which have been implicated as a major population of cells that is responsible for seeding and migration of tumor sites, could contribute to early detection of metastasis and recurrences, consequently increasing the chances of cure. This review article focuses on the current progress in microfluidics technology in CTCs diagnostics, extending to the use of nanomaterials and surface modification techniques for diagnostic applications, with an emphasis on the importance of integrating microchannels, nanomaterials, and surface modification techniques in the isolating and detecting of CTCs.
New insights into the thermal reduction of graphene oxide: Impact of oxygen clustering
(2016-04)
Kumar, Priyank V.
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Bardhan, Neelkanth M.
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Chen, Guan-Yu
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Li, Zeyang
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Belcher, Angela M.
Graphene has attracted interest for a number of applications ranging from electronics, optoelectronics to membrane-based technologies. The thermal reduction of chemically exfoliated graphene oxide (GO) sheets represents an important step for large-scale, solution-based graphene synthesis. Therefore, understanding the reduction process and being able to provide new handles to control the resulting sheet properties is highly desirable. Using atomistic calculations combined with experiments, we study and demonstrate the impact of one such new handle - oxygen clustering on the graphene basal plane - on the structural and electrical properties of reduced GO (rGO) structures. Our calculations reveal that the number of oxygen and carbon atoms removed from the graphene plane during reduction can be tuned depending on the degree of oxygen clustering, without altering the reduction temperature. Further, we demonstrate that rGO thin films with improved sheet resistance (up to 2-fold smaller) can be obtained by facilitating oxygen clustering prior to reduction. Overall, our results highlight that oxygen clustering serves as a useful handle in controlling the structural and electrical properties of the resulting rGO structures, and could be potentially useful toward the synthesis of electrodes, graphene quantum dots and for different graphene-based thin film applications. (C) 2015 Elsevier Ltd. All rights reserved.
Simultaneous drug delivery and cellular imaging using graphene oxide
(2018-04-01)
Cheng, Sheng-Jen
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Chiu, Hsien-Yi
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Kumar, Priyank V.
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Hsieh, Kuan Yu
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Yang, Jia-Wei
Graphene oxide (GO), a derivative of graphene, and its related nanomaterials have attracted much attention in recent years due to the excellent biocompatibility and large surface area of GO with abundant oxygen functional groups, which further enable it to serve as a nano- bio interface. Herein, we demonstrate the induction of blue fluorescence in GO suspensions via a mild thermal annealing procedure. Additionally, this procedure preserves the oxygen functional groups on the graphene plane which enables the conjugation of cancer drugs without obvious cytotoxicity. Consequently, we demonstrate the capability of GO to simultaneously play the dual- role of a: (i) cellular imaging agent and (ii) drug delivery agent in CT26 cancer cells without the need for additional fluorescent protein labeling. Our method offers a simple, controllable strategy to tune and enhance the fluorescence property of GO, which shows potential for biomedical applications and fundamental studies.