Browsing by Author "Ploegh, Hidde L."

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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.
;
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.
Rapid capture and labeling of cells on single domain antibodies-functionalized flow cell
(2017-03-15)
Chen, Guan-Yu
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Li, Zeyang
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Duarte, Joao N.
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Esteban, Alexandre
;
Cheloha, Ross W.
Current techniques to characterize leukocyte subgroups in blood require long sample preparation times and sizable sample volumes. A simplified method for leukocyte characterization using smaller blood volumes would thus be useful in diagnostic settings. Here we describe a flow system comprised of two functionalized graphene oxide (GO) surfaces that allow the capture of distinct leukocyte populations from small volumes blood using camelid single-domain antibodyfragments (VHHs) as capture agents. We used site-specifically labeled leukocytes to detect and identify cells exposed to fungal challenge. Combining the chemical and optical properties of GO with the versatility of the VHH scaffold in the context of a flow system provides a quick and efficient method for the capture and characterization of functional leukocytes.