This is an open access article published under an ACS AuthorChoice License, which permits copying... more This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
This work was supported by DOE (Grant#: DE-AC03-76SF00098). J.-M.N. and P.M.N. would like to than... more This work was supported by DOE (Grant#: DE-AC03-76SF00098). J.-M.N. and P.M.N. would like to thank Nathan Clack and Bryan Jackson for helpful discussion and initial experimental setup, respectively.
Functionalized nanoparticles hold great promise in realizing highly sensitive and selective biode... more Functionalized nanoparticles hold great promise in realizing highly sensitive and selective biodetection. We report a single disposable chip which is capable of carrying out a multi-step process that employs nanoparticles-a bio-barcode assay (BCA) for single protein marker detection. To illustrate the capability of the system, we tested for the presence of prostate specific antigen (PSA) in buffer solution and goat serum. Detection was accomplished at PSA concentrations as low as 500 aM. This corresponds to only 300 copies of protein analytes using 1 mL total sample volume. We established that the on-chip BCA for PSA detection offers four orders of magnitude higher sensitivity compared to commercially available ELISA-based PSA tests.
The nanoparticle-based von Neumann architecture is constructed on a lipid chip to execute nanopar... more The nanoparticle-based von Neumann architecture is constructed on a lipid chip to execute nanoparticle neural networks with DNA.
A supported lipid bilayer is used as a chemical circuit board to carry out molecular computation ... more A supported lipid bilayer is used as a chemical circuit board to carry out molecular computation with a network of nanoparticles.
Cell membranes contain a variety of lipids and functional proteins that offer active platforms th... more Cell membranes contain a variety of lipids and functional proteins that offer active platforms that organize the membrane components into functional assemblies and perform biologically important reactions. The dynamic and complex nature of the membranes makes them attractive materials, but at the same time, researchers report substantial experimental uncertainty in controlling the membrane reactions and extracting valuable information. The fascinating new structures and properties of nanomaterials could be utilized in addressing aforementioned issues, and the design and synthesis of lipid-nanostructure hybrids could be beneficial to the research areas in lipid-membrane biotechnology and nanobiotechnology. These hybrid structures possess dimensions that are comparable to that of biological molecules and structures and physicochemical properties that arise from both lipids and nanomaterials. Therefore, lipid-nanostructure hybrids offer additional options for control of the synthesized structures, provide new insight in understanding nanostructures and biological systems and allow the mimicking of functional subcellular membrane components and monitoring of the membrane-associated reactions in a highly sensitive and controllable manner. In this review, we present recent advances in the synthesis of various lipid-nanostructure hybrids and the application of these structures in biotechnology and nanotechnology. We further describe the scientific and practical applications of lipid-nanostructure hybrids for detecting membrane-targeting molecules, interfacing nanostructures with live cells and creating membrane-mimicking platforms to investigate various intercellular processes.
Nanoparticle tethering to lipid bilayers enables the observation of hundreds of diffusing particl... more Nanoparticle tethering to lipid bilayers enables the observation of hundreds of diffusing particles that are confined within a single field of view. A wide variety of materials ranging from plasmonic metals to soft matter can be stably tethered to the surface of a fluid bilayer by covalent or non-covalent means. The controlled environment of this experimental platform allows direct control over surface compositions and accurate tracking of nanoparticle interactions. This minireview will cover studies that use bilayertethered nanoparticles to investigate physical properties related to lipid mobility, biomolecule sensing, and surface interactions, as well as experiments to reversibly manipulate tethered nanoparticles by electric fields.
Journal of visualized experiments : JoVE, Jan 24, 2014
Single-molecule fluorescence spectroscopy has proven to be instrumental in understanding a wide r... more Single-molecule fluorescence spectroscopy has proven to be instrumental in understanding a wide range of biological phenomena at the nanoscale. Important examples of what this technique can yield to biological sciences are the mechanistic insights on protein-protein and protein-nucleic acid interactions. When interactions of proteins are probed at the single-molecule level, the proteins or their substrates are often immobilized on a glass surface, which allows for a long-term observation. This immobilization scheme may introduce unwanted surface artifacts. Therefore, it is essential to passivate the glass surface to make it inert. Surface coating using polyethylene glycol (PEG) stands out for its high performance in preventing proteins from non-specifically interacting with a glass surface. However, the polymer coating procedure is difficult, due to the complication arising from a series of surface treatments and the stringent requirement that a surface needs to be free of any fluor...
MicroRNA has been identified as a potential biomarker because expression level of microRNA is cor... more MicroRNA has been identified as a potential biomarker because expression level of microRNA is correlated with various cancers. Its detection at low concentrations would be highly beneficial for cancer diagnosis. Here, we develop a new type of a DNA-modified gold nanoparticle-based bio-barcode assay that uses a conventional gel electrophoresis platform and potassium cyanide chemistry and show this assay can detect microRNA at aM levels without enzymatic amplification. It is also shown that single-base-mismatched microRNA can be differentiated from perfectly matched microRNA and the multiplexed detection of various combinations of microRNA sequences is possible with this approach. Finally, differently expressed microRNA levels are selectively detected from cancer cells using the bio-barcode gel assay, and the results are compared with conventional polymerase chain reaction-based results. The method and results shown herein pave the way for practical use of a conventional gel electrophoresis for detecting biomolecules of interest even at aM level without polymerase chain reaction amplification.
Aqueous nanofibres constructed by the self-assembly of small amphiphilic molecules can become ent... more Aqueous nanofibres constructed by the self-assembly of small amphiphilic molecules can become entangled to form hydrogels that have a variety of applications including tissue engineering, and controlled drug delivery. The hydrogels are formed through the random physical cross-linkings of flexible nanofibres. Here we report that self-assembled nanofibres with a nematic substructure are aligned into a nematic liquid crystal and are spontaneously fixed in the aligned state to give rise to anisotropic gels. The liquid-crystal gels respond to temperature by transforming into a fluid solution upon cooling. Thus, the nanofibre solution can be mixed with cells at room temperature and then can be transformed into gels to encapsulate the cells in a three-dimensional environment upon being heated to physiological temperatures. We found that the cells grow within the three-dimensional networks without compromising the cell viability, and that subsequent cooling triggers the encapsulated cells to be released through a sol-gel transition.
and Technology, frequently referred to us as the Russian Caltech. He then crossed the Pond to stu... more and Technology, frequently referred to us as the Russian Caltech. He then crossed the Pond to study at Columbia University, culminating in a PhD in Bioengineering. He simultaneously worked at the Memorial Sloan-Kettering Cancer Center on problems of cancer drug resistance. As a post-doctoral scholar at Caltech, he worked with faculty in Biology and Computer Science on understanding cell signaling in changing environments. Dr. Levchenko was then appointed to a faculty position at Johns Hopkins where he works on Systems Biology of cell signaling and communication. Prof. Jwa-Min Nam received B.S. degree in chemistry from Hanyang University. He moved to Northwestern University, USA to obtain his Ph.D. in chemistry
Plasmonic coupling-based electromagnetic field localization and enhancement are becoming increasi... more Plasmonic coupling-based electromagnetic field localization and enhancement are becoming increasingly important in chemistry, nanoscience, materials science, physics, and engineering over the past decade, generating a number of new concepts and applications. Among the plasmonically coupled nanostructures, metal nanostructures with nanogaps have been of special interest due to their ultrastrong electromagnetic fields and controllable optical properties that can be useful for a variety of signal enhancements such as surface-enhanced Raman scattering (SERS). The Raman scattering process is highly inefficient, with a very small cross-section, and Raman signals are often poorly reproducible, meaning that very strong, controllable SERS is needed to obtain reliable Raman signals with metallic nanostructures and thus open up new avenues for a variety of Raman-based applications. More specifically, plasmonically coupled metallic nanostructures with ultrasmall (∼1 nm or smaller) nanogaps can ...
Microfluidic laboratory-on-a-chip (LOC) systems based on a modular architecture are presented. Th... more Microfluidic laboratory-on-a-chip (LOC) systems based on a modular architecture are presented. The architecture is conceptualized on two levels: a single-chip level and a multiple-chip module (MCM) system level. At the individual chip level, a multilayer approach segregates components belonging to two fundamental categories: passive fluidic components (channels and reaction chambers) and active electromechanical control structures (sensors and actuators). This distinction is explicitly made to simplify the development process and minimize cost. Components belonging to these two categories are built separately on different physical layers and can communicate fluidically via cross-layer interconnects. The chip that hosts the electromechanical control structures is called the microfluidic breadboard (FBB). A single LOC module is constructed by attaching a chip comprised of a custom arrangement of fluid routing channels and reactors (passive chip) to the FBB. Many different LOC functions can be achieved by using different passive chips on an FBB with a standard resource configuration. Multiple modules can be interconnected to form a larger LOC system (MCM level). We demonstrated the utility of this architecture by developing systems for two separate biochemical applications: one for detection of protein markers of cancer and another for detection of metal ions. In the first case, free prostate-specific antigen was detected at 500 aM concentration by using a nanoparticle-based bio-bar-code protocol on a parallel MCM system. In the second case, we used a DNAzyme-based biosensor to identify the presence of Pb 2؉ (lead) at a sensitivity of 500 nM in <1 nl of solution.
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