scholarly journals Nanophotonic biosensors harnessing van der Waals materials

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sang-Hyun Oh ◽  
Hatice Altug ◽  
Xiaojia Jin ◽  
Tony Low ◽  
Steven J. Koester ◽  
...  
Keyword(s):  
Single Molecule ◽  
Van Der Waals ◽  
Form Factors ◽  
Metallic Films ◽  
Unique Form ◽  
One Dimensional ◽  
Nanophotonic Devices ◽  
Low Dimensional ◽  
Walled Carbon Nanotubes

AbstractLow-dimensional van der Waals (vdW) materials can harness tightly confined polaritonic waves to deliver unique advantages for nanophotonic biosensing. The reduced dimensionality of vdW materials, as in the case of two-dimensional graphene, can greatly enhance plasmonic field confinement, boosting sensitivity and efficiency compared to conventional nanophotonic devices that rely on surface plasmon resonance in metallic films. Furthermore, the reduction of dielectric screening in vdW materials enables electrostatic tunability of different polariton modes, including plasmons, excitons, and phonons. One-dimensional vdW materials, particularly single-walled carbon nanotubes, possess unique form factors with confined excitons to enable single-molecule detection as well as in vivo biosensing. We discuss basic sensing principles based on vdW materials, followed by technological challenges such as surface chemistry, integration, and toxicity. Finally, we highlight progress in harnessing vdW materials to demonstrate new sensing functionalities that are difficult to perform with conventional metal/dielectric sensors.

scholarly journals Bio-Molecular Applications of Recent Developments in Optical Tweezers

Biomolecules ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 23 ◽  
Author(s):  
Dhawal Choudhary ◽  
Alessandro Mossa ◽  
Milind Jadhav ◽  
Ciro Cecconi
Keyword(s):  
Photonic Crystal ◽  
Optical Tweezers ◽  
Single Molecule ◽  
Continuous Wave ◽  
Imaging Techniques ◽  
Resolving Power ◽  
Optical Traps ◽  
Laser Source ◽  
One Dimensional

In the past three decades, the ability to optically manipulate biomolecules has spurred a new era of medical and biophysical research. Optical tweezers (OT) have enabled experimenters to trap, sort, and probe cells, as well as discern the structural dynamics of proteins and nucleic acids at single molecule level. The steady improvement in OT’s resolving power has progressively pushed the envelope of their applications; there are, however, some inherent limitations that are prompting researchers to look for alternatives to the conventional techniques. To begin with, OT are restricted by their one-dimensional approach, which makes it difficult to conjure an exhaustive three-dimensional picture of biological systems. The high-intensity trapping laser can damage biological samples, a fact that restricts the feasibility of in vivo applications. Finally, direct manipulation of biological matter at nanometer scale remains a significant challenge for conventional OT. A significant amount of literature has been dedicated in the last 10 years to address the aforementioned shortcomings. Innovations in laser technology and advances in various other spheres of applied physics have been capitalized upon to evolve the next generation OT systems. In this review, we elucidate a few of these developments, with particular focus on their biological applications. The manipulation of nanoscopic objects has been achieved by means of plasmonic optical tweezers (POT), which utilize localized surface plasmons to generate optical traps with enhanced trapping potential, and photonic crystal optical tweezers (PhC OT), which attain the same goal by employing different photonic crystal geometries. Femtosecond optical tweezers (fs OT), constructed by replacing the continuous wave (cw) laser source with a femtosecond laser, promise to greatly reduce the damage to living samples. Finally, one way to transcend the one-dimensional nature of the data gained by OT is to couple them to the other large family of single molecule tools, i.e., fluorescence-based imaging techniques. We discuss the distinct advantages of the aforementioned techniques as well as the alternative experimental perspective they provide in comparison to conventional OT.

SOME NOTES ON LOW-DIMENSIONAL ELASTIC THEORIES OF BIO- AND NANO-STRUCTURES

2010 ◽  
Vol 24 (23) ◽  
pp. 2403-2412 ◽  
Author(s):  
XIAO-HUA ZHOU
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Energy Density ◽  
Helix Angle ◽  
Dimensional Structure ◽  
One Dimensional ◽  
Nano Structures ◽  
Multi Walled Carbon Nanotubes ◽  
Low Dimensional ◽  
Walled Carbon Nanotubes

The shapes of DNA, carbon nanotube (CNT) and vesicle are determined by the minimum of their elastic energy. Two central results about the low-dimensional elastic structure are reported here. Firstly, if the energy density of a one-dimensional structure is only related to its curvature, we generally find that a helix solution with the helix angle θ = ±π/4 will have zero total energy. Secondly, with the fixed length and radii, the helical multi-walled carbon nanotubes (MWNTs) and DNA will have the lowest energy when the helix angle θ = ±π/3.

scholarly journals Fluorescent Single-Walled Carbon Nanotubes for Protein Detection

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5403 ◽  
Author(s):  
Adi Hendler-Neumark ◽  
Gili Bisker
Keyword(s):  
Carbon Nanotubes ◽  
Single Molecule ◽  
Near Infrared ◽  
Protein Detection ◽  
Single Walled Carbon Nanotubes ◽  
Fluorescent Nanoparticles ◽  
Single Molecule Level ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

Nanosensors have a central role in recent approaches to molecular recognition in applications like imaging, drug delivery systems, and phototherapy. Fluorescent nanoparticles are particularly attractive for such tasks owing to their emission signal that can serve as optical reporter for location or environmental properties. Single-walled carbon nanotubes (SWCNTs) fluoresce in the near-infrared part of the spectrum, where biological samples are relatively transparent, and they do not photobleach or blink. These unique optical properties and their biocompatibility make SWCNTs attractive for a variety of biomedical applications. Here, we review recent advancements in protein recognition using SWCNTs functionalized with either natural recognition moieties or synthetic heteropolymers. We emphasize the benefits of the versatile applicability of the SWCNT sensors in different systems ranging from single-molecule level to in-vivo sensing in whole animal models. Finally, we discuss challenges, opportunities, and future perspectives.

scholarly journals Partial magnetic ordering in one-dimensional arrays of endofullerene single-molecule magnet peapods

Nanoscale ◽  
2018 ◽  
Vol 10 (38) ◽  
pp. 18153-18160 ◽  
Author(s):  
Stanislav M. Avdoshenko ◽  
Fabian Fritz ◽  
Christin Schlesier ◽  
Aram Kostanyan ◽  
Jan Dreiser ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Single Molecule ◽  
Magnetic Ordering ◽  
Single Walled Carbon Nanotubes ◽  
Single Molecule Magnets ◽  
Single Molecule Magnet ◽  
One Dimensional ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

Magnetic ordering and bistability of one-dimensional chains of endofullerene Dy2ScN@C80 single-molecule magnets packed inside single-walled carbon nanotubes.

scholarly journals Fluorescent Sp3 Defect-Tailored Carbon Nanotubes Enable NIR-II Single Particle Imaging in Live Brain Slices at Ultra-Low Excitation Doses

2019 ◽  
Author(s):  
Amit Kumar Mandal ◽  
Xiaojian Wu ◽  
Joana S. Ferreira ◽  
Mijin Kim ◽  
Lyndsey R. Powell ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Single Molecule ◽  
Near Infrared ◽  
Brain Slices ◽  
Tissue Imaging ◽  
Light Extinction ◽  
Order Of Magnitude ◽  
Particle Imaging ◽  
Walled Carbon Nanotubes

AbstractCellular and tissue imaging in the second near-infrared window (NIR-II, ∼1000 - 1350 nm) is advantageous for in vivo studies because of low light extinction by biological constituents at these wavelengths. However, deep tissue imaging at the single molecule sensitivity has not been achieved in the NIR-II window due to lack of suitable bio-probes. Single-walled carbon nanotubes have emerged as promising near-infrared luminescent molecular bio-probes; yet, their inefficient photoluminescence (quantum yield ∼1%) drives requirements for sizeable excitation doses (∼1-10 kW/cm2) that are significantly blue-shifted from the NIR-II region (<850 nm) and may thus ultimately compromise live tissue. Here, we show that single nanotube imaging can be achieved in live brain tissue using ultralow excitation doses (∼100 W/cm2), an order of magnitude lower than those currently used. To accomplish this, we synthesized fluorescent sp3-defect tailored (6,5) carbon nanotubes which, when excited at their first order excitonic transition fluoresce brightly at ∼1160 nm. The biocompatibility of these functionalized nanotubes, which are wrapped by state-of-the-art encapsulation agents (phospholipid-polyethylene glycol), is demonstrated using standard cytotoxicity assays. Single molecule photophysical studies of these biocompatible nanotubes allowed us to identify the optimal luminescence properties in the context of biological imaging.

scholarly journals One-dimensional van der Waals heterostructures

Science ◽  
2020 ◽  
Vol 367 (6477) ◽  
pp. 537-542 ◽  
Author(s):  
Rong Xiang ◽  
Taiki Inoue ◽  
Yongjia Zheng ◽  
Akihito Kumamoto ◽  
Yang Qian ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electron Diffraction ◽  
Hexagonal Boron Nitride ◽  
Van Der Waals ◽  
Single Walled Carbon Nanotubes ◽  
Strain Effect ◽  
Van Der Waals Heterostructures ◽  
One Dimensional ◽  
Bn Nanotube ◽  
Walled Carbon Nanotubes

We present the experimental synthesis of one-dimensional (1D) van der Waals heterostructures, a class of materials where different atomic layers are coaxially stacked. We demonstrate the growth of single-crystal layers of hexagonal boron nitride (BN) and molybdenum disulfide (MoS2) crystals on single-walled carbon nanotubes (SWCNTs). For the latter, larger-diameter nanotubes that overcome strain effect were more readily synthesized. We also report a 5-nanometer–diameter heterostructure consisting of an inner SWCNT, a middle three-layer BN nanotube, and an outer MoS2 nanotube. Electron diffraction verifies that all shells in the heterostructures are single crystals. This work suggests that all of the materials in the current 2D library could be rolled into their 1D counterparts and a plethora of function-designable 1D heterostructures could be realized.

scholarly journals Streptococcus pyogenes Cas9 displays biased one-dimensional diffusion on dsDNA to search for a target

2019 ◽  
Author(s):  
Mengyi Yang ◽  
Lijingyao Zhang ◽  
Ruirui Sun ◽  
Weixiong Zhong ◽  
Yuzhuo Yang ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Single Molecule ◽  
Diffusion Length ◽  
Three Dimensional ◽  
Ionic Concentration ◽  
One Dimensional ◽  
Dimensional Diffusion ◽  
Target Strand

AbstractThe RNA-guided Streptococcus pyogenes Cas9 (spCas9) is a sequence-specific DNA endonuclease that works as one of the most powerful genetic editing tools. However, how the Cas9 locates its target among huge amounts of dsDNAs remains controversial. Here, combining biochemical and single-molecule assays, we revealed that Cas9 uses both three-dimensional and one-dimensional diffusion to find its target. We further observed a surprising biased one-dimensional diffusion of Cas9 from 3’ to 5’ end of the non-target strand under physiological salt condition, whereas low ionic concentration or mutations on PAM recognition residues induce unbiased one-dimensional diffusion of Cas9 along dsDNA. We quantified the diffusion length of 27 bp, which accelerates the target search efficiency of Cas9 by ∼ 10 folds. Our results reveal a unique searching mechanism of Cas9 at physiological salt conditions, and provide important guidance for both in-vitro and in-vivo applications of Cas9.

Nitroxyl Modified Tobacco Mosaic Virus as a Metal-Free High-Relaxivity MRI and EPR Active Superoxide Sensor

2018 ◽  
Author(s):  
Madushani Dharmarwardana ◽  
André F. Martins ◽  
Zhuo Chen ◽  
Philip M. Palacios ◽  
Chance M. Nowak ◽  
...  
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Single Molecule ◽  
Biological Fluids ◽  
Cellular Respiration ◽  
Organic Radical ◽  
Paramagnetic Resonance ◽  
Metal Free ◽  
Disease States

Superoxide overproduction is known to occur in multiple disease states requiring critical care yet non-invasive detection of superoxide in deep tissue remains a challenge. Herein, we report a metal-free magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR) active contrast agent prepared by “click conjugating” paramagnetic organic radical contrast agents (ORCAs) to the surface of tobacco mosaic virus (TMV). While ORCAs are known to be reduced <i>in vivo</i> to an MRI/EPR silent state, their oxidation is facilitated specifically by reactive oxygen species—in particular superoxide—and are largely unaffected by peroxides and molecular oxygen. Unfortunately, single molecule ORCAs typically offer weak MRI contrast. In contrast, our data confirm that the macromolecular ORCA-TMV conjugates show marked enhancement for <i>T<sub>1</sub></i> contrast at low field (<3.0 T), and <i>T<sub>2</sub></i> contrast at high field (9.4 T). Additionally, we demonstrated that the unique topology of TMV allows for “quenchless fluorescent” bimodal probe for concurrent fluorescence and MRI/EPR imaging, which was made possible by exploiting the unique inner and outer surface of the TMV nanoparticle. <a>Finally, we show TMV-ORCAs do not respond to normal cellular respiration, minimizing the likelihood for background, yet still respond to enzymatically produced superoxide in complicated biological fluids like serum.</a>

Supramolecular Enhancement of Aminoxyl ORCA Contrast Agents

2019 ◽  
Author(s):  
Hamilton Lee ◽  
Jenica Lumata ◽  
Michael A. Luzuriaga ◽  
Candace Benjamin ◽  
Olivia Brohlin ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Side Effects ◽  
Magnetic Resonance ◽  
Tobacco Mosaic Virus ◽  
Contrast Agents ◽  
Single Molecule ◽  
Organic Radical ◽  
Resonance Imaging ◽  
Physiological Conditions

<div><div><div><p>Many contrast agents for magnetic resonance imaging are based on gadolinium, however side effects limit their use in some patients. Organic radical contrast agents (ORCAs) are potential alternatives, but are reduced rapidly in physiological conditions and have low relaxivities as single molecule contrast agents. Herein, we use a supramolecular strategy where cucurbit[8]uril binds with nanomolar affinities to ORCAs and protects them against biological reductants to create a stable radical in vivo. We further over came the weak contrast by conjugating this complex on the surface of a self-assembled biomacromolecule derived from the tobacco mosaic virus.</p></div></div></div>

Sign in / Sign up

Export Citation Format

Share Document