Science Current Events | Science News |

Light touch keeps a grip on delicate nanoparticles

May 04, 2012

Using a refined technique for trapping and manipulating nanoparticles, researchers at the National Institute of Standards and Technology (NIST) have extended the trapped particles' useful life more than tenfold.* This new approach, which one researcher likens to "attracting moths," promises to give experimenters the trapping time they need to build nanoscale structures and may open the way to working with nanoparticles inside biological cells without damaging the cells with intense laser light.

Scientists routinely trap and move nanoparticles in a solution with "optical tweezers"-a laser focused to a very small point. The tiny dot of laser light creates a strong electric field, or potential well, that attracts particles to the center of the beam. Although the particles are attracted into the field, the molecules of the fluid they are suspended in tend to push them out of the well. This effect only gets worse as particle size decreases because the laser's influence over a particle's movement gets weaker as the particle gets smaller. One can always turn up the power of the laser to generate a stronger electric field, but doing that can fry the nanoparticles too quickly to do anything meaningful with them-if it can hold them at all.

NIST researchers' new approach uses a control and feedback system that nudges the nanoparticle only when needed, lowering the average intensity of the beam and increasing the lifetime of the nanoparticle while reducing its tendency to wander. According to Thomas LeBrun, they do this by turning off the laser when the nanoparticle reaches the center and by constantly tracking the particle and moving the tweezers as the particle moves.

"You can think of it like attracting moths in the dark with a flashlight," says LeBrun. "A moth is naturally attracted to the flashlight beam and will follow it even as the moth flutters around apparently at random. We follow the fluttering particle with our flashlight beam as the particle is pushed around by the neighboring molecules in the fluid. We make the light brighter when it gets too far off course, and we turn the light off when it is where we want it to be. This lets us maximize the time that the nanoparticle is under our control while minimizing the time that the beam is on, increasing the particle's lifetime in the trap."

Using this method at constant average beam power, 100-nanometer gold particles remained trapped 26 times longer than had been seen in previous experiments. Silica particles 350 nanometers in diameter lasted 22 times longer, but with the average beam power reduced by 33 percent. LeBrun says that their approach should be able to be combined with other techniques to trap and hold even smaller nanoparticles for extended periods without damaging them.

"We're more than an order of magnitude ahead of where we were before," says LeBrun. "We now hope to begin building complex nanoscale devices and testing nanoparticles as sensors and drugs in living cells."


* A. Balijepalli, J. Gorman, S. Gupta and T. LeBrun. Significantly Improved Trapping Lifetime of Nanoparticles in an Optical Trap using Feedback Control. Nano Letters. April 10, 2012. Available online

National Institute of Standards and Technology (NIST)

Related Nanoparticles Current Events and Nanoparticles News Articles

Automating DNA origami opens door to many new uses
Researchers can build complex, nanometer-scale structures of almost any shape and form, using strands of DNA. But these particles must be designed by hand, in a complex and laborious process.

Simple attraction: Researchers control protein release from nanoparticles without encapsulation
A U of T Engineering team has designed a simpler way to keep therapeutic proteins where they are needed for long periods of time. The discovery is a potential game-changer for the treatment of chronic illnesses or injuries that often require multiple injections or daily pills.

Restoring chemotherapy sensitivity by boosting microRNA levels
By increasing the level of a specific microRNA (miRNA) molecule, researchers have for the first time restored chemotherapy sensitivity in vitro to a line of human pancreatic cancer cells that had developed resistance to a common treatment drug.

The next generation of carbon monoxide nanosensors
The detection of carbon monoxide (CO) in the air is a vital issue, as CO is a poisonous gas and an environmental pollutant. CO typically derives from the incomplete combustion of carbon-based fuels, such as cooking gas and gasoline; it has no odour, taste, or colour and hence it is difficult to detect.

Single-step hydrogen peroxide production could be cleaner, more efficient
Bottles of dilute hydrogen peroxide sit on shelves in medicine cabinets across the world, yet synthesizing the chemical at the large scale requires a surprisingly complicated process that is economically unfeasible for all but a few industrial facilities.

Nanoscale Trojan horses treat inflammation
Nanosized Trojan horses created from a patient's own immune cells have successfully treated inflammation by overcoming the body's complex defense mechanisms, perhaps leading to broader applications for treating diseases characterized by inflammation, such as cancer and cardiovascular diseases.

Two-stage nanoparticle delivery of piperlongumine and TRAIL anti-cancer therapy
A team of researchers from Cornell University in Ithaca, New York demonstrated a drug delivery mechanism that utilizes two independent vehicles, allowing for delivery of chemically and physically dis-tinct agents.

ORNL demonstrates large-scale technique to produce quantum dots
A method to produce significant amounts of semiconducting nanoparticles for light-emitting displays, sensors, solar panels and biomedical applications has gained momentum with a demonstration by researchers at the Department of Energy's Oak Ridge National Laboratory.

Action of nanoparticles on platelet activation and plasmatic coagulation
Hemostasis is a highly regulated process with key function for human life. The process is based on a rather complex interplay between endothelial cells, plasmatic coagulation and platelets.

Rice experts unveil submicroscopic tunable, optical amplifier
Rice University photonics researchers have unveiled a new nanoparticle amplifier that can generate infrared light and boost the output of one light by capturing and converting energy from a second light.
More Nanoparticles Current Events and Nanoparticles News Articles

Nanoparticles: From Theory to Application

Nanoparticles: From Theory to Application
by Günter Schmid (Editor)

Very small particles are able to show astonishing properties. For example, gold atoms can be combined like strings of pearls, while nanoparticles can form one-, two- and three-dimensional layers. These assemblies can be used, for instance, as semiconductors, but other electronic as well as optical properties are possible.
An introduction to the booming field of "nanoworld" or "nanoscience", from fundamental principles to their use in novel applications.
With its clear structure and comprehensive coverage, backed by numerous examples from recent literature, this is a prime reference for chemists and materials scientists working with and developing nanoparticle systems.
A bestselling title in its second edition. A must-have reference for chemists and materials scientists.

Nanoparticles - Nanocomposites ? Nanomaterials: An Introduction for Beginners

Nanoparticles - Nanocomposites ? Nanomaterials: An Introduction for Beginners
by Dieter Vollath (Author)

Meeting the demand for a readily understandable introduction to nanomaterials and nanotechnology, this textbook specifically addresses the needs of students - and engineers - who need to get the gist of nanoscale phenomena in materials without having to delve too deeply into the physical and chemical details.

The book begins with an overview of the consequences of small particle size, such as the growing importance of surface effects, and covers successful, field-tested synthesis techniques of nanomaterials. The largest part of the book is devoted to the particular magnetic, optical, electrical and mechanical properties of materials at the nanoscale, leading on to emerging and already commercialized applications, such as nanofluids in magnetic resonance imaging,...

Nanoparticle- and Microparticle-based Delivery Systems: Encapsulation, Protection and Release of Active Compounds

Nanoparticle- and Microparticle-based Delivery Systems: Encapsulation, Protection and Release of Active Compounds
by David Julian McClements (Author)

Recent developments in nanoparticle and microparticle delivery systems are revolutionizing delivery systems in the food industry. These developments have the potential to solve many of the technical challenges involved in creating encapsulation, protection, and delivery of active ingredients, such as colors, flavors, preservatives, vitamins, minerals, and nutraceuticals. Nanoparticle- and Microparticle-based Delivery Systems: Encapsulation, Protection and Release of Active Compounds explores various types of colloidal delivery systems available for encapsulating active ingredients, highlighting their relative advantages and limitations and their use. Written by an international authority known for his clear and rigorous technical writing style, this book discusses the numerous kinds of...

Nanoparticles in Humans: Experiments, Methods, and Strategies

Nanoparticles in Humans: Experiments, Methods, and Strategies
by Lev S. Ruzer (Editor)

A peek into the literature on the environmental health implications of the rapidly developing nanotechnology industry shows that the potential problem of exposure to airborne nanoparticles has not been adequately addressed. The health and safety of nanotechnology workers are of concern because these groups run the greatest risk of exposure to elevated concentrations of nanomaterials. However, a gap exists between the currently available particle measurement methods and those appropriate for the assessment of nanoaerosol exposure.
This book presents new ideas and methods to measure the surface area and local deposition of nanoparticles in the lungs and the true value of respirators. It proposes a nanoparticle dosimetric road map that can be used as a general strategy for the assessment...

Nanoparticles in the Water Cycle: Properties, Analysis and Environmental Relevance

Nanoparticles in the Water Cycle: Properties, Analysis and Environmental Relevance
by Fritz H. Frimmel (Editor), R. Niessner (Editor)

As nanotechnology enters everyday life, engineered nanoparticles (ENP) will find their way into nature, including surface and groundwater. Here, distinguished experts of water chemistry present dedicated methods for the analysis of nanoparticles in the aquatic environment, their distribution and fate. This includes the influence of complex matrices such as wastewater, brown water with natural organic matter (NOM), and high salt concentrations as well as available and future standardized methods. The background of geogenic, natural nanoparticles is considered in a discussion of known environmental effects, including strategies to test for potential effects on human and environmental health.

Silica-coated Magnetic Nanoparticles: An Insight into Targeted Drug Delivery and Toxicology (SpringerBriefs in Molecular Science)

Silica-coated Magnetic Nanoparticles: An Insight into Targeted Drug Delivery and Toxicology (SpringerBriefs in Molecular Science)
by Mariela A. Agotegaray (Author), Verónica L. Lassalle (Author)

This brief offers a comprehensive discussion of magnetic targeted drug delivery of silica-coated nanodevices. Focusing on the latest trend in pharmaceutical applications of these nanodevices, a multidisciplinary overview is displayed, from synthesis and design to pharmacokenetics, biodistribution and toxicology.
Chapters include design of silica-coated magnetic nanodevices; techniques for drug loading with features applicable to biological systems; synthesis, characterization and the assessment of biomedical issues with both in vitro and in vivo experiments. Applications in the treatment of different localized diseases are also addressed in order to present the potential use of these nanosystems as global, commercially available therapeutics.

Gold Nanoparticles for Physics, Chemistry and Biology (2nd Edition)

Gold Nanoparticles for Physics, Chemistry and Biology (2nd Edition)
by Olivier Pluchery (Author), Olivier Pluchery (Editor), Catherine Louis (Editor)

Gold Nanoparticles in Physics, Chemistry and Biology offers an overview of recent research into gold nanoparticles, covering their discovery, usage and contemporary practical applications.This Second Edition begins with a history of over 2000 years of the use of gold nanoparticles, with a review of the specific properties which make gold unique. Updated chapters include gold nanoparticle preparation methods, their plasmon resonance and thermo-optical properties, their catalytic properties and their future technological applications. New chapters have been included, and reveal the growing impact of plasmonics in research, with an introduction to quantum plasmonics, plasmon assisted catalysis and electro-photon conversion. The growing field of nanoparticles for health is also addressed with...

Gold Nanoparticles for Physics, Chemistry and Biology

Gold Nanoparticles for Physics, Chemistry and Biology
by Catherine Louis (Author), Olivier Pluchery (Author)

The fascination with gold is a story which spans millennia, however scientists have recently found a new interest for gold when it is divided into miniscule grains, such as gold nanoparticles. This scientific enthusiasm started in various fields of science in the middle of the 1980s and the present book offers a panorama of the major scientific achievements obtained with gold nanoparticles. Various topics are reviewed such as: gold nanoparticle preparation methods, their plasmon resonance and thermo-optical properties, their catalytic properties, their use in biology and medicine as well as their possible toxicity and, finally, their future technological applications. The book also contains an in-depth study of the use of gold nanoparticles throughout the ages, starting from times where...

Modelling the Toxicity of Nanoparticles (Advances in Experimental Medicine and Biology)

Modelling the Toxicity of Nanoparticles (Advances in Experimental Medicine and Biology)
by Lang Tran (Editor), Miguel A. Bañares (Editor), Robert Rallo (Editor)

In today’s nanotechnology and pharmaceutical research, alternative toxicology testing methods are crucial for ethically and commercially sound practice. This book provides practical guidelines on how to develop and validate quantitative nanostructure-toxicity relationship (QNTR) models, which are ideal for rapidly exploring the effects of a large number of variables in complex scenarios.  Through contributions by academic, industrial, and governmental experts, Modelling the Toxicity of Nanoparticles delivers clear instruction on these methods and their integration and use in risk assessment. Specific topics include the physico-chemical characteristics of engineered nanoparticles, nanoparticle interactions, in vivo nanoparticle processing, and more.  A much-needed practical guide,...

Life Cycle Analysis of Nanoparticles

Life Cycle Analysis of Nanoparticles
by Edited by Ashok Vaseashta (Author), Ashok Vaseashta (Editor)

Investigative tools for analyzing environmental nanoparticles with health impacts Basic theories and models of life cycle analysis applied to nanomaterials Connects LCA, detection technologies and sustainability This book addresses the ways life cycle assessment (LCA) concepts can be applied to analyze the fate of nanoparticles in a variety of environmental and manufacturing settings. After introducing LCA theory and modeling concepts, the work discusses risks associated with carbon nanotubes, graphene, silver, fullerenes, iron oxides and other particles generated by manufacturing or medical diagnostics. Chapters in the text discuss biomolecules and the application of in vivo biosensors. Also covered are fate analysis, risk assessment, toxicology and nanopathology with a focus on human...

© 2017