Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Nanocages for gold particles: what is happening inside?

Figure. Structure, metal immobilization, and chemical reaction inside a ferritin crystal. 
(a) Structure of the 24-mer ferritin molecule; (b) a ferritin monomer with the metal-binding sites; (c) a symmetric 3-fold axis channel; (d) preparation and crystallization of Au-containing ferritin; (e) cross-linking of the ferritin crystal and reduction of Au ions (yellow circles) into Au(0) atoms which form nanoclusters (brown particles).
Figure. Structure, metal immobilization, and chemical reaction inside a ferritin crystal. (a) Structure of the 24-mer ferritin molecule; (b) a ferritin monomer with the metal-binding sites; (c) a symmetric 3-fold axis channel; (d) preparation and crystallization of Au-containing ferritin; (e) cross-linking of the ferritin crystal and reduction of Au ions (yellow circles) into Au(0) atoms which form nanoclusters (brown particles).

Abstract:
Scientists at Tokyo Institute of Technology have used high-resolution crystallography to uncover the mechanism behind protein-assisted synthesis of gold nanoparticles, providing a platform for designing nanomaterials tailored for biomedical application.

Nanocages for gold particles: what is happening inside?

Tokyo, Japan | Posted on March 16th, 2017

In living organisms, free metal ions are stored and transported through proteins assembled into highly ordered structures such as protein cages via a reaction called biomineralization. This sophisticated biological strategy has attracted the attention of biotechnologists who speculate that natural ion-storage protein cages can be used to grow metal nanoparticles with desired properties.

Gold nanoparticles (AuNPs) are known for their excellent functions in catalysis, bioimaging, drug delivery, and therapy; therefore, the synthesis of AuPs with controlled sizes and shapes is very important for their application in nanomedicine. In protein scaffolds, AuNPs are formed by a sequential process involving Au deposition and agglomeration into small nanoclusters which act as nucleation centers for AuNP growth. However, the dynamic mechanism underlying the formation of Au nanoclusters in protein environments remains unclear.

To disclose molecular processes behind AuNP growth in protein nanocages, a group of biomolecular engineers at Tokyo Institute of Technology, led by Takafumi Ueno, used high-resolution crystallography and analyzed the formation of Au nanoclusters in ferritin. A universal intracellular iron-storage protein produced by almost all living organisms, ferritin forms a self-assembled 24-subunit nanocage with two specific metal-binding sites: the 3-fold axis channel and the accumulation center (Figure). Since Au ions have high affinity for sulfur, the scientists modified the accumulation center by introducing an additional sulfur-containing cystein residue to enhance Au uptake into the protein cage. Then, they reinforced Au-containing ferritin crystals by cross-linking in glutaraldehyde (Figure) to maintain their lattice structure. These modifications enabled the reduction of Au ions in the crystals and determination of binding positions of Au ions inside the ferritin cage by high resolution crystallography.

In the next step, the immobilized Au ions were reduced into Au(0) atoms using a reducing agent (NaBH4). As a result, the scientists could observe that the reduced Au agglomerated into nanoclusters formed in the 3-fold symmetric channels and in the metal accumulation centers (Figure), which was due to the gradual Au movement and conformational changes of surrounding amino acids.

The results obtained by Professor Ueno and his colleagues uncover the mechanism behind the formation of Au nanoclusters which are expected as nucleation centers for subsequent AuNP growth in the unique protein environment, providing a platform for future investigation of biomineralization and nanoparticle synthesis in biomolecular scaffolds.

Reference
Authors:
Basudev Maity, Satoshi Abe, and Takafumi Ueno
Title of original paper:
Observation of gold sub-nanocluster nucleation within a crystalline protein cage
Journal:
Nature Communications
DOI:
10.1038/NCOMMS14820
Affiliations:
Department of Life Science and Technology, Tokyo Institute of Technology

Correspondence to:

####

About Tokyo Institute of Technology
Tokyo Institute of Technology stands at the forefront of research and higher education as the leading university for science and technology in Japan. Tokyo Tech researchers excel in a variety of fields, such as material science, biology, computer science and physics. Founded in 1881, Tokyo Tech has grown to host 10,000 undergraduate and graduate students who become principled leaders of their fields and some of the most sought-after scientists and engineers at top companies. Embodying the Japanese philosophy of “monotsukuri,” meaning technical ingenuity and innovation, the Tokyo Tech community strives to make significant contributions to society through high-impact research.

For more information, please click here

Contacts:
Emiko Kawaguchi
Center for Public Affairs and Communications,
Tokyo Institute of Technology

+81-3-5734-2975

Copyright © Tokyo Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

New organic molecule shatters phosphorescence efficiency records and paves way for rare metal-free applications July 5th, 2024

Single atoms show their true color July 5th, 2024

New method cracked for high-capacity, secure quantum communication July 5th, 2024

Searching for dark matter with the coldest quantum detectors in the world July 5th, 2024

Crystallography

First measurement of electron energy distributions, could enable sustainable energy technologies June 5th, 2020

How to trick electrons to see the hidden face of crystals: Researchers try a trick for complete 3D analysis of submicron crystals August 3rd, 2019

3-D-printed jars in ball-milling experiments June 29th, 2017

Novel nozzle saves crystals: Double flow concept widens spectrum for protein crystallography March 17th, 2017

Possible Futures

A 2D device for quantum cooling:EPFL engineers have created a device that can efficiently convert heat into electrical voltage at temperatures lower than that of outer space. The innovation could help overcome a significant obstacle to the advancement of quantum computing technol July 5th, 2024

New method cracked for high-capacity, secure quantum communication July 5th, 2024

Searching for dark matter with the coldest quantum detectors in the world July 5th, 2024

Atomic force microscopy in 3D July 5th, 2024

Self Assembly

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Liquid crystal templated chiral nanomaterials October 14th, 2022

Nanoclusters self-organize into centimeter-scale hierarchical assemblies April 22nd, 2022

Atom by atom: building precise smaller nanoparticles with templates March 4th, 2022

Nanomedicine

The mechanism of a novel circular RNA circZFR that promotes colorectal cancer progression July 5th, 2024

Virginia Tech physicists propose path to faster, more flexible robots: Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery May 17th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

Discoveries

Efficient and stable hybrid perovskite-organic light-emitting diodes with external quantum efficiency exceeding 40 per cent July 5th, 2024

A New Blue: Mysterious origin of the ribbontail ray’s electric blue spots revealed July 5th, 2024

New organic molecule shatters phosphorescence efficiency records and paves way for rare metal-free applications July 5th, 2024

Single atoms show their true color July 5th, 2024

Materials/Metamaterials/Magnetoresistance

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

Announcements

New organic molecule shatters phosphorescence efficiency records and paves way for rare metal-free applications July 5th, 2024

Single atoms show their true color July 5th, 2024

New method cracked for high-capacity, secure quantum communication July 5th, 2024

Searching for dark matter with the coldest quantum detectors in the world July 5th, 2024

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Single atoms show their true color July 5th, 2024

New method cracked for high-capacity, secure quantum communication July 5th, 2024

Searching for dark matter with the coldest quantum detectors in the world July 5th, 2024

Atomic force microscopy in 3D July 5th, 2024

Nanobiotechnology

The mechanism of a novel circular RNA circZFR that promotes colorectal cancer progression July 5th, 2024

A New Blue: Mysterious origin of the ribbontail ray’s electric blue spots revealed July 5th, 2024

Diamond glitter: A play of colors with artificial DNA crystals May 17th, 2024

Advances in priming B cell immunity against HIV pave the way to future HIV vaccines, shows quartet of new studies May 17th, 2024

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project