Sizing by weighing: characterizing sizes of ultrasmall-sized iron oxide nanocrystals using MALDI-TOF mass spectrometry.
We present a rapid and reliable method for determining the sizes and size distributions of <5 nm-sized iron oxide nanocrystals (NCs) using matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS). MS data were readily converted to size information using a simple equation. The size distribution obtained from the mass spectrum is well-matched with the data from transmission electron microscopy, which requires long and tedious analysis work. The size distribution obtained from the mass spectrum is highly resolved and can detect size differences of only a few angstroms. We used this MS-based technique to investigate the formation of iron oxide NCs, which is not easy to monitor with other methods. From ex situ measurements, we observed the transition from molecular precursors to clusters and then finally to NCs.
Center for Nanoparticle Research, Institute for Basic Science, and School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea.
Byung Hyo
BH
Kim
Kwangsoo
K
Shin
Soon Gu
SG
Kwon
Youngjin
Y
Jang
Hyun-Seok
HS
Lee
Hyunjae
H
Lee
Samuel Woojoo
SW
Jun
Jisoo
J
Lee
Sang Yun
SY
Han
Yong-Hyeon
YH
Yim
Dae-Hyeong
DH
Kim
Taeghwan
T
Hyeon
D005290:Ferric Compounds / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D008970:Molecular Weight; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D005290:Ferric Compounds; C000499:ferric oxide