Characterization and quantification of nanoparticle-antibody conjugates on cells using C60 ToF SIMS in the event-by-event bombardment/detection mode

Li Jung Chen, Sunny S. Shah, Jaime Silangcruz, Michael J. Eller, Stanislav V. Verkhoturov, Alexander Revzin, Emile A. Schweikert

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Cluster C60 ToF-SIMS (time-of-flight secondary ion mass spectrometry) operated in the event-by-event bombardment-detection method has been applied to: (a) quantify the binding density of Au nanoparticles (AuNPs)-antiCD4 conjugates on the cell surface and (b) identify the binding sites between AuNPs and antibody. Briefly, our method consists of recording the secondary ions, SIs, individually emitted from a single C60 1,2+ impact. From the cumulative mass spectral data we selected events where a specific SI was detected. The selected records revealed the SIs co-ejected from the nanovolume impacted by an individual C60 with an emission area of ∼10 nm in diameter as an emission depth of 5-10 nm. The fractional coverage is obtained as the ratio of the effective number of projectile impacts on a specified sampling area (Ne) to the total number of impacts (No). In the negative ion mass spectrum, the palmitate (C16H31O2 -) and oletate (C18H33O2 -) fatty acid ions present signals from lipid membrane of the cells. The signals at m/z 197 (Au -) and 223 (AuCN-) originate from the AuNPs labeled antibodies (antiCD4) bound to the cell surface antigens. The characteristic amino acid ions validate the presence of antiCD4. A coincidence mass spectrum extracted with ion at m/z 223 (AuCN-) reveals the presence of cysteine at m/z 120, documenting the closeness of cysteine and the AuNP. Their proximity suggests that the binding site for AuNP on the antibody is the sulfur-terminal cysteine. The fractional coverage of membrane lipid was determined to be ∼23% of the cell surfaces while the AuNPs was found to be ∼21%. The novel method can be implemented on smaller size NPs, it should thus be applicable for studies on size dependent binding of NP-antibody conjugates.

Original languageEnglish (US)
Pages (from-to)97-102
Number of pages6
JournalInternational Journal of Mass Spectrometry
Volume303
Issue number2-3
DOIs
StatePublished - Jun 1 2011

Fingerprint

Secondary ion mass spectrometry
antibodies
Antibodies
secondary ion mass spectrometry
bombardment
Nanoparticles
nanoparticles
cysteine
International System of Units
cells
Ions
Cysteine
Binding sites
Membrane Lipids
mass spectra
lipids
ions
Binding Sites
membranes
Palmitates

Keywords

  • AuNPs-antiCD4 conjugates
  • Biological surfaces
  • Cell micropatterns
  • Cluster SIMS
  • Quantification of bioconjugations

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Condensed Matter Physics
  • Instrumentation

Cite this

Characterization and quantification of nanoparticle-antibody conjugates on cells using C60 ToF SIMS in the event-by-event bombardment/detection mode. / Chen, Li Jung; Shah, Sunny S.; Silangcruz, Jaime; Eller, Michael J.; Verkhoturov, Stanislav V.; Revzin, Alexander; Schweikert, Emile A.

In: International Journal of Mass Spectrometry, Vol. 303, No. 2-3, 01.06.2011, p. 97-102.

Research output: Contribution to journalArticle

Chen, Li Jung ; Shah, Sunny S. ; Silangcruz, Jaime ; Eller, Michael J. ; Verkhoturov, Stanislav V. ; Revzin, Alexander ; Schweikert, Emile A. / Characterization and quantification of nanoparticle-antibody conjugates on cells using C60 ToF SIMS in the event-by-event bombardment/detection mode. In: International Journal of Mass Spectrometry. 2011 ; Vol. 303, No. 2-3. pp. 97-102.
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