XPS and SIMS map thioglucose SAMs on gold
Thio-glucose binds gold through Au–S; flat films pack better than citrate AuNPs, and ToF-SIMS sees TG–MBP pocket fragments.
Source
Surface Analysis of Gold Nanoparticles Functionalized with Thiol-Modified Glucose SAMs for Biosensor Applications
Study at a glance
- Design
- Other — XPS/ToF-SIMS of thio-glucose on AuNPs and Au films before/after maltose-binding protein
- N
- Surface-chemistry analysis of ~15 nm AuNPs — no sample N
- Population
- Thio-glucose–functionalized gold nanoparticles and films
- Outcome
- Bound vs unbound thiol fractions and protein uptake differences
Structured fields used in claim comparison tables when every cited study has a complete layer.
Inspect source passages
XPS and SIMS map thioglucose SAMs on gold
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
AuNPs were synthesized at a 15 nm target size.
Synthesis of 15 nm sized Au NPs was carried out by modification of the procedure described by Turkevich et al.
About 30% of unbound TG thiols remain on the Au nanoparticle surface.
the first component, centered at about 162 eV, related to the bound TG thiols, whilst the second component due to the weakly bound thiols, indicating that despite the dialysis cleaning process about 30% of unbound TG thiols is still present on the Au nanoparticles surface.
What they did
Authors made ~15 nm citrate AuNPs, assembled 1-β-D-thio-glucose on NPs and sputtered Au films, then used XPS and ToF-SIMS before/after maltose-binding protein.
What they found
S2p at 162 eV proves chemisorption; C–O (286.5 eV) rises ~6-fold on films. NPs retain ~30% unbound thiol and lower TG density, hence weaker MBP uptake. SIMS peaks at 358 and 375 u mark TG–pocket complexes.
The limits
What it doesn't show
No calibrated binding constant; Ti-supported NP films confound O/C; biosensor performance is not quantified.
Key terms
- SAM
- Self-assembled monolayer, here thiol-glucose on gold.
- S2p 162 eV
- XPS binding energy diagnostic of thiolate bound to gold.
- ToF-SIMS
- Time-of-flight secondary-ion mass spectrometry of surface fragments.
- Maltose-binding protein (MBP)
- Periplasmic protein that recognizes glucose/maltose in a domain cleft.
- Citrate-capped AuNP
- Turkevich gold colloid whose citrate layer competes with thiol exchange.
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Quiz yourself
XPS proof of chemisorbed TG:
Common questions
How do you know TG is chemisorbed?
S2p component at ~162 eV assigned to Au–S.
Films vs NPs?
Films give denser, more ordered TG; NPs keep unbound thiol and citrate.
MBP XPS marker?
C2 peptide-bond component near 288.5 eV.
SIMS proof of pocket binding?
Fragments at 358 and 375 u for TG–MBP.
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