4 research outputs found
Copper-Free Click Biofunctionalization of Silicon Nitride Surfaces via Strain-Promoted AlkyneâAzide Cycloaddition Reactions
Cu-free âclickâ chemistry is explored on
silicon
nitride (Si<sub>3</sub>N<sub>4</sub>) surfaces as an effective way
for oriented immobilization of biomolecules. An Ï-unsaturated
ester was grafted onto Si<sub>3</sub>N<sub>4</sub> using UV irradiation.
Hydrolysis followed by carbodiimide-mediated activation yielded surface-bound
active succinimidyl and pentafluorophenyl ester groups. These reactive
surfaces were employed for the attachment of bicyclononyne with an
amine spacer, which subsequently enabled room temperature strain-promoted
azideâalkyne cycloaddition (SPAAC). This stepwise approach
was characterized by means of static water contact angle, X-ray photoelectron
spectroscopy, and fluorescence microscopy. The surface-bound SPAAC
reaction was studied with both a fluorine-tagged azide and an azide-linked
lactose, yielding hydrophobic and bioactive surfaces for which the
presence of trace amounts of Cu ions would have been problematic.
Additionally, patterning of the Si<sub>3</sub>N<sub>4</sub> surface
using this metal-free click reaction with a fluorescent azide is shown.
These results demonstrate the ability of the SPAAC as a generic tool
for anchoring complex molecules onto a surface under extremely mild,
namely ambient and metal-free, conditions in a clean and relatively
fast manner
Ambient Surface Analysis of Organic Monolayers using Direct Analysis in Real Time Orbitrap Mass Spectrometry
A better characterization of nanometer-thick
organic layers (monolayers)
as used for engineering surface properties, biosensing, nanomedicine,
and smart materials will widen their application. The aim of this
study was to develop direct analysis in real time high-resolution
mass spectrometry (DART-HRMS) into a new and complementary analytical
tool for characterizing organic monolayers. To assess the scope and
formulate general interpretation rules, DART-HRMS was used to analyze
a diverse set of monolayers having different chemistries (amides,
esters, amines, acids, alcohols, alkanes, ethers, thioethers, polymers,
sugars) on five different substrates (Si, Si<sub>3</sub>N<sub>4</sub>, glass, Al<sub>2</sub>O<sub>3</sub>, Au). The substrate did not
play a major role except in the case of gold, for which breaking of
the weak AuâS bond that tethers the monolayer to the surface,
was observed. For monolayers with stronger covalent interfacial bonds,
fragmentation around terminal groups was found. For ester and amide-terminated
monolayers, in situ hydrolysis during DART resulted in the detection
of ions characteristic of the terminal groups (alcohol, amine, carboxylic
acid). For ether and thioether-terminated layers, scission of CâO
or CâS bonds also led to the release of the terminal part of
the monolayer in a predictable manner. Only the spectra of alkane
monolayers could not be interpreted. DART-HRMS allowed for the analysis
of and distinction between monolayers containing biologically relevant
mono or disaccharides. Overall, DART-HRMS is a promising surface analysis
technique that combines detailed structural information on nanomaterials
and ultrathin films with fast analyses under ambient conditions
Ambient Surface Analysis of Organic Monolayers using Direct Analysis in Real Time Orbitrap Mass Spectrometry
A better characterization of nanometer-thick
organic layers (monolayers)
as used for engineering surface properties, biosensing, nanomedicine,
and smart materials will widen their application. The aim of this
study was to develop direct analysis in real time high-resolution
mass spectrometry (DART-HRMS) into a new and complementary analytical
tool for characterizing organic monolayers. To assess the scope and
formulate general interpretation rules, DART-HRMS was used to analyze
a diverse set of monolayers having different chemistries (amides,
esters, amines, acids, alcohols, alkanes, ethers, thioethers, polymers,
sugars) on five different substrates (Si, Si<sub>3</sub>N<sub>4</sub>, glass, Al<sub>2</sub>O<sub>3</sub>, Au). The substrate did not
play a major role except in the case of gold, for which breaking of
the weak AuâS bond that tethers the monolayer to the surface,
was observed. For monolayers with stronger covalent interfacial bonds,
fragmentation around terminal groups was found. For ester and amide-terminated
monolayers, in situ hydrolysis during DART resulted in the detection
of ions characteristic of the terminal groups (alcohol, amine, carboxylic
acid). For ether and thioether-terminated layers, scission of CâO
or CâS bonds also led to the release of the terminal part of
the monolayer in a predictable manner. Only the spectra of alkane
monolayers could not be interpreted. DART-HRMS allowed for the analysis
of and distinction between monolayers containing biologically relevant
mono or disaccharides. Overall, DART-HRMS is a promising surface analysis
technique that combines detailed structural information on nanomaterials
and ultrathin films with fast analyses under ambient conditions