In Situ Bioconjugation and Ambient Surface Modification Using Reactive Charged Droplets

Abstract

Molecular ions are generated in induced electrospray ionization, and they can be transported to grounded ambient surfaces in the form of charged microdroplets. Efficient amide bonds formation between amines and carboxylic acids were observed inside charged droplets during transfer to the surface. Biomolecules derivatized using this method were self-assembled on a bare gold surface via Au-S bonds under the charged microdroplet environment. Cyclic voltammetric analysis of the self-assembled molecular film showed accelerated protein derivatization with cysteine, which allowed the covalent immobilization of the protein to the gold surface. Cytochrome C-functionalized electrodes prepared using the induced dual nanoelectrospray process showed bioactivity toward aqueous solutions of hydrogen peroxide below 50 μM. In effect, we have developed a method that allows derivatization of biomolecules and their immobilization at ambient surfaces in a single experimental step.

Reactive Charged Droplets for Reduction of Matrix Effects in Electrospray Ionization Mass Spectrometry

“…Our motivation was to use the accelerated reaction rates typical under the charged micro-droplet environment [11][12][13][14][15] for on-line analytes modification, and thus enhance their detection. We hypothesized that because all major mechanisms [16][17][18][19] (e.g., competition for charge 16 and space, 17 variation in solvent viscosity and surface tension due to the presence of matrix compounds, 18,19 etc.)…”

From Isolated Ions to Multilayer Functional Materials Using Ion Soft Landing

“…[27] Thec hips were used for the development of bioanalytical assays based on the interaction between the immobilized protein and the sampled analyte directly on the chip.P otential future developments for ambient soft landing as an approach to surface modification include the incorporation of electrode devices capable of focusing,reacting,and separating ions in the open air,thereby achieving some ion manipulations similar to those conducted routinely in vacuum. [30] Thed erivatized species self-assembled on bare gold surfaces through the formation of AuÀSb onds.T he interaction of charged droplets containing organic compounds with solid surfaces was also shown to be more efficient than the equivalent reaction performed in bulk solution. [29] Ambient soft landing benefits from the accelerated reaction kinetics occurring in desolvating microdroplets.F or example,t his approach was employed to derivatize biomolecules through the efficient formation of amide bonds between amines and carboxylic acids in charged microdroplets.…”

Von isolierten Ionen zu mehrschichtigen funktionellen Materialien durch sanfte Landung von Ionen

“…[27] Mit diesen Chips wurden bioanalytische Proben, basiert auf der Wechselwirkung zwischen dem immobilisierten Protein und dem Probenanalyt auf dem Chip, entwickelt. [30] Die derivatisierten Substanzen lagern sich auf reinen Goldoberflächen unter Bildung von Au-S-Bindungen organisiert an. Ionen kçnnen an der Luft fokussiert und getrennt werden.…”

“…Dieser Ansatz wurde beispielsweise genutzt, um Biomoleküle durch effiziente Bildung von Amid-Bindungen (Amine reagieren mit Carbonsäuren) in geladenen Mikrotropfen zu derivatisieren. [30] Die derivatisierten Substanzen lagern sich auf reinen Goldoberflächen unter Bildung von Au-S-Bindungen organisiert an. Die Reaktion von organischen Verbindungen in geladenen Tr çpfchen mit Substanzen auf Oberflächen, welche mit den Trçpfchen in Kontakt waren, ist ebenfalls beschleunigt gegenüber entsprechenden Reaktionen unter Standard-Lçsungsbedingungen.…”