Horizontal γ-PNA immobilization through organophosphonate chemistry for biosensing applications

De, Arpita; Keim, Kevin; Tornow, Marc; Cattani‐Scholz, Anna

doi:10.1109/nano.2015.7485974

Cited by 4 publications

(10 citation statements)

References 9 publications

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“…These observations are confirmed over different fabrication batches, indicating the high reliability of the SAMPs deposition method applied in this work. AFM scratching experiments indicated the thickness of the SAMPs layers ( d SAMPs ) to be on the order of 0.3–0.5 ± 0.1 nm (Figure b), which is in reasonable agreement with previous studies . However, the experimentally determined SAMPs thickness is slightly lower than expected for a well-packed monolayer with a backbone chain length of ca.…”

Section: Resultssupporting

confidence: 90%

“…Wetting properties of silicon native oxide, SAMPs, and PNA-coated samples were investigated by water contact angle measurements (Table S1). After SAMPs’ surface functionalization, the water contact angle increased from 26 ± 1° to 45 ± 3°, indicating a decrease of the surface hydrophilicity, as previously reported. , For the ∥ PNA type, a further increase of the water contact angle to 52 ± 2° is observed, as expected. Contrarily, the ⊥ PNA type interface shows a more hydrophilic behavior with contact angles of 35 ± 3°.…”

Section: Resultssupporting

confidence: 88%

“…For both PNA systems, the experimentally derived values are in good agreement with the theoretical composition. Deviation from the expected values might be related to contributions from the linker, containing one nitrogen atom in a − N < environment per Linker molecule …”

Section: Resultsmentioning

confidence: 96%

“…SAMPs of 2-{2-[2-hydroxy-ethoxy]-ethoxy}-ethyl phosphonic acid molecules (SAMPs for further reference) were prepared using the T-BAG method (tethering by aggregation and growth) with two full T-BAG cycles as reported previously. ,, The chips were immersed in 80 mL of tetrahydrofuran (THF) solution (Sigma-Aldrich, anhydrous, inhibitor-free, ≥99.9%) containing 25 μmol·L –1 phosphonic acid molecules. After each T-BAG cycle, the samples were stored in a N 2 atmosphere at 120 °C for at least 18 h. After the first T-BAG cycle, the chips were cleaned twice in ethanol (EtOH; Sigma-Aldrich, absolute, reag.…”

Section: Experimental Sectionmentioning

confidence: 99%

“…Short (15 bases), single-stranded PNA molecules, modified with reactive SH sites at different points of the backbone, were coupled to SAMPs-terminated silicon native oxide either in a vertical ( ⊥ PNA) or horizontal ( ∥ PNA) surface conformation (Scheme ). The applied PNA immobilization chemistry depends on standard maleimido cross-coupling , and exploits both the hydrolytic stability of organophosphonate anchor groups and the protective properties of ethylene glycol (EG) units against the nonspecific surface binding of charged biomolecules − making them attractive bioreceptor platforms for DNA/RNA detection in a physiological environment.…”

Section: Introductionmentioning

confidence: 99%

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Role of Different Receptor-Surface Binding Modes in the Morphological and Electrochemical Properties of Peptide-Nucleic-Acid-Based Sensing Platforms

et al. 2019

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Label-free detection of charged biomolecules, such as DNA, has experienced an increase in research activity in recent years, mainly to obviate the need for elaborate and expensive pretreatments for labeling target biomolecules. A promising label-free approach is based on the detection of changes in the electrical surface potential on biofunctionalized silicon field-effect devices. These devices require a reliable and selective immobilization of charged biomolecules on the device surface. In this work, self-assembled monolayers of phosphonic acids are used to prepare organic interfaces with a high density of peptide nucleic acid (PNA) bioreceptors, which are a synthetic analogue to DNA, covalently bound either in a multidentate (∥PNA) or monodentate (⊥PNA) fashion to the underlying silicon native oxide surface. The impact of the PNA bioreceptor orientation on the sensing platform’s surface properties is characterized in detail by water contact angle measurements, atomic force microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Our results suggest that the multidentate binding of the bioreceptor via attachment groups at the γ-points along the PNA backbone leads to the formation of an extended, protruding, and netlike three-dimensional metastructure. Typical “mesh” sizes are on the order of 8 ± 2.5 nm in diameter, with no preferential spatial orientation relative to the underlying surface. Contrarily, the monodentate binding provides a spatially more oriented metastructure comprising cylindrical features, of a typical size of 62 ± 23 × 12 ± 2 nm2. Additional cyclic voltammetry measurements in a redox buffer solution containing a small and highly mobile Ru-based complex reveal strikingly different insulating properties (ion diffusion kinetics) of these two PNA systems. Investigation by electrochemical impedance spectroscopy confirms that the binding mode has a significant impact on the electrochemical properties of the functional PNA layers represented by detectable changes of the conductance and capacitance of the underlying silicon substrate in the range of 30–50% depending on the surface organization of the bioreceptors in different bias potential regimes.

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 96%

Section: Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of Different Receptor-Surface Binding Modes in the Morphological and Electrochemical Properties of Peptide-Nucleic-Acid-Based Sensing Platforms

et al. 2019

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Modification of silicon nitride with oligo(ethylene glycol)-terminated organophosphonate monolayers

et al. 2020

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Functional Organophosphonate Interfaces for Nanotechnology: A Review

Cattani‐Scholz

2017

ACS Appl. Mater. Interfaces

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Optimization of interfaces in inorganic-organic device systems depends strongly on understanding both the molecular processes that are involved in surface modification and the effects that such modifications have on the electronic states of the material. In particular, the last several years have seen passivation and functionalization of semiconductor surfaces to be strategies by which to realize devices with superior function by controlling Fermi level energies, band-gap magnitudes, and work functions of semiconducting substrates. Among all of the synthetic routes and deposition methods available for the optimization of functional interfaces in hybrid systems, organophosphonate chemistry has been found to be a powerful tool to control at the molecular level the properties of materials in many different applications. In this Review, we focus on the relevance of organophosphonate chemistry in nanotechnology, giving an overview about some recent advances in surface modification, interface engineering, nanostructure optimization, and biointegration.

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Horizontal γ-PNA immobilization through organophosphonate chemistry for biosensing applications

Cited by 4 publications

References 9 publications

Role of Different Receptor-Surface Binding Modes in the Morphological and Electrochemical Properties of Peptide-Nucleic-Acid-Based Sensing Platforms

Role of Different Receptor-Surface Binding Modes in the Morphological and Electrochemical Properties of Peptide-Nucleic-Acid-Based Sensing Platforms

Modification of silicon nitride with oligo(ethylene glycol)-terminated organophosphonate monolayers

Functional Organophosphonate Interfaces for Nanotechnology: A Review

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