Real Time SPR Assessment of the Structural Changes of Adaptive Dynamic Constitutional Frameworks as a New Route for Sensing.

Sorin David,Mihail Barboiu,Cristina Polonschii,Eugen Gheorghiu,Szilveszter Gáspár,Mihaela Gheorghiu,Raluca-Elena Munteanu,Sanaa Daakour

doi:10.3390/ma15020483

Abstract

Cross linked gold-dynamic constitutional frameworks (DCFs) are functional materials of potential relevance for biosensing applications, given their adaptivity and high responsivity against various external stimuli (such as pH, temperature) or specific interactions with biomolecules (enzymes or DNA) via internal constitutional dynamics. However, characterization and assessment of their dynamic conformational changes in response to external stimuli has never been reported. This study proves the capability of Surface Plasmon Resonance (SPR) assays to analyse the adaptive structural modulation of a functional matrix encompassing 3D gold-dynamic constitutional frameworks (Au-DCFs) when exposed to pH variations, as external stimuli. We analyse Au-DCFs formed from Au nanoparticles, (AuNP) connected through constitutionally dynamic polymers, dynamers, with multiple functionalities. For increased generality of this proof-of-concept assay, Au-DCFs, involving DCFs designed from 1,3,5-benzene-tricarbaldehyde (BTA) connecting centres and polyethylene glycol (PEG) connectors, are covalently attached to standard SPR sensing chips (Au nanolayers, carboxyl terminated or with carboxymethyl dextran, CMD top-layer) and analysed using state-of-the art SPR instrumentation. The SPR effects of the distance from the Au-DCFs matrix to the Au nanolayer of the sensing chip, as well as of Au-DCFs thickness were investigated. This study reveals the SPR response, augmented by the AuNP, to the conformational change, i.e., shrinkage, of the dynamer and AuNP matrix when decreasing the pH, and provides an unexplored insight into the sensing applicability of SPR real-time analysis of adaptive functional materials.

Highlights

Dynamic constitutional frameworks augmented with embedded gold nanoparticles
Dynamic constitutional frameworks augmented with embedded nanoparticles (i.e., Au-dynamic constitutional frameworks (DCFs)) were successfully prepared and investigated usinggold a Surface Plasmon Resonance (SPR)
The SPR data of both CM5 and C1 sensing chips are consistent with a reversible response, i.e., conformational reorganization of the constitutional framework

Summary

Introduction

Several reversible covalent reactions have been explored and the arrangement of dynamic networks has been diversified, providing adaptive systems with higher complexity and multiple responsiveness They can be responsive to internal constitutional interactions, to various external stimuli, such as pH, temperature, pressure, etc. Some of the effective factors, especially pH and redox reactions, are often found in biological systems frameworks, which make the dynamic covalent materials suited to mimic bio-functional systems They are capable of forming strong and resilient hydrogels, including networks of biological macromolecules which can take up large amounts of water while exhibiting ease of processing, self-healing, and antimicrobial or cell supporting features [2,3,4,5].

Methods

Results

Conclusion