Metal Ion Affinity-based Biomolecular Recognition and Conjugation inside Synthetic Polymer Nanopores Modified with Iron–Terpyridine Complexes

Abstract

Here we demonstrate a novel biosensing platform for the detection of lactoferrin (LFN) via metal-organic frameworks, in which the metal ions have accessible free coordination sites for binding, inside the single conical nanopores fabricated in polymeric membrane. First, monolayer of amine-terminated terpyridine (metal-chelating ligand) is covalently immobilized on the inner walls of the nanopore via carbodiimide coupling chemistry. Second, iron-terpyridine (iron-terPy) complexes are obtained by treating the terpyridine modified-nanopores with ferrous sulfate solution. The immobilized iron-terPy complexes can be used as recognition elements to fabricate biosensing nanodevice. The working principle of the proposed biosensor is based on specific noncovalent interactions between LFN and chelated metal ions in the immobilized terpyridine monolayer, leading to the selective detection of analyte protein. In addition, control experiments proved that the designed biosensor exhibits excellent biospecificity and nonfouling properties. Furthermore, complementary experiments are conducted with multipore membranes containing an array of cylindrical nanopores. We demonstrate that in the presence of LFN in the feed solution, permeation of methyl viologen (MV(2+)) and 1,5-naphthalenedisulphate (NDS(2-)) is drastically suppressed across the iron-terPy modified membranes. On the basis of these findings, we envision that apart from conventional ligand-receptor interactions, the designing and immobilization of alternative functional ligands inside the synthetic nanopores would extend this method for the construction of new metal ion affinity-based biomimetic systems for the specific binding and recognition of other biomolecules.

Protein detection using tunable pores: resistive pulses and current rectification

“…Other nanopore systems have either utilised the natural surface functionality of the material or modified the pore walls with gold to allow the facile attachment of materials 44 . To date there has been no reported modification to the tunable polyurethane, PU, pores for RPS studies, although strategies for the modification of PU are available [45][46][47] .…”

Bioinspired Energy Conversion in Nanofluidics: A Paradigm of Material Evolution

“…[17] Furthermore, chemical modification with functional molecules on the inner surface of the asymmetric nanopores endows them with versatile responsiveness and adaptiveness. The transmembrane ionic conductance, as well as the ionic rectifying properties, can be finely modulated in response to changes in the environmental conditions, including pH, [18][19][20][21] temperature, [22,23] light, [24,25] and specific molecular targets, [26,27] which mimics the gating and rectifying functions of biological ion channels. In the past decade, two types of asymmetric ion-transport phenomena have been identified in 1D nanofluidic systems, termed the rectified ionic current and the net diffusion current.…”

A single glass conical nanopore channel modified with 6-carboxymethyl-chitosan to study the binding of bovine serum albumin due to hydrophobic and hydrophilic interactions

“…Therefore the ionic rectified characteristics will be mainly determined by the surface chemical properties of the nanopore. Up to now, the rectification phenomenon of the conical nanopore has been widely utilized in the research of such fields like biosensing [10][11][12][13], molecular separation [4,14], and mimicry of biological channels [15,16].…”

“…To date, different strategies have been developed for the integration of functional groups into the conical nanopores and achieved a series of sensing platforms for the detection of various molecules including nucleic acids [17][18][19], proteins [10][11][12]20], metal ions [21,22] and small molecules [13,23]. Studying how molecules interact with the single nanopore at the nanoscale level is the foundation of constructing nanopore-based biosensing platform.…”

“…Studying how molecules interact with the single nanopore at the nanoscale level is the foundation of constructing nanopore-based biosensing platform. Nowadays, a number of interaction patterns between the functional nanopore surface and the target analytes such as the hydrophobic interaction [8], electrostatic interaction [24], bio-specific interaction [10,20,25] and metal-chelating interaction [11,12] have been investigated inside the synthetic nanopore channels, thus suggesting the construction of promising platforms for sensing the protein molecules. Previously, Ali et al [8] has reported covalently modifying single asymmetric nanochannels in polyethylene terephthalate (PET) membranes with ethylenediamine or propylamine to manipulate the charge polarity and hydrophobicity of the nanochannel, respectively.…”