Rational Design of Porous Poly(ethylene glycol) Films as a Matrix for ssDNA Immobilization and Hybridization

Abstract

Poly(ethylene glycol) (PEG) films, fabricated by thermally induced crosslinking of amine- and epoxy-terminated four-arm STAR-PEG precursors, were used as porous and bioinert matrix for single-stranded DNA (ssDNA) immobilization and hybridization. The immobilization relied on the reaction between the amine groups in the films and N-hydroxy succinimide (NHS) ester groups of the NHS-ester-decorated ssDNA. Whereas the amount of reactive amine groups in the films with the standard 1:1 composition of the precursors turned out to be too low for efficient immobilization, it could be increased noticeably using an excess (2:1) concentration of the amine-terminated precursor. The respective films retained the bioinertness of the 1:1 prototype and could be successfully decorated with probe ssDNA, resulting in porous, 3D PEG-ssDNA sensing assemblies. These assemblies exhibited high selectivity with respect to the target ssDNA strands, with a hybridization efficiency of 78–89% for the matching sequences and full inertness for non-complementary strands. The respective strategy can be applied to the fabrication of DNA microarrays and DNA sensors. As a suitable transduction technique, requiring no ssDNA labeling and showing high sensitivity in the PEG-ssDNA case, electrochemical impedance spectroscopy is suggested.

Poly(ethylene glycol)–Fullerene Composite Films and Free-Standing Nanosheets for Flexible Electronic Devices and Sensors

“…Representative SWV curves for the samples prepared on Au electrodes are displayed in Figure 5b. As expected, 48 no reduction peaks are found for the pure PEG film. In contrast, the SWV curve of the reference, pure C60 sample reveals a single reductive peak at −0.8 V, in agreement with the CV result, proving the consistency of the different electrochemical methods.…”

“…In the present study, we explored a possibility to prepare PEG-C60 composite films on the basis of a porous PEG matrix, which also gave an additional option to isolate such films as mechanically stable, free-standing nanosheetsan issue that has not been addressed so far, to the best of our knowledge. Note that generally, thin PEG films are prepared by spin-casting of PEG precursors on a solid substrate, followed by cross-linking of individual precursors via UV treatment or chemical coupling. − An efficient alternative approach is thermally activated cross-linking of four-armed STAR-PEG precursors, decorated with the complementary amine (STAR-NH 2 ) and epoxy (STAR-EPX) groups, which can build robust ethanol–amine bridges between individual arms of the precursors upon cross-linking, forming thus a robust PEG matrix. , The resulting PEG films were previously utilized as excellent platforms for suppression of protein adhesion, nanofabrication, electron and UV lithography, and preparation of physical and biological sensors. ,− Moreover, PEG films can be separated from the original substrate and used directly as free-standing nanosheets or transferred to a secondary substrate for further applications. ,, …”

Exploiting epoxy-rich poly(ethylene glycol) films for highly selective ssDNA sensing via electrochemical impedance spectroscopy

“…The respective detection limit of 0.1 μM is quite reasonable and comparable with literature data for other types of ssDNA sensors. 14,15 One can reasonably assume that this detection limit can be improved even further, e.g. by a larger loading of the PEG film with the probe ssDNA.…”

“…4 The most popular techniques in this context are surface plasmon resonance (SPR), [6][7][8] fluorescence spectroscopy and microscopy, 5,9,10 and electrochemical tools. [11][12][13][14][15][16] Additional information about the ssDNA arrays and their hybridization efficiency is provided by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, infrared spectroscopy, scanning tunneling microscopy, etc. 7,[17][18][19][20][21] Specific design of immobilized ssDNA arrays varies largely depending on the substrate and the transduction technique used.…”

“…These templates can be prepared in form of PEG brushes or polymer films [36][37][38][39] but also as 3D porous films, featuring a good accessibility of the immobilized probe ssDNA by the target strands. 14,[40][41][42][43] Among other means, such porous films can be prepared by crosslinking of so-called 4-armed STAR-PEG precursors, decorated with amine (STAR-NH 2 ) and epoxy (STAR-EPX) groups, coupled with each other at the elevated temperature and building a porous 3D PEG network. 44,45 The efficiency of these films in terms of protein and DNA sensing was demonstrated in the previous work.…”