Matrix Supported Poly(2-oxazoline)-Based Hydrogels for DNA Catch and Release

Abstract

We describe the synthesis of matrix supported hydrogel structures based on amine containing poly(2-oxazoline)s and their use to bind and release genetic material for potential applications in diagnostics or pathogen detection. Amine containing poly(2-oxazoline)s were synthesized by copolymerization of 2-ethyl-2-oxazoline with a monomer bearing a tert-butyl oxycarbonyl (Boc) protected amine group in the 2-position and subsequent deprotection. The statistical copolymers were used to generate hydrogels and matrix supported hydrogels by cross-linking of a certain fraction of the amine groups with epichlorhydrin. Supported structures were prepared by soaking porous polyethylene (PE) or polypropylene (PP) filter materials in a copolymer/epichlorhydrin solution, which was cross-linked upon heating. Scanning electron microscopy (SEM) of the composites revealed a bead like structure of the gel phase, which could be attributed to a lower critical solution temperature (LCST) behavior of the initial polymer prior to gelation. The dependency of the LCST behavior on the content of amine groups was investigated. Swelling values and the ratio of hydrogel per composite was determined using water sorption analysis. Subsequently, the ability of the systems to absorb and release labeled DNA was tested. Uptake and stimulated release, triggered by changes in pH, temperature, and heparin concentration, were investigated using fluorescence microscopy. Polymerase chain reaction (PCR) proved the successful recovery of the DNA, demonstrating the potential of the presented system for a broad range of molecular biological applications.

Covalently cross-linked poly(2-oxazoline) materials for biomedical applications – from hydrogels to self-assembled and templated structures

“…However, there are also obvious limitations of this approach. 62 Due to the LCST of the precursor polymers in basic aqueous solution the resulting hydrogels showed a bead-like structure with improved surfaceto-volume ratio. Alternatively, CROP allows to incorporate functional repeating units into the polymer using functional 2-oxazoline monomers.…”

“…64 Hartlieb et al 62 The system was used as a photoresist for photolithography. DNA was entrapped and released by heparin, and could be amplified after the release by the polymerase chain reaction.…”

A Low Protein Binding Cationic Poly(2‐oxazoline) as Non‐Viral Vector

“…Polymerization of this monomer followed by deprotection of Boc groups generated POx with pendant cationic groups . Hydrogel scaffolds, produced with a very similar synthetic approach, were applied in bioanalytical systems such as gene chips to capture or enrich DNAs . More recently, Rinkenauer et al have explored a number of cationic 2‐oxazoline polymers by polymer–analog modification of POx side chains with primary or tertiary amines .…”

Lab in a Tube: Purification, Amplification, and Detection of DNA Using Poly(2‐oxazoline) Multilayers

“…[ 15 ] Because of their high water content and the resulting permeability of the 3D matrix, as well as the adjustable functionalities and a high surface to volume ratio, hydrogels represent attractive candidates for DNA immobilization. The suitability of poly(2-oxazoline) (POx) based hydrogels [ 16 ] and networks composed of POx-poly(ethylenimine) copolymers [ 17 ] was already investigated. The amine content and, therefore, the affi nity to DNA are adjustable in both systems, resulting in a tunable DNA binding behavior.…”

“…Furthermore, a release can be induced by the addition of heparin which replaces the DNA, generating eluates compatible with subsequent polymerase chain reaction (PCR) based DNA amplifi cation. [ 16 ] However, the diffusion of genetic material within the gel is the limiting factor preventing fast purifi cation procedures. Additionally, also non-or low-charged residues from cell lysis could be entrapped within the pores of the gel and, hence, interfere with downstream processes.…”