Burgevin, Fannie (2021) Hydrolysable DMAEA and DMAEMA copolymers for dsRNA protection in soil : influence of composition and architecture. PhD thesis, University of Warwick.

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Abstract

RNAi has shown great potential for applications in crop protection. However, double stranded RNA (dsRNA) is quickly degraded in the environment and particularly in soil. Cationic polymers can be used as vectors to transport and efficiently protect the nucleic acids. The aim of this thesis was to synthesise well defined cationic 2-dimethylaminoethyl acrylate (DMAEA)-based copolymers using RAFT polymerisation to improve the protection and delay the release of the dsRNA in soil.

Firstly, four pDMAEA 4-arm stars were synthesised by RAFT polymerisation to compare them to previously reported pDMAEA stars, synthesized by Cu(0)-RDRP, and further study their potential as dsRNA vectors for soil stability and study the effect of the molecular weight. But results showed no prolonged protection of dsRNA in soil and only little effect of the polymer molecular weight on the complexation.

The influence of the composition on the hydrolysis of pDMAEA and time for the release of dsRNA was investigated by incorporating 2-dimethylaminoethyl methacrylate (DMAEMA) as a non-hydrolysable co-monomer. The DMAEMA content was increased by up to 50% leading to slower and lower hydrolysis of the DMAEA side chains and slower dsRNA release (with 20% DMAEMA, the dsRNA was release in about 15 days). However, the binding was not strong enough to give an efficient protection of the dsRNA in the presence of nucleases or in soil conditions, although good complexation was observed with linear copolymers in water.

The successful chain extension of p(DMAEA80-stat-DMAEMA20) with acrylamide monomers allowed the preparation of stars by the arm-first approach to investigate the influence of the architecture on the complexation of dsRNA. Soluble stars with a high number of well-defined arms (Narm ~ 55 – 100) were obtained with the introduction of non-cationic N-acrylmorpholine (NAM) prior to the crosslinking step. The influence of the architecture on the hydrolysis was studied, with only small differences observed compared to the corresponding arm. The binding of the dsRNA with the stars was weaker than with the linear copolymer as the dsRNA interacts only at the surface of multiple dense stars. Therefore, these architectures were not able to extend the stability of the dsRNA in soil.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry S Agriculture > SB Plant culture
Library of Congress Subject Headings (LCSH):	RNA interference, Plants, Protection of, Polymerization
Official Date:	April 2021
Dates:	Date Event April 2021 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Perrier, Sébastien
Format of File:	pdf
Extent:	xvii, 148 leaves : illustrations (some colour)
Language:	eng

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