Three different amphiphilic block copolymer families are synthesized to investigate new opportunities to enhance gene delivery via Hydrodynamic Limb Vein (HLV) injections. First a polyoxazoline-based family containing mostly one poly(2-methyl-2-oxazoline) (PMeOx) block and a second block POx with an ethyl (EtOx), isopropyl (iPrOx) or phenyl substituent (PhOx) is synthesized. Then an ABC poly(2-ethyl-2-oxazoline)-b-poly(2-n-propyl-2-oxazoline)-b-poly(2-methyl-2-oxazoline) triblock copolymer is synthesized, with a thermosensitive middle block. Finally, polyglycidol-b-polybutylenoxide-b-polyglycidol copolymers with various molar masses and amphiphilic balance are produced. The simple architecture of neutral amphiphilic triblock copolymer is not sufficient to obtain enhanced in vivo gene transfection. Double or triple amphiphilic neutral block copolymers are improving the in vivo transfection performances through HLV administration as far as a block having an lower critical solution temperature is incorporated in the vector. The molar mass of the copolymer does not seem to affect the vector performances in a significant manner.
The synthesis of double hydrophilic block copolymers (DHBCs) containing a polyethylenimine (PEI) and a poly(2-alkyl-2-oxazoline) in two steps was investigated in this study. First, well-defined copolymers of poly(2-methyl-2-oxazoline)-b-poly(2-ethyl-2-oxazoline) (PMeOx-b-PEtOx) and poly(2-isopropyl-2-oxazoline)-b-poly(2-methyl-2-oxazoline) (PiPrOx-b-PMeOx) were synthesized. Then, their thermoresponsive properties were analyzed to obtain a selective hydrolysis of the PMeOx block. Concerning the PMeOx-b-PEtOx copolymers, no phase transiton was witnessed, and a selectivity appeared but was quite low regardless of the copolymer composition tested, while for the PiPrOx-b-PMeOx copolymers, a complete selective hydrolysis was achieved, allowing the synthesis of PiPrOx-b-PEI DHBCs due to micelles formations in the reactive media at high temperature. Thus, for different PiPrOx-b-PMeOx with varying composition, a MeOx unit hydrolysis degree higher than 90% was obtained with nearly no hydrolysis of the PiPrOx block, providing block copolymers suitable for gene transfer experiments. The reproducibility of the reaction was also demonstrated.
Abstract Viruses have remarkable physical properties and complex interactions with their environment. However, their aggregation in confined spaces remains unexplored, although this phenomenon is of paramount importance for understanding viral infectivity. Using hydrodynamical driving and optical detection, we developed a method to detect the transport of single virus in real time through synthetic nanopores. We unveiled a jamming phenomenon specifically associated with virus confinement under flow. We showed that the interactions of viral particles with themselves and with the pore surface were critical for clog formation. Based on the detailed screening of the physical and chemical determinants, we proposed a simple dynamical model that recapitulated all the experimental observations. Our results pave the way for the study of jamming phenomena in the presence of more complex interactions.
Abstract This paper reports on the synthesis of dihydroxy terminated poly(chloroethyl vinyl ether)s (PCEVE) via bifunctional living cationic polymerization. The bifunctional chain initiator is obtained by reacting malonaldehyde bis(diethyl acetal) with trimethylsilyl iodide (TMSI) to form the corresponding di‐α‐iodo ether derivative. The polymerization of chloroethylvinyl ether is then triggered by ZnCl 2 . The direct transformation of active ends into aldehyde terminals, as well as their derivatization into hydroxy groups, is described. The synthesis of high molar mass ditelechelics by bifunctional polymerization provides evidence for the occurrence of a monofunctional side initiation. The latter has been attributed to the hydrolysis of TMSI by adventitious water, which leads to the in situ formation of hydrogen iodide. In order to trap hydrogen iodide, the influence of different additives, bulky amines, metals and alkylaluminiums, was investigated. Therefore, in the presence of alkylaluminiums, it is possible to obtain a clean bifunctional polymerization up to relatively high molar mass ditelechelic PCEVE (M̄ n = 33000 g/mol, M̄ w /M̄ n = 1.11).
A new family of bio-based linear polyesters from oleic acid was developed by a bulk polymerization process. First, efficient chemical pathways were selected to synthesize three monomer derivatives from 1,18-(Z)-octadec-9-enedioic acid, allowing the synthesis of four polyesters that differ by the number of double bonds along the polymer backbone. After the analysis of the structure of the polymers, their thermal properties and their biodegradability were investigated. It was shown that the melting temperature of the polyesters increased with the decrease in the unsaturation content in the repeat units of the polymers and they have very low glass-transition temperatures. A biodegradation process was also highlighted for poly(1,18-(Z)-octadec-9-enylene 1,18-(Z)-octadec-9-enedioate) and poly(1,18-octadecylene 1,18-octadecanedioate). Based on their thermal features, these biodegradable polyesters can represent an alternative of the synthetic polymers derived from petroleum hydrocarbons, such as low-density polyethylene.
Background: Gene delivery is a promising technology for treating diseases linked to abnormal gene expression. Since nucleic acids are the therapeutic entities in such approach, a transfecting vector is required because the macromolecules are not able to efficiently enter the cells by themselves. Viral vectors have been evidenced to be highly effective in this context; however, they suffer from fundamental drawbacks, such as the ability to stimulate immune responses. The development of synthetic vectors has accordingly emerged as an alternative. Objectives: Gene delivery by using non-viral vectors is a multi-step process that poses many challenges, either regarding the extracellular or intracellular media. We explore the delivery pathway and afterwards, we review the main classes of non-viral gene delivery vectors. We further focus on the progresses concerning polyethylenimine-based polymer-nucleic acid polyplexes, which have emerged as one of the most efficient systems for delivering genetic material inside the cells. Discussion: The complexity of the whole transfection pathway, along with a lack of fundamental understanding, particularly regarding the intracellular trafficking of nucleic acids complexed to non-viral vectors, probably justifies the current (beginning of 2021) limited number of formulations that have progressed to clinical trials. Truly, successful medical developments still require a lot of basic research. Conclusion: Advances in macromolecular chemistry and high-resolution imaging techniques will be useful to understand fundamental aspects towards further optimizations and future applications. More investigations concerning the dynamics, thermodynamics and structural parameters of polyplexes would be valuable since they can be connected to the different levels of transfection efficiency hitherto evidenced.
