Sieving polymer synthesis by reversible addition fragmentation chain transfer polymerization

Abstract

Replaceable sieving polymers are the fundamental component for high resolution nucleic acids separation in CE. The choice of polymer and its physical properties play significant roles in influencing separation performance. Recently, reversible addition fragmentation chain transfer (RAFT) polymerization has been shown to be a versatile polymerization technique capable of yielding well defined polymers previously unattainable by conventional free radical polymerization. In this study, a high molecular weight PDMA at 765 000 gmol-1 with a PDI of 1.55 was successfully synthesized with the use of chain transfer agent - 2-propionic acidyl butyl trithiocarbonate (PABTC) in a multi-step sequential RAFT polymerization approach. This study represents the first demonstration of RAFT polymerization for synthesizing polymers with the molecular weight range suitable for high resolution DNA separation in sieving electrophoresis. Adjustment of pH in the reaction was found to be crucial for the successful RAFT polymerization of high molecular weight polymer as the buffered condition minimizes the effect of hydrolysis and aminolysis commonly associated with trithiocarbonate chain transfer agents. The separation efficiency of PABTC-PDMA was found to have marginally superior separation performance compared to a commercial PDMA formulation, POP™-CAP, of similar molecular weight range.

Successful in vivo hyperthermal therapy toward breast cancer by Chinese medicine shikonin-loaded thermosensitive micelle

“…In order to improve the tumor accumulation and solubility of the Chinese traditional medicine shikonin, the RAFT polymerization was used to prepare one thermosensitive biodegradable block copolymer PID 118 -b-PLA 39 with symmetric hydrophobic blocks. In addition, the in-house developed experimental device was used to improve the in vivo tumor accumulation of micelles, which targets the high temperature (~40°C) of tumor tissue.…”

“…Data in this study were analyzed using the software SPSS 21.0 (IBM Corporation, Armonk, NY, USA Figure 1A shows the preparation of PID 118 -b-PLA 39 block copolymer. Figure 1B shows the NMR signal of PID 118 -b-PLA 39 , and the characteristic signal at ~4 ppm was attributed to -CH(CH 3 ) 2 of PNIPAM and at ~3.6 ppm was assigned to -N(CH 3 ) 2 of DMAAm.…”

“…Figure 1B shows the NMR signal of PID 118 -b-PLA 39 , and the characteristic signal at ~4 ppm was attributed to -CH(CH 3 ) 2 of PNIPAM and at ~3.6 ppm was assigned to -N(CH 3 ) 2 of DMAAm. The ratio of NIPAM to DMAAm in PID was about 3:1.…”

“…As shown in Figure 1, the block copolymer (PID 118 -b-PLA 39 ) was synthesized using PID 118 as the macro-chain transfer agents. In the conventional ring-open polymerization, proportional calculated amounts of monomers were weighed, and PID 118 (0.75 g, 6×10…”

“…The chinese medicine shikonin-loaded micelle promoted cancer therapy block copolymer PID 118 -b-PLA 39 . Figure 1 shows the signal was not from hydrophobic PLA 39 but from hydrophilic PID 118 .…”