scholarly journals Star polymers with acid-labile diacetal-based cores synthesized by aqueous RAFT polymerization for intracellular DNA delivery

2020 ◽  
Vol 11 (2) ◽  
pp. 344-357 ◽  
Author(s):  
Thomas J. Gibson ◽  
Peter Smyth ◽  
Mona Semsarilar ◽  
Aidan P. McCann ◽  
William J. McDaid ◽  
...  
Keyword(s):  
Low Temperature ◽  
Raft Polymerization ◽  
Star Polymers ◽  
Dna Delivery ◽  
Acid Labile

Facile low temperature aqueous heterogeneous RAFT polymerization for preparation of novel star polymers with acid-labile diacetal-based cores for DNA delivery.

Synthesis of Star Polymers using RAFT Polymerization: What is Possible?

2006 ◽  
Vol 59 (10) ◽  
pp. 719 ◽  
Author(s):  
Christopher Barner-Kowollik ◽  
Thomas P. Davis ◽  
Martina H. Stenzel
Keyword(s):  
Raft Polymerization ◽  
Star Polymers ◽  
Vinyl Pyrrolidone ◽  
Side Reactions ◽  
Radical Concentration ◽  
Reversible Addition ◽  
Polymer Architectures ◽  
Raft Agent ◽  
Poly Vinyl Pyrrolidone ◽  
Careful Design

Various pathways to generate star polymers using reversible addition–fragmentation transfer (RAFT) are discussed. Similar to other polymerization techniques, star polymers can be generated using arm-first and core-first approaches. Unique to the RAFT process is the subdivision of the core-first approach into the R-group and Z-group approaches, depending on the attachment of the RAFT agent to the multifunctional core. The mechanism of the R- and Z-group approaches are discussed in detail and it is shown that both techniques have to overcome difficulties arising from termination reactions. Termination reactions were found to broaden the molecular weight. However, these side reactions can be limited by careful design of the synthesis. Considerations include RAFT and radical concentration, number of arms, type of RAFT agent and monomer. Despite obvious challenges, the RAFT process is highly versatile, allowing the synthesis of novel polymer architectures such as poly(vinyl acetate) and poly(vinyl pyrrolidone) star polymers.

scholarly journals Electrochemical and spectroscopic characterization of the 7Fe form of ferredoxin III from Desulfovibrio africanus

1989 ◽  
Vol 264 (1) ◽  
pp. 265-273 ◽  
Author(s):  
F A Armstrong ◽  
S J George ◽  
R Cammack ◽  
E C Hatchikian ◽  
A J Thomson
Keyword(s):  
Low Temperature ◽  
Pyrolytic Graphite ◽  
Spectroscopic Characterization ◽  
Carbon Electrode ◽  
Standard Hydrogen Electrode ◽  
Hydrogen Electrode ◽  
Iron Cluster ◽  
Desulfovibrio Gigas ◽  
Acid Labile

Desulfovibrio africanus ferredoxin III is a monomeric protein (Mr 6585) containing seven cysteine residues and 7-8 iron atoms and 6-8 atoms of acid-labile sulphur. It is shown that reversible unmediated electrochemistry of the two iron-sulphur clusters can be obtained by using a pyrolytic-graphite-‘edge’ carbon electrode in the presence of an appropriate aminoglycoside, neomycin or tobramycin, as promoter. Cyclic voltammetry reveals two well-defined reversible waves with E0′ = -140 +/- 10 mV and -410 +/- 5 mV (standard hydrogen electrode) at 2 degrees C. Bulk reduction confirms that each of these corresponds to a one-electron process. Low-temperature e.p.r. and magnetic-c.d. spectroscopy identify the higher-potential redox couple with a cluster of core [3Fe-4S]1+.0 and the lower with a [4Fe-4S]2+.1+ centre. The low-temperature magnetic-c.d. spectra and magnetization properties of the three-iron cluster show that it is essentially identical with that in Desulfovibrio gigas ferredoxin II. We assign cysteine-11, -17 and -51 as ligands of the [3Fe-4S] core and cysteine-21, -41, -44 and -47 to the [4Fe-4S] centre.

Doubly-responsive hyperbranched polymers and core-crosslinked star polymers with tunable reversibility

2015 ◽  
Vol 6 (45) ◽  
pp. 7871-7880 ◽  
Author(s):  
Sunirmal Pal ◽  
Megan R. Hill ◽  
Brent S. Sumerlin
Keyword(s):  
Chain Transfer ◽  
Raft Polymerization ◽  
Star Polymers ◽  
Hyperbranched Polymers ◽  
Reversible Addition ◽  
Redox Responsive

Thermo- and redox-responsive hyperbranched copolymers were prepared by statistical copolymerization of N-isopropylacrylamide (NIPAM) and N,N′-bis(acryloyl)cystamine (BAC) by reversible addition–fragmentation chain transfer (RAFT) polymerization.

Synthesis of Functional Core, Star Polymers via RAFT Polymerization for Drug Delivery Applications

2012 ◽  
Vol 33 (9) ◽  
pp. 760-766 ◽  
Author(s):  
Jinna Liu ◽  
Hien Duong ◽  
Michael R. Whittaker ◽  
Thomas P. Davis ◽  
Cyrille Boyer
Keyword(s):  
Drug Delivery ◽  
Raft Polymerization ◽  
Star Polymers ◽  
Drug Delivery Applications

scholarly journals Synthesis of Star Polymers by RAFT Polymerization as Versatile Nanoparticles for Biomedical Applications

2017 ◽  
Vol 70 (11) ◽  
pp. 1161 ◽  
Author(s):  
Jinming Hu ◽  
Ruirui Qiao ◽  
Michael R. Whittaker ◽  
John F. Quinn ◽  
Thomas P. Davis
Keyword(s):  
Biomedical Applications ◽  
Raft Polymerization ◽  
Star Polymers ◽  
Chemotherapeutic Agents ◽  
Star Polymer ◽  
Polymeric Chain ◽  
High Accumulation ◽  
Precise Control ◽  
Signalling Molecules ◽  
Low Viscosity

The precise control of polymer chain architecture has been made possible by developments in polymer synthesis and conjugation chemistry. In particular, the synthesis of polymers in which at least three linear polymeric chains (or arms) are tethered to a central core has yielded a useful category of branched architecture, so-called star polymers. Fabrication of star polymers has traditionally been achieved using either a core-first technique or an arm-first approach. Recently, the ability to couple polymeric chain precursors onto a functionalized core via highly efficient coupling chemistry has provided a powerful new methodology for star synthesis. Star syntheses can be implemented using any of the living polymerization techniques using ionic or living radical intermediates. Consequently, there are innumerable routes to fabricate star polymers with varying chemical composition and arm numbers. In comparison with their linear counterparts, star polymers have unique characteristics such as low viscosity in solution, prolonged blood circulation, and high accumulation in tumour regions. These advantages mean that, far beyond their traditional application as rheology control agents, star polymers may also be useful in the medical and pharmaceutical sciences. In this account, we discuss recent advances made in our laboratory focused on star polymer research ranging from improvements in synthesis through to novel applications of the product materials. Specifically, we examine the core-first and arm-first preparation of stars using reversible addition–fragmentation chain transfer (RAFT) polymerization. Further, we also discuss several biomedical applications of the resulting star polymers, particularly those made by the arm-first protocol. Emphasis is given to applications in the emerging area of nanomedicine, in particular to the use of star polymers for controlled delivery of chemotherapeutic agents, protein inhibitors, signalling molecules, and siRNA. Finally, we examine possible future developments for the technology and suggest the further work required to enable clinical applications of these interesting materials.

Sign in / Sign up

Export Citation Format

Share Document