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Application of Bioresponsive Polymers in Gene Delivery
Published in Deepa H. Patel, Bioresponsive Polymers, 2020
Tamgue Serges William, Drashti Pathak, Deepa H. Patel
Based on these PNIPAAm modifications, various structures could have been realized such as hydrogels, micelles, polymersomes, nanoparticles, and others. Akimoto et al. [35] have prepared thermoresponsive micelles from pre-synthesized diblock copolymers comprising thermoresponsive segments of poly(N-isopropyl acrylamide-co-N,N-dimethylacrylamide) (P(IPAAm-co-DMAAm)) and hydrophobic segments of poly(D,L-lactide). The polymer showed a LCST of 40°C, below which the micelles were 25 nm size, and 600 nm when above the LCST. The thermoresponsive micelles showed time-dependent cellular uptake and lower toxicity above micellar LCST [35]. Lavigne et al. have developed a thermoresponsive polymer with LCST based polyethyleneimine (PEI) grafted with poly(N-isopropyl acrylamide) chains. This polymer displayed a coil globule transition when complexed to DNA. They showed that the applied changes in the vector configuration have enhanced transgene expression [36].
“Smart” Hydrogels in Tissue Engineering and Regenerative Medicine Applications
Published in Gilson Khang, Handbook of Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine, 2017
Ana H. Bacelar, Ibrahim F. Cengiz, Joana Silva-Correia, Rui A. Sousa, Joaquim M. Oliveira, Rui L. Reis
Below the LCST, favorable interactions via hydrogen bonding between hydrophilic groups in polymer and water molecules contribute to the hydrophilicity and lead to dissolution of polymer chains. Above the LCST, the hydrogen bonds become weaker, and water molecules are expelled from the polymer, resulting in a compact and hydrophobically collapsed conformation of the chain (coil–globule transition).46,47
Motion of a polymer globule with Vicsek-like activity: from super-diffusive to ballistic behavior
Published in Soft Materials, 2021
Subhajit Paul, Suman Majumder, Wolfhard Janke
In this regard, efforts were mostly directed to understand the properties of active Brownian filaments.[5,21–24] Such a filament model can be constructed in a straightforward manner by considering the monomeric beads as active Brownian particles and joining them via springs. The focus was mainly on studies of the collective behavior and pattern formation by such filaments, for which in most cases the passive non-bonded monomeric interaction was considered to be a completely repulsive one.[21,23] Recently, via Brownian dynamics simulation of a single active filament in a good solvent, the activity induced conformational changes from coil to globule as well as its enhanced diffusion have been shown.[24] In our very recent work,[27] upon quenching a flexible polymer from good to a poor solvent condition, we looked at the effect of Vicsek-like alignment activity on its coil–globule transition with particular focus on the coarsening kinetics. Such coil–globule transition, in the context of a passive polymer, has similarities with the dynamics of protein folding and chromosome compactification.[28,29] For a passive polymer, the monomers can be made “active” by some external non–thermal forces. Dynamics of such filaments has been studied in active solvent, with or without hydrodynamic interactions.[5,30–32] In experiments active filaments have been designed by joining the chemically synthesized molecules, colloids or Janus particles via DNA strands.[19,20] Then the activity is introduced via various phoretic effects, i.e., application of light, electric or magnetic fields. There also it is shown that the activity enhances the diffusive behavior of the polymer chain.