PH-responsive polymer

Some other degradable (i.e., nonvinyl-type) polymers have been reported as components for amphiphilic block copolymers. For example, Hsiue reported the synthesis of a block copolymer of poly(2-ethyl oxazoline) and PLA by ROP. They reported the use of ABA-type triblock copolymers as pH-responsive polymer... 

Twaites BR, CdlH A, Cunliffe D et al (2004) Thermo and pH responsive polymers as gene delivery vectors effect of polymer architecture on DNA complexation in vitro. J Control Release 97 551-566... 

Lynn, D. M., Amiji, M. M., and Langer, R. (2001), pH-responsive polymer microspheres Rapid release of encapsulated material within the range of intracellular pH, Angew Chem. Int. Ed. Engl., 40(9), 1707-1710. 

Lackey CA, Murthy N, Press OW, Tirrell DA, Hoffman AS, Stayton PS. Hemolytic activity of pH-responsive polymer-streptavidin bioconjugates. Bioconj Chem 1999 10 401-405. 

BIG Bignotti, F., Pence, M., Sartore, L., Peroni, I. Mendichi, R., and Casolaro, M., Synthesis, characterisation and solution behaviour of thermo- and pH-responsive polymers bearing L-leneine residues in the side chains, Polymer, 41, 8247, 2000. 

Schmaljohann D (2006) Thermo-and pH-responsive polymers in drug delivery. Adv Drug Deliv Rev 58 1655... 

K. Christman, H. Maynard, Protein micropalterns using a pH-responsive polymer and light, Langmuir 21 (2005) 8389-8393. 

In a research study conducted by van Vlerken et al, pH responsiveness was utilized for targeting breast cancer with the use of a polymer-blend nanoparticle system of 30% by weight pH-responsive polymer poly(beta-amino ester) and 70% by weight poly(D,L-lactide-co-glycolide) to administer paclitaxel and Cg-ceramide, an apoptotic signaling molecule, respectively [39]. The polymer blend allowed for a delay in the release of Cg-ceramide, which based on preliminary results improved therapeutic efficacy in this specific combination therapy scheme for multidrug-resistant breast and ovarian cancer. Expected conclusions were generated for the accumulation of particles based on the enhanced... 

B. Sahoo, K.S.P. Devi, R. Banerjee, T.K. Maiti, P. Pramanik, D. Dhara, Thermal and pH responsive polymer-tethered multifunctional magnetic nanoparticles for targeted delivery of anticancer drug, ACS Appl. Mater. Interfaces 5 (2013) 3884-3893. 

Lynn DM, Amiji MM, Langer R. pH-Responsive Polymer Microspheres Rapid Release of Encapsulated Material within the Range of Intracellular pH. Angew Chem Int Ed Engl, 2001, 40(9), 1707-10. 

The results of this initial study would indicate that the physical response of pH responsive polymers to changes brought about by non-linear kinetic systems, have great potential to be used to generate usable work in a new generation of... 

Figure 6.3 Stimuli-responsive polymers and their intracellular mechanisms leading to transfection. (A) Cationic polymers containing bioreducible disulfide bonds (S-S) can form tight complexes with DNA, releasing it in the cytosol, due to reduction of disulfide bonds to two thiol groups. (B) Associated polyplexes can he dissociated in the cytosol by temperature decrease, leading to DNA release. (C) The endosomal escape can be promoted by pH-responsive polymers such as PEI that act as proton sponges, preventing the normal acidification of the endosomes the continuous influx of protons, counterions and water eventually leads to endosomal disruption and DNA release.

The unique properties of pH-responsive polymers arise from the facile pH adjustment, which induces ionic interaction and hydrogen bonding, resulting in a reversible microphase separation or self-organization phenomenon. Thus, pH-responsive polymeric systems provide the possibility of preparation of smart functional materials that can be used for potential therapeutic applications, for example, controlled dmg delivery based on pH-triggered release. 

LUO Luo, C., Liu, Y., and Li, Z., Thermo- and pH-responsive polymer derived from methacrylamide and aspartic acid. Macromolecules, 43, 8101, 2010. 

In another way, ct-amino acid N-carboxyanhydrides are attractive monomers for the synthesis of controlled architectures (14AML378). Poly-phosphonohomoalanine is a pH-responsive polymer which undergoes consequent conformational modifications when pH goes from 7.4 to 1.0. At pH 1, circular dichroism experiments showed that the fuUy protonated polyacid was mainly present on a ct-helical form whereas at pH 7.4, electronic repulsions of the polyanionic system induced a disordered chain conformation (Figure 3). 

A common behavior in biopolymers is the pH-responsive conformation change. The pH-responsive polymers can accept and donate protons in response to environmental pH changes. The degree of ionization alters dramatically upon pH change in a polymer bearing weakly ionizable groups, causing the transfer of the hydrodynamic volume of the polymer chains. There are two types of pH-responsive polymers weak... 

Figure 9.8 lists the representative examples of pH-responsive polybases. Poly(A,A -dimethyl aminoethyl methacrylate) (PDMAEMA) (Fig. 9.8a) and poly(A,A-diethyl aminoethyl methacrylate) (PDEAEMA) (Fig. 9.8b) have pH-responsive amine groups in their side chains, which can gain protons under acidic conditions and release them under basic conditions. Poly(4-vinylpyridine) (PVP) shows pH sensitivity (Fig. 9.8c) owing to the pyridine group [8, 53]. Poly(vinyl imidazole) (PVI) is another pH-responsive polymer consisting of an imidazole group (Fig. 9.8d) [54]. 

The proper selection of polyacids and polybases depends on the required application. For pH-responsive polymer systems, functional domains are implanted for controlling the pH-responsive attribute through various interactions. For example, when ionizable groups are protonated, the electrostatic repulsion forces will disappear and hydrophobic properties will become dominant, causing the aggregation of... 

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