pH-sensitive poly(ortho ester urethanes) copolymers with controlled degradation kinetic: Synthesis, characterization, and in vitro evaluation as drug carriers

Design of Smart Size‐, Surface‐, and Shape‐Switching Nanoparticles to Improve Therapeutic Efficacy

“…Responsiveness is typically observed as a result of bond cleavage and/or functional group protonation in the described acidic microenvironments to trigger the targeted physical property (size, surface, or shape) changes, examples of which are listed in Table 1 . Cleavable bonds such as hydrazones or anhydrides can be incorporated into the nanoparticle and subsequently degraded when exposed to the corresponding acidic microenvironment; [ 8,22,26,41,43,65–82 ] for example, the use of anhydrides to amidize amine groups for charge switching was first described in 2007 by the Kataoka and Shen groups. [ 83,84 ] Alternatively, methods that employ protonation typically involve the addition of H + to functional groups to convert the net charge or the hydrophobicity/hydrophilicity of the nanoparticle, [ 12,42,66,85–105 ] thus promoting nanoparticle penetrability/uptake and/or nanoparticle destabilization to form aggregates that deposit drug at the target site.…”

PEGylated amphiphilic polymeric manganese(ii) complexes as magnetic resonance angiographic agents

“…Herein, to evaluate the effect of the chain length of PEG on the size, stability and r 1 relaxivity of the amphiphilic polymeric Mn(II) contrast agents, three PEGs with different molecular weights (1 kD, 2 kD or 4 kD) were respectively introduced. The designed structure has several desirable advantages: (1) the polyurethanebased backbone endows them with good biodegradability and biocompatibility, which avoid long-term accumulation in organs and tissues; 30,31 (2) different from traditional amphiphilic polymer ligands which merely conjugate the ligands as the branched chain or terminal group, small molecule Mn ligand and hydrophobic HMDI are alternately arranged on the polyurethane-based backbone. Each Mn ligand presents significantly reduced rotational motion (prolonging t R ) caused by the adjacent hydrophobic HMDI in this special alternating structure, resulting in an increase in relaxivity; (3) in addition, PEGylation of the micelle will slow down the phagocytosis by the endothelial reticulum system (RES) and prolong the circulation time.…”

pH-Responsive hyperbranched polypeptides based on Schiff bases as drug carriers for reducing toxicity of chemotherapy

“…Researchers endow the polymeric micelles pH responsiveness via introducing acid-sensitive covalent bonds. [23][24][25][26][27][28][29] Among them, Schiff base is oen used as pH-responsive linker in polymer chains. Jin et al 30 constructed a triblock copolymer via the reaction between aminooxy terminals of oxime-tethered polycaprolactone (OPCL) and aldehyde-terminated PEG (PEG-CHO), which can be used as drug carrier responsive to the acidic microenvironment.…”