Benzoic‐Imine‐Based Physiological‐pH‐Responsive Materials for Biomedical Applications

Abstract

The benzoic imine is a dynamic covalent bond, which is stable around neutral pH value (ca. 7.4), but starts to hydrolyze at the extracellular pH value of solid tumors (ca. 6.5) and rapidly disintegrates at endosome and lysosome pH values (ca. 4.5-6.5). This characteristic is promising for the construction of physiological-pH-responsive materials, such as polymeric micelles, nanoparticles, and hydrogels for pharmaceutical and tissue-engineering applications. This Focus Review summarizes recent progress in the design and synthesis of pH-sensitive materials that contain the benzoic imine bond with biomedical objectives.

Reversible-deactivation anionic alternating ring-opening copolymerization of epoxides and cyclic anhydrides: access to orthogonally functionalizable multiblock aliphatic polyesters

“…Imines have garnered interest for use in biomedical applications, particularly for use in drug delivery systems due to the pH sensitive nature of the imine bond. 52 – 54 A polymer with 8 mol% VGE ( M n = 6.4 kDa, Đ = 1.06) was heated to 80 °C for 2.75 h in the presence of isopropylamine ( Scheme 5 ). 55 By 1 H NMR analysis, the aldehyde was cleanly converted to an imine ( Scheme 5 ).…”

Amphiphilic polypyrrole-poly(Schiff base) copolymers with poly(ethylene glycol) side chains: synthesis, properties and applications

“…Due to this behavior, materials containing these functional bonds can find various practical applications, including transient scaffolds and transient bioelectronic devices. 59 The presence of free carboxyl groups in AzbPyBA (Scheme 4) enabled the attachment of the non-ionic PEG by esterification in the second step of synthesis; thus, the structure of the new macromonomer AzbPy-g-PEG was amphiphilic, with high hydrophilicity, water dispersibility and the ability to complex with metal ions. 60 Also, it is known that incorporation of hydrophilic moieties such as PEG can dramatically improve the biocompatibility of polycations without significant loss of antimicrobial activity.…”

Recent Advances of pH‐Induced Charge‐Convertible Polymer‐Mediated Inorganic Nanoparticles for Biomedical Applications

“…Benzoic imine is a dynamic chemical bond that is stable at pH 7.4 but hydrolyzes in slightly acidic environments (pH 6.5), being quickly restored with increasing of pH to 7.4. [ 38 ] Our group prepared a pH‐induced charge‐switchable and CD44‐targeting nanogel for efficient protein delivery. This dual‐targeting nanogel is generated by the reaction of hyaluronic acid (HA) graft‐methoxy poly(ethylene glycol)‐diethylenetriamine with terephthalaldehyde crosslinkers to produce benzoic imines ( Figure ).…”