Oxime Ligation on the Surface of Mesoporous Silica Nanoparticles

Abstract

A versatile surface-functionalization strategy applicable to mesoporous silica nanoparticles, which could potentially serve as drug delivery vehicles, is described that makes use of alkoxyamine tethers on the surface of the nanoparticles. A wide variety of carbonyl compounds can be attached readily to these tethers under the mild conditions of oxime ether formation, simply by incubating the chemically modified mesoporous silica nanoparticles with aldehydes or ketones in water.

A DFT-based mechanistic study on the formation of oximes

“…Oxime chemistry was widely used in the preparation of synthetic proteins and in the coupling reactions of peptides, oligonucleotides, oligosaccharides, and proteins . Novel hybrid materials for a variety of applications comprising nanoparticles, polymers, and synthetic biomolecules were formulated using this chemoselective coupling reaction. Oxime formation is catalyzed under acidic conditions, and it is found that aniline and its derivatives catalyze this reaction appreciably .…”

Dynamic Covalent Self‐Assembly Based on Oxime Condensation

“…Thed ynamic nature of hydra-zone,however, jeopardizes the inherent stabilities of the selfassembled products.F or example,w eo bserved that the catenanes [18,19] containing hydrazone undergo decomposition via hydrazone exchange during counteranion exchange or solvent removal, even in the condition of low temperature and/or in the absence of acid catalyst. Even although oxime condensation has already been employed in various fields such as bioconjugation, [24][25][26] and organic-inorganic ligation, [27] it is surprising to us that using oxime condensation as aDCC reaction motif for self-assembly of topologically complex molecules is not yet reported to the best of our knowledge. Protonation of NH 2 ,t os ome extent, suppresses the latter process leading to C = Nb ond formation.…”

“…Oxime, [21] namely -C= N À O-, is reported [22] to be more robust than hydrazone both thermodynamically and kinetically.T here are af ew reasons that can explain the enhanced stability of oxime compared to its hydrazone counterparts.F irst, the NH 2 unit in either the alkoxyamino (-OÀNH 2 )o rh ydrazide (-NHÀNH 2 )p recursor could undergo protonation in water, which could be considered as ac ompetitive process of nucleophilic addition. Even although oxime condensation has already been employed in various fields such as bioconjugation, [24][25][26] and organic-inorganic ligation, [27] it is surprising to us that using oxime condensation as aDCC reaction motif for self-assembly of topologically complex molecules is not yet reported to the best of our knowledge. In an alkoxyamino (-O-NH 2 )precursor,the NH 2 group is connected with amore electronegative oxygen atom compared to the nitrogen in hydrazide.T he NH 2 function in the former precursor is thus less protonated, and therefore -C=NÀO-bond formation is more favoured.…”

“…As ac onsequence,o xime often becomes more kinetic inert compared to ah ydrazone counterpart. Even although oxime condensation has already been employed in various fields such as bioconjugation, [24][25][26] and organic-inorganic ligation, [27] it is surprising to us that using oxime condensation as aDCC reaction motif for self-assembly of topologically complex molecules is not yet reported to the best of our knowledge. Another advantageous feature of oxime in self-assembly is its switchable kinetics.E liseev et al reported [28] that, in more acidic aqueous solution, oxime is ad ynamic bond which allows error-checking.I nn eutral or basic conditions,i n contrast, oxime behaves like an irreversible bond, which helps to fix the self-assembled molecules to ac lose to full extent.…”

Dynamic Covalent Self‐Assembly Based on Oxime Condensation

“…As a consequence, oxime often becomes more kinetic inert compared to a hydrazone counterpart. Even although oxime condensation has already been employed in various fields such as bioconjugation, and organic‐inorganic ligation, it is surprising to us that using oxime condensation as a DCC reaction motif for self‐assembly of topologically complex molecules is not yet reported to the best of our knowledge. Another advantageous feature of oxime in self‐assembly is its switchable kinetics.…”