Aldehyde-Functional Diblock Copolymer Nano-objects via RAFT Aqueous Dispersion Polymerization

Abstract

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Aldehyde-functional thermoresponsive diblock copolymer worm gels exhibit strong mucoadhesion

“…This approach means that the same cis -diol-functional worm gel precursor was used to produce each aldehyde-functional worm gel examined in this study, which eliminates batch-to-batch variability. Moreover, 1 H NMR spectroscopy studies (data not shown) confirmed that a sample of 100% aldehyde-functional PAGEO5MA 26 -PHPMA 250 worms reported in our prior study 69 remained stable with respect to aerial oxidation for at least one year when stored at ambient temperature. TEM studies confirmed that there was no discernible change in morphology after oxidation (Fig.…”

“…The former worms were subsequently oxidized with sodium periodate targeting periodate/ cis -diol molar ratios of 0.10, 0.20, 0.30 or 0.50 using a previously reported protocol developed for crosslinked PGEO5MA 26 -PHPMA 350 -PEGDMA 20 vesicles. 69 In each case, the extent of oxidation was determined by 1 H NMR spectroscopy (Fig. S10 † ).…”

“…Importantly, the pendent cis-diol units on these copolymer worms can be selectively oxidized using sodium periodate in aqueous solution under mild conditions to introduce aldehyde groups within the steric stabilizer chains (Scheme 1). 68,69 In principle, such derivatization might be expected to produce mucoadhesive worm gels since it is well-known that aldehydes can react readily with amines via Schiff base chemistry. 73 However, uorescence labelling is normally required for mucoadhesion ow-through assays.…”

“…Subsequently, we employed a PGEO5MA precursor for the RAFT aqueous dispersion polymerization of HPMA to prepare a series of well-defined diblock copolymer spheres, worms or vesicles. 69 In particular, it was shown that a model globular protein could be chemically adsorbed onto periodate-treated PGEO5MA-PHPMA vesicles via Schiff base chemistry (followed by in situ reduction of the initial labile imine linkages to produce hydrolytically stable secondary amine bonds). In the present study, we revisit this aqueous PISA formulation to prepare well-defined aldehyde-functional diblock copolymer worm gels and examine whether such materials offer any potential use in the context of mucoadhesion using porcine urinary bladder mucosa as a model system.…”

Influence of Nanoaggregation Routes on the Structure and Thermal Behavior of Multiple-Stimuli-Responsive Micelles from Block Copolymers of Oligo(ethylene glycol) Methacrylate and the Weak Acid [2-(Hydroxyimino)aldehyde]butyl Methacrylate

“…In recent years, we have obtained a 2-(hydroxyimino)­aldehyde butyl methacrylate (HIABMA) monomer, which has a p K a of the oxime group that is at least 3 orders of magnitude higher than that of acrylic and benzoic acids (see herein), provides multiple sites for hydrogen bonding, has potential for metal chelation, and exhibits a wavelength-dependent photochemical behavior (i.e., E / Z oxime isomerism and an unusually chemoselective Norrish–Yang cyclization). , In other words, HIABMA-based amphiphilic block copolymers are good candidates to obtain temperature- and light-sensitive copolymers that aggregate by either pH or solvent switch, potentially leading to different nanostructures with different properties that are also stable at physiological pH. The novelty of the HIABMA group with respect to monomers bearing simple aldehydes − or oximes , derives from the two functional groups being adjacent, which has consequences on aldehyde photochemistry, oxime acidity, and, possibly, on metal chelation (the latter is an ongoing investigation in our group) . Potential applications of HIABMA copolymers are, therefore, quite different from the widely investigated polymeric prodrugs based on CN conjugation chemistry.…”