High Molecular Weight Biodegradable Poly(ethylene glycol) via Carboxyl-Ester Transesterification

Abstract

Poly(ethylene glycol) (PEG) is widely used for covalent conjugation with therapeutic molecules to prolong their biocirculation time. This effect can be further improved by increasing the molecular weight of PEG. However, because of the lack of effective degradation mechanisms, PEG with a molecular mass over 10 kDa is hardly excreted from the body, thus accumulating in the liver and kidneys which increases the risk of toxicity. Herein, biodegradable PEGs were synthesized by linking PEG backbones with ester bonds through the polycondensation of PEG diols and dicarboxylic acids. To overcome the difficulties in synthesis of high molecular weight products by traditional esterification strategies, a novel carboxyl-ester transesterification mechanism was developed to produce biodegradable PEGs with a molecular weight up to 112.6 kDa. It was confirmed that these biodegradable PEGs show comparable characteristics of nondegradable PEGs with similar molecular weights, but they can be metabolized after the cleavage of ester bonds.

Room-temperature Barbier single-atom polymerization induced emission as a versatile approach for the utilization of monofunctional carboxylic acid resources

“…All the above characterization studies verify the proposed polymerization mechanism (Scheme 1, This work). To further verify this proposed mechanism, a model reaction between BPO and bromobenzene or p-methylbromobenzene was carried out under Barbier reaction conditions at room temperature without an activator for 12 h. Triphenylmethanol and 4-4′-dimethyl triphenylmethanol were successfully obtained and confirmed by 1 H and 13 C NMR (Fig. S5-S8 †).…”

“…[2][3][4][5][6][7][8][9][10][11] For example, polyesterification and polyamidation are based on the corresponding esterification and amidation reactions, resulting in significant polyesters and polyamides, e.g., polyethylene terephthalate (PET) and nylon. [12][13][14] A series of coupling polymerizations are based on the corresponding Stille-, Suzuki-, Kumada-coupling reactions, etc. [15][16][17] Living ring-opening metathesis polymerization is based on the olefin metathesis reaction.…”

Versatile Chemical Recycling Strategies: Value‐Added Chemicals from Polyester and Polycarbonate Waste

“…This is possibly due to a number of factors including trace monomer impurities, side reactions and mass transfer limitations. [22] However, such results are amenable to further optimization. Demarteau et al [14b] have previously reported PEA (1)(2), achieving comparable M n with narrower dispersities (Đ = 1.34-1.46).…”

Design of Bio-Conjugated Hydrogels for Regenerative Medicine Applications: From Polymer Scaffold to Biomolecule Choice

“…Degradable polymers containing cleavable moieties within their backbone can reduce their molecular weight overtime, until they are shortened to units small enough to be exerted by the body. A prominent example of degradable synthetic polymer is PLA and its corresponding PGA, which are polyesters that undergo hydrolysis in mild acidic conditions or can be cleaved ‘on demand’ by an esterase [ 103 ]. Such polyesters are obtained via ring-opening polycondensation [ 104 ].…”