Synthesis of highly pH-responsive glucose poly(orthoester)

Area of Science:

• Polymer Chemistry
• Biomedical Engineering
• Materials Science

Background:

• pH-responsive polymers are crucial for targeted drug delivery to acidic tissues.
• Existing polymers with ester or acetal linkages exhibit limited pH sensitivity and long half-lives.
• Orthoester linkages offer greater acid lability but face synthetic challenges and monomer limitations.

Purpose of the Study:

• To synthesize a novel, highly pH-responsive polymer using orthoester linkages.
• To overcome synthetic limitations associated with current orthoester polymers.
• To create a sugar-based poly(orthoester) for enhanced biomedical applications.

Main Methods:

• Synthesis of a sugar poly(orthoester) using 2,3,4-tri-O-acetyl-α-D-glucopyranosyl bromide as a difunctional AB monomer.
• Utilized tetra-n-butylammonium iodide (TBAI) as a promoter for polycondensation.
• Characterized polymer molecular weight and pH-responsive degradation behavior.

Main Results:

• Successfully synthesized glucose poly(orthoester) with molecular weights up to 6.9 kDa.
• The polymer exhibited rapid degradation, with half-lives of 0.9, 0.6, and 0.2 hours at pH 6, 5, and 4, respectively.
• Demonstrated a significant increase in acid lability compared to traditional ester/acetal-based polymers.

Conclusions:

• The novel sugar poly(orthoester) is highly pH-responsive due to its orthoester linkages.
• This polymer shows significant potential for advanced drug delivery systems targeting acidic pathological sites.
• The synthetic approach overcomes previous limitations, enabling broader applications of orthoester-based polymers.