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Second-Generation Tunable pH-Sensitive Phosphoramidate-Based Linkers for Controlled Release.

Cindy J Choy1, Corinne R Ley1, Austen L Davis1

  • 1Washington State University , Department of Chemistry, P.O. Box 644630, Pullman, Washington 99164-4630, United States.

Bioconjugate Chemistry
|August 27, 2016
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Summary
This summary is machine-generated.

Researchers created new pH-sensitive linkers that release drugs in acidic environments without enzymes. These tunable phosphoramidate linkers offer controlled drug delivery and potential for oral administration.

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Area of Science:

  • Bioconjugation Chemistry
  • Drug Delivery Systems
  • Materials Science

Background:

  • Developing controlled drug release systems is crucial for targeted therapies.
  • Existing drug conjugates often rely on intracellular enzymes for drug activation, limiting their application.
  • pH-sensitive linkers offer a promising alternative for triggered drug release in specific environments.

Purpose of the Study:

  • To develop a second generation of tunable pH-sensitive linkers based on a phosphoramidate scaffold.
  • To enable the release of amine-containing drugs under acidic conditions without enzymatic action.
  • To explore the potential for oral administration of drug conjugates using these linkers.

Main Methods:

  • Design and synthesis of novel phosphoramidate-based linkers with tunable properties.
  • Evaluation of linker stability and hydrolysis rates at various pH values, mimicking intracellular conditions.
  • Investigation of the mechanism of pH-triggered amine release, focusing on the role of a proximal carboxylic acid.
  • Assessment of scaffold modification (e.g., esterification, rigidification) to control release kinetics.

Main Results:

  • The developed phosphoramidate linkers effectively release amine-containing drugs in acidic conditions.
  • Release is pH-triggered and does not require intracellular enzymatic activity.
  • A proximal carboxylic acid group is key to promoting phosphoramidate P-N bond hydrolysis.
  • Scaffold modifications, including esterification and rigidification, allow for fine-tuning of release rates.
  • Esterification of the carboxylic acid provides protection against premature release, enabling potential oral prodrug strategies.

Conclusions:

  • The second-generation phosphoramidate linkers offer a versatile platform for pH-triggered drug release.
  • These linkers are suitable for various controlled release applications, including antibody-drug conjugates and drug-eluting stents.
  • The ability to protect the scaffold as an ester prodrug opens new avenues for oral drug conjugate delivery.
  • This technology has broad implications for advancing controlled release applications, particularly in oral drug delivery.