Biodegradable block copolymers as injectable drug-delivery systems

ABSTRACT Polymers that display a physicochemical response to stimuli are widely explored as potential drug-delivery systems1,2,3,4. Stimuli studied to date include chemical substances and

changes in temperature, pH and electric field. Homopolymers or copolymers of _N_-isopropylacrylamide5,6 and poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (known as

poloxamers)7 are typical examples of thermosensitive polymers, but their use in drug delivery is problematic because they are toxic and non-biodegradable. Biodegradable polymers used for

drug delivery to date have mostly been in the form of injectable microspheres or implant systems, which require complicated fabrication processes using organic solvents8. Such systems have

the disadvantage that the use of organic solvents can cause denaturation when protein drugs are to be encapsulated. Furthermore, the solid form requires surgical insertion, which often

results in tissue irritation and damage. Here we report the synthesis of a thermosensitive, biodegradable hydrogel consisting of blocks of poly(ethylene oxide) and poly(L-lactic acid).

Aqueous solutions of these copolymers exhibit temperature-dependent reversible gel–sol transitions. The hydrogel can be loaded with bioactive molecules in an aqueous phase at an elevated

temperature (around 45 °C), where they form a sol. In this form, the polymer is injectable. On subcutaneous injection and subsequent rapid cooling to body temperature, the loaded copolymer

forms a gel that can act as a sustained-release matrix for drugs. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution

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POLYMERS AND HYDROGELS Article 08 February 2021 ASCORBYL PALMITATE NANOFIBER-REINFORCED HYDROGELS FOR DRUG DELIVERY IN SOFT TISSUES Article Open access 20 September 2024 MODEL-BASED MODULAR

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G. G. Krueger for comments on dermatological issues and J. S. Kim for technical assistance. D. S. Lee was supported by the Ministry of Education of Korea. This work was supported by the

University of Utah Research Foundation. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Biomedical Polymers Research Building, Room 205, CCCD/Pharmaceutics, University of Utah, Salt Lake City,

UT 84112, USA Byeongmoon Jeong, You Han Bae, Doo Sung Lee & Sung Wan Kim Authors * Byeongmoon Jeong View author publications You can also search for this author inPubMed Google Scholar

* You Han Bae View author publications You can also search for this author inPubMed Google Scholar * Doo Sung Lee View author publications You can also search for this author inPubMed Google

Scholar * Sung Wan Kim View author publications You can also search for this author inPubMed Google Scholar RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS

ARTICLE Jeong, B., Bae, Y., Lee, D. _et al._ Biodegradable block copolymers as injectable drug-delivery systems. _Nature_ 388, 860–862 (1997). https://doi.org/10.1038/42218 Download citation

* Received: 03 December 1996 * Accepted: 01 July 1997 * Issue Date: 28 August 1997 * DOI: https://doi.org/10.1038/42218 SHARE THIS ARTICLE Anyone you share the following link with will be

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