Doo Sung Lee talks with
ScienceWatch.com and answers a few questions about
this month's Fast Moving Front Paper in the field of Materials
Article: In situ gelling stimuli-sensitive block
copolymer hydrogels for drug delivery
Authors: He, CL;Kim, SW;Lee, DS
Journal: J CONTROL RELEASE, 127 (3): 189-207 MAY 8 2008
Addresses: Sungkyunkwan Univ, Dept Polymer Sci & Engn,
Suwon 440746, Gyeonggi, South Korea.
Sungkyunkwan Univ, Dept Polymer Sci & Engn, Suwon 440746,
Gyeonggi, South Korea.
Univ Utah, Dept Pharmaceut & Pharmaceut Chem, Salt Lake
City, UT 84112 USA.
Hanyang Univ, Dept Bioengn, Seoul 133791, South Korea.
Why do you think your paper is highly
After biodegradable polyester-based in situ gelling
thermosensitive hydrogels were first developed by Dr. Sung Wan Kim and his
co-workers at the University of Utah about a decade ago, these novel
intelligent materials have attracted worldwide interest and received
intensive study for use in drug delivery.
In recent years, more and more interest has been focused on the development
of novel systems capable of responding to multiple stimuli, especially to
both pH and temperature. This paper is the first review on in situ
gelling stimuli-sensitive hydrogels. Some of these concepts were formed on
the basis of our research experiences in this field during a period of more
than 10 years.
In this current paper, the recent development of in situ gelling
stimuli-sensitive hydrogels was summarized based on their detailed
molecular design, preparation, and drug delivery applications. A proper
summary may also include some outline for the further development of this
Does it describe a new discovery, methodology, or
synthesis of knowledge?
To the best of our knowledge, this is the first review paper on the recent
development of in situ gelling stimuli-sensitive hydrogels for
drug delivery applications, even though there had been several review
papers on the subject of thermosensitive hydrogels.
"...these injectable stimuli-sensitive hydrogels may
bring benefits to those who are suffering from
diabetes and other diseases and have potential social
A new generation of injectable hydrogels, capable of responding to multiple
stimuli, especially to both pH and temperature, has lots of advantages in
practical applications and has therefore received increasing attention. In
this paper, the recent development of injectable stimuli-sensitive
hydrogels, including our own work, was first summarized, and the
relationship between structure and function was thoroughly discussed.
Would you summarize the significance of your paper in
This paper summarized the recent development of injectable hydrogels from
materials with an ability to respond to single stimulus to those capable of
responding to multiple stimuli. These new materials possess many advantages
when their use is applied within several complicated environments. The
paper is also a summary of current achievements in the field and also
outlines directions for further development.
How did you become involved in this research and were
any particular problems encountered along the way?
I joined the program on the development of the first generation of
injectable and biodegradable thermogelling hydrogels as a member of Dr.
Sung Wan Kim's group in 1997, and I've been developing new generations of
in situ gelling stimuli-sensitive hydrogels for drug delivery
We found some drawbacks for the first generation of materials and have
tried to improve these materials by adjusting their topological structure,
components, and molecular weight. Very recently, we developed pH- and
temperature-sensitive injectable hydrogels, which show many advantages in
various practical applications, including adjustable degradation behavior,
and are easy to handle, displaying a sustained release profile along with
an ability to maintain pH during their release, while also forming
interactions with proteins and DNA.
Where do you see your research leading in the
The main challenges for the applications of in situ gelling
stimuli-sensitive hydrogels include short response time, proper gelation
conditions, appropriate mechanical strength and persistence time,
biocompatibility, and the likelihood to protect protein drugs in some
adverse environments. This requires a system capable of responding to
complicated changes of its environment. The pH- and temperature-sensitive
hydrogels containing either polyanion or polycation developed in our lab
quite recently, not only exhibit responses to multiple stimuli but also
form interactions with ionic protein drugs and DNA. This new material is
likely to find applications in the delivery of some protein drugs and
Do you foresee any social or political implications for
Because of the sustained release character of these in situ
gelling hydrogels systems, drugs incorporated within the hydrogels may
remain effective in the body for a much longer period of time than those
administrated through conventional methods, i.e., solution injection. For
example, insulin-containing hydrogels may be administrated once every two
weeks, compared to two injections per day by conventional methods.
Therefore, these injectable stimuli-sensitive hydrogels may bring benefits
to those who are suffering from diabetes and other diseases and have
potential social significance. Some conclusions in this paper may be a
useful reference for the further development of injectable hydrogels.
Doo Sung Lee, Ph.D.
Professor, Polymer Science and Engineering
Suwon, Republic of Korea Web