Biomedical Engineering Reference
In-Depth Information
However, only limited amounts of drug could be incorporated by swelling (
1 wt%),
which was theoretically high enough to ensure pharmacological effi ciency of the
model drugs but might be necessary to be increased for other drugs.
It was assumed that a higher drug loading by swelling can be achieved in fully
amorphous SMPs such as the star-shaped PLG networks described above. In
contrast to semicrystalline materials, the entire matrix is amorphous and therefore
accessible for drugs [86]. Furthermore, crystallization is not required for shape
fi xation, thus allowing a wider variability for network composition and network
architecture. Also, loading may not impact shape fi xation. However, drug mole-
cules can possibly act as softeners and reduce the
T
g
of amorphous SMPs, which
can result in an unwanted shift in
T
switch
. Overall, SMPs as a technology platform
can be envisaged to have a high potential for transfer into biomedical applications
requiring biodegradable, multifunctional materials due to the generality of the
underlying fundamental principles of the SME and the synthetic preparation of
SMP network architectures as polymer systems, in which functions and properties
can be tuned in a wide range by only small variations of their chemical structure.
While basic research in SMPs is progressing rapidly, broadening the application
potential of the SMP platform besides biomedical applications, the polymer system
approach enables existing SMPs to be tailored to the challenging demands of the
medicinal sector.
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References
1
Rainer , W.C. , Redding , E.M. , Hitov , J.J. ,
Sloan , A.W. , and Steward , W.D. ( 1964 )
Heat-shrinkable polyethylene. US Patent,
3144398 .
2
Arditti , S.J. , Avedikian , S.Z. , and
Bernstein , B.S. ( 1971 ) Articles with
Polymeric Memory US Patent, 3563973 .
3
Charlesby , A. ( 1960 )
Atomic Radiation
and Polymers
, Pergamon Press , New
York , pp. 198 - 257 .
4
Lendlein , A. and Kelch , S. ( 2002 )
Shape - memory polymers .
Angew. Chem.
Int. Ed.
,
41
(
12
), 2034 - 2057 .
5
Mondal , S. and Hu , J.L. ( 2006 )
Temperature stimulating shape memory
polyurethane for smart clothing.
Indian J.
Fibre Text. Res.
,
31
(
1
), 66 - 71 .
6
Hu , J. ( 2007 )
Shape Memory Polymers and
Textiles
, England Woodhead Publishing
Limited , Cambridge .
7
Gall , K. , Mikulas , M. , Munshi , N.A. ,
Beavers , F. , and Tupper , M. ( 2000 )
Carbon fi ber reinforced shape memory
polymer composites.
J. Intell. Mater. Syst.
Struct.
,
11
(
11
), 877 - 886 .
8
Wache , H.M. , Tartakowska , D.J. ,
Hentrich , A. , and Wagner , M.H. ( 2003 )
Development of a polymer stent with
shape memory effect as a drug delivery
system .
J. Mater. Sci. Mater. Med.
,
14
(
2
),
109 - 112 .
9
Lendlein , A. and Langer , R. ( 2002 )
Biodegradable, elastic shape - memory
polymers for potential biomedical
applications .
Science
,
296
(
5573
),
1673 - 1676 .
10
Metcalfe , A. , Desfaits , A.C. , Salazkin , I. ,
Yahia , L. , Sokolowski , W.M. , and
Raymond , J. ( 2003 ) Cold hibernated
elastic memory foams for endovascular
interventions .
Biomaterials
,
24
(
3
),
491 - 497 .
11
Behl , M. and Lendlein , A. ( 2007 ) Actively
moving polymers.
Soft Matter
,
3
, 58 - 67 .
12
Bellin , I. , Kelch , S. , Langer , R. , and
Lendlein , A. ( 2006 ) Polymeric triple -
shape materials .
Proc. Natl. Acad. Sci.
USA
,
103
(
48
), 18043 - 18047 .
13
Bellin , I. , Kelch , S. , and Lendlein , A.
( 2007 ) Dual - shape properties of
