Page 78 - Advances in Textile Biotechnology

Smart materials containing enzymes or enzyme substrates 57

unwanted properties, such as toxicity or bad taste, at least before the target
environment is reached (Jain, 1989, Risch and Reineccius, 1995, Pothaka-
mury and BarbosaCanovas, 1995, Poznansky and Juliano, 1984, Tomlinson,
1987, Vingerhoeds et al., 1994). Finally, a sustained or triggered release may
be required. Therefore, a polymer, whether natural or synthetic, is judi-
ciously combined with a drug or other active agent in such a way that the
active agent is released from the material in a predesigned manner.
Drug delivery and controlled release are of particular interest in cancer
therapy and the treatment of many endocrinological disorders (Cox, 1993).
For drug release, providing control over drug delivery can be the most
important factor at times when traditional oral or injectable drug formula-
tions cannot be used. A more effective therapy can be achieved while the
risk for both under- and overdosing can be reduced. Other advantages of
using controlled-delivery systems can include the maintenance of drug
levels within a desired range, the need for fewer administrations, optimal
use of the drug in question, and increased patient compliance. The ideal
drug delivery system should be inert, biocompatible, mechanically strong,
comfortable for the patient, capable of achieving high drug loading, safe
from accidental release, simple to administer and remove, and easy to fab-
ricate and sterilize.

The field of controlled release, however, finds increasing application also
in cosmetics and household materials (e.g. Joshi, 1996, Schaeffer and Brooks,
1992, Withenshaw, 1996), food (Risch and Reineccius, 1995, Yolles, 1973),
agrochemicals/crop protectants (e.g. Allan and Neogi, 1971, Cohen et al.,
1977, Knight et al., 1995, Kuderna and Saliman, 1974, Ventakraman, 2000),
fertilizers (e.g., Fersch and Stearns, 1976, Knight et al., 1995) and industrial
and other reactants.
In recent years, controlled drug delivery formulations and the polymers
used in these systems have become very sophisticated. Carrier systems
have been developed including particulate systems like nano- and micro-
capsules, nano- and microspheres and liposomes (Amidon, 1997, Brannon-
Peppas, 1995, Cox, 1993, Felgner, 2009, Risch and Reineccius, 1995).
Materials used for these systems normally consist of natural or synthetic
biocompatible polymers. These can be proteins, such as gelatin, albumin,

casein, or fibrin (Banga, 1995, Bissery et al., 1984, Chen et al., 2009, Gupta
and Hung, 1989, Narayani and Rao, 1996, Senderoff et al., 1991, Wolkoff,
1987, Yu et al., 1996). The release of the active agent may be constant over
a long period, it may be cyclic over a long period, or it may be triggered by
the environment or other external events such as pH, ionic strength, ultra-
sound or by enzymes.
In the following we will discuss the construction, function and application
of smart materials based on the display of enzyme activity or response to
trigger enzymes.

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