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e1
QUESTIONS
1. Alginic acid is a polysaccharide derived from algae
and is commonly used in foods, for cell encapsula-
2. Chondroitin sulfate (CS) is a naturally-occurring
glycosaminoglycan abundant in cartilage and is
3. Collagen is a ubiquitous material in ECMs and its deriv-
atives are used in human medicine. One derivative, the
spongy material Gelfoam™, is used in surgical proce-
dures. A soluble form of collagen is used as a dermal
4. Imagine a novel technique that converts a natural
material into a monolithic form with fixed pores of
defined size and geometry; the new material can be
spun, electrospun, woven, made into sheets, molded,
5. Monolithic and living forms of the biopolymer HA
were discussed in some detail in the chapter. Iden-
ANSWERS
1. The resemblance is quite superficial. While alginate and
HA both contain uronic acids, the similarity ends there.
Alginate is composed of α-L-guluronic acid units and
β-D-mannuronic acid units; HA has alternating using
of glucuronic acid and N-acetylglucosamine. Addition-
ally, alginate has block sections of each guluronic acid
those derived from HA. Additionally, mammalian cells
do not recognize or bind to alginate, while they do have
a variety of specific receptors, including CD44, for HA.
chain. These differences can affect the uptake and
bioavailability of CS when orally ingested or when
being cleared from an implanted device. Additionally,
3. Gelfoam™ is a lyophilized sponge-like material that
absorbs fluid, while collagen-based dermal fillers are
a hydrated gel that is often cross-linked to increase
residence time. Sourcing and purity of natural bio-
materials is strongly regulated today, for example,
produced from cell cultures have entered the market
to address some of these concerns.
4. Clearly this is a complex question, almost requiring the
executive summary of a business plan for an answer.
patent literature to be certain that you have protectable
intellectual property and freedom to operate. Without
tive in the market place. Fourth, you should determine
which of the many potential uses of your new material
would have either the largest market share, be first to
market, or be most disruptive in the market.
5. Chitin is an intractable and monolithic constituent of
the exoskeleton of crustacea, such as shrimp, crabs,
and lobsters. Partial deacetylation of this N-acetylglu-
cosamine homopolymer affords chitosan, which has
CHAPTER I.2.7
Engineered Natural Materials
