Integrated Biomaterials Science

142 Luca Fambri et al.
collagen, silk fibroin from various species of silkworm and spiders has been
proposed as biomaterials (Capello and McGrath, 1993; Heslot, 1998).
In ancient India and Egypt, and among ancient Greeks and Romans,
wounds were sutured by using catgut and silk. For many surgeons, surgical
silk represents the standard of performance by which newer synthetic
materials are judged, especially due to its superior handling characteristics.
Silk filaments can be twisted or braided, the latter providing the best
handling qualities. To establish criteria for characterizing synthetic
sutures, the handling characteristics of silk sutures were analyzed by
Tomita et al. (1993). The characteristics that distinguish silk suture
from other braided suture materials are its good knot security and relatively
low tie-down resistance. Braided silk sutures often act as a nonimmunologic
foreign body and cause a granulomatous inflammatory
reaction years after surgery. Kurosaki et al. (1999) reported a case of
recurrent granulomas with remarkable infiltration of eosinophils that
may have resulted from an IgE-mediated hypersensitivity reaction to
silk fibroin, a component of the braided silk suture. Under normal circumstances
exposure to fibroin is rather rare. One area of current research
interest is the use of silk proteins in immobilization technology (Grasset
et al., 1977), based on glucose oxidase-immobilized silk fibroin membrane
and oxygen electrode (Demura et al., 1989; Liu et al., 1997). Zhang
et al. (1998) have developed an amperometric glucose sensor in flowinjection
analysis. A simple and effective procedure was described for
the immobilization of peroxidase in regenerated silk fibroin membrane
prepared from waste silk (Qian et al., 1996). A water-insoluble silk
fibroin membrane was prepared by Minoura et al. (1990) by immersing
a silk fibroin membrane as cast in 50 vol% aqueous methanol solution
for different periods of time at 25 °C. The membranes of regenerated
silk fibroin with or without peroxidase, before or after the ethanol treatment,
were characterized by infrared spectra. To use the membrane as
a biomaterial, oxygen and water vapor permeability, transparency, mechanical
property, and enzymatic degradation behavior in vitro of the
membrane in the wet state were investigated. Silk fibroins are also proposed
as a burn wound dressing material (Minoura et al., 1990; Santin et
al., 1999).
The growth of animal cells on silk fibroin-coated plates was examined
by Inouhe et al. (1998). In this study the anchorage-dependent cells
exhibited almost the same growth on both fibroin- and collagen-coated
plates, and it was 30–50% higher than that on polystyrene plates coated
with hydrophilic groups. Recently, Hara and Yamakawa (1995) investigated
the antibacterial activity of the hemolymph from Bombyx Mori against
Gram-negative bacteria.