Biomedical Engineering Reference
In-Depth Information
silica (SiO(2)) hybrid nanofibers based on polyethylene oxide (PEO) and a
new solution of modified sol-gel particles of mixture containing tetraeth-
oxysilane (TEOS) and 3-glycidyloxypropyltriethoxysilane (GPTEOS) in a
weight ratio of 3:1. Adding high-molecular-weight PEO into the silica sol
is found to enhance the formation of the silica nanofibers and reduces the
water-soluble carrying polymer to 1.2 wt%. These hybrid silica nanofibers
possess unique collective properties that can have a great impact either in
high-temperature reinforced materials and filtration or in biomedical appli-
cations such as in dentistry and bone tissue engineering (Toskas et al. 2011).
7.2.3.3 Scaffolds
Bioresorbable scaffolds made of poly(L-lactic acid) (PLA) obtained by super-
critical gas foaming were recently described as suitable for tissue engi-
neering, portraying biocompatibility with primary osteoblasts in vitro and
mechanical properties when reinforced with ceramics. The behavior of such
constructs remained to be evaluated in vivo and therefore the present study
was undertaken to compare different PLA/ceramic composite scaffolds
obtained by supercritical gas foaming in a critical size defect craniotomy
model in Sprague-Dawley rats. The host-tissue reaction to the implants was
evaluated semiquantitatively and similar tendencies were noted for all graft
substitutes: initially highly reactive but decreasing with time implanted.
Complete bone bridging was observed 18 weeks after implantation with
PLA/5 wt% beta-TCP (PLA/TCP) and PLA/5 wt% HAp (PLA/HAp) scaf-
folds as assessed by histology and radiography (Montjovent et al. 2007).
Cunningham et al. (2010) demonstrated the potential use of marine sponges
as precursors in the production of ceramic-based tissue-engineered bone scaf-
folds. They chose three species of natural sponge—Dalmata Fina ( Spongia offi-
cinalis Linnaeus , Adriatic Sea), Fina Silk ( Spongia zimocca , Mediterranean) and
elephant ear ( Spongia agaricina , Caribbean)—as replication. The most promis-
ing of the ceramic tissue engineered bone scaffolds developed, Spongia agar-
icina replicas, demonstrated an overall porosity of 56% to 61% with 83% of the
pores ranging between 100 and 500 microm (average pore size 349 microm)
and an interconnectivity of 99.92% (Cunningham et al. 2010).
7.3 Gene Delivery
7.3.1 Calcium Phosphate (CaP)-Based Hybrid
Materials for Gene Delivery
Of all the inorganic vectors, CaP materials as the elementary constituent of
bone and teeth have been so far mostly used due to their inherent material
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