Biomedical Engineering Reference
In-Depth Information
A comparative study on the self-assembled nanostructured morphology
and the rheological and mechanical properties of four dif erent triblock
copolymers, based on poly(styrene-block-butadiene-block-styrene) and
poly(styrene-blockisoprene-block-styrene) matrices, and of their respec-
tive nanocomposites with 1 wt% silver nanoparticles, is reported by Peponi
and coworkers [68]. In order to obtain well-dispersed nanoparticles in the
block copolymer matrix, dodecanethiol was used as surfactant. h e block
copolymer with the highest PS content shows the highest tensile modulus
and tensile strength, but also the smallest elongation at break. When silver
nanoparticles treated with surfactant were added to the block copolymer
matrices, each system studied shows higher mechanical properties due
to the good dispersion and the good interface of Ag nanoparticles in the
matrices. Furthermore, it has been shown that semiempirical models such
as Guth and Gold equation and Halpin-Tsai model can be used to predict
the tensile modulus of the analyzed nanocomposites.
Travan and coworkers have developed an antimicrobial non-cytotoxic
coating for methacrylic thermosets (biomaterials for dental and orthopedic
applications) by means of a nanocomposite material based on a lactose-mod-
ii ed chitosan and antibacterial silver nanoparticles [69]. h e authors have
performed the in vitro tests for a biological characterization of the material
which showed that the nanocomposite coating is ef ective in killing both bac-
terial strains (gram+ and gram- strains) and that this material does not exert
any signii cant cytotoxic ef ect towards tested cells (osteoblast-like cell-lines,
primary human i broblasts and adipose-derived stem cells), which are able
to i rmly attach and proliferate on the surface of the coating. It was stated
that such biocompatible antimicrobial polymeric i lms containing silver
nanoparticles may have good potential for surface modii cation of medical
devices, especially for prosthetic applications in orthopedics and dentistry.
Silver nanoparticles were synthesized into the interlamellar space of
montmorillonite (MMT) by using the γ-irradiation technique in the
absence of any reducing agent or heat treatment by Shameli and coworkers
[70]. h ey have used silver nitrate and γ-irradiation as the silver precursor
and physical reducing agent in MMT as a solid support. h e MMT was
suspended in the aqueous AgNO
3
solution, and at er the absorption of sil-
ver ions, Ag+ was reduced using the γ-irradiation technique. h e proper-
ties of Ag/MMT nanocomposites and the diameters of silver nanoparticles
were studied as a function of γ-irradiation doses. h e interlamellar space
limited particle growth and face-centered cubic silver nanoparticles with a
mean diameter of about 20-30nm were produced. SEM images indicated
that there were structure changes between the initial MMT and Ag/MMT
nanocomposites under the increased doses of γ-irradiation. Furthermore,
