Biomedical Engineering Reference
In-Depth Information
[
(
OH
O
H
3
C
O
O
O
Poly (ethylene glycol) conjugates
n
n
mPEG
PEG
O
mPEG
NH
Peptide
O
O
O
O
NH
2
peptide
SH peptide
OH peptide
mPEG
mPEG
+
O
N
O
Peptide
O
O
O
O
O
mPEG derivative
mPEG
O
N
O
O
S
Peptide
mPEG
⎯−
CH
2
⎯
CH
2
−
NH
2
+
COOH-peptide
mPEG
⎯−
CH
2
⎯
CH
2
−
NH
−
CO-peptide
mPEG derivative
CN
O
CH
2
CH
2
R
2
(
CH
2
C
(
HN
CH
2
CH
2
C
CH
2
O
n
NH
n
C
O
R
1
O
O
OR
Polycaprolactone
Diketopiperazine derivative olyalkyl cyanoacrylates
FIGURE 11.7
Various biomaterials used as gene and drug delivery agents.
can exhibit glutamate toxicity similar to casein. It is concluded that the minor effects of glutamate
toxicity could be considerably aggravated by serum albumin, as well as in pathological situations
in vivo
. Delayed toxicity has been observed in cultures of prenatal hippocampal, which was elicited
in serum containing media [136]. Work done in animals with albumin suspension particles demon-
strated initial pulmonary retention, followed by its clearance from the lungs and transposition to the
liver and spleen. The smaller mean size of the suspension led to a faster clearance from the lungs
and subsequent appearance in the liver and spleen. Likewise, the incidence of capillary emboliza-
tion in the lungs and other organs was greatly diminished, as the mean size and the proportion of
larger particles are reduced. Hence, in spite of this material's widely reported applicability, clinical
trials must be performed with animal investigation to ensure a wide margin of safety [137].
11.4.5 s
IlIca
Another important nanomaterial is mesoporous silica NPs, which is composed of a nanometer-sized
ridged assembly of silica channels (pores) capable of adsorbing small molecules [138]. The surface
of mesoporous silica can be easily functionalized, and this material has tremendous potential toward
the adsorption of drugs and other therapeutic bioactives. Investigators showed that mesoporous silica
has the ability to absorb and release ibuprofen [139]. Mesoporous silica NPs were used to deliver a
hydrophobic anticancer agent to human cancer cells [140,141]. However, reports have shown that sil-
ica architects cause the generation of ROS, which can produce direct damage to the lung epithelium,
induce the expression of inflammatory genes, and, finally, lead to an enhanced lung inflammatory
response. Ultimately, the sustained inflammatory and proliferative response can lead to the long-term
damage described above for particles of low cytotoxicity [64,76,142].
Exposures to silica at submicron sizes is associated with the development of several autoimmune
diseases, including systemic sclerosis, rheumatoid arthritis, lupus, and chronic renal disease, while
certain crystalline silica polymorphs may cause silicosis and lung cancer [64,142]. Several reports
