Biomedical Engineering Reference
In-Depth Information
factor analogs can be used to target cells expressing fibroblast growth factor
receptors (FGFRs). This receptor family is often expressed both on tumor
cells and neo-vasculature. Truncated human basic fibroblast growth factor
peptide (tbFGF) was recently used to achieve targeting of liposomes carry-
ing chemotherapeutic drugs [162]. This peptide contains both the bFGF
receptor binding site and a part of the heparin-binding site, which allows
it to bind FGFRs on a cell surface, without stimulating cellular prolifera-
tion. Somatostatin and its analogs can be used to target somatostatin recep-
tors over-expressed in both small cell and non-small cell lung cancers. The
albumin-bound paclitaxel (Abraxane) is currently being tested as a first-line
therapy, or in combination with other drugs, for metastatic breast cancer and
other cancers that have been shown to be sensitive to taxane drugs, such as
ovarian and prostate. Preclinical studies have shown that the concentration
of paclitaxel, bound to albumin in endothelial cells and in the extra-vascular
space, was significantly increased [163]. Peptides can also act as therapeutic
agents conjugated to NPs. Melittin is a cytolytic peptide that represent a
potential candidate for cancer chemotherapy. Melittin is a 26 amino acid
a-helical peptide derived from the venom of the honeybee
Apis mellifera
.
It is a nonspecific cytolytic peptide that attacks all lipid membranes, lead-
ing to significant toxicity when injected intravenously. The basis of melittin's
action is a physical and chemical disruption of membrane structure result-
ing in a profound compromise of the cell permeability. Recently, it has been
demonstrated that synthetic nanoscale vehicles like PFC nanoparticles can
deliver melittin by flexible passive and active molecular targeting to kill both
established solid tumors and precancerous lesions. This study has proposed
a novel linking strategy to generate biocompatible peptide-nanostructures
for lipidic nanocarriers, including PFC nanoemulsions, liposomes, as well as
cells for combined molecular imaging and cell-targeted therapeutics [164].
5.10 Silica nanoparticles
Silica is major component of sand and glass, and it has been used in the syn-
thesis of NPs. Functional groups can also be added to the surface, making
them appealing for designs for different applications. Immunofluorescent la-
beling of both a cancer cell surface marker and tissue sections by dye-doped
silica NPs has demonstrated high specificity and high intensity [165].
Different strategies have been explored for using silica NP probes to target
cancer cells. Affinity and specificity associated with the antibody-antigen
recognition have been studied in developing immunoassays. Primary or sec-
ondary antibodies are covalently immobilized onto the NP surface in order
to selectively and efficiently bind various cancer cells [166]. In one study, a
mouse anti-human CD10 antibody was used as the recognition element on
NPs. Fluorescence microscopy was then used to image the leukemia cells.
The brightly fluorescent cells bound with NPs were easily detected under
the fluorescence microscope [167]. Other affinity reagents, such as receptor
