Biomedical Engineering Reference
In-Depth Information
One nanomaterial that has been used in the development of nanoneedles is
carbon nanotubes (CNTs). These are attached to the tips of nanoneedles, and
with the aid of atomic force microscopy (AFM), the needles are fabricated from
pyramidal silicon AFM tips using focused ion beam etching. The nanoneedles
can be potentially used by a nanosurgeon to perform an operation on a single
cell without harming the cell. 66
Today, cellular nanosurgery are already being explored using a rapidly
vibrating (100Hz) micropipette with a <1-mm-tip diameter. This device is used to
completely cut dendrites from single neurons without damaging cell viability. 67 It
was reported that femtosecond surgery was performed on roundworm neurons
and were functionally regenerated. 18 The femtolaser functions like a pair of
“nanoscissors” by vaporizing local tissue without affecting adjacent tissue through
the localized nanosurgical ablation of focal adhesions adjoining live mammalian
epithelial cells. 68 It has also been used for microtubule dissection inside yeast
cells, 69 noninvasive intratissue nanodissection of plant cell walls, and selective
destruction of intracellular single plastids or selected parts of them. 70 In addition,
femtolaser had also been reported for the nanosurgery of individual chromosomes
to selectively knock out genomic nanometer-sized regions in the nucleus of liv-
ing Chinese hamster ovary cells. 71 After these nanosurgeries, the cells survived.
Bacterial cell dissection in aqueous medium has also been performed in situ using
atomic force microscopes that revealed 26-nm-thick twisted strands inside the cell
wall after mechanically peeling back large patches of the outer cell wall. 72
6.2.2 Nanocameras
Unlike conventional clinical laboratory setup, medical robots like medical
micro machines that are implanted or ingested can continuously gather diag-
nostic information and fine-tune the mode of treatments continuously over an
extended period of time. 8 Some current examples are pill-sized cameras to view
the digestive tract as well as implanted glucose and bone growth monitors to aid
in the treatment of diabetes and joint replacements. The capabilities of micro
machines are significantly extended to stand-alone millimeter-scale microro-
bots for possible in vivo surgical use. For example, external magnetic fields
from a clinical magnetic resonance imaging (MRI) system can move microro-
bots containing ferromagnetic particles through blood vessels. 73-76
In the field of nanotechnology, continuing development of in vivo machines
has the potential to revolutionize health care 27,77-79 with devices small enough
to reach and interact with individual cells of the body. 80,81 Current efforts focus
on the development and functionalization of nanomaterials 86 that will allow their
applications to enhance diagnostic imaging, 87-94 targeted drug delivery, 87-94 as
well as a combination of both diagnosis and treatment which has been given the
term called nanotheranostics. 95-101 Various studies have focused on the develop-
ment and applications of nanomaterials that target specific cell types for imag-
ing and/or drug delivery. 102-106
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