A Review on Applications of Nanobots in Combating Complex Diseases

Abstract

In the current years, a lot of research works have been continued in the quest to find a desired drug delivery system within the human body. Among different drug delivery systems, nanobots have become much popular due to its capability to perform different tasks like actuating, sensing, signaling, information processing and intelligence at nanoscale dimension. A nanobot is a robotic machine that can be programmed to diagnose, monitor and treat various vital diseases. It works at cellular level with minimum side effects and thus substitute the conventional treatment procedures. The major limitations of nanobots are proper designing and manufacturing process. In spite of its expensive manufacturing set up, they are pre-eminent for medical applications, such as nanobots like respirocytes, microbivores and clottocytes have been designed to act as artificial substitutes of blood. This article describes the use of nanobots in different fields of medical science like diagnosis and treatment of cancer, diabetes, aneurysm, tetanus, HIV, skin disease, gout as well as in the field of dentistry, surgery and treating many other diseases. It also represents the recent research which has been applied in vivo to different animals. Scientists hope that nanobots will act on molecular level, protect the biological system and thus ensure a better and longer life. Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019

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Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019 (January)
A Review on Applications of Nanobots in Combating
Complex Diseases
Tashnuva Rifat, Md. Shahadat Hossain, Md. Mahbubul Alam and
Abu Shara Shamsur Rouf
Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Dhaka
Dhaka-1000, Bangladesh
(Received: September 21, 2018; Accepted: December 31, 2018; Published: January 17, 2019)
Abstract
In the current years, a lot of research works have been continued in the quest to find a desired drug
delivery system within the human body. Among different drug delivery systems, nanobots have become
much popular due to its capability to perform different tasks like actuating, sensing, signaling,
information processing and intelligence at nanoscale dimension. A nanobot is a robotic machine that can
be programmed to diagnose, monitor and treat various vital diseases. It works at cellular level with
minimum side effects and thus substitute the conventional treatment procedures. The major limitations
of nanobots are proper designing and manufacturing process. In spite of its expensive manufacturing set
up, they are pre-eminent for medical applications, such as nanobots like respirocytes, microbivores and
clottocytes have been designed to act as artificial substitutes of blood. This article describes the use of
nanobots in different fields of medical science like diagnosis and treatment of cancer, diabetes,
aneurysm, tetanus, HIV, skin disease, gout as well as in the field of dentistry, surgery and treating many
other diseases. It also represents the recent research which has been applied in vivo to different animals.
Scientists hope that nanobots will act on molecular level, protect the biological system and thus ensure a
better and longer life.
Key words: Nanobot, current research works, respirocyte, microbivore, clottocyte.
Introduction
The word like nanobot or nanorobot has captured
public imagination over the last two decades. This is
a machine of nanoscale dimension that can be viewed
under microscope. Such devices play an essential role
in critical care applications (Nerlich, 2008).
Nanorobotics is a part of nanotechnology that deals
with the study of designing, programming,
manufacturing and controlling of robots at nanoscale
which ranges from 0.1 to 10 μm. A nanobot is an
extremely small robot that has been designed to
perform a specific task with precision at nanoscale.
These are also known as nanorobots, nanites,
nanoagents and nanoids (Manjunath and Kishore,
2014).
The word nanobot was first used in 1989 to
designate a microscopic robot used in
nanotechnology. A nanobot is an extremely small
autonomous self-propelled machine. According to
web-dictionary for nanoscience and nanotechnology -
“A nanobot is an imaginary machine on a scale of
few to few hundreds of nanometers designed to
perform specific tasks”. The prototype models for
most of the futuristic concepts are specific cells e.g.
phagocytes which ingest foreign matters and cellular
molecular machineries like RNA polymerase or
ribosome (Nanobot, Websters New MillenniumTM
Dictionary of English).
Nanobots are designed from the biological model
of bacteria. The principle element used in
Correspondence to:
Abu Shara Shamsur Rouf; Email: rouf321@yahoo.com

100 Rifat et al. / Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019 (January)
construction of nanobot is carbon and it is comprised
probably in the form of carbon or fullerence nano
composites. Due to the inert properties, high thermal
conductivity and strength of diamondoid material, it
is used in the construction of the outer shell of the
nanobot, while the super smooth surface also helps to
reduce the chance of triggering the body’s immune
system. The mechanical parts by which a nanobot is
made of are bearing, gears, motors etc., where the
nanoscale gears and other components can be
constructed using elements like hydrogen, sulfur,
oxygen, nitrogen or silicon. Moreover, the
substructures of nanobot involve onboard power
supply, sensors, nanocomputer, pumps, manipulators
and pressure tanks (Uriarte, 2011).
Applications of nanobots in medicine provide a
new range of tools for the treatment of diseases and
the improvement of human biological system. The
design of various nanobots in medicine
includesrespirocytes, microbivores, clottocyes,
pharmacytes, dentifrobots and vasculoids (Freitas,
2007).
Due to its minimum side effects and quicker
response, nanobot is found to be more innovative and
supportive to the treatment and diagnosis of severe
diseases like cancer, heart attack, diabetes,
atherosclerosis, kidney stones etc (Robert, 2009).
Through the ability for regular monitoring of body
condition, nanobots allow us a personalized treatment
and thus achieve high efficiency against many
diseases (Manjunath and Kishore, 2014). For all of
these reasons nanobots are going to introduce a new
chapter in the field of medical science.
This article mainly focuses on the applications of
nanobots in different fields of medical science e.g.
hematology, cancer, dentistry, diabetes, heart
diseases, gene therapy, skin diseases, surgery etc. It
also contains the information of different research
studies on nanobots along with the advantages over
the conventional treatment procedures, which will
ultimately help the researchers to design and conduct
further research on nanobots.
Applications of nanobots in medical science:
Medical nanobots can be used in diagnosis,
monitoring and treating critical diseases. These are
capable of delivering medicine into the specific target
site in human body. The potential applications of
nanobots include:
Hematology: Nanobots have potential
application in the field of hematology. Its use in
hematology ranges from emergency transfusions of
non-blood oxygen carrying compounds to restoring
primary hemostasis (Saadeh and Vyas, 2014)
Respirocytes are spherical 1 μm diameter sized
nanobots which are designed as artificial mechanical
red blood cells. The respirocyte could deliver 236
times more oxygen to the body tissue when compared
to natural red blood cells. The respirocyte would
manage the carbonic acidity that can be controlled by
gas concentration sensors and on-board
nanocomputer (Freitas, 2005a). Each respirocyte has
3 types of rotors. One rotor releases the stored
oxygen while travelling through the body. The
second rotor captures all the carbon dioxide at blood
stream and releases at the lungs. The third rotor takes
glucose from blood stream and uses as fuel source
(Mishra and Dash, 2012). It can be programmed to
scavenge carbon monoxide and other poisonous
gases from the body. A 5 cc therapeutic dose of 50%
respirocyte saline suspension contains 5 trillion
nanorobots that could exactly replace the gas carrying
capacity of the patient’s entire 5.4 litres of blood
(Freitas, 2005b).
Microbivores are the nanobots that are designed
as artificial WBC and also known as nanobotic
phagocytes. It is a spheroid device made of diamond
and sapphire which measures 3.4μm in diameter
along its major axis and 2μm diameter along its
minor axis. Microbivore absorbs and digests the
pathogens in the blood stream by the process of
phagocytosis (Eshaghian-Wilner, 2009). During the
cycle of operation, the target bacterium binds to the
microbivore surface via specific reversible binding
site. A collision between the bacterium and
microbivore brings in the surface into close contact
and thus the reversible binding site can be recognized
and weakly bound to the bacterium. When the
bacterium is bound to the binding site, the telescopic

Rifat et al. / Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019 (January) 101
robotic grapples rise up from the surface and attach to
the bacterium. Then the bacterium is transported
from the binding site to the injection port by the
grapple’s handoff motion. Then the bacterium is
internalized into the morcellation chamber where the
bacterium is minced into nanoscale pieces. These
pieces of bacterium are pistoned into digestive
chamber which consists of pre-programmed set of
digestive enzymes. Then it is converted into amino
acids, mononucleotides, free fatty acids and simple
sugars which are then discharged into blood stream
through the exhaust port. It needs 30 seconds to
complete the entire cycle of phagocytosis by
microbivore (Manjunath and Kishore, 2014).
Microbivore acts 1000 times faster than antibiotic
aided WBCs and the pathogen stand no chance of
multiple drug resistance which occurs in case of
antibiotic. They can also be used in case of
respiratory and cerebrospinal bacterial infection or
infection in urinary fluid and synovial fluid
(Eshaghian-Wilner, 2009).
Clottocyte is a nanobot that is designed as
artificial platelets. It would complete hemostasis
within 1 second. The response time is 100-1000 times
faster than the natural hemostatic system which takes
2-5 minutes to complete the whole process
(Boonrong and Kaewkamnerdpong, 2011). The
application of nanobots as clottocytes has reduced the
clotting time and blood loss. Again, blood clots are
found to occur irregularly in some patients. This
abnormality is treated by corticosteroids which is
associated with side effects such as hormonal
secretion, lung damage and allergic reaction.
Clottocytes can be used as an alternative treatment
which is free from these side effects (Manjunath and
Kishore, 2014).
Dentistry: The nanobots designed to apply in
dental treatment are known as dentifrobots (Abhilash,
2010). These are used in routine cleaning, tooth
whitening, hypersensitivity and even in orthodontics
(Sahoo et al., 2007).
A mouth wash and toothpaste full of nanobots
can identify and destroy the pathogenic bacteria
while allow the harmless flora of mouth. These
devices can identify food particles, plaque or tartar
and can remove them effectively. Nanobots provide
complete dentition replacement therapy including
both mineral and cellular components.
Orthodenticnanobots can manipulate the periodontal
tissue including periodontal ligament, gingiva,
alveolar bone and cementum (Sujatha et al., 2010).
Nanobots can be covered by highly specific proteins
that bind to the targeted pathogens for the treatment
of infection. In case of root canal, the use of tiny
camera can provide visualization of root and thus
reduces any guess work. In hypersensitive teeth, the
number and diameter of dentinal tubules are
significantly increased, where penetration of
nanobotswith selective ablation or occlusion ability
can prevent these stimuli within minute (Sharples,
2011).
Cancer detection and treatment: Cancer can be
successfully diagnosed and treated with the help of
nanobots. Unlike the conventional drug, nanobots are
highly site specific i.e. it is programmed to detect
only the diseased cells to act upon them, the healthy
cells are left aside and thus show minimum side
effects. Nanobots with embedded biosensors can be
used in detection of tumor cells in the early stage of
development inside the patient’s body (Sivasankar
and Durairaj, 2012). Kumar et al. (2014) has reported
that, scientists have genetically modified salmonella
bacteria carrying microscopic robots (3 μm) named
bacteriobots, which are drawn to tumors by
chemicals secreted by the cancerous cells. These
deliver drug directly to the tumor leaving the healthy
cells alone and thus protect the patient from side
effects of chemotherapy. But these bacteriobot can
only detect the tumor in case of breast cancer and
colorectal cancers. On the contrary, nanobot is able to
detect and treat other cancers (Kumar et al., 2014)
This nanobot can be constructed to different cell
surface receptors. The payload it releases upon
activation, can also be changed as necessary. The
nanobot is constructed using engineered DNA strands
that have been made to fold into a desired tertiary
structure (Dietz et al., 2009). After binding to the
desired target, the conformation of the DNA nanobot

102 Rifat et al. / Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019 (January)
changes from closed state to tertiary state to release
the stored therapy (Douglas et al., 2012).
Murnanehas reported that nanobots can combat
the tumor by preventing the flow of blood to the
tumor cells. As without blood flow tumor cells
cannot survive, the researchers have targeted this
weak point. This nanobot is made from a flat DNA
sheet to which an enzyme thrombin is attached which
is responsible for blood clotting. This sheet is then
rolled into a tube with thrombin inside (Murnane,
2018). DNA aptamers are attached to the surface of
the tube that seeks out a protein called nucleoin that
present in the endothelial cells on the surface of only
the tumor cells not on the surface of healthy cells.
The DNA aptamers seek out nucleoin and attach to
the surface of the tumor. Then the nanobots penetrate
the blood vessels that feed to the tumor and by
unrolling release the thrombin molecules, which start
clotting process that reduces blood flow to the tumor
and starves the tumor (Murnane, 2018).
Anti-HIV nanobots: HIV virus destroys the
immune system and thus the host become vulnerable
to small diseases. By this process AIDS turns into a
fatal disease. The HIV virus attacks WBCs and
convert them to HIV. Thus the immune system fails
and this is the reason for the death of the patient.
There is no conventional drug that can cure this
deadly disease. By usingnanobots, AIDS affected
WBCs are converted to original form of WBC and
thus maintain the constant amount of immune system
(Bhuyan and Bardoloi, 2016).
Host WBC + HIV virus = Infected WBC
Nanorobot + Infected WBC = Restored WBC
(Joshi and Pardeshi, 2013)
Surgery: Surgery is an invasive method and also
liable for injury. It is also expensive and time-
consuming method whose success rate depends upon
the skill and efficiency of the operating surgeon and
his team. These limitations can be overcome by using
nanobots (Eshaghian-Wilner, 2009). Surgically
programmed nanobot can act as a semiautonomous
onsite surgeon inside the body (Kshirsagar et al.,
2014). When nanorobots treat the interior of the
body, the controlling is preset to be done by the
single machine itself thus ensuring much safer and
exact treatment (Biswas and Sen, 2016). It would
perform various functions such as detection of
pathology, diagnosis, correcting lesions by nano-
manipulation coordinated by an on-board computer
(Manjunath and Kishore, 2014).
Neurosurgery: Spinal cord injury and nerve
damage is an important topic of concern within the
field of neurosurgery. Recently, different ways have
been pursued with the goal of optimizing and
improving nerve reconnection outcomes, including
promoting the regeneration of axons via growth
factors (Bregman et al., 2002) and enriched scaffolds
(Chen et al., 2009). Restoring connectivity to
transected axons is an inevitable step to the
restoration function. However, this is limited by
technical limitations of surgery (Chang et al., 2010).
Advancements in technology have led to the
development of nanoscale device which allow
manipulation of individual axons. A nanoknife with
40 nanometer diameter has been developed which is
effective for axon surgery (Chang et al., 2007).The
use of dielectrophoresis has been found to be
effective in achieving controlled movement of axons
within a surgical field (Sretavan et al., 2005).
Following controlled transaction of axons and
maneuvering them into position using
dielectrophoresis, fusion between the two ends can be
induced via electrofusion (berg, 1994), polyethylene
glycol (Whittemore and Snyder, 1996) or laser-
induced cell fusion (Steubing et al., 1991) amongst
other methods.
One of the most effective ways to prevent
morbidity and mortality in the field of neurosurgery
is the treatment of cerebral aneurysm before rupture.
About 10% patients die before arriving to the
hospital, 5% die within 24 hours of aneurysm rupture
and 50% die within 30 days (Broderick et al., 1994).
Nanobots can be used for screening a new aneurysm
or closer monitoring of identified aneurysm. A design
for an intravascular nanobot with the capability to
detect aneurysm formation by detecting increased
levels of nitric oxide synthase protein within the
affected blood vessel has been proposed by

Rifat et al. / Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019 (January) 103
Cavalcanti et al. (2009). These nanorobots can be
given the capability of wirelessly communicate
information about pertinent vascular changes to care
providers, potentially decreasing screening costs of
imaging and frequent follow up visits (Saadeh and
Vyas, 2014).
S. Stupp and J. Kessler at Northwestern
University in Chicago, designed small rod like
nanofibers (Xu et al., 2002). This nanofiber was
incorporated in nanobots called an amphiphiles and
are capped with amino acids which incite the growth
of neuron and ultimately prevent scar tissue
formation (Chawla and Amiji, 2002).
Gene therapy: Medical nanobots can readily
treat genetic diseases by comparing the molecular
structures of both DNA and proteins found in the cell
to desired reference structures (Sivasankar and
Durairaj, 2012). Floating inside the nucleus of a
human cell, an assembler built repair vessel performs
some genetic maintenance. Stretching a super coil of
DNA between its lower pair of robot arms, the nano
machine gently pulls the unwound strand through an
opening in its prow for analysis. Upper arms,
meanwhile, detach regulatory proteins from the chain
and place them in an intake port. The molecular
structures of both DNA and proteins are compared to
information stored in the database of a larger nano
computer positioned outside the nucleus and
connected to the cell-repair ship by a
communications link. Irregularities found in either
structure are corrected and the proteins reattached to
the DNA chain, which re-coils into its original form
with a diameter of only 50 nanometers, the repair
vessel would be smaller than most bacteria and
viruses, yet capable of therapies and cures well be
beyond the reach of present-day physicians. “Internal
medicine” would take on new significance (Adleman,
1995; Hamdi et al. 2008). Disease would be attacked
at the molecular level and such maladies as cancer,
viral infections and arteriosclerosis could be wiped
out. Most human diseases involve a molecular
malfunction at the cellular level, and cell function is
largely controlled by gene expression and its
resulting protein synthesis. One common practice of
genetic therapy which has enjoyed only limited
success is to supplement existing genetic material by
inserting new genetic material into the cell nucleus,
commonly using viral bacteriophage bacterial system
cell plasmid/phospholipid microbubble cationic
liposome, dendrimeric, chemical, nanoparticulate or
other appropriate transfer vectors to breach the cell
membrane (Freitas, 2007).
However, permanent gene replacement using
viral carriers has largely failed thus far in human
patients due to immune responses to antigens of the
viral carrier as well as inflammatory responses,
insertional mutagenesis and transient effectiveness.
Excess gene copies, repeat gene clusters and partial
trisomies and higher polysomies can often cause
significant pathologies, sometimes mimicking aging.
Attempting to correct excessive expression caused by
these errors by implementing antisense transcription
silencing on a whole-body, multigeneor whole-
chromosome basis would be far less desirable than
developing more effective therapeutic methods that
did not require such extensive remediation (Freitas,
2007).
Diabetes: At a typical glucose concentration, the
nanobots try to keep the glucose levels ranging
around 130 mg/dl as a target for the Blood Glucose
Levels (BGLs). A variation of 30 mg/dl can be
adopted as a displacement range, though this can be
changed based on medical prescriptions. Medical
nanobots can be designed in such a way that the
significantly measured data can be transferred
automatically through the radio frequency signals to
the mobile phone carried by the patient and if the
glucose achieves critical levels, the nanorobots emits
an alarm through the mobile phone (Abhilash, 2010).
The SGLT3 (human sodium glucose co-
transporter type 3) has influenced in regulating
extracellular glucose concentration and define
glucose level in the body and acts as sensor to
identify glucose. According to Nandkishore et al.
nanobots use chemo sensor that involve the
modulation of SGLT3 glucosensor activity. By the
help of this chemo sensor, nanobots determine the

104 Rifat et al. / Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019 (January)
requirement of insulin and other treatment effectively
(Kshirsagar et al., 2014).
Tetanus: Tetanus is caused by the pathogen
Clostridium tetani that naturally present on the
surface of the rusty nail and metallic object. When
body surface is punctured by this rusty nail or
metallic object, this bacterium may enter the body
and release neurotoxin TeTx within a short period of
time. This neurotoxin TeTx causes paralysis or
locking of the whole body from head to foot leading
to subsequent death. The conventional treatment is to
inject anti-tetanus vaccine that counteract the C.
tetani and neurotoxin TeTx within a short period of
time. But it has several side effects like fever, redness
and painful swelling around the injection site. In rare
cases it causes brachial neuritis. An alternative
treatment is to use programmable nanobot. When
injected into the body, this nanobot will destroy the
C. tetani and the released deadly neurotoxin TeTx
and thus heal at a cellular level sparing the side
effects of conventional vaccination (Nagalet al.,
2012).
Myocardial infarction: The blood vessel
blocking factors or plaque that is responsible for
myocardial infarction can be detected and removed
by nanobot molecule. The conventional treatment of
myocardial infarction e.g. angioplasty depends on the
surgical skills and sometimes has side effects but the
process followed by nanobots is immune to these
effects (Biswas and Sen, 2014).
Gout: When kidneys lose ability to remove
waste from the breakdown of fats from the blood
stream, this condition is called gout. This waste
sometimes crystallizes at points near joints like knees
and ankles and causes intense pain at these joints. A
nanobot could break up the crystalline structures at
the joints and provide relief from the symptoms
(Strickland, 2010).
Alzheimer diseases: The amyloid-β protein
deposits show changes on gradients as a symptom of
Alzheimer disease. This information serves for the
early diagnosis of Alzheimer disease and to guide
possible immunotherapy treatments, with more
efficient neurotransmitters delivery, like dopamine
and amino acids such as g-aminobutyrate (GABA),
with better medical administration like nanobots
(Cavalcanti et al., 2007).
Damaged tissue repair: Nanobots can easily
repair and heal damaged tissue by taking existing
molecules, replicating them and assembling new
molecules into new layers of tissue. Nanorobots can
slowly regrow portions of the damaged bone. It is
hoped that one day, nanobot might be able to
reproduce bone marrow. Other functional
possibilities in the aspect of damaged tissue repair
include: Closing of a split vein, reforming damaged
skin, reducing dead flesh from a wound (Biswas and
Sen, 2014).
Breaking up kidney stones: Nanorobots are used
to break the kidney stones with the help of ultrasonic
shocks. Kidney stones are painful and a large stone
does not pass out in urine. Sometimes doctor break
this stones by ultrasonic frequency, but these are not
effective always. Nanorobots break up these kidney
stones by using small laser and these smaller pieces
are passing out in urine outside the body (Martinac
and Metelko, 2005).
Skin diseases: A cream containing nanobots may
be used to cure skin diseases. It removes the dead
skin and excess oil, add missing oil, apply right
amount of natural moisturizing compounds and
participate in deep pore cleansing (Cavalcanti et al.,
2004).
Inducing anesthesia: Nanobots may also be used
as both general and local anesthesia. Being highly
specific and target oriented, it reduces the anesthesia
associated morbidity and mortality (Agarwal, 2012).
Body surveillance: By using nanobots, it is
possible to monitor the vital organs and wireless
transmission continuously which is not possible in
case of conventional drug (Abeer, 2012). It will also
give a quick response in case of sudden change in
vital organs or warn against a possible risk e.g. high
blood glucose in case of diabetes (Bhat, 2014).
Nanobot for detoxification: Self-propelled
nanorobots have also been used as powerful
detoxification tools with high cleaning capability.
Similar to biosensing, detoxification strategies rely

Rifat et al. / Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019 (January) 105
on self-propelled nanorobots that rapidly capture and
remove the toxin to render the environment nontoxic.
Efficient motion would facilitate the collision and
binding of toxins to the motors, which are coated
with desired functional materials. For example,
nanomotors have been combined with cell-derived
natural materials capable of mimicking the natural
properties of their source cells toward novel
nanoscale biodetoxification devices. Among different
cell derivatives, red blood cells (RBCs) have shown
excellent capability to function as toxin-absorbing
nanosponges to neutralize and remove dangerous
“pore-forming toxins” (PFTs) from the bloodstream
(Hu et al., 2013). Motivated by the biological
properties of RBCs, several different types of cell-
mimicking micromotors have been developed for
detoxification. Wu et al. (2015a) presented a cell-
mimicking, water-powered micromotor based on
RBC membrane– coated magnesium microparticles,
which were able to effectively absorb and neutralize
toxin in biological fluids (Wu et al., 2015a). Another
detoxification strategy explored the combination of
RBC membranes with ultrasound-propelled
nanomotors as a biomimetic platform to effectively
absorb and neutralize PFTs (Wu et al., 2015b).
Nanobots for targeted delivery: Drug delivery
nanobots depend on systemic circulation and the
force and navigation required for localized delivery
and tissue penetration. To achieve precise delivery of
therapeutic payloads to targeted disease sites, drug
delivery vehicles are desired to have some unique
capability that involve propelling force, controlled
navigation and tissue penetration. The motor-like
nanobots have the potential of rapidly transporting
and delivering therapeutic payloads directly to
disease sites and thus improve the therapeutic
efficacy and reduce systemic side effects of highly
toxic drugs (Li et al., 2017). A number of initial
studies have been conducted to demonstrate the
delivery function and performance of these nanobots
in test tubes and in vitro environments. For example,
Wu et al. (2015a) reported the preparation of a
multilayer tubular polymeric nanomotor that is
encapsulated by anticancer drug doxorubicin via a
porous-membrane template-assisted layer-by-layer
assembly. The nanomotor was able to deliver the
loaded drug to the cancer cells (Wu et al., 2013). Ma
et al. (2015) reported a chemically powered Janus
nanomotor that functioned as an active nanoscale
cargo delivery system and enabled a 100% diffusion
enhancement when compared with passive targeting
without propulsion (Ma et al., 2015). SiRNA-loaded
nanowires were shown to penetrate rapidly into
different cell lines and noticeably improve the
efficiency and speed of gene silencing process as
compared with their static nanowire counterparts.
Magnetic helical micro swimmers have also been
used for targeted delivery of plasmid DNA (pDNA)
to human embryonic kidney cells. The pDNA loaded
motors were moved towards the cells and released
their genetic cargo into the cells upon contact (Qiu
et al., 2015).
Studies of in vivo activities of nanobots: Most of
the studies have been performed in vitro but initial in
vivo studies have already been performed and have
demonstrated encouraging results. Recently Gao
et al. (2015) conducted the very first in vivo study of
chemically powered micromotors. The distribution,
retention, cargo delivery ability and acute toxicity
profile of the motors in a mouse’s stomach have been
carefully evaluated. The acid driven propulsion in the
stomach enhanced the binding and retention of the
motors in the stomach wall effectively considering
zinc-based micro motor as a model. The micro
motors gradually dissolve in the gastric acid,
releasing their payloads and leaving nothing toxic
behind (Gao et al., 2015).
The experiment of nanobots that destroy the
tumor cells by preventing blood supply was
performed on mice and pigs. The nanobots were
injected intravenously into the blood stream of mice
with breast cancer, melanoma, ovarian and lung
cancer. The nanobots had located and surrounded the
tumors within hours. Tissue damage that occurred
due to blocking of blood supply was observed within
24 hrs. After 48 hrs advanced blood clotting was
observed and blood clot in all tumor was observed
after 72 hrs. Nanobots were clearly successful in
attacking the cancerous cells but if they could attack

106 Rifat et al. / Bangladesh Pharmaceutical Journal 22(1): 99-108, 2019 (January)
the healthy tissue the consequence would be more
severe. But fortunately, such occurrence did not
happen. Nanobots were also injected in mice and pig
without tumors but no detectable change was found
in normal blood coagulation and cell morphology.
Such effectiveness of the treatment by nanobots
against a variety of cancers holds a great hope for
future (Murnane, 2018). There are two ways to
remove the nanobots from the body. One, when
nanobots task are completed they can be excreted
from the body by human excretory channels. They
can also be removed by active scavenger system
(Requicha, 2003). Two, blood that is needed to be
cleared may be passed from the patient to a
specialized centrifugation apparatus. Here aural
transmitters command nanobots to establish neutral
buoyancy. No other solid blood component can
maintain exact neutral buoyancy, hence those other
components precipitate outward during gentle
centrifugation and added back to filtered plasma on
the other side of the apparatus. Meanwhile, after a
period of centrifugation, the plasma that contains
mostly suspended nanobots but few other solids, are
drawn off through a 1micron filter, removing the
nanorobots. Filtered plasma is recombined with
centrifuged solid components and returned
undamaged to the patient's body (Kharwade et al.,
2013).
Conclusion
The recent invention of nanobots in the field of
nanotechnology gives hope for the diagnosis and
treatment of many hazardous diseases like cancer,
heart disease, genetic disorder, HIV, diabetes with
minimum side effects. It is also very much useful in
the field of surgery and dentistry. Scientists are
hopeful that, within next 10 years human blood will
probably be streaming with tiny nanobots which will
help to keep them away from getting sick. These will
act on molecular level, protecting the biological
system and thus ensuring a good and long life.
More research students are needed to develop the
architecture and functions of nanobots and also to
ensure its effectiveness and safety in human body.
This paper will help to provide a lot of information
about nanobots which will help to perform these
researches.
Conflict of interest
The authors declare that there is no conflict of
interest.
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