|Cancer is a major cause of death worldwide and is on the increase,
and its clinical effective therapy remains poor. In the traditional clinical
treatment of disease, diagnosis and therapy are two separate processes
and also use two independent drugs; therefore, patients often delay the
best period of disease therapy for taking two treatments. At present,
the most common methods for medical imaging diagnosis are X-ray,
tomography, CT, B ultrasound, magnetic resonance and endoscopy.
Nevertheless, there are some serious problems, such as the sensitivity of
these techniques is low, it is the reason that some early tumor is difficult
to find, which bring about the patient losing the best treatment time;
in addition, the dose of a drug required to achieve clinically effective
cytotoxicity in tumors often causes severe damage to non-malignant
cells, producing undesirable side effects. There is a growing need for
the designing of novel image agent to allow noninvasive, combinatory
therapeutic-diagnostic applications. Recently, a word “theranosis” has
been created, combining the words to describe the implementation
of these two distinct pursuits simultaneously. Therefore, theranostic
agents have received a great deal of research interest in cancer diagnosis
|Gold nanoparticles are allowed to be used in biological and medical
application owing to their good biocompatibility as well as excellent
optical and electronic properties. In recent years, Au nanomaterials
have attracted greater attention from researchers because it was
demonstrated that Au nanomaterials have great potential for cancer
photothermal therapy. Gold nanoshells are an excellent candidate for
near-infrared irradiation (NIR) light-triggered drug release, which
provide an attractive approach for the spatiotemporal control of drug
delivery. It may offer precise, on-demand drug delivery within individual
cells in vitro and precise treatment of cancer in vivo. Furthermore,
the strong optical absorption of gold nanoshells can rapidly increase
the local temperature under NIR to kill selectively tumor cells, not
harming normal cells. Tumor cells are very sensitive to heat, and can
cause their death. Therefore, the gold nanoshells can be used for tumor
photothermal ablation therapy .
|Liposomes are proven candidates for delivery of a wide range of
therapeutics, since hydrophilic drug can be encapsulated in their
internal aqueous compartment or hydrophobic one embedded within
the phospholipid bilayer. Liposomes have shown some advantages such
as higher stability, good biocompatibility, non-toxicity, biodegradability,
and controlled release of the encapsulated drug. Especially, the longcirculating
liposomes could slowly accumulate in tumor, inflammation
or infarcted sites with affected and leaky vasculature via enhanced
permeability and retention effect (EPR effect) . Clinical applications
of liposomes on the delivery of anticancer agents for the treatment
of different cancer are well-established. Liposomes’ permeability is
greatly enhanced around the membrane melting temperature (Tm),
which depends on the lipid composition. A drug can be released if the
liposome membrane is heated above Tm .
|A novel anticancer drug can be designed, which is Au nanoparticleliposome
hybrids delivery system. The delivery system allows deep tissue detection, therapy, and monitoring on living body, and the hybrids
can be designed by controlling the thickness of the gold shell and the
diameter of the core, which realizes that the surface plasmon resonance
and the optical absorption of gold nanoshells can be tuned to the NIR
to enhance spectral signal in the cytoplasm and obtain the detection
signal. Furthermore, when the tunability is designed in the 690-900 nm,
the absorption of human tissues is minimal and penetration is optimal,
which can reach the tissues under several inches . Therefore,
the advantages of gold particle-liposome hybrids are as follows: (1)
biodistribution can be controlled by the change of the nanoparticle
properties, (2) preservation an effective blood concentration by
escaping the removal carried out by the reticuloendothelial system, (3)
high potency hydrophobic compounds can be dispersed in water and
delivered systemically by nanoparticles, (4) nanoparticles can enhance
the level of signal detection for the more sensitive detection of disease.
|Gold nanoparticle-liposome hybrids can improve the efficiency of
diagnosis by providing better detection signal contrast and biological
distribution. These properties make it possible as a new biological
contrast agent. Ke et al. successfully constructed gold nanoshelled
microcapsules, which can kill HeLa cells in vitro by exposure to 808 nm
light irradiation. Meanwhile, it also can still maintain adequate acoustic
properties that are required to act as an ultrasound contrast agent .
The research showed that the liposome release can be initiated within
seconds by irradiating hollow gold nanoshells with a NIR pulsed laser.
NIR light penetrates into the tissue up to 10 cm, allowing these gold
nanoparticle-liposome complexes to be addressed noninvasively within
a significant fraction of the human body .
|The integration of nanotechnology, materials science, pharmacy,
and biotechnology is bringing about advances in the medical
technologies used for the diagnosis and therapy of cancer, as well as the
monitoring of drug distribution. For the success of gold nanoparticleliposome
hybrids nanomedicine, further studies are required. It is also
necessary to devise a means of mass and easy producing gold-liposome
hybrids, as well as optimizing their dose or concentration, size, flow rate
in blood stream and so on. The hybrids have great potential in clinical
practice for the purpose of early detection and minimally noninvasive
treatment of cancer, and are expected to bring about an improvement in the detection accuracy, clinical outcome, and patient quality of life.
Meanwhile, the long-term safety of nanodrugs for in vivo applications
should be confirmed. This is a favorable starting point for anticancer
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