60~70% of prostate cancer’s tumor cells have androgen receptors. these significant amount of hormone receptors play a role in intermolecular actions. this role is now used by targeting and therapeutic ligands on gold nanoparticles to target tissue-selective anti-tumor drug delivery. in order to have multiple targeting and therapeutic ligands bind with gold nanoparticles, the gold nanoparticles must first undergo polymer stabilization. then, anti-estrogen molecules with thiolated peg are bound to gold nanoparticles via au-s bonds, forming thiolate protected gold nanoparticles. pegylated gold nanoparticles docetaxel is packed into pegylated gold nanoparticles docetaxel is an anti-mitotic chemotherapy medicine which showing great performance in clinical trial. docetaxel was approved by fda, to treat several different kinds of cancer. i.e. breast cancer(include locally advanced or metastatic). market approval a pilot study of aurolase™ therapy (gold nano shells) in refractory and/or recurrent tumors of the head and neck was completed in 2009 and two trials are currently using aurolase™ therapy for the treatment of primary/metastatic lung cancer and for prostate cancer. other gold nanoparticles on the market are mostly for synthesis of nanoparticle complexes in research. nanocomposix specializes in the production of various sizes of nanoparticles, controlled by varying the concentrations of reducing reagent and haucl4. sigma aldrich offers six different sizes of spherical gold nanoparticles and have developed gold nanourchins for similar usage. the surface causes a red shift in the surface plasmon peak as compared to spherical gold nanoaprticles. nanopartz offers gold nanoparticles and gold nanorods for preclinical in vivo therapeutics that have been used extensively in preclinical therapeutics including photothermal hyperthermia and chemotherapeutic drug delivery. the pilot study using the ntracker gold nanorods was completed in 2012 and was used on seven canines with varying degrees of solid cancer tumors. the results showed significant loading of the gold nanorods after intravenous injection into the cancer tumors and significant heating of the tumors from an external laser. images are found at adverse effects and limitations shape depending on the shape of the molecule, the absorbance will vary, i.e. spherical particles will absorb wavelengths in the nir region with a relatively low absorbance compared to long rods. chan et al observed that 50 nm spherical nanoparticles were taken up more efficiently than both larger and smaller particles of the same shape. in regards to size, the spheres were taken up more efficiently than the rods. ability of greater uptake of nanoshells into the cell will localize in the perinuclear membrane and accumulate to deliver toxic effects. charge electrostatic interactions were also investigated by rotello et al by conjugating aunps with anionic and cationic functional groups. their results showed that toxicity was more established in aunps conjugated with cationic functional groups as a consequence of electrostatic interactions with the anionic cell membrane. concentration the concentrations of gold nanoparticles in biological systems for practical usage range from 1-100 nanoparticles per cell. high concentrations may lead to adverse effects for cell structure and function, which may not appear non-toxic in assays but preparation of the particles have been found to produce abnormal effects in the cell. if large concentrations quickly clear the blood vessels, the nanoshells may accumulate in major organs (mainly the liver and spleen). residual concentrations of these particles were also found in kidneys, lungs, muscle, brain, and bone of mice after 28 days. the concentration of the solution injected intravenously 2.4*1011 nanoshells/ml. even without complete clearance from the system, the nanoshells did not cause any physiological complications in the mice. su et al observed a correlation with the concentration of au3cu and cell damage. cells were incubated in concentrations of 0.001 and 200 mg ml−1 au3cu. they concluded a 15% cell viability and dose dependent cell damage. reduction in cell viability was detected in vivo experiments; also related to dosage. cytotoxicity is not a major concern in the usage of aunps, as they localize in the vesicles and cytoplasm as opposed to the nucleus. thus, no complications spawned due to their aggregation in these parts of the cell. heating two key factors to consider when irradiating gold nanoparticles in cancer cells are the lattice cooling rate and lattice heat content. the lattice cooling rate is how fast heat in the particle is distributed to its surroundings. if the cooling rate for a particle is too low, the lattice heat content can be increased with moderate energy radiation (40 µj/fs with 100-fs laser at 800 nm) to the point where gold nanorods can be melted to create spherical nanoparticles which become photothermally inactive. this decomposition has been shown using gold nanorods coated with phosphatidylcholine ligands in hela cells using a pulsed laser and were no longer useful for treatment due to their low nir radiation absorbance. high energy laser pulses have also been shown to fragment nanorods into smaller particles. while these structural changes induced by laser pulses could be used to deactivate the photothermal effects of these particles after treatment, the resulting spherical particles or other particle fragments could lead to complications during or after treatment when gold nanoparticles are used for clinical treatment and imaging of cancer cells. a limitation of photothermal chemotherapy using gold nanoparticles involves the choice of laser when conducting treatment. pulsed lasers offer very selective treatment of cancer cells within a small, localized area, but can lead to potential destruction of particles and have a low heating efficiency due to heat lost during the single pulse excitation. continuous wave lasers have a higher heating efficiency and work better in heating larger areas with lower risk of destroying the nanoparticles being heated. however, treatment with continuous wave lasers are much longer compared to treatment with a pulsed laser. a limitation of photothermal therapy with respect to the laser used is the depth of the tumor being treated. most lasers used to induce tumor ablation using gold nanoparticles can only reach several centimeters into soft tissue, making it impossible to reach tumors farther in the body. finding a way to carry out therapy in cells farther into the body without damaging surrounding cells is essential to making this technique viable as a cancer treatment in the future. toxic precursors studies in human leukemia cells revealed that prolonged exposure in aunps did not harm the cells, even at ~100 μm of au. rather they reduced the amount of reactive oxygen species in the cell. however, precursors to aunp synthesis (ctab and haucl4) were found to be toxic at small concentrations (10 μm); free ctab especially. studies in hela cells by niidome et al further support this statement by examining the correlation with the removal of excess ctab and cell viability rose to 90%. toxicity of nanoparticles in vivo and in vitro after using nanoparticles for photothermal therapy, it has been shown in vitro that high concentrations of reactive oxygen species (ros) are formed within the treated cancer cells. while these species are not of concern to the dead cancer cells, they can cause oxidative stress in surrounding healthy cells if enough ros are created leading to healthy cell death. this oxidative stress can be passivated using polymers as reducing agents (after degradation of the nanoparticle) and damage from ros can be reduced using targeted uptake of the nanoparticles to the cancer cells. the mechanism for the oxidative stress caused by nanoparticles in the body is still the subject of study and provides a possible limitation when using gold nanoparticles with radiation within the body. while there are many in vitro studies of gold nanoparticles used for chemotherapy, in vivo studies are both rare and often report conflicting results. for example, one in vivo study has shown that 13-nm gold nanoparticles circulated in the bloodstream often “accumulate in the liver and spleen and…have long blood circulation times." also, nanoparticles from 8 to 37 nanometers have been shown to cause abnormal symptoms leading to death in mice due to medical complications in the spleen, liver, and lungs. yet, other studies have shown that 20 nm gold nanoparticles can pass into the retina without causing any cytotoxic effects and nanoparticles of 13 nm diameter were not toxic in the body. many argue that these results differ due to different concentrations on nanoparticles used for these experiments and requires further research. biosafety and biokinetics investigations on biodegradable ultrasmall-in-nano architectures have demonstrated that gold nanoparticles are able to avoid metal accumulation in organisms through escaping by the renal pathway. part of the issue with these studies is the lack of reliable methods for determining the uptake of gold nanoparticles in vivo without examining the tumor site post-mortem. gold nanoparticle uptake in cells is often carried out by examining the organs of injected mice post-mortem. this technique cannot be replicated during clinical trials, so new methods need to be developed to determine the uptake of cells to avoid higher concentrations of gold nanoparticles in the body leading to toxic effects. one recently suggested method to counter this limitation is radiolabeling. the uptake of thiolated gold nanoparticles has recently been monitored using 111in-labeled polymer shells that surround the gold nanoparticle and shows a possible way around this problem, but these polymer shells can be removed from the particle making a more stable labeling system required for these kinds of studies. other uses the ligand used to decrease aggregation of gold nanorods. gold nanoparticles may be used in an indirectly therapeutic way. the issue of angiogenesis describes the formation of new blood vessels, which not only increased spread of cancerous cells, but may proliferate the spread of proteins responsible for rheumatoid arthritis. as aunps reduce angiogenesis, rheumatoid arthritis is reduced as a result. chamberland et al studied the use of anti-tnf conjugated gold nanorods (aunrs) ex vivo in rat tail joints to reduce the effect of rheumatoid arthritis. they observed the effects of the drug delivery system via pat technology. the properties of the aunrs found to be the most efficient had measurements of 45 x 15 nm with an absorption peak of 660 nm. this tuning allowed for better contrast between the targeted areas and intra-articular tissue. thus, the etanercept conjugated aunrs were seen to increase the light sensitivity. the imaging technique provides greater opportunities for sensitive in vivo drug tracking in biothechnology. hiv several valences of aunps were found to inhibit hiv fusion. 2-nm aunp-mercaptobenzoic acid were conjugated to a derivative of a known ccr5 antagonist, which is a small molecule that antagonize ccr5 receptor, and ccr5 is commonly used by hiv to enter the cell. the ccr5 antagonist would bind to ccr5, leaving no spots for hiv to bind. this will ultimately lead to an effect that restrict hiv infection. hepatitis b prepared aunps-hepatitis b virus (hbv) dna gene probes could be used to detect hbv dna directly. the detection-visualized fluorescence-based method is highly sensitive, simple, low cost, which could potentially apply to multi-gene detection chips. the probe used here is essentially a biosensor, to specifically detect a certain material. tuberculosis a successful application of the aunp-nanoprobe colorimetric method to clinical diagnosis reported by baptista et al. was the sensitive detection in clinical samples of mycobacterium tuberculosis, the cause of human tuberculosis.