348
N. Ashwin Kumar et al.
Later, the same group studied the toxicological effects of GNPs in vivo by different
administration routes using 13 nm sized particles. Parameters considered for toxicity involves concentration, organ index, hematology, weight, and longevity of the
animal. GNPs concentration used range from 137.5 to 2200 μg/kg for 14–28 days.
Data obtained from the experiments revealed that lower concentration of GNPs has
less toxic, but at higher concentrations, GNPs have a substantial effect over the
organ index. Also, comparing the administration routes, they suggested that administering targeted GNPs via intravenously is more promising for imaging applications
[69]. Size-dependent radiosensitization have studied intensively, suggested that PEGcoated GNPs size range between 12.1 and 27.3 nm are considered to be effective
with high accumulation in tumor region compared to other sized NPs [70].
Development of particular types of GNPs was used to improve the CT contrast
like mixing of metals, incorporation of lanthanide materials, having dendrimers
as a template, and site-specific functionalization over the particles. In particular,
bimetallic nanoparticles have been more useful compared to the single metallic particles with the allied conjugations [71]. A combination of gold and silver with 2 nm
size coated with bovine serum albumin via green synthesis. These nanoparticles
were explicitly targeted to lysosome with high viability and reduction in the cost of
materials. X-ray attenuation behavior was studied by varying the different concentrations of Au-Ag combinations (Au: 0, 40, 50, 60, 90, and 100) having Iodine as
a control sample. In comparison, Au:60 showed increased X-ray attenuation and
decreased at Au:90, and 100 for 80 mM could be due to an increase in the concentration of silver [72]. Dendrimers have also used a template to synthesize uniform
particles with a size less than gold and silver particles as a potential CT contrast [73,
74]. The advantage of using these dendrimers is that they can modify the terminal
groups in the Gold-dendrimer complex. Similar to GNPs, Gold nanorods also pose
higher attenuation due to the increase in size and can also act as therapeutic agents.
Gold nanorods possess strong absorption in the NIR region makes it suitable for
photothermal therapy. Due to some controversial aspects of GNRs, toxicity, and
pharmacodynamic studies have to be studied in more detail within-Vivo X-ray CT
imaging applications compared to GNPs [75].
6.3 Targeted GNPs for CT Imaging
Conjugation of GNPs with different targeting agents has been deployed for early
detection of cancer and plaque detection in valves. Localization of targeted nanoparticles in the diseased region to enhance the contrast between the normal and abnormal
tissues. Various techniques involved in conjugating antibodies on the surface of
GNPs are physical interaction and chemical interactions [76]. Physical interactions
such as ionic interaction, hydrophobic interaction, and dative binding similarly thiol
conjugation, linkers binding, and adapter molecules for chemical interactions [77].
Commonly used targeting moiety is vitamin B9, i.e., folate receptor binds with folic
acid for intracellular delivery [39, 40, 78]. Wherein many cancers like breast, colon,
N. Ashwin Kumar et al.
Later, the same group studied the toxicological effects of GNPs in vivo by different
administration routes using 13 nm sized particles. Parameters considered for toxicity involves concentration, organ index, hematology, weight, and longevity of the
animal. GNPs concentration used range from 137.5 to 2200 μg/kg for 14–28 days.
Data obtained from the experiments revealed that lower concentration of GNPs has
less toxic, but at higher concentrations, GNPs have a substantial effect over the
organ index. Also, comparing the administration routes, they suggested that administering targeted GNPs via intravenously is more promising for imaging applications
[69]. Size-dependent radiosensitization have studied intensively, suggested that PEGcoated GNPs size range between 12.1 and 27.3 nm are considered to be effective
with high accumulation in tumor region compared to other sized NPs [70].
Development of particular types of GNPs was used to improve the CT contrast
like mixing of metals, incorporation of lanthanide materials, having dendrimers
as a template, and site-specific functionalization over the particles. In particular,
bimetallic nanoparticles have been more useful compared to the single metallic particles with the allied conjugations [71]. A combination of gold and silver with 2 nm
size coated with bovine serum albumin via green synthesis. These nanoparticles
were explicitly targeted to lysosome with high viability and reduction in the cost of
materials. X-ray attenuation behavior was studied by varying the different concentrations of Au-Ag combinations (Au: 0, 40, 50, 60, 90, and 100) having Iodine as
a control sample. In comparison, Au:60 showed increased X-ray attenuation and
decreased at Au:90, and 100 for 80 mM could be due to an increase in the concentration of silver [72]. Dendrimers have also used a template to synthesize uniform
particles with a size less than gold and silver particles as a potential CT contrast [73,
74]. The advantage of using these dendrimers is that they can modify the terminal
groups in the Gold-dendrimer complex. Similar to GNPs, Gold nanorods also pose
higher attenuation due to the increase in size and can also act as therapeutic agents.
Gold nanorods possess strong absorption in the NIR region makes it suitable for
photothermal therapy. Due to some controversial aspects of GNRs, toxicity, and
pharmacodynamic studies have to be studied in more detail within-Vivo X-ray CT
imaging applications compared to GNPs [75].
6.3 Targeted GNPs for CT Imaging
Conjugation of GNPs with different targeting agents has been deployed for early
detection of cancer and plaque detection in valves. Localization of targeted nanoparticles in the diseased region to enhance the contrast between the normal and abnormal
tissues. Various techniques involved in conjugating antibodies on the surface of
GNPs are physical interaction and chemical interactions [76]. Physical interactions
such as ionic interaction, hydrophobic interaction, and dative binding similarly thiol
conjugation, linkers binding, and adapter molecules for chemical interactions [77].
Commonly used targeting moiety is vitamin B9, i.e., folate receptor binds with folic
acid for intracellular delivery [39, 40, 78]. Wherein many cancers like breast, colon,