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N. Ashwin Kumar et al.
delivery [27]. Also other types of magnesium, diamond and titanium based intracellular delivery using optoporation techniques [28, 29]. Also these materials also
involved in the combination with imaging applications.
In particular, anisotropic nano gold and iron oxide are excellent materials for
photoacoustic imaging (PAI)/CT and MR Imaging aided for cancer hyperthermia
[30, 31]. In MRI, T1 and T2 relaxivity are affected based on the shape of the IO NPs.
For example, cubic shaped particles showed higher in T2 contrast agents compared
to rods or clusters [32]. The addition of rare earth dopant into nanomaterials might
be suitable for optical as well as CT/MRI imaging. Some combinations change the
physicochemical properties of a nanomaterial, e.g. by conjugating fluorescent dye,
doping with different rare earth metals in CT/MR contrast, etc. Bimetallic (goldiron) and core-shell particles are some of the best ways of using nanomaterials for
imaging [5, 12, 33–35]. Similarly, bioresorbable nanomaterials like calcium phosphate, hydroxyapatite, and ceramic composites are used as a host material for loading
drugs and dopants. Also, radiolabeling nanoparticles enables them to be used for
hybrid or multi-modal imaging. Liposomes provide a multifunction capability that
can hold imaging agents for MR/CT contrast with high payload drug molecules [12].
The next level of visualizing disease is through multi-modal imaging techniques
that offer combinatorial structure and functional information about the disease. Multimodal imaging is defined as the fusion of images from different modalities to form one
single image [36]. Multi-modal imaging systems like PET-CT, CT-Optical PET-MRI
are currently in clinical use to overcome the drawbacks associated with individual
modality [37]. But probes that are required to use in these type of imaging systems is
challenging. This core problem is addressed by nanotechnology, wherein one single
probe can be either used for one or more modality. Nano based contrast agents provide
more room for doping various elements into host material like Gadolinium, Iodine,
loaded with fluorescent dyes [38]. The addition of these moieties mentioned above
would enable a nano host material to act as a multifunctional probe for in vivo and
in vitro cell imaging [39, 40]. Interconnection between imaging and therapy are close
to each other to increase the usefulness of multi-modal imaging systems. For instance,
image-guided therapy combines CT and echocardiography into a single image for
heart valve replacement and catheter locations and to deliver contrast agents [41,
42]. Imaging parameters that are involved in increasing sensitivity, contrast, resolution, and in reducing artifacts, noise, and distortions. Conventional agents like Iodine,
gadolinium, and fluorophore dyes have these better imaging properties in their respective imaging systems. But the usefulness of these agents inside biological systems
showed limitations in terms of toxicity, circulation time, fast clearance, biological
artifacts (i.e., autofluorescence), and photo instability [43]. Nano researchers need to
consider these parameters and limitations to design nanoprobes for imaging systems.
Also, it is mandatory to compromise the balance between image quality and concentration of nanoparticles. Many such agents developed were not useful for in vivo
imaging due to their toxicity at a concentration to obtain an excellent image. In the
case of a multi-modal imaging nanoprobe, understanding the optimum concentration
to acquire images in this system would be affected [44, 45].
N. Ashwin Kumar et al.
delivery [27]. Also other types of magnesium, diamond and titanium based intracellular delivery using optoporation techniques [28, 29]. Also these materials also
involved in the combination with imaging applications.
In particular, anisotropic nano gold and iron oxide are excellent materials for
photoacoustic imaging (PAI)/CT and MR Imaging aided for cancer hyperthermia
[30, 31]. In MRI, T1 and T2 relaxivity are affected based on the shape of the IO NPs.
For example, cubic shaped particles showed higher in T2 contrast agents compared
to rods or clusters [32]. The addition of rare earth dopant into nanomaterials might
be suitable for optical as well as CT/MRI imaging. Some combinations change the
physicochemical properties of a nanomaterial, e.g. by conjugating fluorescent dye,
doping with different rare earth metals in CT/MR contrast, etc. Bimetallic (goldiron) and core-shell particles are some of the best ways of using nanomaterials for
imaging [5, 12, 33–35]. Similarly, bioresorbable nanomaterials like calcium phosphate, hydroxyapatite, and ceramic composites are used as a host material for loading
drugs and dopants. Also, radiolabeling nanoparticles enables them to be used for
hybrid or multi-modal imaging. Liposomes provide a multifunction capability that
can hold imaging agents for MR/CT contrast with high payload drug molecules [12].
The next level of visualizing disease is through multi-modal imaging techniques
that offer combinatorial structure and functional information about the disease. Multimodal imaging is defined as the fusion of images from different modalities to form one
single image [36]. Multi-modal imaging systems like PET-CT, CT-Optical PET-MRI
are currently in clinical use to overcome the drawbacks associated with individual
modality [37]. But probes that are required to use in these type of imaging systems is
challenging. This core problem is addressed by nanotechnology, wherein one single
probe can be either used for one or more modality. Nano based contrast agents provide
more room for doping various elements into host material like Gadolinium, Iodine,
loaded with fluorescent dyes [38]. The addition of these moieties mentioned above
would enable a nano host material to act as a multifunctional probe for in vivo and
in vitro cell imaging [39, 40]. Interconnection between imaging and therapy are close
to each other to increase the usefulness of multi-modal imaging systems. For instance,
image-guided therapy combines CT and echocardiography into a single image for
heart valve replacement and catheter locations and to deliver contrast agents [41,
42]. Imaging parameters that are involved in increasing sensitivity, contrast, resolution, and in reducing artifacts, noise, and distortions. Conventional agents like Iodine,
gadolinium, and fluorophore dyes have these better imaging properties in their respective imaging systems. But the usefulness of these agents inside biological systems
showed limitations in terms of toxicity, circulation time, fast clearance, biological
artifacts (i.e., autofluorescence), and photo instability [43]. Nano researchers need to
consider these parameters and limitations to design nanoprobes for imaging systems.
Also, it is mandatory to compromise the balance between image quality and concentration of nanoparticles. Many such agents developed were not useful for in vivo
imaging due to their toxicity at a concentration to obtain an excellent image. In the
case of a multi-modal imaging nanoprobe, understanding the optimum concentration
to acquire images in this system would be affected [44, 45].