Nanomaterials for Medical Imaging …
373
MONPs showed enhanced positive contrast over time compared to the surrounding
region [234]. The anti-stealth properties of MONPs were prepared via a solvothermal
process using citrate as a reducing agent and coated with PEG and functionalized
with cysteine by wang and his coworkers [235]. Phantom studies of T 1 weighted MR
signals were determined for MONPs with and without cysteine as a capping agent.
Wherein, the concentration of MONPs increases the contrast of the MR signals also
increases linearly and similar to Gd-DTPA. After 90 min of post-injection of MONPs,
the MR signals in C6 glioma was higher with cysteine capped MONPs. The distribution of nanomaterials within the rodents within tumor and organs were determined
using ICP-OES (inductively coupled plasma—optical emission spectrometry). They
reported that particles were uptake of MONPs with large amounts in liver and spleen
and cleared out within 48 h post-injection. As a promising alternative of gadoliniumDTPA is chelates of Manganese. Due to clinical problems associated with Mn cations
such as cellular toxicity at higher concentration requires efficient nanocarriers for
delivery. For instance, chelates play a major role in delivering the Mn cations at
the desired location. Venter et al., developed from a single manganese porphyrin
(MnPNH 2 ) molecule for enhanced cell tracking applications. These MnPNH 2 does
not show any changes in cellular structures with no adverse effects on subcellular
organelles [236].
Nanogels are another type of particle that can be used to load drugs, chelates, and
other bioimaging probes via physical adsorption [237]. Nanogels have a swelling
nature depending on the pH or other biological environment like GSH: GSSG
(reduced or oxidized glutathione at intracellular level) [223]. Recently, nanogels
loaded with chelates of Mn cations vary MR signals when exposed with different
pH environments. Swelling with the nanogels is based on the number of protons that
adhere shorter relaxation times [238]. At higher pH, the relaxivity increases while at
lower pH, the relaxivity decreases. The stability of the nanogels is lesser compared to
the other types of nanomaterials. To overcome such issues, Addisu et al. synthesized
alginate-dopamine nanogels by crosslinking them with Ca chelates and improves
the stability for loading manganese chelates. Calcium cations have carboxyl groups
readily binds with alginate and form this complex mechanism, thereby increased
the stability of nanogels and manganese cations [239]. Positive contrast enhancement with r 1 = 12.5 mM s
−1 when exposed with 7.0 T MR stable for a prolonged
period in the liver and tumor region due to EPR effect. A variety of techniques were
involved in improving the delivery of these manganese cations in tumor imaging.
One such study performed by wang and his coworkers synthesized complex carrier
of hyaluronic acid/dendrimer loaded with Mn ion chelates with gold nanomaterials
for hepatocellular carcinoma. Dual modal imaging was stable, biocompatible, and
displayed high X-ray attenuation with better relaxivity property. CT and MR signals
were acquired after 30 min of post-injection with hyaluronic acid showed higher
intensity compared to non-targeted dendrimers. The distribution of targeted nanomaterial was 5 times higher in the liver and spleen compared to non-targeted particles
[240].
373
MONPs showed enhanced positive contrast over time compared to the surrounding
region [234]. The anti-stealth properties of MONPs were prepared via a solvothermal
process using citrate as a reducing agent and coated with PEG and functionalized
with cysteine by wang and his coworkers [235]. Phantom studies of T 1 weighted MR
signals were determined for MONPs with and without cysteine as a capping agent.
Wherein, the concentration of MONPs increases the contrast of the MR signals also
increases linearly and similar to Gd-DTPA. After 90 min of post-injection of MONPs,
the MR signals in C6 glioma was higher with cysteine capped MONPs. The distribution of nanomaterials within the rodents within tumor and organs were determined
using ICP-OES (inductively coupled plasma—optical emission spectrometry). They
reported that particles were uptake of MONPs with large amounts in liver and spleen
and cleared out within 48 h post-injection. As a promising alternative of gadoliniumDTPA is chelates of Manganese. Due to clinical problems associated with Mn cations
such as cellular toxicity at higher concentration requires efficient nanocarriers for
delivery. For instance, chelates play a major role in delivering the Mn cations at
the desired location. Venter et al., developed from a single manganese porphyrin
(MnPNH 2 ) molecule for enhanced cell tracking applications. These MnPNH 2 does
not show any changes in cellular structures with no adverse effects on subcellular
organelles [236].
Nanogels are another type of particle that can be used to load drugs, chelates, and
other bioimaging probes via physical adsorption [237]. Nanogels have a swelling
nature depending on the pH or other biological environment like GSH: GSSG
(reduced or oxidized glutathione at intracellular level) [223]. Recently, nanogels
loaded with chelates of Mn cations vary MR signals when exposed with different
pH environments. Swelling with the nanogels is based on the number of protons that
adhere shorter relaxation times [238]. At higher pH, the relaxivity increases while at
lower pH, the relaxivity decreases. The stability of the nanogels is lesser compared to
the other types of nanomaterials. To overcome such issues, Addisu et al. synthesized
alginate-dopamine nanogels by crosslinking them with Ca chelates and improves
the stability for loading manganese chelates. Calcium cations have carboxyl groups
readily binds with alginate and form this complex mechanism, thereby increased
the stability of nanogels and manganese cations [239]. Positive contrast enhancement with r 1 = 12.5 mM s
−1 when exposed with 7.0 T MR stable for a prolonged
period in the liver and tumor region due to EPR effect. A variety of techniques were
involved in improving the delivery of these manganese cations in tumor imaging.
One such study performed by wang and his coworkers synthesized complex carrier
of hyaluronic acid/dendrimer loaded with Mn ion chelates with gold nanomaterials
for hepatocellular carcinoma. Dual modal imaging was stable, biocompatible, and
displayed high X-ray attenuation with better relaxivity property. CT and MR signals
were acquired after 30 min of post-injection with hyaluronic acid showed higher
intensity compared to non-targeted dendrimers. The distribution of targeted nanomaterial was 5 times higher in the liver and spleen compared to non-targeted particles
[240].