496
T. Pal et al.
due to improper ligand orientation, bond constraints, molecular saturation, steric
constraints from neighboring cells. Similarly, higher binding affinity in solid tumors
decreases binding efficacy due to the “binding site barrier” caused by a decrease in
penetration of nanocarriers due to strong binding with the target (Rosenblum et al.
2018).
In passive targeting, drug-encapsulated nanocarriers are generally administered
via intravenous injection circumventing absorption in intestinal epithelium that is
imperative via oral administration for enhancement of permeability and retention
effect (EPR effect), forms the basis of passive targeting. Generally, tumors are characterized by poor lymphatic function, which does not clear the accumulating nanoparticles rapidly in the tumor interstitium, and leaky vessels that enable the nanocarriers
to extravasate into the tumor site (Rosenblum et al. 2018). Again, certain drugs are
incapable of diffusing efficiently making it difficult to target cells within the target
site. Thus, controlling the random nature of the approach is arduous, failing to which
induces multiple drug resistance (MDR) leading to the failure of the treatment.
4 Nanomaterials and Drug Delivery
Nanoparticles consisted of organic and inorganic materials are being developed for
a wide range of applications ranging from imaging to treatment. Here, we discuss
various nanocarriers that are being widely used in nanotherapeutics.
4.1 Organic Nanomaterials
A significant characteristic of any nanomaterial for drug delivery is its biocompatibility and biodegradability, thus making organic nanomaterials a promising candidate
for these systems.
The use of nanomaterials as a drug delivery vehicle was started with liposomes in
1965. They are spherical colloids made by self-assembling of lipid bilayers of either
natural or synthetic phospholipids surrounding a central aqueous space, called liposome, which are truly advantageous for carrying desired drugs and other molecules
in the aqueous core or lipid bilayer to the target site without any severe side effects.
Various drugs have been delivered using PEGylated liposomes in the treatment of
glioma and breast cancer. Newer generations of smart multifunctional liposomes are
being developed despite extensive research and preclinical development, but FDA
has approved very few drugs encapsulated in liposomes (Olusanya et al. 2018).
Further, drug delivery via active or passive targeting can be efficiently achieved
using polymeric nanoparticles. Targeting cells using polymeric nanocarriers helps in
drug delivery in high concentrations within the cell. Several studies using ligands such
as peptides, antibodies, and aptamers to target tumor cells have been demonstrated to
show higher anticancer activity. The outset of utilizing biodegradable polymer as a
T. Pal et al.
due to improper ligand orientation, bond constraints, molecular saturation, steric
constraints from neighboring cells. Similarly, higher binding affinity in solid tumors
decreases binding efficacy due to the “binding site barrier” caused by a decrease in
penetration of nanocarriers due to strong binding with the target (Rosenblum et al.
2018).
In passive targeting, drug-encapsulated nanocarriers are generally administered
via intravenous injection circumventing absorption in intestinal epithelium that is
imperative via oral administration for enhancement of permeability and retention
effect (EPR effect), forms the basis of passive targeting. Generally, tumors are characterized by poor lymphatic function, which does not clear the accumulating nanoparticles rapidly in the tumor interstitium, and leaky vessels that enable the nanocarriers
to extravasate into the tumor site (Rosenblum et al. 2018). Again, certain drugs are
incapable of diffusing efficiently making it difficult to target cells within the target
site. Thus, controlling the random nature of the approach is arduous, failing to which
induces multiple drug resistance (MDR) leading to the failure of the treatment.
4 Nanomaterials and Drug Delivery
Nanoparticles consisted of organic and inorganic materials are being developed for
a wide range of applications ranging from imaging to treatment. Here, we discuss
various nanocarriers that are being widely used in nanotherapeutics.
4.1 Organic Nanomaterials
A significant characteristic of any nanomaterial for drug delivery is its biocompatibility and biodegradability, thus making organic nanomaterials a promising candidate
for these systems.
The use of nanomaterials as a drug delivery vehicle was started with liposomes in
1965. They are spherical colloids made by self-assembling of lipid bilayers of either
natural or synthetic phospholipids surrounding a central aqueous space, called liposome, which are truly advantageous for carrying desired drugs and other molecules
in the aqueous core or lipid bilayer to the target site without any severe side effects.
Various drugs have been delivered using PEGylated liposomes in the treatment of
glioma and breast cancer. Newer generations of smart multifunctional liposomes are
being developed despite extensive research and preclinical development, but FDA
has approved very few drugs encapsulated in liposomes (Olusanya et al. 2018).
Further, drug delivery via active or passive targeting can be efficiently achieved
using polymeric nanoparticles. Targeting cells using polymeric nanocarriers helps in
drug delivery in high concentrations within the cell. Several studies using ligands such
as peptides, antibodies, and aptamers to target tumor cells have been demonstrated to
show higher anticancer activity. The outset of utilizing biodegradable polymer as a