therapy due to its high chemical reactivity [161]. Insulin-loaded chitosan
nanoparticles enhanced intestinal absorption of insulin in comparison to oral
administration of free insulin due to the mucoadhesive properties of chitosan
[118]. Cyclosporin-A-loaded chitosan nanoparticles can make contact very well
with the corneal and conjunctiva surfaces, thereby increasing delivery to external
ocular tissues, which helps to supply long-term drug levels at target tissues [162].
Chitosan nanoparticles have revealed an excellent capability for the association of
ammonium glycyrrhizinate [163]. Addition of PEG results in the reduction of
encapsulation efficiency and also reduces the positive charge, which has been
achieved by co-synthesis of chitosan polymer along with tripolyphosphate anions
(TPP) and PEG using ionic gelation methods. Release of ammonium glycyrrizinate
from chitosan nanoparticles follows a slow and continuous release profile, which
may improve the oral absorption of ammonium glycyrrhizinate [163].
6.7 Gelatin
Gelatin, a natural polymer derived from collagen, is commonly used for pharmaceutical and biomedical applications due to its biodegradability [164, 165] and
biocompatibility in physiological environments [166]. It is also used in food and
medical products and is attractive for controlled release due to its nontoxic,
biodegradable, and bioactive properties. Gelatin is a polyampholyte having both
cationic and anionic groups along with hydrophilic groups. The mechanical and
thermal properties and swelling behavior of gelatin significantly depend on the
degree of crosslinking. The efficiency of gelatin carriers to encapsulate charged
biomolecules such as proteins and plasmid DNA occurs through polyion complexation. Acidic gelatin with an isoelectric point of 5.0 should be used as a carrier for
basic proteins in vivo, whereas basic gelatin with an isoelectric point of 9.0 should
be used for the sustained release of acidic proteins under physiological conditions
[167]. Nanoparticles of gelatin and BSA can absorb 51–72% of water and release
BSA from the nanoparticulate matrix following a diffusion-controlled mechanism
[168]. Paclitaxel-loaded gelatin nanoparticles have been used against human bladder transitional cancer cells [114]. Didanosine was localized to a greater extent in
the spleen lymph nodes and brain after administration of mannan-coated gelatin
nanoparticles as compared to its localization after injection in PBS [115]. The toxic
effect of the antimalarial chloroquine is reduced by encapsulating it in gelatin
nanoparticles [116].
6.8 Polyurethane
Polyurethanes (PUs) are synthesized using diisocyanate, polyol, and a chain
extender. PUs consist of alternating hard and soft segments, which control most
190
S.K. Pandey et al.
nanoparticles enhanced intestinal absorption of insulin in comparison to oral
administration of free insulin due to the mucoadhesive properties of chitosan
[118]. Cyclosporin-A-loaded chitosan nanoparticles can make contact very well
with the corneal and conjunctiva surfaces, thereby increasing delivery to external
ocular tissues, which helps to supply long-term drug levels at target tissues [162].
Chitosan nanoparticles have revealed an excellent capability for the association of
ammonium glycyrrhizinate [163]. Addition of PEG results in the reduction of
encapsulation efficiency and also reduces the positive charge, which has been
achieved by co-synthesis of chitosan polymer along with tripolyphosphate anions
(TPP) and PEG using ionic gelation methods. Release of ammonium glycyrrizinate
from chitosan nanoparticles follows a slow and continuous release profile, which
may improve the oral absorption of ammonium glycyrrhizinate [163].
6.7 Gelatin
Gelatin, a natural polymer derived from collagen, is commonly used for pharmaceutical and biomedical applications due to its biodegradability [164, 165] and
biocompatibility in physiological environments [166]. It is also used in food and
medical products and is attractive for controlled release due to its nontoxic,
biodegradable, and bioactive properties. Gelatin is a polyampholyte having both
cationic and anionic groups along with hydrophilic groups. The mechanical and
thermal properties and swelling behavior of gelatin significantly depend on the
degree of crosslinking. The efficiency of gelatin carriers to encapsulate charged
biomolecules such as proteins and plasmid DNA occurs through polyion complexation. Acidic gelatin with an isoelectric point of 5.0 should be used as a carrier for
basic proteins in vivo, whereas basic gelatin with an isoelectric point of 9.0 should
be used for the sustained release of acidic proteins under physiological conditions
[167]. Nanoparticles of gelatin and BSA can absorb 51–72% of water and release
BSA from the nanoparticulate matrix following a diffusion-controlled mechanism
[168]. Paclitaxel-loaded gelatin nanoparticles have been used against human bladder transitional cancer cells [114]. Didanosine was localized to a greater extent in
the spleen lymph nodes and brain after administration of mannan-coated gelatin
nanoparticles as compared to its localization after injection in PBS [115]. The toxic
effect of the antimalarial chloroquine is reduced by encapsulating it in gelatin
nanoparticles [116].
6.8 Polyurethane
Polyurethanes (PUs) are synthesized using diisocyanate, polyol, and a chain
extender. PUs consist of alternating hard and soft segments, which control most
190
S.K. Pandey et al.