196
M. Irfan et al.
prostate-specific membrane antigen (PSMA)(+) cancer cells [111]. AS1411, a nucleolin binding aptamer, was conjugated to PEGylated cationic liposome. This conjugate, AS1411-PEG-liposome (ASLP) reacted with anti-BRAF siRNA (siBraf) via
electrostatic interaction and efficiently silenced the activity of BRAF gene (in malignant melanoma) with much higher levels of the siRNA in tumor cells compared
with normal cells due to ASLP targeting strategy [112]. For the circumvention of
drug resistance in breast cancer (MCF-7/Adr) nuclear-targeted delivery system was
designed. In the aqueous interior of liposome (Lip(Ap-Dox)), Dox·HCl was inserted
in the aptamer AS1411 (Ap-Dox).The results of in vitro experiments revealed that
after the Lip(Ap-Dox) diffusion into MCF-7/Adr cells, Ap-Dox complex bound
with nucleolin efficiently and ultimately crossed the nuclei. By making use of this
kind of delivery system, Dox·HCl can proficiently accumulate in the cancer nuclei
to successfully kill the cancer cells [113].
7.3.4 Aptamer-Nanoparticles Conjugates
Nanoparticles (NPs) in either from, soluble and insoluble, have a number of applications. Nanoparticles have the capacity to encapsulate drugs or antibiotics and to
subsequently release them to the target cells. A number of nanosystems have been
formulated for systemic therapy, such as polymeric micelles, liposomes, albuminbased particles, PEGylated proteins, biodegradable polymer-drug composites and so
on over the past few decades. For cancer treatment, various drugs including anthracycline, etoposide, and mitoxantrone can be capsulated more prominently in soluble
nanoparticles.
Nanoparticle-aptamer (NP-Apt) conjugates demonstrate wide variety of applications ranging from disease diagnosis to targeted drug delivery in certain diseases. Of
the vast variety of nanoparticles, gold nanoparticles (GNP) have been widely implemented in conjugation with aptamers due to distinct properties like easy dispersal in
water, biologically non-reactive nature, which make GNPs a decent choice to be used
in conjugation with aptamers for different applications. Free aptamers have lower
binding affinities, however, conjugates of aptamer and nanoparticle confer multivalent bonding ensuing improved binding affinities to targets in the cells or on the cells
[114, 115]. Many studies have been reported about NP-Apt conjugates for effective
and target-specific delivery of drugs. In the case of anti-EGFR aptamer, complementary sequences present at the 5
end of aptamer capture DNA sequences present on
gold nanoparticle, which helped in forming the conjugate. Aptamer-mediated drug
delivery has been well studied in case of prostate cancer and leukemia cells. Using
anti-PSMAA10 RNA aptamer, the NP-Apt conjugate has revealed the anticancerous
activity and greater efficacy, in vitro as well as in vivo [116]. For specifically targeting
PSMA on the cancerous cell surface, a conjugate comprising NP-Apt-Dtxl was established. The nanoparticle was prepared using a special biocompatible and biodegradable copolymer [117]. Similar approach was used for cisplatin in cancerous cells [118,
119]. In another approach cancer biomarker-specific aptamer was bonded to hollow
M. Irfan et al.
prostate-specific membrane antigen (PSMA)(+) cancer cells [111]. AS1411, a nucleolin binding aptamer, was conjugated to PEGylated cationic liposome. This conjugate, AS1411-PEG-liposome (ASLP) reacted with anti-BRAF siRNA (siBraf) via
electrostatic interaction and efficiently silenced the activity of BRAF gene (in malignant melanoma) with much higher levels of the siRNA in tumor cells compared
with normal cells due to ASLP targeting strategy [112]. For the circumvention of
drug resistance in breast cancer (MCF-7/Adr) nuclear-targeted delivery system was
designed. In the aqueous interior of liposome (Lip(Ap-Dox)), Dox·HCl was inserted
in the aptamer AS1411 (Ap-Dox).The results of in vitro experiments revealed that
after the Lip(Ap-Dox) diffusion into MCF-7/Adr cells, Ap-Dox complex bound
with nucleolin efficiently and ultimately crossed the nuclei. By making use of this
kind of delivery system, Dox·HCl can proficiently accumulate in the cancer nuclei
to successfully kill the cancer cells [113].
7.3.4 Aptamer-Nanoparticles Conjugates
Nanoparticles (NPs) in either from, soluble and insoluble, have a number of applications. Nanoparticles have the capacity to encapsulate drugs or antibiotics and to
subsequently release them to the target cells. A number of nanosystems have been
formulated for systemic therapy, such as polymeric micelles, liposomes, albuminbased particles, PEGylated proteins, biodegradable polymer-drug composites and so
on over the past few decades. For cancer treatment, various drugs including anthracycline, etoposide, and mitoxantrone can be capsulated more prominently in soluble
nanoparticles.
Nanoparticle-aptamer (NP-Apt) conjugates demonstrate wide variety of applications ranging from disease diagnosis to targeted drug delivery in certain diseases. Of
the vast variety of nanoparticles, gold nanoparticles (GNP) have been widely implemented in conjugation with aptamers due to distinct properties like easy dispersal in
water, biologically non-reactive nature, which make GNPs a decent choice to be used
in conjugation with aptamers for different applications. Free aptamers have lower
binding affinities, however, conjugates of aptamer and nanoparticle confer multivalent bonding ensuing improved binding affinities to targets in the cells or on the cells
[114, 115]. Many studies have been reported about NP-Apt conjugates for effective
and target-specific delivery of drugs. In the case of anti-EGFR aptamer, complementary sequences present at the 5
end of aptamer capture DNA sequences present on
gold nanoparticle, which helped in forming the conjugate. Aptamer-mediated drug
delivery has been well studied in case of prostate cancer and leukemia cells. Using
anti-PSMAA10 RNA aptamer, the NP-Apt conjugate has revealed the anticancerous
activity and greater efficacy, in vitro as well as in vivo [116]. For specifically targeting
PSMA on the cancerous cell surface, a conjugate comprising NP-Apt-Dtxl was established. The nanoparticle was prepared using a special biocompatible and biodegradable copolymer [117]. Similar approach was used for cisplatin in cancerous cells [118,
119]. In another approach cancer biomarker-specific aptamer was bonded to hollow