Polymer conjugates: nanosized medicines for treating cancer

Nano-titanium dioxide induced cardiac injury in rat under oxidative stress

Heart diseases, which are related to oxidative stress (OS), negatively affect millions of people from kids to the elderly. Titanium dioxide (TiO2) has widespread applications in our daily life, especially nanoscale TiO2. Compared to the high risk of particulate matter (≤2.5μm) in air to heart disease patients, related research of TiO2 on diseased body is still unknown, which suggest us to explore the potential effects of nanoscale and microscale TiO2 to heart under OS conditions. Here, we used alloxan to induce OS conditions in rat, and investigated the response of heart tissue to TiO2 in healthy and alloxan treated rats. Compared with NMs treatment only, the synergistic interaction between OS conditions and nano-TiO2 significantly reduced the heart-related function indexes, inducing pathological changes of myocardium with significantly increased levels of cardiac troponin I and creatine kinase-MB. In contrast with the void response of micro-TiO2 to heart functions in alloxan treated rats, aggravation of OS conditions might play an important role in cardiac injury after alloxan and nano-TiO2 dual exposure. Our results demonstrated that OS conditions enhanced the adverse effects of nano-TiO2 to heart, suggesting that the use of NMs in stressed conditions (e.g., drug delivery) needs to be carefully monitored.

Polyarginine molecular weight determines transfection efficiency of calcium condensed complexes

Cell penetrating peptides (CPPs) have been extensively studied in polyelectrolyte complexes as a means to enhance the transfection efficiency of plasmid DNA (pDNA). Increasing the molecular weight of CPPs often enhances gene expression but poses a risk of increased cytotoxicity and immunogenicity compared to low molecular weight CCPs. Conversely, low molecular weight CPPs typically have low transfection efficiency due to large complex size. Complexes made using low molecular weight CPPs were found to be condensed to a small size by adding calcium. In this study, complexes of low molecular weight polyarginine and pDNA were condensed with calcium. These complexes showed high transfection efficiency and low cytotoxicity in A549 carcinomic human alveolar basal epithelial cells. The relationships between transfection efficiency and polyarginine size (5, 7, 9, or 11 amino acids), polyarginine/pDNA charge ratios, and calcium concentrations were studied. Polyarginine 7 was significantly more effective than other polyarginines under most formulation conditions, suggesting a link between cell penetration ability and transfection efficiency.

Markedly enhanced permeability and retention effects induced by photo-immunotherapy of tumors

A major barrier to cancer treatment is the inability to deliver sufficient concentrations of drug to the tumor without incurring systemic toxicities. Nanomaterials are appealing because they can carry a large drug payload; however, tumor delivery is limited by modest leakage and retention in most tumors. We observed that after photoimmunotherapy (PIT), which is a light-mediated treatment based on an antibody-photosensitizer conjugate, there was surprisingly high leakage of nanosized (10-200 nm) agents into the tumor bed. PIT rapidly induced death in perivascular cancer cells, leading to immediate and dramatic increases in vascular permeability, resulting in up to 24-fold greater accumulation of nanomaterials within the PIT-treated tumor compared with controls, an effect termed "super-enhanced permeability and retention". In a treatment study, PIT followed by liposome-containing daunorubicin, DaunoXome (diameter 50 nm), resulted in greater survival in tumor-bearing mice than either PIT or DaunoXome alone. Thus, PIT greatly enhances delivery of nanosized reagents and thus holds promise to improve therapeutic responses.

Dextran-catechin conjugate: a potential treatment against the pancreatic ductal adenocarcinoma

PURPOSE

A polysaccharide-flavonoid conjugate was developend and proposed for the treatment of pancreatic ductal adenocarcinoma (PDAC).

METHODS

The conjugate was synthesized by free radical grafting reaction between catechin and dextran. The chemical characterization of the conjugate was obtained by UV-Vis, 1H-NMR, FT-IR and GPC analyses, while the functionalization degree was determined by the Folin-Ciocalteu assay. The biological activity of the catechin-dextran conjugate was tested on two different cell lines derived from human pancreatic cancer (MIA PaCa-2 and PL45 cells), and the toxicity towards human pancreatic nestin-expressing cells evaluated.

RESULTS

Both the cancer cell lines are killed when exposed to the conjugate, and undergo apoptosis after the incubation with catechin-dextran which resulted more effective in killing pancreatic tumor cells compared to the catechin alone. Moreover, our experimental data indicate that the conjugate was less cytotoxic to human pancreatic nestin-expressing cells which are considered a good model of non-neoplastic pancreatic cells.

CONCLUSION

The suitability of newly synthesized Dextran-Catechin conjugate in the treatment of PDAC was proved confirming the high potential application of the proposed macromolecula system in the cancer therapy.

Poly(amidoamine) polymers: soluble linear amphiphilic drug-delivery systems for genes, proteins and oligonucleotides

Polymer-drug and polymer-protein conjugates are emerging as a robust and well-characterized class of therapeutic entity. Although there are no low-molecular-weight soluble polymer conjugates in routine clinical use, there are many examples of routinely used high-molecular-weight drugs conjugated to soluble polymers (e.g., Oncospar). Advances in synthetic polymer chemistry have fostered the development of linear poly(amidoamine)s (PAA)s that impart both biodegradability, 'smart' (pH responsive) biological activity and biocompatibility. In their linear form, such as hyper-branched poly(amidoamine) (PAMAM) dendrimers, linear PAAs can be used to deliver large therapeutic entities such as peptides, proteins and genes to either the cytosol or nucleus. Furthermore, these polymers offer great potential in vivo due to their ability to either target the liver or be directed away from the liver and enter tumor mass via the enhanced permeability and retention (EPR) effect. PAAs also exhibit minimal toxicity (dependent upon backbone chemistry), relative to well-characterized polymers used for gene delivery. The propensity of PAAs to modulate intracellular trafficking resulting in their cytosolic translocation has also recently been quantified in vivo and is the primary focus of this article.

Quantum dots hold promise for early cancer imaging and detection

Despite all major breakthroughs in recent years of research concerning the complex events that lead to cancer expression and metastasis, we are not yet able to effectively treat cancer that has spread to vital organs. The various clinical phases originating from cancer diagnosis through treatment and prognosis require a comprehensive understanding of these events, to utilise pre-symptomatic, minimally invasive and targeted cancer management techniques. Current imaging modalities such as ultrasound, computed tomography, magnetic resonance imaging and gamma scintigraphy facilitate the pre-operative study of tumours, but they have been rendered unable to visualise cancer in early stages, due to their intrinsic limitations. The semiconductor nanocrystal quantum dots (QDs) have excellent photo-physical properties, and the QDs-based probes have achieved encouraging developments in cellular (in vitro) and in vivo molecular imaging. However, the same unique physical and chemical properties which renowned QDs attractive may be associated with their potentially catastrophic effects on living cells and tissues. There are critical issues that need to be further examined to properly assess the risks associated with the manufacturing and use of QDs in cancer management. In this review, we aim to describe the current utilisation of QDs as well as their future prospective to decipher and confront cancer.

Advanced materials for co-delivery of drugs and genes in cancer therapy

With cancer being the major cause of mortality worldwide, the continued development of safe and efficacious treatments is warranted. A better understanding of the molecular mechanism and genetic basis of tumor initiation and progression, coupled with advances in chemistry, molecular biology and engineering have led to discovery of a wide range of therapeutic agents for cancer therapy. However, multidrug-resistance, which is mainly caused by malfunction of genes, has become a major problem in chemotherapy. To overcome this problem, the simultaneous delivery of genes to cancer cells has been proposed to correct the malfunctioned genes to sensitize the cells to chemotherapeutics. This progress report summarizes key advances in drug and gene delivery with focus on the development of polymers, peptides, liposomes and inorganic materials as nanocarriers for co-delivery of small molecular drugs and macromolecular genes or proteins. In addition, challenges and future perspectives in the design of nanocarriers for the co-delivery of therapeutic drugs and genes are discussed.

Antitumor effect and pharmacokinetics of intraperitoneal NK105, a nanomicellar paclitaxel formulation for peritoneal dissemination

The intraperitoneal administration of paclitaxel has been shown to be a promising treatment strategy for peritoneal malignancy. The present study evaluated the effects of intraperitoneal administration of NK105, a paclitaxel-incorporating micellar nanoparticle, which has been shown to have a remarkable effect in a mouse model of gastric cancer. Intraperitoneal NK105 significantly reduced peritoneal tumors in vivo compared with the conventional paclitaxel formulation of paclitaxel solubilized in Cremophor EL and ethanol (PTX-Cre). Moreover, intraperitoneal NK105 significantly reduced the size of subcutaneously inoculated tumors, whereas no such effect was seen with PTX-Cre. Similar systemic toxic effects were observed following the intraperitoneal administration of both NK105 and PTX-Cre. Although NK105 disappeared rapidly almost within a day from the peritoneal cavity, the paclitaxel concentration in peritoneal nodules 4 h after intraperitoneal administration was significantly higher in the NK105 group than in the PTX-Cre group (P < 0.05), whereas there were no significant differences in liver paclitaxel concentrations between the two groups. We also evaluated the pharmacokinetics following intraperitoneal administration of NK105 and PTX-Cre. Serum paclitaxel concentrations 6, 12, 24, and 48 h after the intraperitoneal administration of the drugs were significantly higher in the NK105 than the PTX-Cre group. Furthermore, the peak serum concentration was higher in the NK105 than PTX-Cre group (24 100 ± 3560 vs 108 ± 25 ng/mL, respectively; P < 0.001), as was the area under the concentration-time curve from 0 to 48 h (191 000 ± 32 100 vs 1500 ± 108 ng·h/mL, respectively; P < 0.001). Therefore, intraperitoneal chemotherapy with nanoparticulate paclitaxel NK105 may offer a novel treatment strategy for improving drug delivery in gastric cancer with peritoneal dissemination because of enhanced drug penetration into peritoneal nodules and its prolonged presence in the systemic circulation.

Bifunctional PAMAM dendrimer conjugates of folic acid and methotrexate with defined ratio

Our group previously developed a multifunctional, targeted cancer therapeutic based on Generation 5 (G5) polyamidoamine (PAMAM) dendrimers. In those studies we conjugated the targeting molecule folic acid (FA) and the chemotherapeutic drug methotrexate (MTX) sequentially. This complex macromolecule was shown to selectively bind and kill KB tumor cells that overexpress folate receptor (FR) in vitro and in vivo. However, the multistep conjugation strategy employed in the synthesis of the molecule resulted in heterogeneous populations having differing numbers and ratios of the functionally antagonistic FA and MTX. This led to inconsistent and sometimes biologically inactive batches of molecules, especially during large-scale synthesis. We here resolved this issue by using a novel triazine scaffold approach that reduces the number of dendrimer conjugation steps required and allows for the synthesis of G5 conjugates with defined ratios of FA and MTX. Although an unoccupied γ-glutamyl carboxylate of FA has been previously suggested to be nonessential for FR binding, the functional requirement of an open α-carboxylate still remains unclear. In an attempt to also address this question, we have synthesized isomeric FA dendrimer conjugates (α-carboxyl or γ-carboxyl linked). Competitive binding studies revealed that both linkages have virtually identical affinity toward FR on KB cells. Our studies show that a novel bifunctional triazine-based conjugate G5-Triazine-γMTX-αFA with identical numbers of FA and MTX binds to FR through a polyvalent interaction and induces cytotoxicity in KB cells through FR-mediated cellular internalization, inducing higher toxicity as compared to conjugates synthesized by the multistep strategy. This work serves as a proof of concept for the development of bifunctional dendrimer conjugates that require a defined ratio of two functional molecules.

Dual fluorescent HPMA copolymers for passive tumor targeting with pH-sensitive drug release: synthesis and characterization of distribution and tumor accumulation in mice by noninvasive multispectral optical imaging

Preclinical in vivo characterization of new polymeric drug conjugate candidates is crucial for understanding the effects of certain chemical modifications on distribution and elimination of these carrier systems, which is the basis for rational drug design. In our study we synthesized dual fluorescent HPMA copolymers of different architectures and molecular weights, containing one fluorescent dye coupled via a stable hydrazide bond functioning as the carrier label and the other one modeling the drug bound to a carrier via a pH-sensitive hydrolytically cleavable hydrazone bond. Thus, it was possible to track the in vivo fate, namely distribution, elimination and tumor accumulation, of the polymer drug carrier and a cleavable model drug simultaneously and noninvasively in nude mice using multispectral optical imaging. We confirmed our in vivo results by more detailed ex vivo characterization (imaging and microscopy) of autopsied organs and tumors. There was no significant difference in relative biodistribution in the body between the 30 KDa linear and 200 KDa star-like polymer, but the star-like polymer circulated much longer. We observed a moderate accumulation of the polymeric carriers in the tumors. The accumulation of the pH-sensitive releasable model drug was even higher compared to the polymer accumulation. Additionally, we were able to follow the long-term in vivo fate and to prove a time-dependent tumor accumulation of HPMA copolymers over several days.

Anticancer efficacy of perillyl alcohol-bearing PLGA microparticles

In the present study, a novel poly-lactic glycolic acid (PLGA)-based microparticle formulation of perillyl alcohol (POH) was prepared and characterized. Further, its efficacy was evaluated against di-methyl benzo anthracene-induced skin papilloma in Swiss albino mice. The characterization studies showed that POH-bearing PLGA microparticles were of the size 768 ± 215 nm with a ζ-potential value of -7.56 ± 0.88 mV. The entrapment efficiency of the active drug in particles was 42.4% ± 3.5%. POH-bearing PLGA microparticles were stable and released entrapped drug gradually over an extended time period. The in vitro efficacy of POH-bearing PLGA microparticles was evaluated by examining their differential cytotoxicity and assessing their ability to inhibit epidermoid carcinoma cell line (A253). The POH-based microparticles when administered to tumor-bearing animals caused greater tumor regression and increased survival rate (∼80%) as compared with the group receiving free form of POH (survival rate 40%). The superiority of POH-PLGA microparticles over free form of POH was further evident from their ability to modulate apoptosis-regulating factors.

Multifunctional dendritic polymers in nanomedicine: opportunities and challenges

Nanotechnology has resulted in materials that have greatly improved the effectiveness of drug delivery because of their ability to control matter on the nanoscale. Advanced forms of nanomedicine have been synthesized for better pharmacokinetics to obtain higher efficacy, less systemic toxicity, and better targeting. These criteria have long been the goal in nanomedicine, in particular, for systemic applications in oncological disorders. Now, the "holy grail" in nanomedicine is to design and synthesize new advanced macromolecular nanocarriers and to translate them from lab to clinic. This review describes the current and future perspectives of nanomedicine with particular emphasis on the clinical targets in cancer and inflammation. The advanced forms of liposomes and polyethylene glycol (PEG) based nanocarriers, as well as dendritic polymer conjugates will be discussed with particular attention paid to designs, synthetic strategies, and chemical pathways. In this critical review, we also report on the current status and perspective of dendritic polymer nanoconjugate platforms (e.g. polyamidoamine dendrimers and dendritic polyglycerols) for cellular localization and targeting of specific tissues (192 references).

Noninvasive detection of passively targeted poly(ethylene glycol) nanocarriers in tumors

The present studies noninvasively investigate the passive tumor distribution potential of a series of poly(ethylene glycol) (PEG) nanocarriers using a SkinSkan spectrofluorometer and an In Vivo Imaging System (IVIS) 100. Fluorescein conjugated PEG nanocarriers of varying molecular weights (10, 20, 30, 40, and 60 kDa) were prepared and characterized. The nanocarriers were administered intravenously to female balb/c mice bearing subcutaneous 4T1 tumors. Passive distribution was measured in vivo (λ(exc), 480 nm; λ(em), 515-520 nm) from the tumor and a contralateral skin site (i.e., control site). The signal intensity from the tumor was always significantly higher than that from the contralateral site. Trends in results between the two methods were consistent with tumor distribution increasing in a molecular weight-dependent manner (10 < 20 < 30 ≪ 40 ≪ 60 kDa). The 10 kDa nanocarrier was not detected in tumors at 24 h, whereas 40-60 kDa nanocarriers were detected in tumors for up to 96 h. The 30, 40, and 60 kDa nanocarriers showed 2.1, 5.3, and 4.1 times higher passive distribution in tumors at 24 h, respectively, as compared to the 20 kDa nanocarrier. The 60 kDa nanocarrier exhibited 1.5 times higher tumor distribution than 40 kDa nanocarrier at 96 h. Thus, PEG nanocarriers (40 and 60 kDa) with molecular weights close to or above the renal exclusion limit, which for globular proteins is ≥45 kDa, showed significantly higher tumor distribution than those below it. The hydrodynamic radii of PEG polymers, measured using dynamic light scattering (DLS), showed that nanocarriers obtained from polymers with hydrodynamic radii ≥8 nm exhibited higher tumor distribution. Ex vivo mass balance studies revealed that nanocarrier tissue distribution followed the rank order tumor > lung > spleen > liver > kidney > muscle > heart, thus validating the in vivo studies. The results of the current studies suggest that noninvasive dermal imaging of tumors provides a reliable and rapid method for the initial screening of nanocarrier tumor distribution pharmacokinetics.

Microfabricated particulate drug-delivery systems

Micro- and nanoparticulate drug-delivery systems (DDSs) play a significant role in formulation sciences. Most particulate DDSs are scaffold-free, although some particles are encapsulated inside other biomaterials for controlled release. Despite rapid progress in recent years, challenges still remain in controlling the homogenicity of micro-/nanoparticles, especially for two crucial factors in particulate DDSs: the size and shape of the particles. Recent approaches make use of microfabrication techniques to generate micro-/nanoparticles with highly controllable architectures free of scaffolds. This review presents an overview of a burgeoning field of DDSs, which can potentially overcome some drawbacks of conventional techniques for particle fabrication and offer better control of particulate DDSs.

Polymeric nanohybrids and functionalized carbon nanotubes as drug delivery carriers for cancer therapy

The scope of nanotechnology to develop target specific carriers to achieve higher therapeutic efficacy is gaining importance in the pharmaceutical and other industries. Specifically, the emergence of nanohybrid materials is posed to edge over chemotherapy and radiation therapy as cancer therapeutics. This is primarily because nanohybrid materials engage controlled production parameters in the making of engineered particles with specific size, shape, and other essential properties. It is widely expressed that these materials will significantly contribute to the next generation of medical care technology and pharmaceuticals in areas of disease diagnosis, disease prevention and many other treatment procedures. This review focuses on the currently used nanohybrid materials, polymeric nanoparticles and nanotubes, which show great potential as effective drug delivery systems for cancer therapy, as they can be grafted with cell-specific receptors and intracellular targeting molecules for the targeted delivery of therapeutics. Specifically, this article focuses on the current status, recent advancements, potentials and limitations of polymeric nanohybrids and functionalized carbon nanotubes as drug delivery carriers.

RAFT-synthesized graft copolymers that enhance pH-dependent membrane destabilization and protein circulation times

Here we describe a new graft copolymer architecture of poly(propylacrylic acid) (polyPAA) that displays potent pH-dependent, membrane-destabilizing activity and in addition is shown to enhance protein blood circulation kinetics. PolyPAA containing a single telechelic alkyne functionality was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization with an alkyne-functional chain transfer agent (CTA) and coupled to RAFT polymerized poly(azidopropyl methacrylate) (polyAPMA) through azide-alkyne [3 + 2] Huisgen cycloaddition. The graft copolymers become membrane destabilizing at endosomal pH values and are active at significantly lower concentrations than the linear polyPAA. A biotin terminated polyPAA graft copolymer was prepared by grafting PAA onto polyAPMA polymerized with a biotin functional RAFT CTA. The blood circulation time and biodistribution of tritium labeled avidin conjugated to the polyPAA graft copolymer was characterized along with a clinically utilized 40kDa branched polyethylene glycol (PEG) also possessing biotin functionalization. The linear and graft polyPAA increase the area under the curve (AUC) over avidin alone by 9 and 12 times, respectively. Furthermore, polyPAA graft copolymer conjugates accumulated in tumor tissue significantly more than the linear polyPAA and the branched PEG conjugates. The collective data presented in this report indicate that the polyPAA graft copolymers exhibit robust pH-dependent membrane-destabilizing activity, low cytotoxicity, significantly enhanced blood circulation time, and increased tumor accumulation.

Folic acid conjugated amino acid-based star polymers for active targeting of cancer cells

Amino acid-based core cross-linked star (CCS) polymers (poly(L-lysine)(arm)poly(L-cystine)(core)) with peripheral allyl functionalities were synthesized by sequential ring-opening polymerization (ROP) of amino acid N-carboxyanhydrides (NCAs) via the arm-first approach, using N-(trimethylsilyl)allylamine as the initiator. Subsequent functionalization with a poly(ethylene glycol) (PEG)-folic acid conjugate via thiol-ene click chemistry afforded poly(PEG-b-L-lysine)(arm)poly(L-cystine)(core) stars with outer PEG coronas decorated with folic acid targeting moieties. Similarly, a control was prepared without folic acid, using just PEG. A fluorophore was used to track both star polymers incubated with breast cancer cells (MDA-MB-231) in vitro. Confocal microscopy and flow cytometry revealed that the stars could be internalized into the cells, and higher cell internalization was observed when folic acid moieties were present. Cytotoxicity studies indicate that both stars are nontoxic to MDA-MB-231 cells at concentrations of up to 50 μg/mL. These results make this amino acid-based star polymer an attractive candidate in targeted drug delivery applications including chemotherapy.

Folate-targeted nanoparticles show efficacy in the treatment of inflammatory arthritis

OBJECTIVE

To investigate the uptake of a poly(amidoamine) dendrimer (generation 5 [G5]) nanoparticle covalently conjugated to polyvalent folic acid (FA) as the targeting ligand into macrophages, and to investigate the activity of an FA- and methotrexate (MTX)-conjugated dendrimer (G5-FA-MTX) as a therapeutic for the inflammatory disease of arthritis.

METHODS

In vitro studies were performed in macrophage cell lines and in isolated mouse macrophages to check the cellular uptake of fluorescence-tagged G5-FA nanoparticles, using flow cytometry and confocal microscopy. In vivo studies were conducted in a rat model of collagen-induced arthritis to evaluate the therapeutic potential of G5-FA-MTX.

RESULTS

Folate-targeted dendrimer bound and internalized in a receptor-specific manner into both folate receptor β-expressing macrophage cell lines and primary mouse macrophages. The conjugate G5-FA-MTX acted as a potent antiinflammatory agent and reduced arthritis-induced parameters of inflammation such as ankle swelling, paw volume, cartilage damage, bone resorption, and body weight decrease.

CONCLUSION

The use of folate-targeted nanoparticles to specifically target MTX into macrophages may provide an effective clinical approach for antiinflammatory therapy in rheumatoid arthritis.

A polymeric nanoparticle formulation of curcumin (NanoCurc™) ameliorates CCl4-induced hepatic injury and fibrosis through reduction of pro-inflammatory cytokines and stellate cell activation

Plant-derived polyphenols such as curcumin hold promise as a therapeutic agent in the treatment of chronic liver diseases. However, its development is plagued by poor aqueous solubility resulting in poor bioavailability. To circumvent the suboptimal bioavailability of free curcumin, we have developed a polymeric nanoparticle formulation of curcumin (NanoCurc™) that overcomes this major pitfall of the free compound. In this study, we show that NanoCurc™ results in sustained intrahepatic curcumin levels that can be found in both hepatocytes and non-parenchymal cells. NanoCurc™ markedly inhibits carbon tetrachloride-induced liver injury, production of pro-inflammatory cytokines and fibrosis. It also enhances antioxidant levels in the liver and inhibits pro-fibrogenic transcripts associated with activated myofibroblasts. Finally, we show that NanoCurc™ directly induces stellate cell apoptosis in vitro. Our results suggest that NanoCurc™ might be an effective therapy for patients with chronic liver disease.

Calcium condensed cell penetrating peptide complexes offer highly efficient, low toxicity gene silencing

The development of short-interfering RNA (siRNA) offers new strategies for manipulating specific genes responsible for pathological disorders. Myriad cationic polymer and lipid formulations have been explored, but an effective, non-toxic carrier remains a major barrier to clinical translation. Among the emerging candidates for siRNA carriers are cell penetrating peptides (CPPs), which can traverse the plasma membrane and facilitate the intracellular delivery of siRNA. Previously, a highly efficient and non-cytotoxic means of gene delivery was designed by complexing plasmid DNA with CPPs, then condensing with calcium. Here, the CPP TAT and a longer, 'double' TAT (dTAT) were investigated as potential carriers for siRNA. Various N/P ratios and calcium concentrations were used to optimize siRNA complexes in vitro. Upon addition of calcium, 'loose' siRNA/CPP complexes were condensed into small nanoparticles. Knockdown of luciferase expression in the human epithelial lung cell line A549-luc-C8 was high (up to 93%) with no evidence of cytotoxicity. Selected formulations of the dTAT complexes were dosed intravenously up to 1000 mg/kg with minimal toxicity. Biodistribution studies revealed high levels of gene knockdown in the lung and muscle tissue suggesting these simple vectors may offer a translatable approach to siRNA delivery.

Novel PH Sensitive Nanocarrier Agents Based on Citric Acid Dendrimers Containing Conjugated β-Cyclodextrins

INTRODUCTION

In this work, the use of β-cyclodextrine (β-CD)-modified dendrimers as a nanocapsule with a biocompatible shell have studied. β-CD-modifieddendrimers have designed and synthesized to enhance the loading capacity of the final dendrimers with encapsulation properties.

METHODS

To achieve β-CD-modified dendrimers, first citric acid dendrimers were synthesized and then the end functional groups of dendrimers were grafted to β-CD through ester linkages. The molecular structures of resulted dendrimers were verified using common spectroscopic methods such as 1H NMR, FT-IR and the diameters of obtained nanocarriers were evaluated with using dynamic light scattering (DLS) experiments. The isolated dendrimers were utilized as the drug delivery agents and the encapsulation and the controlled release of guest drug molecule Naltrexone (NLX) was investigated in different pH's using UV spectroscopy method.

RESULTS

It was established that the loading capacity of dendrimers depend on several factors such as their generation and the structure and number of conjugated modifier end groups.

CONCLUSION

Increasing in the number of branches and the size of interior voids and number of conjugated β-CDs cause to enhance the loading capacity.