Dendrimer-based Nanoparticles Research Articles

Multimodal neuro-nanotechnology: Challenging the existing paradigm in glioblastoma therapy

Integrating multimodal neuro- and nanotechnology-enabled precision immunotherapies with extant systemic immunotherapies may finally provide a significant breakthrough for combatting glioblastoma (GBM). The potency of this approach lies in its ability to train the immune system to efficiently identify and eradicate cancer cells, thereby creating anti-tumor immune memory while minimizing multi-mechanistic immune suppression. A critical aspect of these therapies is the controlled, spatiotemporal delivery of structurally defined nanotherapeutics into the GBM tumor microenvironment (TME). Architectures such as spherical nucleic acids or poly(beta-amino ester)/dendrimer-based nanoparticles have shown promising results in preclinical models due to their multivalency and abilities to activate antigen-presenting cells and prime antigen-specific T cells. These nanostructures also permit systematic variation to optimize their distribution, TME accumulation, cellular uptake, and overall immunostimulatory effects. Delving deeper into the relationships between nanotherapeutic structures and their performance will accelerate nano-drug development and pave the way for the rapid clinical translation of advanced nanomedicines. In addition, the efficacy of nanotechnology-based immunotherapies may be enhanced when integrated with emerging precision surgical techniques, such as laser interstitial thermal therapy, and when combined with systemic immunotherapies, particularly inhibitors of immune-mediated checkpoints and immunosuppressive adenosine signaling. In this perspective, we highlight the potential of emerging treatment modalities, combining advances in biomedical engineering and neurotechnology development with existing immunotherapies to overcome treatment resistance and transform the management of GBM. We conclude with a call to action for researchers to leverage these technologies and accelerate their translation into the clinic.

Exploring nanotechnology-based approaches using miRNAs to treat neurodegenerative disorders

Abstract MicroRNAs (miRNAs) are small non-coding molecules that play a pivotal part in brain development and the processes of establishment and maintenance of dendrites and neurite outgrowth by modulating gene expression. Dysregulation of miRNAs has been linked with neurological disorders. Exogenous miRNAs are unstable in the plasma due to degradation by nucleases; hence, choosing a harmless and effective delivery mode is crucial in the quest for miRNA-based therapeutics to treat neurological disorders. This review aims to shed light on the emerging role of nanotechnology-based approaches using miRNAs to treat neurodegenerative disorders. Nanotechnology encompasses a broad spectrum of applications, one of which is its role in developing nanoscale drug delivery systems. Nanotechnology-based drug delivery systems have attracted the attention of researchers due to the superiority of this mode over conventional treatment systems in terms of their favorable attributes such as bio-compatibility, bio-degradability, extremely small size, and the ability to cross the blood-brain barrier. This review explores nanotechnology-based approaches using miRNAs highlighting the use of viral vectors as well as non-viral vectors (such as exosomes, liposome nanoparticles, gold and magnetic nanoparticles, dendrimer-based nanoparticles, polymeric nanoparticles) to treat neurodegenerative disorders.

Magnetic triazine-based dendrimer as a versatile nanocarrier for efficient antiviral drugs delivery

Nanoscale engineering is an efficient method for the treatment of multiple infectious diseases. Due to the controllable functionalities, surface properties, and internal cavities, dendrimer-based nanoparticles represent high performance in drug delivery, making their application attractive in pharmaceutical and medicinal chemistry. In this study, a dendritic nanostructure (Fe3O4@SiO2@TAD-G3) was designed and fabricated by grafting a triazine-based dendrimer on a magnetic nanomaterial. The structure of synthesized hybrid nanostructure was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, elemental mapping, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The prepared nanostructure (Fe3O4@SiO2@TAD-G3) combines the unique properties of magnetic nanoparticles and a hyperbranched dendrimer for biomedical applications. Its dual nature and highly exposed active sites, could make the transportation of drugs to targeted sites of interest through the magnetic field. A study was conducted on model drugs loading (Favipiravir and Zidovudine) and in vitro release behaviour of Fe3O4@SiO2@TAD-G3, which was monitored by ultraviolet spectroscopy. The dendritic nanostructure exhibited high drug-loading capacity for Favipiravir (63.2%) and Zidovudine (76.5%). About (90.8% and 80.2%) and (95.5% and 83.4%) of loaded Favipiravir and Zidovudine were released from Fe3O4@SiO2@TAD-G3 at pH 1.5 and 6.8 respectively, within 600 min and at 37 °C. The initial fast release attributed to the drug molecules on the surface of nanostructure while the drugs incorporated deeply into the pores of the Fe3O4@SiO2@TAD-G3 released with a delay. We proposed that Fe3O4@SiO2@TAD-G3 could be tested as an effective carrier in the targeted (cellular or tissue) delivery of drugs. We think that the prepared nanostructure will not deposit in the liver and lungs due to the small size of the nanoparticles.

AgCl-TiO2/dendrimer-based nanoparticles for superhydrophobic and antibacterial multifunctional textiles

Multifunctional textile finishing applications have raised concern over environmental issues due to multiple baths and complicated steps. The main focus of this study is the development of multifunctional textiles with superhydrophobic and antibacterial nanoparticles for medical purposes via a one-step electrospraying method. The pad-dry-cure method was also investigated. Silver chloride-titanium dioxide (AgCl-TiO2) and dendritic polymer with methyl end group (CH3)-based (DP) coating solutions were applied. Coating solutions’ characteristics in addition to surface morphology, particle size, and distribution were investigated with nano size measurements, SEM, and FESEM images. Relative humidity condition effects were observed. Achieved functionality was investigated. Uncoated surface’s water repellency was dramatically improved. The water contact angle has increased from 125.4° (±2.3°) and reached up to 168.5° after electrospraying. Over 99% antibacterial activity was obtained for Escherichia coli and Staphylococcus aureus bacteria. Formed nanoparticles have multifunctional characteristics and extensive practicability potential for various kinds of applications.

Vaccination against cocaine using a modifiable dendrimer nanoparticle platform

Pharmacological therapies for the treatment of cocaine addiction have had disappointing efficacy, and the lack of recent developments in the clinical care of cocaine-addicted patients indicates a need for novel treatment strategies. Recent studies have shown that vaccination against cocaine to elicit production of antibodies that reduce concentrations of free drug in the blood is a promising method to protect against the effects of cocaine and reduce rates of relapse. However, the poorly immunogenic nature of cocaine remains a major hurdle to active immunization. Therefore, we hypothesized that strategies to increase targeted exposure of cocaine to the immune system may produce a more effective vaccine. To specifically direct an immune response against cocaine, in the present study we have conjugated a cocaine analog to a dendrimer-based nanoparticle carrier with MHC II-binding moieties that previously has been shown to activate antigen-presenting cells necessary for antibody production. This strategy produced a rapid, prolonged, and high affinity anti-cocaine antibody response without the need for an adjuvant. Surprisingly, additional evaluation using multiple adjuvant formulations in two strains of inbred mice found adjuvants were either functionally redundant or deleterious in the vaccination against cocaine using this platform. The use of conditioned place preference in rats after administration of this vaccine provided proof of concept for the ability of this vaccine to diminish cocaine reward. Together these data demonstrate the intrinsic efficacy of an immune-targeting dendrimer-based cocaine vaccine, with a vast potential for design of future vaccines against other poorly immunogenic antigens by substitution of the conjugated cargo.

Charge reversible hyaluronic acid-modified dendrimer-based nanoparticles for siMDR-1 and doxorubicin co-delivery

Dendrimer-based nanoparticles have shown promising applications in delivery of small interference RNA (siRNA) to downregulate proteins that contribute to multidrug resistance (MDR). Various types of modification can further enhance the anti-tumor efficacy of dendrimer-based nanoparticles. In this study, generation 4 polyamodoamine (PAMAM) was conjugated with PEG2k-DOPE. The PAMAM-PEG2k-DOPE co-polymer, together with mPEG2k-DOPE, was formulated into mixed dendrimer micelles (MDMs) that can complex siRNA through the cationic PAMAM moieties and encapsulate hydrophobic drug in the micellar lipid cores. DOPE-conjugated hyaluronic acid (HA) was coated on the surface of MDMs to shield the exposed positive charge on PAMAM and to increase the cellular association with CD44+ cancer cells. The HA-modified MDMs could form stable complexes with siRNA, prevent RNase-mediated siRNA degradation and maintain its integrity. Cellular association and cytotoxicity of HA-modified MDMs were investigated in A2780 ADR, MDA-MB-231 and HCT 116 cell lines. The HA-modified MDMs alleviated the toxicity from cationic charge, increase the cancer cell specificity and enhance the cancer cell killing effect in CD44+ cell line.

Cell-Penetrating Peptide and α-Tocopherol-Conjugated Poly(amidoamine) Dendrimers for Improved Delivery and Anticancer Activity of Loaded Paclitaxel.

Even though existing chemotherapeutic agents, including paclitaxel (PTX), possess superior anticancer activity, their application is limited because of extreme hydrophobicity. Here, a dendrimer-based nanoparticles system has been prepared for improved delivery of loaded paclitaxel to the tumor. The cell-penetrating peptides, octa-arginine (R) and vitamin-E succinate (VES), had been conjugated to the PEGylated generation 4 polyamidoamine dendrimer (D) to form RVES-PD. The synthesized polymers had been characterized by 1NMR, IR, and gel permeation chromatography. The PTX-loaded RVES-PD (RVES-PD-PTX) was physicochemically characterized for particle size, zeta potential analysis, drug loading, release, and encapsulation studies. Cellular uptake, cytotoxicity, and apoptosis determination studies were carried out in human lung cancer cells (A549) in monolayers and spheroids. In vivo antitumor efficacy of RVES-PD-PTX was determined using B16F10 tumor-bearing mice. The results indicated that the RVES-PD nanoparticles were taken up by cancer cells effectively and demonstrated improved cellular translocation compared to nontargeted VES-PD. The cytotoxicity study revealed that RVES-PD-PTX exhibited the highest cytotoxicity of PTX compared to nontargeted VES-PD-PTX and free PTX in the PTX concentration range of 0-50 μg/mL. RVES-PD-PTX-induced apoptosis as analyzed by the Annexin V assay and suppressed the growth of spheroids to the highest extent compared to VES-PD-PTX and free PTX. Furthermore, the biodistribution study indicated that the RVES-PD had higher accumulation in tumor compared to VES-PD. The in vivo experiment using B16F10 tumor-bearing mice demonstrated that the RVES-PD treatment resulted in the highest rate of tumor volume reduction and apoptosis primarily by upregulating caspase 3/7 to the highest extent compared to VES-PD and free PTX. In conclusion, the developed RVES-PD could load PTX and showed efficient cell penetration and improved PTX-mediated cytotoxicity in all tested in vitro and in vivo assay systems. The results strongly suggest further exploration of this developed PTX-nanoformulation in cancer treatment.

Synthesis and Applications of Dendrimer-Based Inorganic Nanoparticles

Synthesis and Applications of Dendrimer-Based Inorganic Nanoparticles

Tumor-Targeted Dendrimer Nanoparticles for Combinatorial Delivery of siRNA and Chemotherapy for Cancer Treatment.

In current cancer therapy, the combined targeted delivery of treatments is an important method to enhance the therapeutic efficiency and reduce adverse side effects. Dendrimer-based nanoparticles have received considerable attention for multifunctional therapeutic delivery. In this chapter, we describe the methods for encapsulating the chemotherapeutic drug, cisplatin (CDDP), and human antigen R (HuR)-targeted siRNA into dendrimer nanoparticles for folate receptor-targeted delivery. We discuss the methodologies for physical and biological characterization of synthesized multifunctional (Den-PEI-CDDP-HuR-FA) nanoparticles in detail. Physical characterization includes size and charge determination, drug encapsulation and release kinetics, ligand conjugation, etc., and functional characterization involves testing of the nanoparticles for receptor-specific uptake and cytotoxicity on human lung cancer and normal cells. The protocol provided is geared to provide the readers an overview of developing multifunctional dendrimer-based nanoparticles. However, based on the individual's objective and the type of combinatorial drugs to deliver, the protocol may need modifications in achieving maximal efficacy.

Experimental study of dendrimer-based nanoparticles with RGD-peptide for anticancer radionuclide therapy

Radionuclide therapy (RNT) is an effective modality for treating multiple metastases in patients with cancer. The list of malignancies that can be managed with RNT expands with the arrival of novel tumoritropic radiopharmaceuticals (RP). A versatile delivery platform capable of carrying various therapeutic and diagnostic radionuclides, as well as vector molecules needed to achieve sufficient specificity to tumor cells and ensure therapeutic efficacy may hold great promise for radiation therapy. The aim of this work was to assess the performance of a delivery system based on the original dendrimer. The dendrimer demonstrated low toxicity in mice (LD50 was 779 ± 111 mg/kg). To study the specificity of the dendrimer to tumor cells and its therapeutic efficacy, we used a nanostructure (NS) composed of the dendrimer itself, the RGD peptide and 188Re (188Re-NS). Lewis lung carcinoma LLC1 was used as a tumor model. The biodistribution analysis revealed that the compound effectively accumulated in the tumor demonstrating a tumor-to-normal ratio >1 (relative to healthy organs and tissues) and retention time of at least 6 hours. Injections of 185 MBq/kg 188Re-NS caused a statistically significant inhibition of tumor growth (p < 0.05) by day 7 following the injection (Т/С = 5%), which remained stable for 6 days. Our findings suggest that the proposed dendrimer is a promising platform for RP delivery.

Perspectives of Dendrimer-based Nanoparticles in Cancer Therapy.

Currently, cancer is the second most common cause of death in the United States, exceeded only by heart disease. Chemotherapy traditionally suffers from a non-specific distribution, with only a small fraction of the drug reaching the tumor, in this sense, the use of dendrimers incorporating drugs non-covalently encapsulated inside the dendrimer or covalently conjugated have proven to be effectives against different cancer cell lines. However, at present the dendrimers used as drug-carriers still do not meet the necessary characteristic to be considered as an ideal dendrimer for drug delivery; high toxicity, bio-degradability, low toxicity, biodistribution characteristics, and favorable retention with appropriate specificity and bioavailability have not been fully covered by the current available dendrimers. However, the development and study of new dendrimers drug-carriers continues to be an important tool in the cancer therapy as they can be functionalized with varied ligands to reach the tumor tissue through the different body barriers in the body with minimal loss of activity in the bloodstream, have the ability to selectively kill tumor cells without affecting the normal cells and most important with a release mechanism controlling actively. Given the continuous efforts and research in this area of interest, we presented in this review the work done with a special emphasis on the development of dendrimers as a major tool in the combination with drugs, as a potential adjunctive agent in anticancer therapy.

Dendrimer-based nanoparticles in cancer chemotherapy and gene therapy

This review discusses recent studies on dendrimer-based nanoparticles in cancer chemotherapy and gene therapy. In order to achieve the high efficacy and low side effects of chemotherapy and gene therapy, it is essential to combine the unique features of dendrimers and the specific tumor microenvironment to target delivery and control release of therapeutic agents to tumor tissues and cells. Strategies to design the dendrimer-based delivery system in this review include non-modified dendrimers, dendrimer conjugates, assembled amphiphilic dendrimers, nanohybrid dendrimer carriers and dendrimers with inherent activity. In addition, specific functional groups on these dendrimers as stimuli-responsive system for targeting delivery and controlled release of therapeutic agents are discussed.

Dendrimer-based Nanoparticle for Dye Sensitized Solar Cells with Improved Efficiency.

Dye sensitized solar cells were fabricated with DyLight680 (DL680) dye and its corresponding europium conjugated dendrimer, DL680-Eu-G5PAMAM, to study the effect of europium on the current and voltage characteristics of the DL680 dye sensitized solar cell. The dye samples were characterized by using Absorption Spectroscopy, Emission Spectroscopy, Fluorescence lifetime and Fourier Transform Infrared measurements. Transmission electron microscopy imaging was carried out on the DL680-Eu-G5PAMAM dye and DL680-Eu-G5PAMAM dye sensitized titanium dioxide nanoparticles to analyze the size of the dye molecules and examine the interaction of the dye with titanium dioxide nanoparticles. The DL680-Eu-G5PAMAM dye sensitized solar cells demonstrated an enhanced solar-to-electric energy conversion of 0.32% under full light illumination (100 mWcm−2, AM 1.5 Global) in comparison with that of DL680 dye sensitized cells which recorded an average solar-to-electric energy conversion of only 0.19%. The improvement of the efficiency could be due to the presence of the europium that enhances the propensity of dye to absorb sunlight.

Application of Dendrimer-based Nanoparticles in Glioma Imaging.

Dendritic polymers or dendrimers present an alternate template for the development of nanoparticulate-based drug delivery and imaging systems. The smaller size (~7–12 nm) of dendrimers have the advantage over the other particles, because its smaller size can possibly improve tumor penetration and the inclusion of tumor specific drug release mechanisms. A Paramagnetic Chemical Exchange Saturation Transfer (PARACEST) MRI contrast agent, Eu-DOTA-Gly4 or a clinical relevant Gd-DOTA was conjugated on the surface of a G5 PAMAM dendrimer. To create a dual mode MRI-optical imaging nanoparticle, Dylight680 was also incorporated on the amines surface of a G5 dendrimer. The particle was detected with in vivo MRI in preclinical glioma animal model. Furthermore, noninvasive imaging results were validated with in vivo and ex-vivo optical imaging.

Abstract 1316: Targeted therapeutic approach for triple negative breast cancer using paramagnetic nanoparticle

Abstract Breast cancer (BC) is a spectrum of diseases with distinct molecular alterations accounting for differences in treatment response and outcome. Gene expression profiling defines much of this molecular heterogeneity and has been used to stratify the disease into different molecular subtypes. Triple-negative breast cancer (TNBC) refers to a subtype of breast cancer that is negative for estrogen receptors (ER) and/or progesterone receptors (PR), and lacks HER2 overexpression. Therefore, this subtype of breast cancer lacks the benefits of specific therapies which target these receptors. TNBC has been characterized by an acidic extracellular environment. In human aggressive breast tumors, extracellular pH (pHe) has been measured by microelectrode and the values are in good agreement with the values observed in animal systems i.e. that the pHe is significantly acidic in the range from 6.2 to 7.0. However, tumor intracellular pH is either neutral or alkaline. Interestingly, a similar pH gradient is not observed in normal tissues. Therefore, this acidic extracellular pH (pHe) within tumor tissues can be exploited for targeted delivery of drugs and imaging agents. Recently, A pH low insertion peptide (pHLIP) derived from the protein bacteriorhodopsin has been found to target tumor acidic pHe. The peptide inserts across cell membranes as an alpha-helix when extracellular pH (pHe) is acidic, but does not form the helix at normal or alkaline pH. Since aggressive TNBC has an acidic environment, the pHLIP will insert into the cancer cell membrane, but the pHLIP will not insert into the cell membranes of normal tissues, providing excellent specificity for targeting TNBC. Our initial study demonstrated the detection of breast tumor in rodent by dendrimer-based paramagnetic nanoparticles nonspecifically. To develop this nanoparticle as a platform, it should easily accommodate targeting ligands for selective localization at the acidic tumor microenvironment and for therapeutic drugs that can be released selectively into TNBC tumor cells. Here, we demonstrate that pHLIP-tagged nanoparticles bind to and are internalized by TNBC cells in in-vitro. Systemic delivery of paramagnetic nanoparticle, Gd-G5-pHLIP (NP-pHLIP) leads to accumulation of the NPs in a flank mouse model of TNBC tumor that are detected by both optical and MR imaging. Finally, we have conjugated doxorubicin (dox) with pHLIP3-NP via hydrazone bond formation. We have successfully incorporated 20 dox molecules with pHLIP3-NP via a pH-sensitive hydrazone bond as evidenced by maldi-tof analyses. A cohort of 6 mice was treated with pHLIP-NP-dox and a second cohort of 6 mice was treated with vehicle. A solution of 0.04 mmol/kg pHLIP-NP-dox (12mg/kg equivalent dose of dox) was injected through the tail vein catheter at day 8 and 14. We generated T2 maps on day 21′to calculate tumor volume by following our previous reports. We observed a short-term tumor regression by pHLIP-NP-dox infusion. Citation Format: Meser M. Ali, Li Zhang, Hassan Bagher Ebadian, James R. Ewing. Targeted therapeutic approach for triple negative breast cancer using paramagnetic nanoparticle. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1316.

Dendrimer-based nanoparticles for potential personalized therapy in chronic lymphocytic leukemia: Targeting the BCR-signaling pathway

Chronic lymphocytic leukemia (CLL) is one of the most prevalent forms of leukemia in western society. Although classic chemoimmune therapy is still the gold standard of care for leukemic patients, effective therapy of CLL is yet to be achieved. The present study examines the influence of poly(propylene)imine (PPI) dendrimers with primary amino surface groups modified with maltotriose residues in approximately 90% (PPI-G4-DS-Mal-III) or 30% (PPI-G4-OS-Mal-III) of cases on CLL cells (MEC-1 cell line with del(17p)), and confirms that the main trigger in this interaction is the induction of the apoptotic mechanism. The efficacy of each dendrimer was compared using fludarabine (FA). Gene expression profiling (GEP) by microarray identified a group of genes in the BCR signaling pathway characterized by different levels of expression directly associated with the tested agent and type of interaction. Network analysis revealed the potential patterns involved in potential personalized therapy of CLL. The expression of most BCR genes decreased under the influence of dendrimers, which might translate into decreased maturation and proliferation of CLL lymphocytes. Moreover, PPI-G4-OS/DS-Mal-III dendrimers affected gene expression and CLL cells in a different way to FA. Thanks to unique properties, dendrimers may be specifically targeted, thus improving the effectiveness of CLL therapy.

Targeting Triple Negative Breast Cancer with a Small-sized Paramagnetic Nanoparticle.

There is no available targeted therapy or imaging agent for triple negative breast cancer (TNBC). We developed a small-sized dendrimer-based nanoparticle containing a clinical relevant MRI contrast agent, GdDOTA and a NIR fluorescent dye, DL680. Systemic delivery of dual-modal nanoparticles led to accumulation of the agents in a flank mouse model of TNBC that were detected by both optical and MR imaging. In-vivo fluorescence images, as well as ex-vivo fluorescence images of individual organs, demonstrated that nanoparticles accumulated into tumor selectively. A dual modal strategy resulted in a selective delivery of a small-sized (GdDOTA)42-G4-DL680 dendrimeric agent to TNBC tumors, avoiding other major organs.

Investigation of Dendrimer-based nanoparticles cellular uptake and cell tracking in a semi-automated microfluidic platform

Investigation of Dendrimer-based nanoparticles cellular uptake and cell tracking in a semi-automated microfluidic platform

Multifunctional dendrimer-based nanoparticles for in vivo MR/CT dual-modal molecular imaging of breast cancer.

Development of dual-mode or multi-mode imaging contrast agents is important for accurate and self-confirmatory diagnosis of cancer. We report a new multifunctional, dendrimer-based gold nanoparticle (AuNP) as a dual-modality contrast agent for magnetic resonance (MR)/computed tomography (CT) imaging of breast cancer cells in vitro and in vivo. In this study, amine-terminated generation 5 poly(amidoamine) dendrimers modified with gadolinium chelate (DOTA-NHS) and polyethylene glycol monomethyl ether were used as templates to synthesize AuNPs, followed by Gd(III) chelation and acetylation of the remaining dendrimer terminal amine groups; multifunctional dendrimer-entrapped AuNPs (Gd-Au DENPs) were formed. The formed Gd-Au DENPs were used for both in vitro and in vivo MR/CT imaging of human MCF-7 cancer cells. Both MR and CT images demonstrate that MCF-7 cells and the xenograft tumor model can be effectively imaged. The Gd-Au DENPs uptake, mainly in the cell cytoplasm, was confirmed by transmission electron microscopy. The cell cytotoxicity assay, cell morphology observation, and flow cytometry show that the developed Gd-Au DENPs have good biocompatibility in the given concentration range. Our results clearly suggest that the synthetic Gd-Au DENPs are amenable for dual-modality MR/CT imaging of breast cancer cells.

Abstract 4445: Novel antibody-dendrimer conjugates efficiently complex plasmid DNA

Abstract Introduction: Cationic polymers, such as polylysine, polyethylenimine, or polyamidoamine (PAMAM)-based dendrimers, form complexes with nucleic acids. However, their potential applications in nanomedicne as non-viral vectors for delivering therapeutic genes or siRNAs remain a challenge. One approach to improve selectivity and potency of a dendrimeric nanoparticle may be achieved by conjugation with an antibody that internalizes upon binding to target cells. In this study, we describe the synthesis and initial characterization of a novel immunoconjugate, designated E1-G5/2, which was made by the modular Dock-and-Lock (DNL) method to comprise half of a generation 5 (G5) PAMAM dendrimer (G5/2) site-specifically linked to a stabilized dimer of Fab derived from hRS7, a humanized antibody that is rapidly internalized upon binding to the Trop-2 antigen expressed on various solid cancers. Methods: E1-G5/2 was prepared by combining two self-assembling modules, AD2-G5/2 and hRS7-Fab-DDD2, under mild redox conditions, followed by purification on a Protein L column. To make AD2-G5/2, we derivatized the AD2 peptide with a maleimide group to react with the single thiol generated from reducing a G5 PAMAM with a cystamine core and used reversed-phase HPLC to isolate AD2-G5/2. We produced hRS7-Fab-DDD2 as a fusion protein in myeloma cells. The molecular size, purity and composition of E1-G5/2 were analyzed by size-exclusion HPLC, SDS-PAGE, and Western blotting. The biological functions of E1-G5/2 were assessed by binding to an anti-idiotype antibody against hRS7, a gel retardation assay, and a DNase protection assay. Results: E1-G5/2 was shown by size-exclusion HPLC to consist of a major peak (>90%) flanked by several minor peaks. The three constituents of E1-G5/2 (Fd-DDD2, the light chain, and AD2-G5/2) were detected by reducing SDS-PAGE and confirmed by Western blotting. Anti-idiotype binding analysis revealed E1-G5/2 contains a population of antibody-dendrimer conjugates of different size, all of which are capable of recognizing the anti-idiotype antibody, thus suggesting structural imperfections in the commercial supply of the G5 dendrimer. Gel retardation assay showed E1-G5/2 was able to maximally condense plasmid DNA at a charge ratio of 6:1 (+/-), with the resulting dendriplexes completely protecting the complexed DNA from degradation by DNase I. Conclusion: The DNL method can be used to build dendrimer-based nanoparticles that are targetable with antibodies. Such agents may have improved properties as carriers of drugs, plasmids, or siRNAs for diverse applications in vitro and in vivo. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4445. doi:10.1158/1538-7445.AM2011-4445