Amphiphilic Dendrimers Research Articles

Accelerated Ten-Gram-Scale Synthesis of One-Component Multifunctional Sequence-Defined Ionizable Amphiphilic Janus Dendrimer 97.

One-component multifunctional sequence-defined ionizable amphiphilic Janus dendrimers (IAJDs) were discovered in our laboratories in 2021 to represent a new class of synthetic vectors for the targeted delivery of messenger RNA (mRNA). They coassemble with mRNA by simple injection of their ethanol solution into a pH 4 acetate buffer containing the nucleic acid into monodisperse dendrimersome nanoparticles (DNPs) with predictable dimensions. DNPs are competitive with 4-component lipid nanoparticles (LNPs), which are used in commercial COVID-19 vaccines, except that IAJDs are prepared in fewer reaction steps than each individual component of the LNPs. This simple methodology for the synthesis of IAJDs and their coassembly with mRNA into DNPs, together with the precise placement of their individual components and indefinite stability at room temperature in air, make them attractive candidates for the development of nanomedicine-based targeted mRNA delivery. Access to the large-scale synthesis of IAJDs without the need for sophisticated technologies, instrumentation, and synthetic skills is expected to open numerous new opportunities worldwide in nanomedicine. The goal of this publication is to report an accelerated ten-gram-scale synthesis of IAJD97 from inexpensive food additives obtained from renewable plant phenolic acid starting materials by methodologies accessible to any laboratory. This accelerated synthesis can be accomplished in 4 days. We expect that the work reported here will impact the field of nanomedicine in both developed and less developed countries.

Targeting the phosphatidylglycerol lipid: An amphiphilic dendrimer as a promising antibacterial candidate.

The rapid emergence and spread of multidrug-resistant bacterial pathogens require the development of antibacterial agents that are robustly effective while inducing no toxicity or resistance development. In this context, we designed and synthesized amphiphilic dendrimers as antibacterial candidates. We report the promising potent antibacterial activity shown by the amphiphilic dendrimer AD1b, composed of a long hydrophobic alkyl chain and a tertiary amine-terminated poly(amidoamine) dendron, against a panel of Gram-negative bacteria, including multidrug-resistant Escherichia coli and Acinetobacter baumannii. AD1b exhibited effective activity against drug-resistant bacterial infections in vivo. Mechanistic studies revealed that AD1b targeted the membrane phospholipids phosphatidylglycerol (PG) and cardiolipin (CL), leading to the disruption of the bacterial membrane and proton motive force, metabolic disturbance, leakage of cellular components, and, ultimately, cell death. Together, AD1b that specifically interacts with PG/CL in bacterial membranes supports the use of small amphiphilic dendrimers as a promising strategy to target drug-resistant bacterial pathogens and addresses the global antibiotic crisis.

Amphiphilic Janus dendrimer for targeted-drug delivery to human cancer cells

The synthesis of a non-steroidal anti-inflammatory dendritic drug carrier, indomethacin-based polyester Janus dendrimer was carried out using a conventional Steglich reaction. The first dendron was obtained from triethyleneglycol glycol as focal nucleus joined with diethanolamine-indomethacin drug as terminal group and the second dendron with Behera's amine moiety with terminal acid group as focal point, the dendrons were joined by Steglich reaction obtaining the Janus dendrimer, and the subsequent deprotection of the tert-butyl groups to obtain the terminal carboxylic acid in the Behera's amine dendron. The dendrimers were characterized by one- and two-dimension NMR spectroscopy to verify expected compounds. The cytotoxic activity showed that dendrimers were active against human mammary and prostatic cancer cells.

ROS-Responsive Ferrocenyl Amphiphilic PAMAM Dendrimers for On-Demand Delivery of siRNA Therapeutics to Cancer Cells.

Small interfering RNA (siRNA) therapeutics, characterized by high specificity, potency, and durability, hold great promise in the treatment of cancer and other diseases. However, the clinic implementation of siRNA therapeutics critically depends on the safe and on-demand delivery of siRNA to the target cells. Here, we reported a family of ferrocenyl amphiphilic dendrimers (Fc-AmDs) for on-demand delivery of siRNA in response to the high ROS content in cancer cells. These dendrimers bear ROS-sensitive ferrocene moieties in the hydrophobic components and positively chargeable poly(amidoamine) dendrons as the hydrophilic entities, possessing favorable safety profiles and ROS responsive properties. One of these ferrocenyl amphiphilic dendrimers, Fc-C8-AmD 8A, outperforms in siRNA delivery, benefiting from its optimal balance of hydrophobicity and hydrophilicity. Its ROS feature facilitates specific and efficient disassembly of its complex with siRNA in ROS-rich cancer cells for effective siRNA delivery and gene silencing. Moreover, Fc-C8-AmD 8A also integrates the features and beneficial properties of both lipid and dendrimer vectors. Therefore, it represents a novel on-demand delivery system for cancer cell-specific siRNA delivery. This work opens new perspectives for designing self-assembly nanosystems for on-demand drug delivery.

Targeted delivery of TGF-β mRNA to lung parenchyma using one-component ionizable amphiphilic Janus Dendrimers.

Current clinical strategies for the delivery of pulmonary therapeutics to the lung are primarily targeted to the upper portions of the airways. However, targeted delivery to the lower regions of the lung is necessary for the treatment of parenchymal lung injury and disease. Here, we have developed an mRNA therapeutic for the lower lung using one-component Ionizable Amphiphilic Janus Dendrimers (IAJDs) as a delivery vehicle. We deliver an anti-inflammatory cytokine mRNA, transforming growth factor-beta (TGF-β), to produce transient protein expression in the lower regions of the lung. This study highlights IAJD's potential for precise, effective, and safe delivery of TGF-β mRNA to the lung. This delivery system offers a promising approach for targeting therapeutics to the specific tissues, a strategy necessary to fill the current clinical gap in treating parenchymal lung injury and disease.

Self-assembling dendrimer nanosystems for specific fluorine magnetic resonance imaging and effective theranostic treatment of tumors

Fluorine magnetic resonance imaging (19F-MRI) is particularly promising for biomedical applications owing to the absence of fluorine in most biological systems. However, its use has been limited by the lack of safe and water-soluble imaging agents with high fluorine contents and suitable relaxation properties. We report innovative 19F-MRI agents based on supramolecular dendrimers self-assembled by an amphiphilic dendrimer composed of a hydrophobic alkyl chain and a hydrophilic dendron. Specifically, this amphiphilic dendrimer bears multiple negatively charged terminals with high fluorine content, which effectively prevented intra- and intermolecular aggregation of fluorinated entities via electrostatic repulsion. This permitted high fluorine nuclei mobility alongside good water solubility with favorable relaxation properties for use in 19F-MRI. Importantly, the self-assembling 19F-MRI agent was able to encapsulate the near-infrared fluorescence (NIRF) agent DiR and the anticancer drug paclitaxel for multimodal 19F-MRI and NIRF imaging of and theranostics for pancreatic cancer, a deadly disease for which there remains no adequate early detection method or efficacious treatment. The 19F-MRI and multimodal 19F-MRI and NIRF imaging studies on human pancreatic cancer xenografts in mice confirmed the capability of both imaging modalities to specifically image the tumors and demonstrated the efficacy of the theranostic agent in cancer treatment, largely outperforming the clinical anticancer drug paclitaxel. Consequently, these dendrimer nanosystems constitute promising 19F-MRI agents for effective cancer management. This study offers a broad avenue to the construction of 19F-MRI agents and theranostics, exploiting self-assembling supramolecular dendrimer chemistry.

Capture and flocculation of toxic cyanobacteria by amphiphilic peptide dendrimers for mitigating harmful blooms

Harmful and toxic cyanobacterial blooms in freshwater constitute critical environmental problems and are becoming more frequent as a consequence of global climate change. One mitigation strategy is flocculation, which could be achieved with treatment by highly efficient, non-toxic, and biodegradable agents. Here, we report two amphiphilic peptide dendrimers (AmPDs), KK2 and KK2K4, for the removal of the toxic and bloom-forming cyanobacterium Microcystis aeruginosa from freshwater. KK2 and KK2K4 are composed of a hydrophobic alkyl chain and a positively charged polylysine dendron of the first and second generation, respectively. Owing to electrostatic interactions with the negatively charged cell surface of M. aeruginosa, KK2 and KK2K4 could quickly capture the cyanobacterial cell population via flocculation at very low concentrations. When combined with the natural clay sepiolite, the two AmPDs were even more efficient in promoting cell flocculation. The most performant system, with 3.0 mg/L KK2K4 and sepiolite clay, could remove 97.1 % of M. aeruginosa within 15 min by forming stable flocs. Remarkably, such a system was able to trap toxin molecules released by cyanobacterial cells, thus limiting its destructive impact on ecosystems. This study demonstrates how self-assembling dendrimer materials can resolve cyanobacterial blooms, providing an innovative solution to this environmental challenge.

Molecular Ballet: Investigating the Complex Interaction between Self-Assembling Dendrimers and Human Serum Albumin via Computational and Experimental Methods.

Dendrimers, intricate macromolecules with highly branched nanostructures, offer unique attributes including precise control over size, shape, and functionality, making them promising candidates for a wide range of biomedical applications. The exploration of their interaction with biological environments, particularly human serum albumin (HSA), holds significant importance for biomedical utilization. In this study, the interaction between HSA and a recently developed self-assembling amphiphilic dendrimer (AD) was investigated using various experimental techniques. Fluorescence spectroscopy and isothermal titration calorimetry revealed moderate interactions between the protein and the AD nanomicelles (NMs), primarily attributed to favorable enthalpic contributions arising from electrostatic interactions and hydrogen bonding. Structural analysis indicated minimal changes in HSA upon complexation with the AD NMs, which was further supported by computational simulations demonstrating stable interactions at the atomistic level. These findings provide valuable insights into the binding mechanisms and thermodynamic parameters governing HSA/AD NM interactions, thereby contributing to the understanding of their potential biomedical applications.

Abstract 3168: Amphiphilic dendrimer-mediated siRNA delivery for precision regulation of cAMP pathway in cancer cells

Abstract Exchange proteins directly activated by cAMP (EPACs) are involved in multiple cellular processes. The two EPAC isoforms (EPAC1 and EPAC2) have fundamental differences in structure, expression pattern, and signaling specificity, indicating that they may function independently. Therefore, the highly specific regulation of EPAC1 and EPAC2 could be beneficial in targeting cAMP pathway-related therapies. Small RNA molecules could theoretically target genetic components based on Watson-Crick base pairing, offering a unique and promising approach to achieve precision medicine. In this study, we successfully design small interfere (si)RNAs that specifically target EPAC1 and 2, without cross-reactivity with other isoforms. The use of the amphiphilic dendrimer (AD) efficiently delivers siRNAs, resulting in significant down-regulations of EPAC1 and 2 mRNA and protein expressions in multiple cancer cells, including ovarian, breast, colon, and pancreatic cancers. Functional analysis demonstrate that EPAC1 and EPAC2 regulate cancer progression depending on different mechanisms. siEPAC2-AD is more potent compared to siEPAC1-AD in suppressing cell proliferation by altering energy metabolism. Hence, this siEPACs-AD system not only enhances the drug specificity and reduces potential side effects, but also provides a new strategy for precision pharmaceutical control of the cAMP/PKA/EPAC signaling pathway for cancer treatment. Keywords: EPAC1; EPAC2; siRNA; amphiphilic dendrimer; cAMP signaling; cancer Citation Format: Wanjun Yuan, Zhengyin Gao, Ling Peng, Leo Tsz On Lee. Amphiphilic dendrimer-mediated siRNA delivery for precision regulation of cAMP pathway in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3168.

Aptamer-Targeted Dendrimersomes Assembled from Azido-Modified Janus Dendrimers "Clicked" to DNA.

Amphiphilic Janus dendrimers (JDs), synthetic alternatives to lipids, have the potential to expand the scope of nanocarrier delivery systems. JDs self-assemble into vesicles called dendrimersomes, encapsulate both hydrophobic cargo and nucleic acids, and demonstrate enhanced stability in comparison to lipid nanoparticles (LNPs). Here, we report the ability to enhance the cellular uptake of Janus dendrimersomes using DNA aptamers. Azido-modified JDs were synthesized and conjugated to alkyne-modified DNAs using copper-catalyzed azide alkyne cycloaddition. DNA-functionalized JDs form nanometer-sized dendrimersomes in aqueous solution via thin film hydration. These vesicles, now displaying short DNAs, are then hybridized to transferrin receptor binding DNA aptamers. Aptamer-targeted dendrimersomes show improved cellular uptake as compared to control vesicles via fluorescence microscopy and flow cytometry. This work demonstrates the versatility of using click chemistry to conjugate functionalized JDs with biologically relevant molecules and the feasibility of targeting DNA-modified dendrimersomes for drug delivery applications.

The Constitutional Isomerism of One-Component Ionizable Amphiphilic Janus Dendrimers Orchestrates the Total and Targeted Activities of mRNA Delivery.

Constitutional isomerism has been previously demonstrated by one of our laboratories to represent a powerful design strategy for the elaboration of complex functional self-organizations. Here we report the design, synthesis, and characterization of 14 positional, skeletal, and functional constitutional isomeric one-component, multifunctional, sequence-defined, amphiphilic ionizable Janus dendrimers (IAJDs). Their coassembly by simple injection with luciferase mRNA (Luc-mRNA) to form dendrimersome nanoparticles (DNPs) was studied. Subsequently, the resulting DNPs were employed to investigate, with screening experiments, the delivery of Luc-mRNA in vivo. Constitutional isomerism was shown to produce changes of up to two orders of magnitude of the total-body luciferase activity and targeted luciferase activity to the spleen and liver, of up to three orders of magnitude difference in targeted luciferase activity to the lungs and up to six orders of magnitude to lymph nodes. These results indicate that constitutional isomerism may represent not only a simple but also an important synthetic strategy that most probably may impact the activity of all components of synthetic vectors used in RNA-based nanomedicine, including in mRNA vaccines and therapeutics.

Amphiphilic Dendrimer as Potent Antibacterial against Drug-Resistant Bacteria in Mouse Models of Human Infectious Diseases.

Modern medicine continues to struggle against antibiotic-resistant bacterial pathogens. Among the pathogens of critical concerns are the multidrug-resistant (MDR) Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae. These pathogens are major causes of nosocomial infections among immunocompromised individuals, involving major organs such as lung, skin, spleen, kidney, liver, and bloodstream. Therefore, novel approaches are direly needed. Recently, we developed an amphiphilic dendrimer DDC18-8A exhibiting high antibacterial and antibiofilm efficacy in vitro. DDC18-8A is composed of a long hydrophobic alkyl chain and a small hydrophilic poly(amidoamine) dendron bearing amine terminals, exerting its antibacterial activity by attaching and inserting itself into bacterial membranes to trigger cell lysis. Here, we examined the pharmacokinetics and in vivo toxicity as well as the antibacterial efficacy of DDC18-8A in mouse models of human infectious diseases. Remarkably, DDC18-8A significantly reduced the bacterial burden in mouse models of acute pneumonia and bacteremia by P. aeruginosa, methicillin-resistant S. aureus (MRSA), and carbapenem-resistant K. pneumoniae and neutropenic soft tissue infection by P. aeruginosa and MRSA. Most importantly, DDC18-8A outperformed pathogen-specific antibiotics against all three pathogens by achieving a similar bacterial clearance at 10-fold lower therapeutic concentrations. In addition, it showed superior stability and biodistribution in vivo, with excellent safety profiles yet without any observable abnormalities in histopathological analysis of major organs, blood serum biochemistry, and hematology. Collectively, we provide strong evidence that DDC18-8A is a promising alternative to the currently prescribed antibiotics in addressing challenges associated with nosocomial infections by MDR pathogens.

From Frank-Kasper, Quasicrystals, and Biological Membrane Mimics to Reprogramming In Vivo the Living Factory to Target the Delivery of mRNA with One-Component Amphiphilic Janus Dendrimers.

This Perspective is dedicated to the 25th Anniversary of Biomacromolecules. It provides a personal view on the developing field of the polymer and biology interface over the 25 years since the journal was launched by the American Chemical Society (ACS). This Perspective is meant to bridge an article published in the first issue of the journal and recent bioinspired developments in the laboratory of the corresponding author. The discovery of supramolecular spherical helices self-organizing into Frank-Kasper and quasicrystals as models of icosahedral viruses, as well as of columnar helical assemblies that mimic rodlike viruses by supramolecular dendrimers, is briefly presented. The transplant of these assemblies from supramolecular dendrimers to block copolymers, giant surfactants, and other self-organized soft matter follows. Amphiphilic self-assembling Janus dendrimers and glycodendrimers as mimics of biological membranes and their glycans are discussed. New concepts derived from them that evolved in the in vivo targeted delivery of mRNA with the simplest one-component synthetic vector systems are introduced. Some synthetic methodologies employed during the synthesis and self-assembly are explained. Unraveling bioinspired applications of novel materials concludes this brief 25th Anniversary Perspective of Biomacromolecules.

Amphiphilic Janus dendrimer-stabilized Au, Ag and Pd nanoparticles for the reduction of 4-nitrophenol and Suzuki-Miyaura cross-coupling reactions

Dendrimers with symmetrical 3D structures can be designed with various interior or exterior functional groups, which has been regarded as good stabilizers for various metal nanoparticles in catalysis. Nevertheless, Janus dendrimers with asymmetric structures are hardly researched to load metal nanoparticle catalysts. Here, an amphiphilic Janus dendrimer is used to stabilize metal (Au, Ag and Pd) nanoparticles, whose catalytic activities are also investigated. Au, Ag and Pd nanoparticles have the average diameters of 2.6 ± 2.0 nm, 5.8 ± 3.0 nm and 2.0 ± 1.0 nm, respectively, and show clear lattice fringes. Au and Pd nanoparticles are observed to have significantly higher catalytic performance than that of Ag nanoparticles in the 4-nitrophenol reduction, and Pd nanoparticles possess the highest catalytic activity (TOF: 2250 h−1). In addition, Pd nanoparticles are also highly active in the Suzuki-Miyaura reactions with low catalyst loading (50 ppm) and high TOF (2475 h−1) and show good applicability to tolerate various substituents.

Epichlorohydrin-based CuAAC dendrimers with a calix[4]arene core and polar hydroxyl/oxyethyl terminal groups: synthesis, aggregation and use in catalysis

1st and 2nd generation amphiphilic dendrimers were obtained. Spherical palladium nanodendrites stabilized by amphiphilic dendrimers show excellent catalytic activities in coupling and reduction of aromatics in water.

Molecular interactions driving the complexation of rose bengal by triazine-carbosilane dendrons.

Amphiphilic dendrons or Janus dendrimers self-assembling into nanoscale vesicles offer promising avenues for drug delivery. Triazine-carbosilane dendrons have shown great potential for the intracellular delivery of rose bengal, additionally enhancing its phototoxic activity through non-covalent interactions. Thus, understanding the complexation dynamics between dendrons and photosensitizers is crucial for the development of efficient drug carriers. To address this issue, we employed computational modelling and experimental approaches to investigate the formation of stable complexes between triazine-carbosilane dendrons and rose bengal. Molecular dynamics simulations revealed rapid and stable complex formation, primarily driven by electrostatic interactions, particularly under acidic conditions. Conformational dynamics of dendrons significantly influenced complex stability and configurational entropy. Experimental validation confirmed dendron-rose bengal complexation, with pH influencing stoichiometry and thermodynamics of complexes. Overall, our study underscores the critical role of electrostatic interactions in mediating dendron-drug complexation and highlights the importance of pH in modulating complex formation dynamics.

Self-assembly of amphiphilic dendrimers investigated by standard, cryo and liquid TEM

Self-assembly of amphiphilic dendrimers investigated by standard, cryo and liquid TEM

Bifunctional Carbosilane Dendrimers for the Design of Multipurpose Hydrogels with Antibacterial Action.

The emergence of antibiotic resistance is a serious global health problem. There is an incessant demand for new antimicrobial drugs and materials that can address this global issue from different angles. Dendritic hydrogels have appeared as a promising strategy. A family of bifunctional amphiphilic carbosilane dendrimers was designed and employed as nanosized cross-linking points for the synthesis of high-swelling hydrogels using the highly efficient Thiol-Ene click reaction for their preparation. Both stoichiometric and off-stoichiometric conditions were studied, generating hydrogels with pendant hydroxyl or alkene moieties. These hydrogels were found to be tunable antibacterial materials. They can easily be postmodified with relevant antibiotic moieties through covalent attachment on the hydroxyl or alkene pendant groups, generating ammonium-decorated networks with temperature and pH-responsive properties. Additionally, they can efficiently encapsulate drugs with poor solubility in water, like ciprofloxacin, and perform a sustained release over time, as demonstrated in preliminary assays against Staphylococcus aureus.

Modular Self-Assembling Dendrimer Nanosystems for Magnetic Resonance and Multimodality Imaging of Tumors.

Bioimaging is a powerful tool for diagnosing tumors but remains limited in terms of sensitivity and specificity. Nanotechnology-based imaging probes able to accommodate abundant imaging units with different imaging modalities are particularly promising for overcoming these limitations. In addition, the nanosized imaging agents can specifically increase the contrast of tumors by exploiting the enhanced permeability and retention effect. A proof-of-concept study is performed on pancreatic cancer to demonstrate the use of modular amphiphilic dendrimer-based nanoprobes for magnetic resonance (MR) imaging (MRI) or MR/near-infrared fluorescence (NIRF) multimodality imaging. Specifically, the self-assembly of an amphiphilic dendrimer bearing multiple Gd3+ units at its terminals, generates a nanomicellar agent exhibiting favorable relaxivity for MRI with a good safety profile. MRI reveals an up to two-fold higher contrast enhancement in tumors than in normal muscle. Encapsulating the NIRF dye within the core of the nanoprobe yields an MR/NIRF bimodal imaging agent for tumor detection that is efficient both for MRI, at Gd3+ concentrations 1/10 the standard clinical dose, and for NIRF imaging, allowing over two-fold stronger fluorescence intensities. These self-assembling dendrimer nanosystems thus constitute effective probes for MRI and MR/NIRF multimodality imaging, offering a promising nanotechnology platform for elaborating multimodality imaging probes in biomedical applications.

Phase behavior of mixtures of hard colloids and soft coarse-grained macromolecules.

Effective "soft" interactions between macromolecules such as polymers, amphiphilic dendrimers, and suitably designed DNA based dendritic molecules have been shown to be purely repulsive and non-diverging. We report the structure and phase behavior of a mixture of hard colloids and soft coarse-grained macromolecules. Through the use of Reference Interaction Site Model theory and molecular dynamics simulations we find that hard colloids and soft macromolecules act as depletants toward each other, generating a medium-induced effective attraction. This effective attraction leads to the formation of non-dispersed phases at high densities. At low and high fractions of hard colloids the system macrophase separates into two disparate regions of hard colloids and soft macromolecules. However, this system microphase separates into a hard-rich and soft-rich self-assembled domains at intermediate compositions. The formation of microphase separated structure in this system of isotropic, disconnected, and purely repulsive colloids is surprising and quite novel. This behavior is likely due to a softening of the interface between hard-rich and soft-rich self-assembled domains. Molecular dynamics simulations have revealed that the microphase separated state has an overall disordered bicontinuous morphology. The hard-rich domain forms an ordered FCC structure and the soft-rich domain forms a disordered cluster-fluid, making the structure simultaneously ordered and disordered.