A Family of Hierarchically Self-Assembling Linear-Dendritic Hybrid Polymers for Highly Efficient Targeted Gene Delivery

Polymeric nanoparticles for DNA vaccine-based cancer immunotherapy: a review

Cancer is one of the leading causes of death and mortality in the world. There is an essential need to develop new drugs or therapeutic approaches to manage treatment-resistant cancers. Cancer immunotherapy is a type of cancer treatment that uses the power of the body's immune system to prevent, control, and eliminate cancer. One of the materials used as a vaccine in immunotherapy is DNA. The application of polymeric nanoparticles as carriers for DNA vaccines could be an effective therapeutic approach to activate immune responses and increase antigen presentation efficiency. Various materials have been used as polymeric nanoparticles, including: chitosan, poly (lactic-co-glycolic acid), Polyethylenimine, dendrimers, polypeptides, and polyesters. Application of these polymer nanoparticles has several advantages, including increased vaccine delivery, enhanced antigen presentation, adjuvant effects, and more sustainable induction of the immune system. Besides many clinical trials and commercial products that were developed based on polymer nanoparticles, there is still a need for more comprehensive studies to increase the DNA vaccine efficiency in cancer immunotherapy using this type of carrier.

A Fluorophore-Labeled Lysine Dendrimer with an Oxo-Anion-Binding Motif for Tracking Gene Transfection

A transfection vector based on a peptide dendrimer (1) has been developed and its abilities for DNA binding and transport have been investigated. By attaching a fluorophore to the vector system (1*), several steps in the transfection process could be monitored directly. As DLS and AFM studies showed, the labeled vector 1* condensed DNA into tightly packed aggregates able to enter eukaryotic cells. Co-localization experiments revealed that the ligand/plasmid complex is taken up by the endosomal pathway followed by an endosomal escape or lysosomal degradation. Afterwards, the plasmid DNA seems to enter the nucleus due to a breakdown of the nuclear envelope during mitosis, as only cells that have recently undergone mitosis showed H2B-GFP expression.

Screening Libraries to Discover Molecular Design Principles for the Targeted Delivery of mRNA with One-Component Ionizable Amphiphilic Janus Dendrimers Derived from Plant Phenolic Acids

Viral and synthetic vectors to deliver nucleic acids were key to the rapid development of extraordinarily efficient COVID-19 vaccines. The four-component lipid nanoparticles (LNPs), containing phospholipids, PEG-conjugated lipids, cholesterol, and ionizable lipids, co-assembled with mRNA via a microfluidic technology, are the leading nonviral delivery vector used by BioNTech/Pfizer and Moderna to access COVID-19 mRNA vaccines. LNPs exhibit a statistical distribution of their four components when delivering mRNA. Here, we report a methodology that involves screening libraries to discover the molecular design principles required to realize organ-targeted mRNA delivery and mediate activity with a one-component ionizable multifunctional amphiphilic Janus dendrimer (IAJD) derived from plant phenolic acids. IAJDs co-assemble with mRNA into monodisperse dendrimersome nanoparticles (DNPs) with predictable dimensions, via the simple injection of their ethanol solution in a buffer. The precise location of the functional groups in one-component IAJDs demonstrated that the targeted organs, including the liver, spleen, lymph nodes, and lung, are selected based on the hydrophilic region, while activity is associated with the hydrophobic domain of IAJDs. These principles, and a mechanistic hypothesis to explain activity, simplify the synthesis of IAJDs, the assembly of DNPs, handling, and storage of vaccines, and reduce price, despite employing renewable plant starting materials. Using simple molecular design principles will lead to increased accessibility to a large diversity of mRNA-based vaccines and nanotherapeutics.

High-throughput screening of nanoparticles in drug delivery

The use of pharmacologically active compounds to manage and treat diseases is of utmost relevance in clinical practice. It is well recognized that spatial-temporal control over the delivery of these biomolecules will greatly impact their pharmacokinetic profile and ultimately their therapeutic effect. Nanoparticles (NPs) prepared from different materials have been tested successfully in the clinic for the delivery of several biomolecules including non-coding RNAs (siRNA and miRNA) and mRNAs. Indeed, the recent success of mRNA vaccines is in part due to progress in the delivery systems (NP based) that have been developed for many years. In most cases, the identification of the best formulation was done by testing a small number of novel formulations or by modification of pre-existing ones. Unfortunately, this is a low throughput and time-consuming process that hinders the identification of formulations with the highest potential. Alternatively, high-throughput combinatorial design of NP libraries may allow the rapid identification of formulations with the required release and cell/tissue targeting profile for a given application. Combinatorial approaches offer several advantages over conventional methods since they allow the incorporation of multiple components with varied chemical properties into materials, such as polymers or lipid-like materials, that will subsequently form NPs by self-assembly or chemical conjugation processes. The current review highlights the impact of high-throughput in the development of more efficient drug delivery systems with enhanced targeting and release kinetics. It also describes the current challenges in this research area as well as future directions.

Long-Term Retarded Release for the Proteasome Inhibitor Bortezomib through Temperature-Sensitive Dendritic Glycopolymers as Drug Delivery System from Calcium Phosphate Bone Cement

For the local treatment of bone defects, highly adaptable macromolecular architectures are still required as drug delivery system (DDS) in solid bone substitute materials. Novel DDS fabricated by host-guest interactions between β-cyclodextrin-modified dendritic glycopolymers and adamantane-modified temperature-sensitive polymers for the proteasome inhibitor bortezomib (BZM) is presented. These DDS induce a short- and long-term (up to two weeks) retarded release of BZM from calcium phosphate bone cement (CPC) in comparison to a burst release of the drug alone. Different release parameters of BZM/DDS/CPC are evaluated in phosphate buffer at 37 °C to further improve the long-term retarded release of BZM. This is achieved by increasing the amount of drug (50-100 µg) and/or DDS (100-400 µg) versus CPC (1 g), by adapting the complexes better to the porous bone cement environment, and by applying molar ratios of excess BZM toward DDS with 1:10, 1:25, and 1:100. The temperature-sensitive polymer shells of BZM/DDS complexes in CPC, which allow drug loading at room temperature but are collapsed at body temperature, support the retarding long-term release of BZM from DDS/CPC. Thus, the concept of temperature-sensitive DDS for BZM/DDS complexes in CPC works and matches key points for a local therapy of osteolytic bone lesions.

A Mixed-Surface Polyamidoamine Dendrimer for In Vitro and In Vivo Delivery of Large Plasmids

Drug delivery to the brain is highly hindered by the presence of the blood-brain barrier (BBB), which prevents the entry of many potential drugs/biomolecules into the brain. One of the current strategies to achieve gene therapy for neurodegenerative diseases involves direct injection of a viral vector into the brain. There are various disadvantages of viral vectors, including limitations of cargo size and safety concerns. Nanomolecules, such as dendrimers, serve as an excellent alternative to viral delivery. In this study, as proof-of-concept, we used a surface-modified dendrimer complex and delivered large plasmids to cells in vitro and in vivo in healthy rats via intracranial injection. The dendrimers were biodegradable by chemicals found within cells and toxicity assays revealed that the modified dendrimers were much less toxic than unmodified amine-surface dendrimers. As mentioned in our previous publication, these dendrimers with appropriately modified surfaces are safe, can deliver large plasmids to the brain, and can overcome the cargo size limitations associated with viral vectors. The biocompatibility of this dendritic nanomolecule and the ability to finely tune its surface chemistry provides a gene delivery system that could facilitate future in vivo cellular reprograming and other gene therapies.

Experiments and Simulations of Complex Sugar-Based Coil-Brush Block Polymer Nanoassemblies in Aqueous Solution

In this work, we investigated the fundamental molecular parameters that guide the supramolecular assembly of glucose-based amphiphilic coil-brush block polymers in aqueous solution and elucidated architecture-morphology relationships through experimental and simulation tools. Well-defined coil-brush polymers were synthesized through ring-opening polymerizations (ROP) of glucose carbonates to afford norbornenyl-functionalized poly(glucose carbonate) (NB-PGC) macromonomers, followed by sequential ring-opening metathesis polymerizations (ROMP) of norbornene N-hydroxysuccinimidyl (NHS) esters and the NB-PGC macromonomers. Variation of the macromonomer length and grafting through ROMP conditions allowed for a series of coil-brush polymers to be synthesized with differences in the brush and coil dimensions, independently, where the side chain graft length and brush backbone were used to tune the brush, and the coil block length was used to vary the coil. Hydrolysis of the NHS moieties gave the amphiphilic coil-brush polymers, where the hydrophilic-hydrophobic ratios were dependent on the brush and coil relative dimensions. Experimental assembly in solution was studied and found to yield a variety of structurally dependent nanostructures. Simulations were conducted on the solution assembly of coil-brush polymers, where the polymers were represented by a coarse-grained model and the solvent was represented implicitly. There is qualitative agreement in the phase diagrams obtained from simulations and experiments, in terms of the morphologies of the assembled nanoscopic structures achieved as a function of coil-brush design parameters ( e.g., brush and coil lengths, composition). The simulations further showed the chain conformations adopted by the coil-brush polymers and the packing within these assembled nanoscopic structures. This work enables the predictive design of nanostructures from this glucose-based coil-brush polymer platform while providing a fundamental understanding of interactions within solution assembly of complex polymer building blocks.

Hyaluronic acid/poly(ethylenimine) polyelectrolyte multilayer coatings for siRNA-mediated local gene silencing

Local gene delivery systems utilizing RNA interference technology are a promising approach for therapeutic applications where site-specific release of agents is desired. Polyelectrolyte multilayers (PEMs) can be constructed using the layer-by-layer (LbL) technique and serve as a depot for bioactive substances, which can then be released in a controlled manner. Multilayers of hyaluronic acid/poly(ethylenimine) HA/PEI were built up with different numbers of bilayers and PEI-siRNA particles were embedded in bioactive layers for gene silencing. The increase of the bilayers and the release of siRNA particles were demonstrated by fluorescence intensity measurement with a fluorescence reader. Two different LbL techniques were tested for the reduction of ICAM–1 expression in EA.hy926: PEM build-up by dipping or drying steps, respectively. Herein, the drying technique of the bioactive layers with ICAM siRNA mediated a significant reduction of the ICAM–1 expression from 3 to 24 bilayers. The fluorescent siRNA release study and the re-culturing of the HA/PEI films demonstrated a release of the transfection particles within the first hour. The advantage of dried built-up PEMs compared to a dried monolayer of PEI-siRNA particles with the same siRNA concentration was a significant higher amount of viable cells.

Novel peptide-dendrimer/lipid/oligonucleotide ternary complexes for efficient cellular uptake and improved splice-switching activity

Despite the advances in gene therapy and in oligonucleotide (ON) chemistry, efficient cellular delivery remains an obstacle. Most current transfection reagents suffer from low efficacy or high cytotoxicity. In this report, we describe the synergism between lipid and dendrimer delivery vectors to enhance the transfection efficiency, while avoiding high toxicity. We screened a library of 20 peptide dendrimers representing three different generations and evaluated their capability to deliver a single-stranded splice-switching ON after formulating with lipids (DOTMA/DOPE). The transfection efficiency was analyzed in 5 reporter cell lines, in serum-free and serum conditions, and with 5 different formulation protocols. All formulations displayed low cytotoxicity to the majority of the tested cell lines. The complex sizes were < 200 nm; particle size distributions of effective mixtures were < 80 nm; and, the zeta potential was dependent on the formulation buffer used. The best dendrimer enhanced transfection in a HeLa reporter cell line by 30-fold compared to untreated cells under serum-free conditions. Interestingly, addition of sucrose to the formulation enabled - for the first time - peptide dendrimers/lipid complexes to efficiently deliver splice-switching ON in the presence of serum, reaching 40-fold increase in splice switching. Finally, in vivo studies highlighted the potential of these formulae to change the biodistribution pattern to be more towards the liver (90% of injected dose) compared to the kidneys (5% of injected dose) or to unformulated ON. This success encourages further development of peptide dendrimer complexes active in serum and future investigation of mechanisms behind the influence of additives on transfection efficacy.

Drug Delivery Systems from Self-Assembly of Dendron-Polymer Conjugates †

This review highlights the utilization of dendron-polymer conjugates as building blocks for the fabrication of nanosized drug delivery vehicles. The examples given provide an overview of the evolution of these delivery platforms, from simple micellar containers to smart stimuli- responsive drug delivery systems through their design at the macromolecular level. Variations in chemical composition and connectivity of the dendritic and polymeric segments provide a variety of self-assembled micellar nanostructures that embody desirable attributes of viable drug delivery systems.

Electrostatically assembled dendrimer complex with a high-affinity protein binder for targeted gene delivery

Although a variety of non-viral gene delivery systems have been developed, they still suffer from low efficiency and specificity. Herein, we present the assembly of a dendrimer complex comprising a DNA cargo and a targeting moiety as a new format for targeted gene delivery. A PAMAM dendrimer modified with histidine and arginine (HR-dendrimer) was used to enhance the endosomal escape and transfection efficiency. An EGFR-specific repebody, composed of leucine-rich repeat (LRR) modules, was employed as a targeting moiety. A polyanionic peptide was genetically fused to the repebody, followed by incubation with an HR-dendrimer and a DNA cargo to assemble the dendrimer complex through an electrostatic interaction. The resulting dendrimer complex was shown to deliver a DNA cargo with high efficiency in a receptor-specific manner. An analysis using a confocal microscope confirmed the internalization of the dendrimer complex and subsequent dissociation of a DNA cargo from the complex. The present approach can be broadly used in a targeted gene delivery in many areas.

Development of cholate conjugated hybrid polymeric micelles for FXR receptor mediated effective site-specific delivery of paclitaxel

The aim of the present study was to explore the tumor targeting potential of a cholic acid (CA) conjugated polymeric micelle system for the effective delivery of paclitaxel (PTX).

Biodegradable PEG–dendritic block copolymers: synthesis and biofunctionality assessment as vectors of siRNA

New hybrid-biodegradable PEG–dendritic block copolymers as versatile delivery vectors for biomedical applications. Here, their biofunctionality as siRNA vectors is presented.

Tweaking dendrimers and dendritic nanoparticles for controlled nano-bio interactions: potential nanocarriers for improved cancer targeting

Nanoparticles have shown great promise in the treatment of cancer, with a demonstrated potential in targeted drug delivery. Among a myriad of nanocarriers that have been recently developed, dendrimers have attracted a great deal of scientific interests due to their unique chemical and structural properties that allow for precise engineering of their characteristics. Despite this, the clinical translation of dendrimers has been hindered due to their drawbacks, such as scale-up issues, rapid systemic elimination, inefficient tumor accumulation and limited drug loading. In order to overcome these limitations, a series of reengineered dendrimers have been recently introduced using various approaches, including: (i) modifications of structure and surfaces; (ii) integration with linear polymers and (iii) hybridization with other types of nanocarriers. Chemical modifications and surface engineering have tailored dendrimers to improve their pharmacokinetics and tissue permeation. Copolymerization of dendritic polymers with linear polymers has resulted in various amphiphilic copolymers with self-assembly capabilities and improved drug loading efficiencies. Hybridization with other nanocarriers integrates advantageous characteristics of both systems, which includes prolonged plasma circulation times and enhanced tumor targeting. This review provides a comprehensive summary of the newly emerging drug delivery systems that involve reengineering of dendrimers in an effort to precisely control their nano-bio interactions, mitigating their inherent weaknesses.

Guanidiniocarbonyl pyrrole (GCP) conjugated PAMAM-G2, a highly efficient vector for gene delivery: the importance of DNA condensation

A novel hybrid compound1efficiently shuttles genetic material into HeLa cells at concentrations as low as 0.6 μM, whereas the parent compound PAMAM-G2 is ineffective even at 200 μM.

Structural mediation on polycation nanoparticles by sulfadiazine to enhance DNA transfection efficiency and reduce toxicity

Reducing the toxicity while maintaining high transfection efficiency is an important issue for cationic polymers as gene carriers in clinical application. In this paper, a new zwitterionic copolymer, polycaprolactone-g-poly(dimethylaminoethyl methyacrylate-co-sulfadiazine methacrylate) (PC-SDZ) with unique pH-sensitivity, was designed and prepared. The incorporation of sulfadiazine into poly(dimethylaminoethyl methacrylate) (PDMAEMA) chains successfully mediates the surface properties including compacter shell structure, lower density of positive charges, stronger proton buffer capability, and enhanced hydrophobicity, which lead to reduction in toxicity and enhancements in stability, cellular uptake, endosome escape, and transfection efficiency for the PC-SDZ2 nanoparticles (NPs)/DNA complexes. Excellent transfection efficiency at the optimal N/P ratio of 10 was observed for PC-SDZ2 NPs/DNA complexes, which was higher than that of the commercial reagent-branched polyethylenimine (PEI). The cytotoxicity was evaluated by CCK8 measurement, and the results showed significant reduction in cytotoxicity even at high concentration of complexes after sulfadiazine modification. Therefore, this work may demonstrate a new way of structural mediation of cationic polymer carriers for gene delivery with high efficiency and low toxicity.

The Present and the Future of Degradable Dendrimers and Derivatives in Theranostics

Interest in dendrimer-based nanomedicines has been growing recently, as it is possible to precisely manipulate the molecular weight, chemical composition, and surface functionality of dendrimers, tuning their properties according to the desired biomedical application. However, one important concern about dendrimer-based therapeutics remains-the nondegradability under physiological conditions of the most commonly used dendrimers. Therefore, biodegradable dendrimers represent an attractive class of nanomaterials, since they present advantages over conventional nondegradable dendrimers regarding the release of the loaded molecules and the prevention of bioaccumulation of synthetic materials and subsequent cytotoxicity. Here, we present an overview of the state-of-the-art of the design of biodegradable dendritic structures, with particular focus on the hurdles regarding the use of these as vectors of drugs and nucleic acids, as well as macromolecular contrast agents.

Dendritic glycopolymers based on dendritic polyamine scaffolds: view on their synthetic approaches, characteristics and potential for biomedical applications

The potential of dendritic glycopolymers based on dendritic polyamine scaffolds for biomedical applications is presented and compared with that of the structurally related anti-adhesive dendritic glycoconjugates.

Predicting cytotoxicity of PAMAM dendrimers using molecular descriptors

The use of data mining techniques in the field of nanomedicine has been very limited. In this paper we demonstrate that data mining techniques can be used for the development of predictive models of the cytotoxicity of poly(amido amine) (PAMAM) dendrimers using their chemical and structural properties. We present predictive models developed using 103 PAMAM dendrimer cytotoxicity values that were extracted from twelve cancer nanomedicine journal articles. The results indicate that data mining and machine learning can be effectively used to predict the cytotoxicity of PAMAM dendrimers on Caco-2 cells.

Poly(2-oxazoline)-based nanogels as biocompatible pseudopolypeptide nanoparticles

Hydrophilic nanogels based on partially hydrolyzed poly(2-ethyl-2-oxazoline) were synthesized in dilute aqueous media in the presence of 1,6-hexanediol diglycidyl ether as a cross-linker. Nanogel formation was monitored by DLS and HSQC NMR spectroscopy, and the final nano-objects were characterized by DLS, TEM, AFM, and NanoSight analyses. Nanogels with a hydrodynamic radius of 78 nm exhibiting a slight positive surface charge were obtained. MTS assays (cell metabolic activity test) evidenced that nanogels were nontoxic in the investigated concentration range (i.e., 0.1 to 400 μg/mL) and that no specific interaction with bovine serum albumin was observed.

Bio-inspired supramolecular hybrid dendrimers self-assembled from low-generation peptide dendrons for highly efficient gene delivery and biological tracking

Currently, supramolecular self-assembly of dendrons and dendrimers emerges as a powerful and challenging strategy for developing sophisticated nanostructures with excellent performances. Here we report a supramolecular hybrid strategy to fabricate a bio-inspired dendritic system as a versatile delivery nanoplatform. With a rational design, dual-functionalized low-generation peptide dendrons (PDs) self-assemble onto inorganic nanoparticles via coordination interactions to generate multifunctional supramolecular hybrid dendrimers (SHDs). These SHDs exhibit well-defined nanostructure, arginine-rich peptide corona, and fluorescent signaling properties. As expected, our bio-inspired supramolecular hybrid strategy largely enhances the gene transfection efficiency of SHDs approximately 50 000-fold as compared to single PDs at the same R/P ratio. Meanwhile the bio-inspired SHDs also (i) provide low cytotoxicity and serum resistance in gene delivery; (ii) provide inherent fluorescence for tracking intracellular pathways including cellular uptake, endosomal escape, and gene release; and (iii) work as an alternative reference for monitoring desired protein expression. More importantly, in vivo animal experiments demonstrate that SHDs offer considerable gene transfection efficiency (in muscular tissue and in HepG2 tumor xenografts) and real-time bioimaging capabilities. These SHDs will likely stimulate studies on bio-inspired supramolecular hybrid dendritic systems for biomedical applications both in vitro and in vivo.

Sandwich-type Au-PEI/DNA/PEI-Dexa nanocomplex for nucleus-targeted gene delivery in vitro and in vivo

Many synthetic Au-based cationic nanoparticles (AuNPs) for nonviral gene delivery show high efficiency in vitro, but their excessive charge density, harsh reducing conditions, and nontarget delivery prevent their application in vivo. Herein, we constructed a sandwich-type layered polyethylenimine (PEI)-coated gold nanocomposite outerlaid with a nucleus-targeted Dexamethasone (Dexa), namely, Au-PEI/DNA/PEI-Dexa nanocomplex, for DNA delivery system using a low molecular weight PEI as a mild reducing agent. The nucleus-targeting Au-PEI/DNA/PEI-Dexa nanocomplex with low positive charge and low cytotoxicity condensed DNA and protected from enzymatic degradation. In vitro transfection studies demonstrated that Au-PEI/DNA/PEI-Dexa nanocomplex exhibited much more efficient nucleus transfection than Au-PEI/DNA/PEI without nucleus-targeted residues and commercially available PEI 25 kDa due to the Dexa targeting of the nucleus. Furthermore, the nanocomplex markedly transfected pTRAIL (TRAIL = tumor-necrosis-factor-related apoptosis-inducing ligand) to tumors in vivo and subsequently inhibited the tumor growth with minimal side effects. These findings suggest that nucleus-targeting Au-PEI/DNA/PEI-Dexa ternary complexes have promising potential in gene delivery.

GATG dendrimers and PEGylated block copolymers: from synthesis to bioapplications

Dendrimers are synthetic macromolecules composed of repetitive layers of branching units that emerge from a central core. They are characterized by a tunable size and precise number of peripheral groups which determine their physicochemical properties and function. Their high multivalency, functional surface, and globular architecture with diameters in the nanometer scale makes them ideal candidates for a wide range of applications. Gallic acid-triethylene glycol (GATG) dendrimers have attracted our attention as a promising platform in the biomedical field because of their high tunability and versatility. The presence of terminal azides in GATG dendrimers and poly(ethylene glycol) (PEG)-dendritic block copolymers allows their efficient functionalization with a variety of ligands of biomedical relevance including anionic and cationic groups, carbohydrates, peptides, or imaging agents. The resulting functionalized dendrimers have found application in drug and gene delivery, as antiviral agents and for the treatment of neurodegenerative diseases, in diagnosis and as tools to study multivalent carbohydrate recognition and dendrimer dynamics. Herein, we present an account on the preparation and recent applications of GATG dendrimers in these fields.

Advanced Materials for Gene Delivery

Gene therapy is a widespread and promising treatment of many diseases resulting from genetic disorders, infections and cancer. The feasibility of the gene therapy is mainly depends on the development of appropriate method and suitable vectors. For an efficient gene delivery, it is very important to use a carrier that is easy to produce, stable, non-oncogenic and non-immunogenic. Currently most of the vectors actually suffer from many problems. Therefore, the ideal gene therapy delivery system should be developed that can be easily used for highly efficient delivery and able to maintain long-term gene expression, and can be applicable to basic research as well as clinical settings. This article provides a brief over view on the concept and aim of gene delivery, the different gene delivery systems and use of different materials as a carrier in the area of gene therapy.

Responsive linear-dendritic block copolymers

The combination of dendritic and linear polymeric structures in the same macromolecule opens up new possibilities for the design of block copolymers and for applications of functional polymers that have self-assembly properties. There are three main strategies for the synthesis of linear-dendritic block copolymers (LDBCs) and, in particular, the emergence of click chemistry has made the coupling of preformed blocks one of the most efficient ways of obtaining libraries of LDBCs. In these materials, the periphery of the dendron can be precisely functionalised to obtain functional LDBCs with self-assembly properties of interest in different technological areas. The incorporation of stimuli-responsive moieties gives rise to smart materials that are generally processed as self-assemblies of amphiphilic LDBCs with a morphology that can be controlled by an external stimulus. Particular emphasis is placed on light-responsive LDBCs. Furthermore, a brief review of the biomedical or materials science applications of LDBCs is presented.

Nonviral gene delivery with dendritic self-assembling architectures

In this review, we outline the concept and applicability of self-assembling dendrimers for gene-delivery applications. Low-molecular-weight, well-defined cationic dendritic arrays which have been modified with hydrophobic domains can form self-organized multivalent systems that have significant advantages over nonassembling, high-molecular-weight/polymeric gene vectors. Particular structural variations have been highlighted with respect to the individual components of the displayed dendritic amphiphiles, namely, the employed amine termini, the hydrophobic segment, the size of the dendritic array, and the integration of special features such as targeting ability and cleavability/degradability, which can all have a crucial effect on gene-transfection efficiencies. Accordingly, the scientific efforts to create new synthetic gene-delivery vectors to act as promising in vivo transfection agents in the future will be presented and discussed here.

Automatic extraction of nanoparticle properties using natural language processing: NanoSifter an application to acquire PAMAM dendrimer properties

In this study, we demonstrate the use of natural language processing methods to extract, from nanomedicine literature, numeric values of biomedical property terms of poly(amidoamine) dendrimers. We have developed a method for extracting these values for properties taken from the NanoParticle Ontology, using the General Architecture for Text Engineering and a Nearly-New Information Extraction System. We also created a method for associating the identified numeric values with their corresponding dendrimer properties, called NanoSifter.

We demonstrate that our system can correctly extract numeric values of dendrimer properties reported in the cancer treatment literature with high recall, precision, and f-measure. The micro-averaged recall was 0.99, precision was 0.84, and f-measure was 0.91. Similarly, the macro-averaged recall was 0.99, precision was 0.87, and f-measure was 0.92. To our knowledge, these results are the first application of text mining to extract and associate dendrimer property terms and their corresponding numeric values.

Convenient divergent synthesis of linear-dendron block polyphosphoesters via acyclic diene metathesis polymerization

ADMET polymerization was successfully applied for the synthesis of linear-dendritic polyphosphoester structures by using macromolecular chain stoppers.

Double-degradable responsive self-assembled multivalent arrays--temporary nanoscale recognition between dendrons and DNA

This article reports self-assembling dendrons which bind DNA in a multivalent manner. The molecular design directly impacts on self-assembly which subsequently controls the way these multivalent nanostructures bind DNA--this can be simulated by multiscale modelling. Incorporation of an S-S linkage between the multivalent hydrophilic dendron and the hydrophobic units responsible for self-assembly allows these structures to undergo triggered reductive cleavage, with dithiothreitol (DTT) inducing controlled breakdown, enabling the release of bound DNA. As such, the high-affinity self-assembled multivalent binding is temporary. Furthermore, because the multivalent dendrons are constructed from esters, a second slow degradation step causes further breakdown of these structures. This two-step double-degradation mechanism converts a large self-assembling unit with high affinity for DNA into small units with no measurable binding affinity--demonstrating the advantage of self-assembled multivalency (SAMul) in achieving highly responsive nanoscale binding of biological targets.

Mitigated cytotoxicity and tremendously enhanced gene transfection efficiency of PEI through facile one-step carbamate modification

Extremely efficacious gene transfection vector: The rapid and facile modification of PEI with commercially available TMC produces an extremely efficacious gene delivery vector with minimal cytotoxicity. Functionalization of PEI is easily controlled by PEI:cyclic carbonate feed ratios and allows for the addition of functionality. Modified PEIs hold great potential as gene delivery systems due to easy synthesis, scalability, low cost, low toxicity, and outstanding transfection capacity.

Controlling cellular uptake of nanoparticles with pH-sensitive polymers

The major challenge in cancer therapy is to efficiently translocate drug molecules into cancer tumors without doing any damage to healthy tissues. Since there exist pH gradients between tumor and normal tissues, pH-sensitive materials may have great potential to overcome such challenge. Here, we report one new type of pH-responsive drug delivery system where pH-sensitive polymers are introduced to control the cellular uptake of nanoparticles under different pH environments through dissipative particle dynamics simulations. Interestingly, the behavior of cellular uptake of nanoparticles here exhibits "smart" pH-responsive properties: for lower and higher pH, the nanoparticles can be taken up by cell membranes, while for pH in middle range, the endocytosis is blocked. Further, it is found that receptor-ligand interactions as well as surface charge property of nanoparticles and membranes can also have important impacts on the endocytosis. The present study may give some significant insights into future stimulus-responsive medical materials design.