Plasmid-templated shape control of condensed DNA-block copolymer nanoparticles

Supramolecular assembly of polycation/mRNA nanoparticles and in vivo monocyte programming

Size-dependent phagocytosis is a well-characterized phenomenon in monocytes and macrophages. However, this size effect for preferential gene delivery to these important cell targets has not been fully exploited because commonly adopted stabilization methods for electrostatically complexed nucleic acid nanoparticles, such as PEGylation and charge repulsion, typically arrest the vehicle size below 200 nm. Here, we bridge the technical gap in scalable synthesis of larger submicron gene delivery vehicles by electrostatic self-assembly of charged nanoparticles, facilitated by a polymer structurally designed to modulate internanoparticle Coulombic and van der Waals forces. Specifically, our strategy permits controlled assembly of small poly(β-amino ester)/messenger ribonucleic acid (mRNA) nanoparticles into particles with a size that is kinetically tunable between 200 and 1,000 nm with high colloidal stability in physiological media. We found that assembled particles with an average size of 400 nm safely and most efficiently transfect monocytes following intravenous administration and mediate their differentiation into macrophages in the periphery. When a CpG adjuvant is co-loaded into the particles with an antigen mRNA, the monocytes differentiate into inflammatory dendritic cells and prime adaptive anticancer immunity in the tumor-draining lymph node. This platform technology offers a unique ligand-independent, particle-size-mediated strategy for preferential mRNA delivery and enables therapeutic paradigms via monocyte programming.

Complexation of Poly(ethylene glycol)-(ds)OligoDNA Conjugates with Ionic Liquids

We report the complexation of poly(ethylene glycol) conjugated double-stranded oligoDNA (PEG-(ds)oligoDNA) with imidazolium-based ionic liquids (ILs) to form polyelectrolyte complex aggregates (PCAs). The PEG-(ds)oligoDNA conjugates are prepared following a solution-phase coupling reaction. The binding of PEG-(ds)oligoDNA with either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) or 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIM][BF4]) is confirmed by a fluorescence displacement assay. Both ILs show stronger binding affinity to PEG-(ds)oligoDNA than bare (ds)oligoDNA due to the PEG-assisted increase in IL cation concentration in the vicinity of (ds)oligoDNA. The complex morphology formed at various amine (N) to phosphate (P) ratios is also examined. At high N/P ratios above 4, nanosized PCAs are formed, driven by a counterion-mediated attraction among the IL-bound (ds)oligoDNA segments and stabilized by the conjugated PEG segments. The PCAs exhibit near-neutral surface charges and resistance to DNase degradation, suggesting their potential use in gene delivery applications.

Nanotherapeutic Heterogeneity: Sources, Effects, and Solutions

Nanomaterials have revolutionized medicine by enabling control over drugs' pharmacokinetics, biodistribution, and biocompatibility. However, most nanotherapeutic batches are highly heterogeneous, meaning they comprise nanoparticles that vary in size, shape, charge, composition, and ligand functionalization. Similarly, individual nanotherapeutics often have heterogeneously distributed components, ligands, and charges. This review discusses nanotherapeutic heterogeneity's sources and effects on experimental readouts and therapeutic efficacy. Among other topics, it demonstrates that heterogeneity exists in nearly all nanotherapeutic types, examines how nanotherapeutic heterogeneity arises, and discusses how heterogeneity impacts nanomaterials' in vitro and in vivo behavior. How nanotherapeutic heterogeneity skews experimental readouts and complicates their optimization and clinical translation is also shown. Lastly, strategies for limiting nanotherapeutic heterogeneity are reviewed and recommendations for developing more reproducible and effective nanotherapeutics provided.

Stimuli-Responsive Non-viral Nanoparticles for Gene Delivery

Considering nucleic acids as the language of life and the genome as the instruction manual of cells, their targeted modulation promises great opportunities in treating and healing diseases. In addition to viral gene transfer, the overwhelming power of non-viral mRNA-based vaccines is driving the development of novel gene transporters. Thereby, various nucleic acids such as DNA (pDNA) or RNA (mRNA, siRNA, miRNA, gRNA, or ASOs) need to be delivered, requiring a transporter due to their high molar mass and negative charge in contrast to classical agents. This chapter presents the specific biological hurdles for using nucleic acids and shows how new materials can overcome these.

Non-spherical Polymeric Nanocarriers for Therapeutics: The Effect of Shape on Biological Systems and Drug Delivery Properties

This review aims to highlight the importance of particle shape in the design of polymeric nanocarriers for drug delivery systems, along with their size, surface chemistry, density, and rigidity. Current manufacturing methods used to obtain non-spherical polymeric nanocarriers such as filomicelles or nanoworms, nanorods and nanodisks, are firstly described. Then, their interactions with biological barriers are presented, including how shape affects nanoparticle clearance, their biodistribution and targeting. Finally, their drug delivery properties and their therapeutic efficacy, both in vitro and in vivo, are discussed and compared with the characteristics of their spherical counterparts.

Length-Controlled Nanofiber Micelleplexes as Efficient Nucleic Acid Delivery Vehicles

Micelleplexes show great promise as effective polymeric delivery systems for nucleic acids. Although studies have shown that spherical micelleplexes can exhibit superior cellular transfection to polyplexes, to date there has been no report on the effects of micelleplex morphology on cellular transfection. In this work, we prepared precision, length-tunable poly(fluorenetrimethylenecarbonate)-b-poly(2-(dimethylamino)ethyl methacrylate) (PFTMC₁₆-b-PDMAEMA₁₃₁) nanofiber micelleplexes and compared their properties and transfection activity to those of the equivalent nanosphere micelleplexes and polyplexes. We studied the DNA complexation process in detail via a range of techniques including cryo-transmission electron microscopy, atomic force microscopy, dynamic light scattering, and ζ-potential measurements, thereby examining how nanofiber micelleplexes form, as well the key differences that exist compared to nanosphere micelleplexes and polyplexes in terms of DNA loading and colloidal stability. The effects of particle morphology and nanofiber length on the transfection and cell viability of U-87 MG glioblastoma cells with a luciferase plasmid were explored, revealing that short nanofiber micelleplexes (length < ca. 100 nm) were the most effective delivery vehicle examined, outperforming nanosphere micelleplexes, polyplexes, and longer nanofiber micelleplexes as well as the Lipofectamine 2000 control. This study highlights the potential importance of 1D micelleplex morphologies for achieving optimal transfection activity and provides a fundamental platform for the future development of more effective polymeric nucleic acid delivery vehicles.

Non-Viral Delivery of Gene Therapy to the Tendon

The tendon, as a compact connective tissue, is difficult to treat after an acute laceration or chronic degeneration. Gene-based therapy is a highly efficient strategy for diverse diseases which has been increasingly applied in tendons in recent years. As technology improves by leaps and bounds, a wide variety of non-viral vectors have been manufactured that attempt to have high biosecurity and transfection efficiency, considered to be a promising treatment modality. In this review, we examine the unwanted biological barriers, the categories of applicable genes, and the introduction and comparison of non-viral vectors. We focus on lipid-based nanoparticles and polymer-based nanoparticles, differentiating between them based on their combination with diverse chemical modifications and scaffolds.

Non-viral vectors for RNA delivery

RNA-based therapy is a promising and potential strategy for disease treatment by introducing exogenous nucleic acids such as messenger RNA (mRNA), small interfering RNA (siRNA), microRNA (miRNA) or antisense oligonucleotides (ASO) to modulate gene expression in specific cells. It is exciting that mRNA encoding the spike protein of COVID-19 (coronavirus disease 2019) delivered by lipid nanoparticles (LNPs) exhibits the efficient protection of lungs infection against the virus. In this review, we introduce the biological barriers to RNA delivery in vivo and discuss recent advances in non-viral delivery systems, such as lipid-based nanoparticles, polymeric nanoparticles, N-acetylgalactosamine (GalNAc)-siRNA conjugate, and biomimetic nanovectors, which can protect RNAs against degradation by ribonucleases, accumulate in specific tissue, facilitate cell internalization, and allow for the controlled release of the encapsulated therapeutics.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Biomedical nanoparticle design: What we can learn from viruses

Viruses are nanomaterials with a number of properties that surpass those of many synthetic nanoparticles (NPs) for biomedical applications. They possess a rigorously ordered structure, come in a variety of shapes, and present unique surface elements, such as spikes. These attributes facilitate propitious biodistribution, the crossing of complex biological barriers and a minutely coordinated interaction with cells. Due to the orchestrated sequence of interactions of their stringently arranged particle corona with cellular surface receptors they effectively identify and infect their host cells with utmost specificity, while evading the immune system at the same time. Furthermore, their efficacy is enhanced by their response to stimuli and the ability to spread from cell to cell. Over the years, great efforts have been made to mimic distinct viral traits to improve biomedical nanomaterial performance. However, a closer look at the literature reveals that no comprehensive evaluation of the benefit of virus-mimetic material design on the targeting efficiency of nanomaterials exists. In this review we, therefore, elucidate the impact that viral properties had on fundamental advances in outfitting nanomaterials with the ability to interact specifically with their target cells. We give a comprehensive overview of the diverse design strategies and identify critical steps on the way to reducing them to practice. More so, we discuss the advantages and future perspectives of a virus-mimetic nanomaterial design and try to elucidate if viral mimicry holds the key for better NP targeting.

Synthesis and applications of anisotropic nanoparticles with precisely defined dimensions

Shape and size play powerful roles in determining the properties of a material; controlling these aspects with precision is therefore an important, fundamental goal of the chemical sciences. In particular, the introduction of shape anisotropy at the nanoscale has emerged as a potent way to access new properties and functionality, enabling the exploration of complex nanomaterials across a range of applications. Recent advances in DNA and protein nanotechnology, inorganic crystallization techniques, and precision polymer self-assembly are now enabling unprecedented control over the synthesis of anisotropic nanoparticles with a variety of shapes, encompassing one-dimensional rods, dumbbells and wires, two-dimensional and three-dimensional platelets, rings, polyhedra, stars, and more. This has, in turn, enabled much progress to be made in our understanding of how anisotropy and particle dimensions can be tuned to produce materials with unique and optimized properties. In this Review, we bring these recent developments together to critically appraise the different methods for the bottom-up synthesis of anisotropic nanoparticles enabling exquisite control over morphology and dimensions. We highlight the unique properties of these materials in arenas as diverse as electron transport and biological processing, illustrating how they can be leveraged to produce devices and materials with otherwise inaccessible functionality. By making size and shape our focus, we aim to identify potential synergies between different disciplines and produce a road map for future research in this crucial area.

Tuning the Topological Landscape of DNA-Cyclodextrin Nanocomplexes by Molecular Design

Original molecular vectors that ensure broad flexibility to tune the shape and surface properties of plasmid DNA (pDNA) condensates are reported herein. The prototypic design involves a cyclodextrin (CD) platform bearing a polycationic cluster at the primary face and a doubly linked aromatic module bridging two consecutive monosaccharide units at the secondary face that behaves as a topology-encoding element. Subtle differences at the molecular level then translate into disparate morphologies at the nanoscale, including rods, worms, toroids, globules, ellipsoids, and spheroids. In vitro evaluation of the transfection capabilities revealed marked selectivity differences as a function of nanocomplex morphology. Remarkably high transfection efficiencies were associated with ellipsoidal or spherical shapes with a lamellar internal arrangement of pDNA chains and CD bilayers. Computational studies support that the stability of such supramolecular edifices is directly related to the tendency of the molecular vector to form noncovalent dimers upon DNA templating. Because the stability of the dimers depends on the protonation state of the polycationic clusters, the coaggregates display pH responsiveness, which facilitates endosomal escape and timely DNA release, a key step in successful transfection. The results provide a versatile strategy for the construction of fully synthetic and perfectly monodisperse nonviral gene delivery systems uniquely suited for optimization schemes.

Computational studies of shape control of charged deformable nanocontainers

Biological matter is often compartmentalized by soft membranes that dynamically change their shape in response to chemical and mechanical cues. Deformable soft-matter-based nanoscale membranes or nanocontainers that mimic this behavior can be used as drug-delivery carriers that can adapt to evolving physiological conditions, or as dynamic building blocks for the design of novel hierarchical materials via assembly engineering. Here, we connect the intrinsic features of charged deformable nanocontainers such as their size, charge, surface tension, and elasticity with their equilibrium shapes for a wide range of solution conditions using molecular dynamics simulations. These links identify the fundamental mechanisms that establish the chemical and materials design control strategies for modulating the equilibrium shape of these nanocontainers. We show that flexible nanocontainers of radii ranging from 10-20 nm exhibit sphere-to-rod-to-disc shape transitions yielding rods and discs over a wide range of aspect ratio λ (0.3 < λ < 5). The shape transitions can be controlled by tuning salt and/or surfactant concentration as well as material elastic parameters. The shape changes are driven by reduction in the global electrostatic energy and are associated with dramatic changes in local surface elastic energy distributions. To illustrate the shape transition mechanisms, exact analytical calculations for idealized spheroidal nanocontainers in salt-free conditions are performed. Explicit counterion simulations near nanocontainers and associated Manning model calculations provide an assessment of the stability of observed shape deformations in the event of ion condensation.

On Complex Coacervate Core Micelles: Structure-Function Perspectives

The co-assembly of ionic-neutral block copolymers with oppositely charged species produces nanometric colloidal complexes, known, among other names, as complex coacervates core micelles (C3Ms). C3Ms are of widespread interest in nanomedicine for controlled delivery and release, whilst research activity into other application areas, such as gelation, catalysis, nanoparticle synthesis, and sensing, is increasing. In this review, we discuss recent studies on the functional roles that C3Ms can fulfil in these and other fields, focusing on emerging structure-function relations and remaining knowledge gaps.

Structural Polymorphism of Single pDNA Condensates Elicited by Cationic Block Polyelectrolytes

DNA folding is a core phenomenon in genome packaging within a nucleus. Such a phenomenon is induced by polyelectrolyte complexation between anionic DNA and cationic proteins of histones. In this regard, complexes formed between DNA and cationic polyelectrolytes have been investigated as models to gain insight into genome packaging. Upon complexation, DNA undergoes folding to reduce its occupied volume, which often results in multi-complex associated aggregates. However, when cationic copolymers comprising a polycation block and a neutral hydrophilic polymer block are used instead, DNA undergoes folding as a single molecule within a spontaneously formed polyplex micelle (PM), thereby allowing the observation of the higher-order structures that DNA forms. The DNA complex forms polymorphic structures, including globular, rod-shaped, and ring-shaped (toroidal) structures. This review focuses on the polymorphism of DNA, particularly, to elucidate when, how, and why DNA organizes into these structures with cationic copolymers. The interactions between DNA and the copolymers, and the specific nature of DNA in rigidity; i.e., rigid but foldable, play significant roles in the observed polymorphism. Moreover, PMs serve as potential gene vectors for systemic application. The significance of the controlled DNA folding for such an application is addressed briefly in the last part.

Enhancement of sciatic nerve regeneration with dual delivery of vascular endothelial growth factor and nerve growth factor genes

BACKGROUND

Peripheral nerve injury is one common clinical disease worldwide, in which sciatic nerve is anatomically the most challenging to regenerate given its length and large cross-sectional area. For the present, autologous nerve grafting remains to be the most ideal strategy when treating with sciatic nerve injury. However, this method sacrifices healthy nerves and requires highly intensive surgery, still calling for other advanced alternatives for nerve grafting.

RESULTS

In this study, we utilized previously well-established gene delivery system to dually deliver plasmid DNA (pDNA) encoding vascular endothelial growth factor (VEGF) and nerve growth factor (NGF), exploring therapeutics for sciatic nerve injury. Low-molecular-weight branched polyethylenimine (bPEI) was constructed as the backbone structure of gene vectors, and it was further crosslinked to synthesize degradable polycations via the conjugation of dialdehydes. Potential synergistic effect between VEGF and NGF proteins were observed on rat sciatic nerve crush injury model in this study.

CONCLUSIONS

We concluded that dual delivery of plasmid VEGF and NGF as gene therapy could enhance sciatic nerve regeneration.

Helix Self-Assembly Behavior of Amino Acid-Modified Camptothecin Prodrugs and Its Antitumor Effect

For effective antitumor treatment, it is important to increase the water solubility of hydrophobic antitumor drugs and improve their cell absorption efficiency and nuclear transmission capacity. Here, we use endogenous hydrophilic arginine to modify camptothecin (CPT) to increase its water solubility. Surprisingly, the modified CPT can self-assemble into helical nanofibers through intermolecular π-π stacking and hydrophilic-hydrophobic interactions. Prodrug-based nanofibers were better endocytosed into the nucleus than their nonassembled CPT. Moreover, in vivo, such nanofibers had a longer blood circulation time and a better ability to accumulate in the tumor site. Further, we found that the cationic nanofibers can be combined with the anionic cisplatin-polyglutamic acid through electrostatic interaction to achieve a combined antitumor effect. This provides a new idea for achieving more effective cancer chemotherapy effects.

Influence of pH on the formation of a polyelectrolyte complex by dissipative particle dynamics simulation: From an extended to a compact shape

This work aims to investigate the influence of pH on the mechanism of assembly of macromolecules. We studied the effect of the pH on the interaction of two polyelectrolytes of opposed charge, having the same size, by means of dissipative particle dynamics method. The system consisted of a strong cationic and a weak anionic polyelectrolyte in an aqueous solution containing monovalent counterions. The analysis was made by varying the pH of the solution, which modifies the charge fraction of the weak anionic polyelectrolyte with a dissociation acid constant pKa of 5.5, while the polycation is fully charged in all the pH range used, characteristic of a strong polyelectrolyte. In order to describe the influence of pH on the complexation process, we have analyzed the pair radial distribution functions polyanion-counterion, polycation-counterion, and polyanion-polycation. The complex conformation was studied by means of the radius of gyration and the end-to-end distance of both chains as the pH varied from 1 to 14. A relevant finding obtained here was the relationship between the radial distribution functions and the counterion release from the polyelectrolytes, which leads to a reduction in the size of the complex when pH increased. Surprisingly, a transition from an extended to a compact polyelectrolyte complex was obtained when the pH reached the dissociation acid constant pKa of the weak polyelectrolyte. This systematic study can help to understand a large number of more realistic problems in biological systems such as protein complex, chromatin phase transition, or in complex systems applied in biomedical science.

Applications of carbon nanomaterials in the plant system: A perspective view on the pros and cons

With the remarkable development in the field of nanotechnology, carbon-based nanomaterials (CNMs) have been widely used for numerous applications in different areas of the plant system. The current understanding about the CNMs' accumulation, translocation, plant growth responses, and stress modulations in the plant system is far from complete. There have been relentless efforts by the researchers worldwide in order to acquire newer insights into the plant-CNMs interactions and the consequences. The present review intends to update the reader with the status of the impacts of the different CNMs on plant growth. Research reports from the plant biotechnologists have documented mixed effects (which are dependent on CNMs' concentration) of the CNMs' exposure on plants ranging from enhanced crop yield to acute cytotoxicity. The growth and yield pattern vary from species to species and are dependent on the dosage of the CNMs applied. Studies found an increase in vegetative growth and yield of fruit/seed at lower concentration of CNMs, but a decrease in these observables were also noted when higher concentrations of CNMs were used. In general, at lower concentrations, CNMs were found to be effective in enhancing (water uptake, water transport, seed germination, nitrogenase, photosystem and antioxidant activities), activating (water channels proteins) and promoting (nutrition absorption); all these change when concentrations are raised. All these aspects have been reviewed thoroughly in this article, with a focus on the recent updates on the role of the CNMs in augmenting or retarding plant growth. Sections have been devoted to the various features of the CNMs and their roles in inducing plant growth, phytotoxic responses of the plants and overall crop improvement. Concluding remarks have been added to propose future directions of research on the CNMs-plant interactions and also to sound a warning on the use of CNMs in agriculture.

Subtle changes in surface-tethered groups on PEGylated DNA nanoparticles significantly influence gene transfection and cellular uptake

PEGylation strategy has been widely used to enhance colloidal stability of polycation/DNA nanoparticles (NPs) for gene delivery. To investigate the effect of polyethylene glycol (PEG) terminal groups on the transfection properties of these NPs, we synthesized DNA NPs using PEG-g-linear polyethyleneimine (lPEI) with PEG terminal groups containing alkyl chains of various lengths with or without a hydroxyl terminal group. For both alkyl- and hydroxyalkyl-decorated NPs with PEG grafting densities of 1.5, 3, or 5% on lPEI, the highest levels of transfection and uptake were consistently achieved at intermediate alkyl chain lengths of 3 to 6 carbons, where the transfection efficiency is significantly higher than that of nonfunctionalized lPEI/DNA NPs. Molecular dynamics simulations revealed that both alkyl- and hydroxyalkyl-decorated NPs with intermediate alkyl chain length exhibited more rapid engulfment than NPs with shorter or longer alkyl chains. This study identifies a new parameter for the engineering design of PEGylated DNA NPs.

From Tunable DNA/Polymer Self-Assembly to Tailorable and Morphologically Pure Core-Shell Nanofibers

In reported experimental studies, DNA/polymer self-assemblies are usually kinetically trapped, leading to the encapsulation and irregular collapse of DNA chains within the resultant assemblies. In striking contrast, eukaryotic cells use tetrasome-to-nucleosome pathways to escape possible kinetic trapping for the formation of well-defined 10 nm chromatin fibers. Here, we report a novel pathway for DNA and amphiphilic diblock copolymer self-assembly inspired by the tetrasome pathway with highly controllable kinetics. The polymer is an A- b-B diblock copolymer with a hydrophilic and noninteractive block A and a hydrophobic and interactive block B. Below the critical water content for the micellization, B blocks wrap the backbone of a DNA chain by weak electrostatic interactions to form a linear DNA/polymer complex. With a gradual increase in the water content, the diblock copolymer unimers in the bulk solution tend to aggregate on the linear DNA/polymer complex, which induces the originally wrapped DNA chain, to change its conformation to wrap around the polymer aggregate, guiding and tailoring the self-assembly. Highly controllable kinetics is achieved via the reduced DNA/polymer electrostatic interactions and the high dynamics of the polymer chains in the system. DNA/polymer self-assembly leads to tailorable and morphologically pure core-shell nanofibers. Compared to the DNA/micelle self-assembly pathway described in our previous study, the present self-assembly pathway exhibits advantages for the fabrication of flexible nanofibers with lengths in micrometers and the potential for unique applications in preparing not only 2D networks at extremely low percolation thresholds but also chemiresistors with large on/off current ratios.

A facile strategy for fine-tuning the stability and drug release of stimuli-responsive cross-linked micellar nanoparticles towards precision drug delivery

Precision drug delivery has a great impact on the application of precision oncology for better patient care. Here we report a facile strategy for fine-tuning the stability, drug release and responsiveness of stimuli-responsive cross-linked nanoparticles towards precision drug delivery. A series of micellar nanoparticles with different levels of intramicellar disulfide crosslinkages could be conveniently produced with a mixed micelle approach. These micellar nanoparticles were all within a size range of 25-40 nm so that they could take full advantage of the enhanced permeability and retention (EPR) effect for tumor-targeted drug delivery. The properties of these nanoparticles such as critical micelle concentration (CMC), stability, drug release and responsiveness to a reductive environment could be well correlated with the levels of crosslinking (LOC). Compared to the micellar nanoparticles with a LOC at 0% that caused the death of animals of two species (mouse and rat) due to the acute toxicity such as hemolysis, the nanoparticles at all other levels of crosslinking were much safer to be administered into animals. The in vitro antitumor efficacy of micellar nanoparticles crosslinked at lower levels (20% & 50%) were much more effective than that of 100% crosslinked micellar nanoparticles in SKOV-3 ovarian cancer cells.

Functional biodegradable polymers via ring-opening polymerization of monomers without protective groups

Biodegradable polymers are of current interest and chemical functionality in such materials is often demanded in advanced biomedical applications. Functional groups often are not tolerated in the polymerization process of ring-opening polymerization (ROP) and therefore protective groups need to be applied. Advantageously, several orthogonally reactive functions are available, which do not demand protection during ROP. We give an insight into available, orthogonally reactive cyclic monomers and the corresponding functional synthetic and biodegradable polymers, obtained from ROP. Functionalities in the monomer are reviewed, which are tolerated by ROP without further protection and allow further post-modification of the corresponding chemically functional polymers after polymerization. Synthetic concepts to these monomers are summarized in detail, preferably using precursor molecules. Post-modification strategies for the reported functionalities are presented and selected applications highlighted.

Block Copolymer Micelles in Nanomedicine Applications

Polymeric micelles are demonstrating high potential as nanomedicines capable of controlling the distribution and function of loaded bioactive agents in the body, effectively overcoming biological barriers, and various formulations are engaged in intensive preclinical and clinical testing. This Review focuses on polymeric micelles assembled through multimolecular interactions between block copolymers and the loaded drugs, proteins, or nucleic acids as translationable nanomedicines. The aspects involved in the design of successful micellar carriers are described in detail on the basis of the type of polymer/payload interaction, as well as the interplay of micelles with the biological interface, emphasizing on the chemistry and engineering of the block copolymers. By shaping these features, polymeric micelles have been propitious for delivering a wide range of therapeutics through effective sensing of targets in the body and adjustment of their properties in response to particular stimuli, modulating the activity of the loaded drugs at the targeted sites, even at the subcellular level. Finally, the future perspectives and imminent challenges for polymeric micelles as nanomedicines are discussed, anticipating to spur further innovations.

Anisotropic biodegradable lipid coated particles for spatially dynamic protein presentation

There has been growing interest in the use of particles coated with lipids for applications ranging from drug delivery, gene delivery, and diagnostic imaging to immunoengineering. To date, almost all particles with lipid coatings have been spherical despite emerging evidence that non-spherical shapes can provide important advantages including reduced non-specific elimination and increased target-specific binding. We combine control of core particle geometry with control of particle surface functionality by developing anisotropic, biodegradable ellipsoidal particles with lipid coatings. We demonstrate that these lipid coated ellipsoidal particles maintain advantageous properties of lipid polymer hybrid particles, such as the ability for modular protein conjugation to the particle surface using versatile bioorthogonal ligation reactions. In addition, they exhibit biomimetic membrane fluidity and demonstrate lateral diffusive properties characteristic of natural membrane proteins. These ellipsoidal particles simultaneously provide benefits of non-spherical particles in terms of stability and resistance to non-specific phagocytosis by macrophages as well as enhanced targeted binding. These biomaterials provide a novel and flexible platform for numerous biomedical applications.

STATEMENT OF SIGNIFICANCE

The research reported here documents the ability of non-spherical polymeric particles to be coated with lipids to form anisotropic biomimetic particles. In addition, we demonstrate that these lipid-coated biodegradable polymeric particles can be conjugated to a wide variety of biological molecules in a "click-like" fashion. This is of interest due to the multiple types of cellular mimicry enabled by this biomaterial based technology. These features include mimicry of the highly anisotropic shape exhibited by cells, surface presentation of membrane bound protein mimetics, and lateral diffusivity of membrane bound substrates comparable to that of a plasma membrane. This platform is demonstrated to facilitate targeted cell binding while being resistant to non-specific cellular uptake. Such a platform could allow for investigations into how physical parameters of a particle and its surface affect the interface between biomaterials and cells, as well as provide biomimetic technology platforms for drug delivery and cellular engineering.

Morphology-Variable Aggregates Prepared from Cholesterol-Containing Amphiphilic Glycopolymers: Their Protein Recognition/Adsorption and Drug Delivery Applications

In this study, a series of diblock glycopolymers, poly(6-O-methacryloyl-d-galactopyranose)-b-poly(6-cholesteryloxyhexyl methacrylate) (PMAgala-b-PMAChols), with cholesterol/galactose grafts were prepared through a sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and deprotection process. The glycopolymers could self-assemble into aggregates with various morphologies depending on cholesterol/galactose-containing block weight ratios, as determined by transmission electronic microscopy (TEM) and dynamic laser light scattering (DLS). In addition, the lectin (Ricinus communis agglutinin II, RCA120) recognition and bovine serum albumin (BSA) adsorption of the PMAgala-b-PMAChol aggregates were evaluated. The SK-Hep-1 tumor cell inhibition properties of the PMAgala-b-PMAChol/doxorubicin (DOX) complex aggregates were further examined in vitro. Results indicate that the PMAgala-b-PMAChol aggregates with various morphologies showed different interaction/recognition features with RCA120 and BSA. Spherical aggregates (d ≈ 92 nm) possessed the highest RCA120 recognition ability and lowest BSA protein adsorption. In addition, the DOX-loaded spherical complex aggregates exhibited a better tumor cell inhibition property than those of nanofibrous complex aggregates. The morphology-variable aggregates derived from the amphiphilic glycopolymers may serve as multifunctional biomaterials with biomolecular recognition and drug delivery features.

Plasmid-Templated Control of DNA-Cyclodextrin Nanoparticle Morphology through Molecular Vector Design for Effective Gene Delivery

Engineering self-assembled superstructures through complexation of plasmid DNA (pDNA) and single-isomer nanometric size macromolecules (molecular nanoparticles) is a promising strategy for gene delivery. Notably, the functionality and overall architecture of the vector can be precisely molded at the atomic level by chemical tailoring, thereby enabling unprecedented opportunities for structure/self-assembling/pDNA delivery relationship studies. Beyond this notion, by judiciously preorganizing the functional elements in cyclodextrin (CD)-based molecular nanoparticles through covalent dimerization, here we demonstrate that the morphology of the resulting nanocomplexes (CDplexes) can be tuned, from spherical to ellipsoidal, rod-type, or worm-like nanoparticles, which makes it possible to gain understanding of their shape-dependent transfection properties. The experimental findings are in agreement with a shift from chelate to cross-linking interactions on going from primary-face- to secondary-face-linked CD dimers, the pDNA partner acting as an active payload and as a template. Most interestingly, the transfection efficiency in different cells was shown to be differently impacted by modifications of the CDplex morphology, which has led to the identification of an optimal prototype for tissue-selective DNA delivery to the spleen in vivo.

Novel morphologies of poly(allyamine hydrochloride)-methotrexate nanoassemblies for methotrexate delivery

Poly(allylamine hydrochloride)-methotrexate (PAH-MTX) nanoassemblies with novel morphologies (i.e. nanostrips, nanorolls, nanosheets, and nanospheres) were achieved for the first time via supramolecular self-assembly directed by the synergistic action of various non-covalent interactions between PAH and MTX molecules in aqueous solution. Herein, MTX acted in a versatile manner as both a morphology-regulating agent and a small molecular hydrophobic anticancer drug. Moreover, different morphologies presented diverse drug release profiles, which may be caused by the distinctive interactions between PAH and MTX molecules. Synergistically non-covalent interactions, including electrostatic interactions, van der Waals forces, and hydrogen bonding, favored easier matrix corrosion and more rapid drug release of non-spherical structures (i.e. nanostrips, nanorolls, and nanosheets) through the ligand exchange process. On the other hand, the highly sealed encapsulation mode for hydrophobic MTX molecules made the nanospheres exhibit slower and better controlled release. In addition, in vitro bioassay tests showed that nanostrips displayed the most obvious suppression on the viability of cancer cells among other morphologies, especially after a longer duration. The strategy of using small molecular anticancer drugs not as passively delivered cargoes but as effective molecular building blocks, opens up a new way to develop self-delivering drugs for anticancer therapy.

Ultrasound-enhanced gene delivery to alfalfa cells by hPAMAM dendrimer nanoparticles

Cationic polyamidoamine (PAMAM) dendrimers are highly branched nanoparticles with unique molecular properties, which make them promising nanocarriers for gene delivery into cells. This research evaluated the ability of hyperbranched PAMAM (hPAMAM)-G2 with a diethylenetriamine core to interact with DNA, its protection from ultrasonic damage, and delivery to alfalfa cells. Additionally, the effects of ultrasound on the efficacy of hPAMAM-G2 for the delivery and expression of the gus A gene in the alfalfa cells were investigated. The electrophoresis retardation of plasmid DNA occurred at an N/P ratio (where N is the number of hPAMAM nitrogen atoms and P is the number of DNA phosphorus atoms) of 3 and above, and hPAMAM-G2 dendrimers completely immobilized the DNA at an N/P ratio of 4. The analysis of the DNA dissociated from the dendriplexes revealed a partial protection of the DNA from ultrasound damage at N/P ratios lower than 2, and with increasing N/P ratios, the DNA was better protected. Sonication of the alfalfa cells in the presence of ssDNA-FITC-hPAMAM increased the ssDNA delivery efficiency to 36%, which was significantly higher than that of ssDNA-FITC-hPAMAM without sonication. Additionally, the efficiency of transfection and the expression of the gus A gene were dependent on the N/P ratio and the highest efficiency (1.4%) was achieved at an N/P ratio of 10. The combination of 120 s of ultrasound and hPAMAM-DNA increased the gusA gene transfection and expression to 3.86%.

Genomic form of rhodopsin DNA nanoparticles rescued autosomal dominant Retinitis pigmentosa in the P23H knock-in mouse model

Retinitis pigmentosa (RP) is a group of inherited retinal degenerative conditions and a leading cause of irreversible blindness. 25%-30% of RP cases are caused by inherited autosomal dominant (ad) mutations in the rhodopsin (Rho) protein of the retina, which impose a barrier for developing therapeutic treatments for this genetically heterogeneous disorder, as simple gene replacement is not sufficient to overcome dominant disease alleles. Previously, we have explored using the genomic short-form of Rho (sgRho) for gene augmentation therapy of RP in a Rho knockout mouse model. We have shown improved gene expression and fewer epigenetic modifications compared with the use of a Rho cDNA expression construct. In the current study, we altered our strategy by delivering a codon-optimized genomic form of Rho (co-sgRho) (for gene replacement) in combination with an RNAi-based inactivation of endogenous Rho alleles (gene suppression of both mutant Rho alleles, but mismatched with the co-sgRho) into a homozygous Rho^P23H/P23H knock-in (KI) RP mouse model, which has a severe phenotype of adRP. In addition, we have conjugated a cell penetrating TAT peptide sequence to our previously established CK30PEG10 diblock co-polymer. The DNAs were compacted with CK30PEG10-TAT diblock co-polymer to form DNA nanoparticles (NPs). These NPs were injected into the sub-retinal space of the KI mouse eyes. As a proof of concept, we demonstrated the efficiency of this strategy in the partial improvement of visual function in the Rho^P23H/P23H KI mouse model.

Gene delivery nanoparticles to modulate angiogenesis

Angiogenesis is naturally balanced by many pro- and anti-angiogenic factors while an imbalance of these factors leads to aberrant angiogenesis, which is closely associated with many diseases. Gene therapy has become a promising strategy for the treatment of such a disordered state through the introduction of exogenous nucleic acids that express or silence the target agents, thereby engineering neovascularization in both directions. Numerous non-viral gene delivery nanoparticles have been investigated towards this goal, but their clinical translation has been hampered by issues associated with safety, delivery efficiency, and therapeutic effect. This review summarizes key factors targeted for therapeutic angiogenesis and anti-angiogenesis gene therapy, non-viral nanoparticle-mediated approaches to gene delivery, and recent gene therapy applications in pre-clinical and clinical trials for ischemia, tissue regeneration, cancer, and wet age-related macular degeneration. Enhanced nanoparticle design strategies are also proposed to further improve the efficacy of gene delivery nanoparticles to modulate angiogenesis.

Nonviral cancer gene therapy: Delivery cascade and vector nanoproperty integration

Gene therapy represents a promising cancer treatment featuring high efficacy and limited side effects, but it is stymied by a lack of safe and efficient gene-delivery vectors. Cationic polymers and lipid-based nonviral gene vectors have many advantages and have been extensively explored for cancer gene delivery, but their low gene-expression efficiencies relative to viral vectors limit their clinical translations. Great efforts have thus been devoted to developing new carrier materials and fabricating functional vectors aimed at improving gene expression, but the overall efficiencies are still more or less at the same level. This review analyzes the cancer gene-delivery cascade and the barriers, the needed nanoproperties and the current strategies for overcoming these barriers, and outlines PEGylation, surface-charge, size, and stability dilemmas in vector nanoproperties to efficiently accomplish the cancer gene-delivery cascade. Stability, surface, and size transitions (3S Transitions) are proposed to resolve those dilemmas and strategies to realize these transitions are comprehensively summarized. The review concludes with a discussion of the future research directions to design high-performance nonviral gene vectors.

Improved siRNA delivery efficiency via solvent-induced condensation of micellar nanoparticles

Efficient delivery of short interfering RNA (siRNA) remains one of the primary challenges of RNA interference therapy. Polyethylene glycol (PEG)ylated polycationic carriers have been widely used for the condensation of DNA and RNA molecules into complex-core micelles. The PEG corona of such nanoparticles can significantly improve their colloidal stability in serum, but PEGylation of the carriers also reduces their condensation capacity, hindering the generation of micellar particles with sufficient complex stability. This presents a particularly significant challenge for packaging siRNA into complex micelles, as it has a much smaller size and more rigid chain structure than DNA plasmids. Here, we report a new method to enhance the condensation of siRNA with PEGylated linear polyethylenimine using organic solvent and to prepare smaller siRNA nanoparticles with a more extended PEG corona and consequently higher stability. As a proof of principle, we have demonstrated the improved gene knockdown efficiency resulting from the reduced siRNA micelle size in mice livers following intravenous administration.

The Influence of Block Ionomer Microstructure on Polyplex Properties: Can Simulations Help to Understand Differences in Transfection Efficiency?

Gene therapies enable therapeutic interventions at gene transcription and translation level, providing enormous potential to improve standards of care for multiple diseases. Nonviral transfection agents and in particular polyplexes based on block ionomers are-besides viral vectors and cationic lipid formulations-among the most promising systems for this purpose. Block ionomers combine a hydrophilic noncharged block, e.g., polyethylene glycol (PEG), with a hydrophilic cationic block. For efficient transfection, however, endosomolytic moieties, e.g., imidazoles, are additionally required to facilitate endosomal escape, which raises the general question how to distribute these functionalities within the block copolymer. Combining molecular dynamics simulation with physicochemical and biological characterization, this work aims to provide a first rational for the influence of block ionomer microstructure on polyplex properties, e.g., size, shape, and transfection efficiency. Our findings underline that a triblock microstructure is most efficient in compacting pDNA, which reduces polyplex size, enhances stability against degradation by DNase I, and thus provides better transfection performance.

Mimicking biological functionality with polymers for biomedical applications

The vast opportunities for biomaterials design and functionality enabled by mimicking nature continue to stretch the limits of imagination. As both biological understanding and engineering capabilities develop, more sophisticated biomedical materials can be synthesized that have multifaceted chemical, biological and physical characteristics designed to achieve specific therapeutic goals. Mimicry is being used in the design of polymers for biomedical applications that are required locally in tissues, systemically throughout the body, and at the interface with tissues.

Gel phase formation in dilute triblock copolyelectrolyte complexes

Assembly of oppositely charged triblock copolyelectrolytes into phase-separated gels at low polymer concentrations (<1% by mass) has been observed in scattering experiments and molecular dynamics simulations. Here we show that in contrast to uncharged, amphiphilic block copolymers that form discrete micelles at low concentrations and enter a phase of strongly interacting micelles in a gradual manner with increasing concentration, the formation of a dilute phase of individual micelles is prevented in polyelectrolyte complexation-driven assembly of triblock copolyelectrolytes. Gel phases form and phase separate almost instantaneously on solvation of the copolymers. Furthermore, molecular models of self-assembly demonstrate the presence of oligo-chain aggregates in early stages of copolyelectrolyte assembly, at experimentally unobservable polymer concentrations. Our discoveries contribute to the fundamental understanding of the structure and pathways of complexation-driven assemblies, and raise intriguing prospects for gel formation at extraordinarily low concentrations, with applications in tissue engineering, agriculture, water purification and theranostics.

"Click" chemistry mediated construction of cationic curdlan nanocarriers for efficient gene delivery

A cationic group has been quantitatively and selectively introduced into C6 position of each glucose units of Curdlan by "Click Chemistry" successfully. The resulting cationic Curdlan-Imidazole-lysine polymers (Cur-6-100Lys) exhibit excellent water solubility. Structure of the Cur-6-100Lys complexes was verified by FTIR and NMR spectroscopic measurements, and analysis of Cur-6-100Lys by GPC, DLS and SEM revealed that they have stoichiometric, nanosized spheroidal structures. Cytotoxicity measurement, electrophoretic mobility shift assay and EGFP-pDNA transfection have been carried out respectively. The results clearly show that Cur-6-100Lys nanocarriers have bound to dsDNA promptly, are less cytotoxic to both 7901 cells and HeLa cells, and are readily able to transport EGFP-pDNA into HepG2 cells. Our studies indicated that Cur-6-100Lys can potentially be used as a versatile nano platform for efficient gene delivery in living cells.

A rod bacterium-like magnetic polymer micelle for strongly enhancing selective accumulation and internalization of nanocarriers

The precise and highly efficient delivery of a therapeutic agent with nanocarriers to a tumor site to achieve excellent therapeutic efficacy remains a major challenge in cancer chemotherapy.

Systematic coarse-grained modeling of complexation between small interfering RNA and polycations

All-atom molecular dynamics simulations can provide insight into the properties of polymeric gene-delivery carriers by elucidating their interactions and detailed binding patterns with nucleic acids. However, to explore nanoparticle formation through complexation of these polymers and nucleic acids and study their behavior at experimentally relevant time and length scales, a reliable coarse-grained model is needed. Here, we systematically develop such a model for the complexation of small interfering RNA (siRNA) and grafted polyethyleneimine copolymers, a promising candidate for siRNA delivery. We compare the predictions of this model with all-atom simulations and demonstrate that it is capable of reproducing detailed binding patterns, charge characteristics, and water release kinetics. Since the coarse-grained model accelerates the simulations by one to two orders of magnitude, it will make it possible to quantitatively investigate nanoparticle formation involving multiple siRNA molecules and cationic copolymers.