Hydroxyl-Rich PGMA-Based Cationic Glycopolymers for Intracellular siRNA Delivery: Biocompatibility and Effect of Sugar Decoration Degree

Glycopolymers Mediate Suicide Gene Therapy in ASGPR-Expressing Hepatocellular Carcinoma Cells in Tandem with Docetaxel

Cationic glycopolymers stand out as gene delivery nanosystems due to their inherent biocompatibility and high binding affinity to the asialoglycoprotein receptor (ASGPR), a target receptor overexpressed in hepatocellular carcinoma (HCC) cells. However, their synthesis procedure remains laborious and complex, with problems of solubilization and the need for protection/deprotection steps. Here, a mini-library of well-defined poly(2-aminoethyl methacrylate hydrochloride-co-poly(2-lactobionamidoethyl methacrylate) (PAMA-co-PLAMA) glycopolymers was synthesized by activators regenerated by electron transfer (ARGET) ATRP to develop an efficient gene delivery nanosystem. The glycoplexes generated had suitable physicochemical properties and showed high ASGPR specificity and high transfection efficiency. Moreover, the HSV-TK/GCV suicide gene therapy strategy, mediated by PAMA₁₄₄-co-PLAMA₁₉-based nanocarriers, resulted in high antitumor activity in 2D and 3D culture models of HCC, which was significantly enhanced by the combination with small amounts of docetaxel. Overall, our results demonstrated the potential of primary-amine polymethacrylate-containing-glycopolymers as HCC-targeted suicide gene delivery nanosystems and highlight the importance of combined strategies for HCC treatment.

Application of vinyl polymer-based materials as nucleic acids carriers in cancer therapy

Nucleic acid-based therapies have changed the paradigm of cancer treatment, where conventional treatment modalities still have several limitations in terms of efficacy and severe side effects. However, these biomolecules have a short half-life in vivo, requiring multiple administrations, resulting in severe suffering, discomfort, and poor patient compliance. In the early days of (nano)biotechnology, these problems caused concern in the medical community, but recently it has been recognized that these challenges can be overcome by developing innovative formulations. This review focuses on the use of vinyl polymer-based materials for the protection and delivery of nucleic acids in cancer. First, an overview of the properties of nucleic acids and their versatility as drugs is provided. Then, key information on the achievements to date, the most effective delivery methods, and the evaluation of functionalization approaches (stimulatory strategies) are critically discussed to highlight the importance of vinyl polymers in the new cancer treatment approaches. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Synthetic Conjugated Oligoelectrolytes Are Effective siRNA Transfection Carriers: Relevance to Pancreatic Cancer Gene Therapy

Conjugated oligoelectrolyte COE-S6 contains an elongated conjugated core with three cationic charges at each termini of the internal core. As an analogue of bolaamphiphiles, these structural attributes lead to the formation of spherical nanoplexes with Dh = 205 ± 5.0 nm upon mixing with small interfering RNA (siRNA). COE-S6/siRNA nanocomplexes were shown to be protective toward RNase, stimulate endosome escape, and achieve transfection efficiencies comparable to those achieved with commercially available LIP3000. Moreover, COE-S6/siRNA nanocomplexes enabled efficient silencing of the K-ras gene in pancreatic cancer cells and significant inhibition of cancer tumor growth with negligible in vitro toxicities. More importantly, cell invasion and colony formation of the Panc-1 cells were significantly inhibited, and apoptosis of the pancreatic cancer cells was also promoted. We also note that COE-S6 is much less toxic relative to commercial lipid formulations, and it provides optical signatures that can enable subsequent mechanistic work without the need to label nucleotides. COE-S6-based nanoplexes are thus a promising candidate as nonviral vectors for gene delivery.

Towards a protein-selective Raman enhancement by a glycopolymer-based composite surface

Surface-enhanced Raman scattering (SERS), which is based on the surface plasmon resonance (LSPR) of noble metal nanostructures, is widely used in the biological field due to its advantages of non-damaging samples and detection up to the molecular level. For biological SERS detection, preparation of substrates with biocompatibility and specific adsorption, leading to selective enhancement of the target biomolecules, are important design strategies. Utilizing the specific interaction between a carbohydrate and protein, a glycopolymer-based composite surface is fabricated to realize specific SERS detection of proteins. Herein, we use N-3,4-dihydroxybenzeneethyl methacrylamide (DMA), 2-deoxy-2-(methacrylamido)glucopyranose (MAG) and methacrylic acid (MAA) as monomers in a sunlight-induced RAFT polymerization to synthesize a dopamine-containing glycopolymer. The glycopolymers are used to prepare a SERS substrate. The composite surface shows specific protein adsorption capacity, and the selective Raman enhancement of specific proteins was successfully achieved between the two different proteins Con A and BSA. This provides a feasible approach to design a SERS surface for protein detection and the study of the interaction between sugar and proteins.

Glycopolymer based LbL Multilayer Thin Films with Embedded Liposomes

Layer-by-layer (LbL) self-assembly emerged as an efficient technique for fabricating coating systems for, e.g., drug delivery systems with great versatility and control. In this work, we describe protecting group free and aqueous-based syntheses of bioinspired glycopolymer electrolytes. Thin films of the glycopolymers are fabricated by LbL self-assembly and function as scaffolds for liposomes, which potentially can encapsulate active substances. We investigate the adsorbed mass, pH stability and integrity of glycopolymer coatings as well as the embedded liposomes via whispering gallery mode (WGM) technology and quartz crystal microbalance with dissipation (QCM-D) monitoring, which enable label-free characterization. Glycopolymer thin films, with and without liposomes, are stable in the physiological pH range. QCM-D measurements verify the integrity of lipid vesicles. Thus, we present the fabrication of glycopolymer-based surface coatings with embedded and intact liposomes. This article is protected by copyright. All rights reserved.

Tailor-made Glycopolymers via Reversible Deactivation Radical Polymerization: Design, Properties and Applications

Investigating the underlying mechanism of biological interactions using glycopolymer is becoming increasingly important owing to their unique recognition properties. The multivalent interactions between lectin and glycopolymer are significantly influenced by...

Versatile fully-substituted triazole-functionalized polypeptides with a stable α-helical conformation for gene delivery

A library of polypeptides bearing fully-substituted triazoles (FT) was developed via a Cu-catalyzed multicomponent reaction (MCR), which avoided the undesired hydrogen bonding and stabilized the α-helix in a broad pH range.

A review of the tortuous path of nonviral gene delivery and recent progress

Gene therapy encompasses the transfer of exogenous genetic materials into the patient's target cells to treat or prevent diseases. Nevertheless, the transfer of genetic material into desired cells is challenging and often requires specialized tools or delivery systems. For the past 40 years, scientists are mainly pursuing various viruses as gene delivery vectors, and the overall progress has been slow and far from the expectation. As an alternative, nonviral vectors have gained substantial attention due to their several advantages, including superior safety profile, enhanced payload capacity, and stealth abilities. Since nonviral vectors encounter multiple extra- and intra-cellular barriers limiting the transfer of genetic payload into the target cell nucleus, we have discussed these barriers in detail for this review. A direct approach, utilizing physical methods like electroporation, sonoporation, gene gun, eliminate the requirement for a specific carrier for gene delivery. In contrast, chemical methods of gene transfer exploit natural or synthetic compounds as carriers to increase cellular targeting and gene therapy effectiveness. We have also emphasized the recent advancements aimed at enhancing the current nonviral approaches. Therefore, in this review, we have focused on discussing the current evolving state of nonviral gene delivery systems and their future perspectives.

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.

Glycomacromolecules: Addressing challenges in drug delivery and therapeutic development

Carbohydrate-based materials offer exciting opportunities for drug delivery. They present readily available, biocompatible components for the construction of macromolecular systems which can be loaded with cargo, and can enable targeting of a payload to particular cell types through carbohydrate recognition events established in biological systems. These systems can additionally be engineered to respond to environmental stimuli, enabling triggered release of payload, to encompass multiple modes of therapeutic action, or to simultaneously fulfil a secondary function such as enabling imaging of target tissue. Here, we will explore the use of glycomacromolecules to deliver therapeutic benefits to address key health challenges, and suggest future directions for development of next-generation systems.

Fabrication of aminated poly(glycidyl methacrylate)-based polymers for co-delivery of anticancer drugs and the p53 gene

Aminated poly(glycidyl methacrylate)s-based polymers for gene delivery not only can reduce toxicity and improve solubility, but can improve gene transfection efficiency and reduce protein aggregation. In this study, we first prepared poly(glycidyl methacrylate) (PGMA) via reversible addition-fragmentation chain transfer (RAFT) polymerization, and then the obtained PGMA homopolymer was post-modified with ethanol amine (EA), 1-amino-2-propanol (AP), 3-(dibutylamino)propylamine (DA) and N-(2-hydroxyethyl)ethylenediamine (HA), respectively, to yield four kinds of PGMA-based gene vectors containing hydroxyl groups (abbreviated as PGEA, PGAP, PGDA and PGHA). The effects of the different side chains and hydroxyl groups on the biological properties of these four cationic polymers were investigated. We found that the transfection efficiency of the PGHA/p53 complex was higher than those of the other three polymer/gene complexes through MTT assay and laser scanning confocal microscopy. Hence, we chose HA for further post-modification to fabricate a cationic copolymer, PCL-ss-P(PEGMA-co-GHA) (abbreviated as PGHAP), via a combination of ring opening polymerization (ROP) and RAFT copolymerization. The PCL-ss-P(PEGMA-co-GHA) amphiphilic copolymer could self-assemble into nanoparticles, which could be used to encapsulate anticancer drug doxorubicin (DOX) and compress the p53 gene to form the DOX-loaded PCL-ss-P(PEGMA-co-GHA)/p53 complex (abbreviated as DPGHAP/p53). The gel retardation assay showed that p53 gene could be well immobilized and remained stable under the electronegative conditions. MTT assay showed that the DPGHAP/p53 complex had a significant antitumor effect on A549 cells and H1299 cells compared with free DOX or/and p53 gene therapy alone. Furthermore, the test results from live cell imaging systems revealed that the DPGHAP/p53 complexes could effectively deliver DOX and the p53 gene into A549 cells. Therefore, the constructed cationic polymer PCL-ss-P(PEGMA-co-GHA) has potential application prospects as a co-vector of anticancer drugs and genes.

Harnessing molecular recognition for localized drug delivery

A grand challenge in drug delivery is providing the right dose, at the right anatomic location, for the right duration of time to maximize therapeutic efficacy while minimizing off-target toxicity and other deleterious side-effects. Two general modalities are receiving broad attention for localized drug delivery. In the first, referred to as "targeted accumulation", drugs or drug carriers are engineered to have targeting moieties that promote their accumulation at a specific tissue site from circulation. In the second, referred to as "local anchoring", drugs or drug carriers are inserted directly into the tissue site of interest where they persist for a specified duration of time. This review surveys recent advances in harnessing molecular recognition between proteins, peptides, nucleic acids, lipids, and carbohydrates to mediate targeted accumulation and local anchoring of drugs and drug carriers.

Carbohydrate–lectin recognition of well-defined heterogeneous dendronized glycopolymers: systematic studies on the heterogeneity in glycopolymer–lectin binding

A platform for achieving dendronized heteroglycopolymers via gradient CuAAC click reaction and PPM was developed. Further systematic studies revealed the synergistic effect of heterogeneity plays a crucial role in glycopolymer–lectin binding.

Oncogenic Epidermal Growth Factor Receptor Silencing in Cervical Carcinoma Mediated by Dynamic Sugar-Benzoxaborole Polyplexes

Although, various types of pharmaceuticals have been developed for cervical carcinomas, treatment with these drugs often results in a number of undesirable side effects, toxicity and multidrug resistance. Here, we aimed at modifying the genetic profiling of cancer cells by silencing the expression of the epidermal growth factor receptor (EGFR) gene. We have synthesized two kinds of RAFT-made, biocompatible, and cationic polymers for the encapsulation of silencing RNA (siRNA). This vector has a dual capability: it contains a cationic segment to complex with the siRNA and an omega-end modified with an oxaborole group via thiol-ene click chemistry that responds to the acidic tumor microenvironment. This structural innovation enables this macromolecule to interact with multiple polyplexes and release the siRNA in a mild acidic environment. A strategy that has shown enhanced gene silencing without elevating the cytotoxicity of the system, as determined by Western blot analysis. The success of this approach has afforded further interest in utilizing boron-carbohydrate interaction in the development of nonviral vectors for gene therapy.

Multicomponent Polymerization toward Cationic Polymers for Efficient Gene Delivery

A new class of cationic polymers containing tertiary amine, thioether, and hydroxyl groups are prepared via a catalyst-free, multicomponent polymerization method using dithiol, formaldehyde, and di-sec-amine with a ratio of 1:2:1, to access a library of water-soluble polymers with well-defined structures and suitable molecular weights (M_w ranging from 5000 to 8000 Da) in high yields (up to 90%). Such polycations are demonstrated to be promising nonviral gene delivery vectors with high transfection efficiency (up to 3.5-fold of PEI25k) and low toxicity with multiple functionalities: 1) efficient gene condensation by tertiary amine groups; 2) reactive oxygen species scavenging by thioether groups; and 3) positive charge shielding by hydroxyl groups. Both the thioether and hydroxyl groups are contributed to reduce the cytotoxicity of the polycations by tuning the oxidative stress and preventing the undesired serum binding. The optimized polycations can achieve high transfection efficiency under the serum conditions, indicating the great potential as a nonviral gene delivery vector candidate for clinical application.

Multi-Arm Star-Shaped Glycopolymers with Precisely Controlled Core Size and Arm Length

Star-shaped glycopolymers provide very high binding activities toward lectins. However, a straightforward synthesis method for the preparation of multi-arm glycopolymers in a one-pot approach has been challenging. Herein, we report a rapid synthesis of well-defined multi-arm glycopolymers via Cu(0)-mediated reversible deactivation radical polymerization in aqueous media. d-Mannose acrylamide has been homo- and copolymerized with NIPAM to provide linear arms and then core cross-linked with a bisacrylamide monomer. Thus, the arm length and core size of multi-arm glycopolymers were tuned. Moreover, the stability of multi-arm glycopolymers was investigated, and degradation reactions under acidic or basic conditions were observed. The binding activities of the obtained multi-arm glycopolymers with mannose-specific human lectins, DC-SIGN and MBL, were investigated via surface plasmon resonance spectroscopy. Finally, the encapsulation ability of multi-arm glycopolymers was examined using DHA and Saquinavir below and above the lower critical solution temperature (LCST) of P(NIPAM).

pH-triggered intracellular release of doxorubicin by a poly(glycidyl methacrylate)-based double-shell magnetic nanocarrier

Two core-double-shell pH-sensitive nanocarriers were fabricated using Fe₃O₄ as magnetic core, poly(glycidyl methacrylate-PEG) and salep dialdehyde as the first and the second shell, and doxorubicin as the hydrophobic anticancer drug. Two nanocarriers were different in the drug loading steps. The interaction between the first and the second shell assumed to be pH-sensitive via acetal cross linkages. The structure of nanocarriers, organic shell loading, magnetic responsibility, morphology, size, dispersibility, and drug loading content were investigated by IR, NMR, TG, VSM, XRD, DLS, HRTEM and UV-Vis analyses. The long-term drug release profiles of both nanocarriers showed that the drug loading before cross-linking between the first and second shell led to a more pH-sensitive nanocarrier exhibiting higher control on DOX release. Cellular toxicity assay (MTT) showed that DOX-free nanocarrier is biocompatible having cell viability greater than 80% for HEK-293 and MCF-7 cell lines. Besides, high cytotoxic effect observed for drug-loaded nanocarrier on MCF-7 cancer cells. Cellular uptake analysis showed that the nanocarrier is able to transport DOX into the cytoplasm and perinuclear regions of MCF-7 cells. In vitro hemolysis and coagulation assays demonstrated high blood compatibility of nanocarrier. The results also suggested that low concentration of nanocarrier have a great potential as a contrast agent in magnetic resonance imaging (MRI).