In vivo targeting of alveolar macrophages via RAFT-based glycopolymers

Water-soluble PEG segmented mannose-based macromolecules: Synthesis and their biocompatibility

The macromolecular architectures, namely mannose-based methacrylate acetyl-mannopyranoside and PEG block copolymers (AB type copolymer [PEG-b-PMAM], poly(ethyleneglycol)-b-poly(methacryl-2,3,4,6-tetra-O-acetyl-D-mannopyranoside and ABA type copolymer [PMAM-b-PEG-b-PMAM], poly(methacryl-2,3,4,6-tetra-O-acetyl-D-mannopyranoside-b-poly(ethyleneglycol)-b-poly(methacryl-2,3,4,6-tetra-O-acetyl-D-mannopyranoside) were synthesized by atom transfer radical polymerization (ATRP) method that were deacetylated to generate the corresponding water-soluble and biocompatible glycopolymer macromolecules. The molecular weight of acetyl and deacetylate macromolecules was in the range of 7083-9499 and 4659-6026, as determined by GPC and proton NMR spectra. The 5 % decomposition temperatures for acetylated methacrylate macromolecules (218-299 °C) were higher than the corresponding water-soluble macromolecules (204-248 °C). The conjugation of poly(methacryl-2,3,4,6-tetra-O-acetyl-D-mannopyranoside (PMAM) segment with the PEG block decreased the glass transition (Tg) value, and the water-soluble macromolecules displayed Tg in the range of 92-95 °C. The biocompatibility of the synthesized water-soluble mannose-based macromolecules was determined using Human Bone Derived Cells (HBDC) culture with the TCP (Tissue culture plastic) template as control. Using three different concentrations of the synthesized glycopolymers, HBDC's were cultured for 1, 3, and 7 days. The effect of mannomethacrylate macromolecules on mitochondrial activity of HBDC's was estimated using colorimetry that showed the conversion of MTS [3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium-bromide] to formazan (MTS assay). ABA type diblock copolymer architecture exhibited increased absorbance values of 3 and 7 day cultures at 1-100 M concentrations, with the highest values observed at a concentration of 1 M for day 3 cultures. The design of these novel mannose-based macromolecules is important for improving cell proliferation, cell adhesion, and osteointegration efficiency.

Incorporation of Targeting Biomolecule Improves Interpolymer Complex-Superparamagnetic Iron Oxide Nanoparticles Attachment to and Activation of T2 MR Signals in M2 Macrophages

Introduction

Inflammatory diseases are the leading cause of death in the world, accounting for 3 out of 5 deaths. Despite the abundance of diagnostic tools for detection, most screening and diagnostic methods are indirect and insufficient as they are unable to reliably discriminate between high-risk or low-risk stages of inflammatory diseases. Previously, we showed that the selective activation of interpolymer complexed superparamagnetic iron oxide nanoparticles (IPC-SPIOs) under oxidative conditions can be detected by a change in T₂ magnetic resonance (MR) contrast. In this work, IPC-SPIOs were further modified by incorporating mannose as a targeting biomolecule to enhance nanoparticle delivery to M2 macrophages at inflammatory sites.

Methods

Uncoated SPIOs were synthesized via coprecipitation from a mixture of FeCl₂ and FeCl₃, PEGylated by adsorbing PEG 300 kDa (40 mg/mL in water) to SPIOs (3 mg/mL in water) over 24 hours, and complexed by mixing 0.25 mg/mL aqueous poly(gallol) with 2 mg/mL PEG-SPIOs and adding 1 M of phosphate buffer in a 9:9:2 ratio. Mannose-PEG attachment was accomplished conducting a second complexation of mannose-PEG to IPC-SPIOs. M2 macrophages were treated with 150, 100, and 75 µg/mL of IPC-SPIOs and mannose-IPC-SPIOs to investigate activation of T₂ MRI signals.

Results and Discussion

Surface modification resulted in a slight reduction in ROS scavenging capacity; however, nanoparticle uptake by M2 macrophages increased by over 50%. The higher uptake did not cause a reduction in cellular viability. In fact, mannose-IPC-SPIOs induced significant T₂ MR contrast in M2 macrophages compared to IPC-SPIOs and nanoparticles exposed to M1 macrophages. M2 macrophages activated over 30% of mannose-IPC-SPIOs after 6 hours of exposure compared to M1 macrophages and untargeted M2 macrophages. These findings demonstrated that mannose-IPC-SPIOs specifically targeted M2 macrophages and scavenged cellular ROS to activate T₂ MR signal, which can be used to detect inflammation.

Dual-Responsive Glycopolymers for Intracellular Codelivery of Antigen and Lipophilic Adjuvants

Traditional approaches to vaccines use whole organisms to trigger an immune response, but they do not typically generate robust cellular-mediated immunity and have various safety risks. Subunit vaccines composed of proteins and/or peptides represent an attractive and safe alternative to whole organism vaccines, but they are poorly immunogenic. Though there are biological reasons for the poor immunogenicity of proteins and peptides, one other key to their relative lack of immunogenicity could be attributed to the poor pharmacokinetic properties of exogenously delivered proteins and peptides. For instance, peptides often aggregate at the site of injection and are not stable in biological fluids, proteins and peptides are rapidly cleared from circulation, and both have poor cellular internalization and endosomal escape. Herein, we developed a delivery system to address the lack of protein immunogenicity by overcoming delivery barriers as well as codelivering immune-stimulating adjuvants. The glycopolymeric nanoparticles (glycoNPs) are composed of a dual-stimuli-responsive block glycopolymer, poly[2-(diisopropylamino)ethyl methacrylate]-b-poly[(pyridyl disulfide ethyl methacrylate)-co-(methacrylamidoglucopyranose)] (p[DPA-b-(PDSMA-co-MAG)]). This polymer facilitates protein conjugation and cytosolic release, the pH-responsive release of lipophilic adjuvants, and pH-dependent membrane disruption to ensure cytosolic delivery of antigens. We synthesized p[DPA-b-(PDSMA-co-MAG)] by reversible addition-fragmentation chain transfer (RAFT) polymerization, followed by the formation and physicochemical characterization of glycoNPs using the p[DPA-b-(PDSMA-co-MAG)] building blocks. These glycoNPs conjugated the model antigen ovalbumin (OVA) and released OVA in response to elevated glutathione levels. Moreover, the glycoNPs displayed pH-dependent drug release of the model hydrophobic drug Nile Red while also exhibiting pH-responsive endosomolytic behavior as indicated by a red blood cell hemolysis assay. GlycoNPs coloaded with OVA and the toll-like receptor 7/8 (TLR-7/8) agonist Resiquimod (R848) activated DC 2.4 dendritic cells (DCs) significantly more than free OVA and R848 and led to robust antigen presentation of the OVA epitope SIINFEKL on major histocompatibility complex I (MHC-I). In sum, the dual-stimuli-responsive glycopolymer introduced here overcomes major protein and peptide delivery barriers and could vastly improve the immunogenicity of protein-based vaccines.

ROS-Responsive Glycopolymeric Nanoparticles for Enhanced Drug Delivery to Macrophages

Macrophages play a diverse, key role in many pathologies, including inflammatory diseases, cardiovascular diseases, and cancer. However, many therapeutic strategies targeting macrophages suffer from systemic off-target toxicity resulting in notoriously narrow therapeutic windows. To address this shortcoming, the development of poly(propylene sulfide)-b-poly(methacrylamidoglucopyranose) [PPS-b-PMAG] diblock copolymer-based nanoparticles (PMAG NPs) capable of targeting macrophages and releasing drug in the presence of reactive oxygen species (ROS) is reported. PMAG NPs have desirable physicochemical properties for systemic drug delivery, including slightly negative surface charge, ≈100 nm diameter, and hemo-compatibility. Additionally, due to the presence of PPS in the NP core, PMAG NPs release drug cargo preferentially in the presence of ROS. Importantly, PMAG NPs display high cytocompatibility and are taken up by macrophages in cell culture at a rate ≈18-fold higher than PEGMA NPs-NPs composed of PPS-b-poly(oligoethylene glycol methacrylate). Computational studies indicate that PMAG NPs likely bind with glucose transporters such as GLUT 1/3 on the macrophage cell surface to facilitate high levels of internalization. Collectively, this study introduces glycopolymeric NPs that are uniquely capable of both receptor-ligand targeting to macrophages and ROS-dependent drug release and that can be useful in many immunotherapeutic settings.

Glycopolymer-Functionalized MOF-808 Nanoparticles as a Cancer-Targeted Dual Drug Delivery System for Carboplatin and Floxuridine

Codelivery of chemotherapeutics via nanomaterials has attracted much attention over the last decades due to improved drug delivery to tumor tissues, decreased systemic effects, and increased therapeutic efficacies. High porosities, large pore volumes and surface areas, and tunable structures have positioned metal-organic frameworks (MOFs) as promising drug delivery systems (DDSs). In particular, nanoscale Zr-linked MOFs such as MOF-808 offer notable advantages for biomedical applications such as high porosity, good stability, and biocompatibility. In this study, we report efficient dual drug delivery of floxuridine (FUDR) and carboplatin (CARB) loaded in MOF-808 nanoparticles to cancer cells. The nanoparticles were further functionalized by a poly(acrylic acid-mannose acrylamide) (PAAMAM) glycopolymer coating to obtain a highly selective DDS in cancer cells and enhance the therapeutic efficacy of chemotherapy. While MOF-808 was found to enhance the individual therapeutic effects of FUDR and CARB toward cancerous cells, combining FUDR and CARB was seen to cause a synergistic effect, further enhancing the cytotoxicity of the free drugs. Enhancement of CARB loading and therefore cytotoxicity of the CARB-loaded MOFs could be induced through a modified activation protocol, while coating of MOF-808 with the PAAMAM glycopolymer increased the uptake of the nanoparticles in cancer cells used in the study and offered a particularly significant selective drug delivery with high cytotoxicity in HepG2 human hepatocellular carcinoma cells. These results show how the enhancement of cytotoxicity is possible through both nanovector delivery and synergistic treatment, and that MOF-808 is a viable candidate for future drug delivery studies.

Recent Developments in Drug Delivery for Treatment of Tuberculosis by Targeting Macrophages

Tuberculosis (TB) is among the greatest public health and safety concerns in the 21st century, Mycobacterium tuberculosis, which causes TB, infects alveolar macrophages and uses these cells as one of its primary sites of replication. The current TB treatment regimen, which consist of chemotherapy involving a combination of 3-4 antimicrobials for a duration of 6-12 months, is marked with significant side effects, toxicity, and poor compliance. Targeted drug delivery offers a strategy that could overcome many of the problems of current TB treatment by specifically targeting infected macrophages. Recent advances in nanotechnology and material science have opened an avenue to explore drug carriers that actively and passively target macrophages. This approach can increase the drug penetration into macrophages by using ligands on the nanocarrier that interact with specific receptors for macrophages. This review encompasses the recent development of drug carriers specifically targeting macrophages actively and passively. Future directions and challenges associated with development of effective TB treatment is also discussed.

A Virus-like-inspired Nanoparticles Facilitates Bacterial Internalization for Enhanced Eradication of Drug-resistant Pathogen

The emergence and rapid spread of bacterial resistance pose an extremely serious threat to treat infections. Inspired that the spiny surface structure of virus plays an important role in mediating...

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...

Nanocarriers for pancreatic cancer imaging, treatments, and immunotherapies

Pancreatic tumors are highly desmoplastic and immunosuppressive. Delivery and distribution of drugs within pancreatic tumors are compromised due to intrinsic physical and biochemical stresses that lead to increased interstitial fluid pressure, vascular compression, and hypoxia. Immunotherapy-based approaches, including therapeutic vaccines, immune checkpoint inhibition, CAR-T cell therapy, and adoptive T cell therapies, are challenged by an immunosuppressive tumor microenvironment. Together, extensive fibrosis and immunosuppression present major challenges to developing treatments for pancreatic cancer. In this context, nanoparticles have been extensively studied as delivery platforms and adjuvants for cancer and other disease therapies. Recent advances in nanotechnology have led to the development of multiple nanocarrier-based formulations that not only improve drug delivery but also enhance immunotherapy-based approaches for pancreatic cancer. This review discusses and critically analyzes the novel nanoscale strategies that have been used for drug delivery and immunomodulation to improve treatment efficacy, including newly emerging immunotherapy-based approaches. This review also presents important perspectives on future research directions that will guide the rational design of novel and robust nanoscale platforms to treat pancreatic tumors, particularly with respect to targeted therapies and immunotherapies. These insights will inform the next generation of clinical treatments to help patients manage this debilitating disease and enhance survival rates.

A Targeted Photosensitizer Mediated by Visible Light for Efficient Therapy of Bacterial Keratitis

Bacterial keratitis is a serious bacterial infection of the cornea that can cause sight loss in severe cases because of the sharp decline of efficacious antibiotics. Herein, a targeted photosensitizer based on BODIPY severing as a photobactericidal agent was developed for treating bacterial keratitis. The water solubility of the material was as high as 10 mg/mL, which was attributable to the introduction of pathogen-targeting galactose and fucose. The photosensitizer was able to preferentially bind Pseudomonas aeruginosa instead of mammalian cells and trigger the aggregation of bacteria, which ultimately facilitated effective pathogen ablation upon the generation of reactive oxygen species (ROS) via laser irradiation. Photoexcited targeted photosensitizers can promote wound healing by eradicating P. aeruginosa in rat eyes and reducing the inflammatory response, thus exhibiting the significant therapeutic effect on bacterial keratitis. We also performed molecular level mechanistic studies using the unique field-induced droplet ionization mass spectrometry methodology and confirmed that the generated ROS were mainly singlet oxygen that caused lipid peroxidation (Type II mechanism). We anticipate that the targeted photosensitizer will have great potential in the application of clinical photodynamic therapy to ocular infection.

Polymer-Based Drug-Free Therapeutics for Anticancer, Anti-Inflammatory, and Antibacterial Treatment

This paper summarizes the area of biomedicinal polymers, which serve as nanomedicines even though they do not contain any anticancer or antiinflammatory drugs. These polymer nanomedicines with unique design are in the literature highlighted as a novel class of therapeutics called "drug-free macromolecular therapeutics." Their therapeutic efficacy is based on the tailored multiple presentations of biologically active vectors, i.e., peptides, oligopeptides, or oligosaccharides. Thus, they enable, for example, to directly induce the apoptosis of malignant cells by the crosslinking of surface slowly internalizing receptors, or to deplete the efficacy of tumor-associated proteins. The precise biorecognition of natural binding motifs by multiple vectors on the polymer construct remains the crucial part in the designing of these drug-free nanomedicines. Here, the rationales, designs, synthetic approaches, and therapeutic potential of drug-free macromolecular therapeutics consisting of various active vectors are described in detail. Recent developments and achievements for namely B-cell lymphoma treatment, Gal-3-positive tumors, inflammative liver injury, and bacterial treatment are reviewed and highlighted. Finally, a possible future prospect within this highly exciting new field of nanomedicine research is presented.

Modulation of Macrophages M1/M2 Polarization Using Carbohydrate-Functionalized Polymeric Nanoparticles

Exploiting surface endocytosis receptors using carbohydrate-conjugated nanocarriers brings outstanding approaches to an efficient delivery towards a specific target. Macrophages are cells of innate immunity found throughout the body. Plasticity of macrophages is evidenced by alterations in phenotypic polarization in response to stimuli, and is associated with changes in effector molecules, receptor expression, and cytokine profile. M1-polarized macrophages are involved in pro-inflammatory responses while M2 macrophages are capable of anti-inflammatory response and tissue repair. Modulation of macrophages’ activation state is an effective approach for several disease therapies, mediated by carbohydrate-coated nanocarriers. In this review, polymeric nanocarriers targeting macrophages are described in terms of production methods and conjugation strategies, highlighting the role of mannose receptor in the polarization of macrophages, and targeting approaches for infectious diseases, cancer immunotherapy, and prevention. Translation of this nanomedicine approach still requires further elucidation of the interaction mechanism between nanocarriers and macrophages towards clinical applications.

Protonation-Activity Relationship of Bioinspired Ionizable Glycomimetics for the Growth Inhibition of Bacteria

Variations in physiological parameters (i.e., pH, redox potential, and ions) for distinct types of diseases make them attractive targets. Ionizable groups capable of pH-dependent charge conversion impart pH-switchable materials under acid condition through the protonation effect, which stimulates the emergence of various pH-inspired materials. However, it is confusing to distinguish preferable groups for high-efficiency drug-delivery vehicles attributing to the lack of perceiving the relationship between protonation and activity. Herein, we developed a series of bioinspired ionizable glycomimetics responses to the ambient variation from physiological environment (pH 7.4) to bacterial infectious acidic microenvironment (pH 6.0) to explore the protonation-activity relationship of various ionizable groups. The nanoparticles are coated with bacterial adhesion molecules galactose and fucose to target Pseudomonas aeruginosa. Moreover, the particle cores were composed of ionizable polymers responding to acidic microenvironment changes and entrapped antibiotic payload. Ionizable glyconanoparticles targeted bacteria and local cues as triggers to transfer payloads in on-demand patterns for the inhibition of bacteria-related infection. Significantly, we find that the nanoparticles with the pH-sensitive block of ionizable poly(2-(diisopropylamino)ethyl methacrylate) (pDPA) exhibit predominant bacterial adhesion and killing and growth inhibition of biofilm in acid environment (pH 6.0) due to the ionizable polymer protonation effect with more positive charge cooperated with the lectin-targeted effect of polysaccharide causing a huge bacterial aggregation and a highly favorable germicidal effect. The nanoparticles with poly(2-(hexamethyleneimino)ethyl methacrylate) (pHMEMA) have suboptimal antibacterial activity but advanced protonation at pH 6.3 compared to pDPA at 6.1, suggesting its selection as an applicable pH-switchable group for a slightly higher acid microenvironment like tumor (pH 6.9-6.5) because of the efficient performance after protonation than at deprotonation. On the other hand, the glycomimetic containing poly(2-(dibutylamino)ethyl methacrylate) (pDBA) as a pH-sensitive moiety displayed weak antimicrobial activity and superior stability before protonation (pH 4.7), which make it possible to prevent premature drug leakage, suggesting that pDBA is a good candidate to be applied to construct pH-sensitive drug-delivery carriers for the treatment of bacteria-related infection with a low acidic microenvironment. Overall, the structure-activity relationship of ionizable glycomimetics for the inhibition of bacteria signifies not only the development of a drug-delivery system but also the mechanism-dependent treatment of nanomedicine for infectious diseases.

A Novel Bivalent Mannosylated Targeting Ligand Displayed on Nanoparticles Selectively Targets Anti-Inflammatory M2 Macrophages

Persistent activation of macrophages (MP)s into a proinflammatory M1 or anti-inflammatory M2 phenotype plays a role in several pathological conditions, including autoimmune diseases, fibrosis, infections, atherosclerosis and tumor development. The mannose receptor (MR, CD206), expressed at low levels on resting MPs and absent on M1 MPs, is highly expressed on M2 MPs, making it a potential target and drug delivery portal. Recently, we developed a novel, highly selective MR targeting ligand (MRTL), consisting of two mannose molecules separated by a monodisperse 12 unit poly(ethylene glycol) linker, to enhance the cellular uptake of polymeric nanocarriers. The feasibility of using the MRTL ligand for selectively targeting M2 MPs for intracellular delivery of nanoparticles (NPs) was investigated. Rat peritoneal MPs were differentiated into an M1 or M2 phenotype using IFN-γ and IL-4/IL-13, respectively. Expression of the M1 marker, inducible nitric oxide synthase (iNOS), and the M2 markers arginase (Arg)-1 and MR (at both the mRNA and protein levels) confirmed MP phenotypic activation. Resting, M1 and M2 MPs were treated with fluorescein isothiocyanate (FITC)-labeled MRTL or NPs displaying FITC-labeled MRTL at two surface densities (1 and 10%) and examined by confocal microscopy. Intracellular fluorescence was also quantified. Uptake of the MRTL was 2.4- and 11.8-fold higher in M2 MPs when compared to resting or M1 MPs, respectively, consistent with marker expression levels. Mannan, a competitive inhibitor of the MR, abrogated MRTL uptake. MRTL also co-localized with a fluid-phase endocytosis marker, further suggesting that uptake was mediated by MR-mediated endocytosis. Intracellular NP fluorescence was confirmed by flow cytometry and by confocal microscopy. MRTL-NPs accumulated intracellularly with no significant cell surface binding, suggesting efficient translocation. NPs displaying a low surface density (1%) of the MRTL exhibited significantly higher (2.3-fold) uptake into M2 MPs, relative to resting and M1 MPs. The 10% MRTL-NPs displayed greater uptake by M2 MPs when compared to resting and M1 MPs, but less uptake than 1% MRTL-NPs into M2 MPs. Control FITC-labeled plain NPs did not exhibit selective MP uptake. These studies demonstrate that M2 MPs are selectively targeted by NPs displaying a novel bivalent ligand that utilizes the MR as a target/portal for cell entry. This study also establishes the feasibility of the approach allowing for further investigation in vivo.

Bio-Inspired Amphiphilic Block-Copolymers Based on Synthetic Glycopolymer and Poly(Amino Acid) as Potential Drug Delivery Systems

In this work, a method to prepare hybrid amphiphilic block copolymers consisting of biocompatible synthetic glycopolymer with non-degradable backbone and biodegradable poly(amino acid) (PAA) was developed. The glycopolymer, poly(2-deoxy-2-methacrylamido-D-glucose) (PMAG), was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Two methods for modifying the terminal dithiobenzoate-group of PMAG was investigated to obtain the macroinitiator bearing a primary aliphatic amino group, which is required for ring-opening polymerization of N-carboxyanhydrides of hydrophobic α-amino acids. The synthesized amphiphilic block copolymers were carefully analyzed using a set of different physico-chemical methods to establish their composition and molecular weight. The developed amphiphilic copolymers tended to self-assemble in nanoparticles of different morphology that depended on the nature of the hydrophobic amino acid present in the copolymer. The hydrodynamic diameter, morphology, and cytotoxicity of polymer particles based on PMAG-b-PAA were evaluated using dynamic light scattering (DLS) and transmission electron microscopy (TEM), as well as CellTiter-Blue (CTB) assay, respectively. The redox-responsive properties of nanoparticles were evaluated in the presence of glutathione taken at different concentrations. Moreover, the encapsulation of paclitaxel into PMAG-b-PAA particles and their cytotoxicity on human lung carcinoma cells (A549) and human breast adenocarcinoma cells (MCF-7) were studied.

Pillar[5]arene-based, dual pH and enzyme responsive supramolecular vesicles for targeted antibiotic delivery against intracellular MRSA

A rationally designed mannosylated amphiphilic pillar[5]arene (Man@AP5) self-assembles into supramolecular vesicles with encapsulated vancomycin (Man@AP5-Van), enhancing vancomycin's antibacterial efficacy against intracellular MRSA.

Carbohydrate-based nanocarriers and their application to target macrophages and deliver antimicrobial agents

Many deadly infections are produced by microorganisms capable of sustained survival in macrophages. This reduces exposure to chemadrotherapy, prevents immune detection, and is akin to criminals hiding in police stations. Therefore, the use of glyco-nanoparticles (GNPs) as carriers of therapeutic agents is a burgeoning field. Such an approach can enhance the penetration of drugs into macrophages with specific carbohydrate targeting molecules on the nanocarrier to interact with macrophage lectins. Carbohydrates are natural biological molecules and the key constituents in a large variety of biological events such as cellular communication, infection, inflammation, enzyme trafficking, cellular migration, cancer metastasis and immune functions. The prominent characteristics of carbohydrates including biodegradability, biocompatibility, hydrophilicity and the highly specific interaction of targeting cell-surface receptors support their potential application to drug delivery systems (DDS). This review presents the 21^st century development of carbohydrate-based nanocarriers for drug targeting of therapeutic agents for diseases localized in macrophages. The significance of natural carbohydrate-derived nanoparticles (GNPs) as anti-microbial drug carriers is highlighted in several areas of treatment including tuberculosis, salmonellosis, leishmaniasis, candidiasis, and HIV/AIDS.

Glycan targeted polymeric antibiotic prodrugs for alveolar macrophage infections

Alveolar macrophages resident in the lung are prominent phagocytic effector cells of the pulmonary innate immune response, and paradoxically, are attractive harbors for pathogens. Consequently, facultative intracellular bacteria, such as Francisella tularensis, can cause severe systemic disease and sepsis, with high morbidity and mortality associated with pulmonary infection. Current clinical treatment, which involves exhaustive oral or intravenous antibiotic therapy, has limitations such as systemic toxicity and off-target effects. Pulmonary administration represents a promising alternative to systemic dosing for delivering antibiotics directly to the lung. Here, we present synthesized mannosylated ciprofloxacin polymeric prodrugs for efficient pulmonary delivery, targeting, and subsequent internalization by alveolar macrophages. We demonstrate significant improvement in efficacy against intracellular infections in an otherwise uniformly lethal airborne Francisella murine model (F. novicida). When administered to the lungs of mice in a prophylactic regimen, the mannosylated ciprofloxacin polymeric prodrugs led to 50% survival. In a treatment regimen that was concurrent with infection, the survival of mice increased to 87.5%. Free ciprofloxacin antibiotic was ineffective in both cases. This significant difference in antibacterial efficacy demonstrates the impact of this delivery platform based on improved physiochemical, pharmacokinetic, and pharmacodynamic properties of ciprofloxacin administered via our glycan polymeric prodrug. This modular platform provides a route for overcoming the limitations of free drug and increasing efficacy in treatment of intracellular infection.

Immunogene therapy with fusogenic nanoparticles modulates macrophage response to Staphylococcus aureus

The incidence of adverse effects and pathogen resistance encountered with small molecule antibiotics is increasing. As such, there is mounting focus on immunogene therapy to augment the immune system’s response to infection and accelerate healing. A major obstacle to in vivo gene delivery is that the primary uptake pathway, cellular endocytosis, results in extracellular excretion and lysosomal degradation of genetic material. Here we show a nanosystem that bypasses endocytosis and achieves potent gene knockdown efficacy. Porous silicon nanoparticles containing an outer sheath of homing peptides and fusogenic liposome selectively target macrophages and directly introduce an oligonucleotide payload into the cytosol. Highly effective knockdown of the proinflammatory macrophage marker IRF5 enhances the clearance capability of macrophages and improves survival in a mouse model of Staphyloccocus aureus pneumonia.

In the context of increasing bacterial antibiotic-resistance, gene therapy that targets the immune system to clear infection is a major goal. Here the authors show a silicon based nanosystem that modulates the macrophage response in an in vivo model of Staphylococcal pneumonia.

Mannose-Decorated Multicomponent Supramolecular Polymers Trigger Effective Uptake into Antigen-Presenting Cells

A modular route to prepare functional self-assembling dendritic peptide amphiphiles decorated with mannosides, to effectively target antigen-presenting cells, such as macrophages, is reported. The monomeric building blocks were equipped with tetra(ethylene glycol)s (TEGs) or labeled with a Cy3 fluorescent probe. Experiments on the uptake of the multifunctional supramolecular particles into murine macrophages (Mφs) were monitored by confocal microscopy and fluorescence-activated cell sorting. Mannose-decorated supramolecular polymers trigger a significantly higher cellular uptake and distribution, relative to TEG carrying bare polymers. No cytotoxicity or negative impact on cytokine production of the treated Mφs was observed, which emphasized their biocompatibility. The modular nature of the multicomponent supramolecular polymer coassembly protocol is a promising platform to develop fully synthetic multifunctional vaccines, for example, in cancer immunotherapy.

NO prodrug-conjugated, self-assembled, pH-responsive and galactose receptor targeted nanoparticles for co-delivery of nitric oxide and doxorubicin

Targeted delivery and controlled release of nitric oxide (NO) locoregionally are in high demand and challenging in cancer treatment. Herein, we report an example of galactose receptor targeted, pH-responsive and self-assembled nanoparticle-based delivery of the NO prodrug O²-(2,4-dinitrophenyl) 1-[4-(propargyloxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (alkynyl-JSK), which was chemically conjugated to an amphiphilic block copolymer through a click reaction for the first time. The assembled NO prodrug nanoparticles show high NO capacity (the content of the NO prodrug in the copolymer, ∼23.4% (w/w)), good stability and a sustained NO release pattern with unique glutathione/glutathione S-transferase (GSH/GST) activated NO-releasing kinetics. Such NO-loaded nanoparticles exhibit superior cytotoxicity to HepG2 cells. More importantly, in combination with doxorubicin (DOX) chemotherapy a significant synergistic therapeutic effect was achieved, due to its excellent galactose receptor-targeting capability, rapid acid-triggered DOX release and sustained NO release. Our findings indicate that these multifunctional nanoparticles can serve as an efficient NO and chemotherapeutic agent delivery platform, holding great promise in cancer combinatorial treatment.

Radiant star nanoparticle prodrugs for the treatment of intracellular alveolar infections

Radiant star nanoparticle prodrugs were synthesized in a two-step process by first homopolymerizing RAFT transmers followed by copolymerization from the hyperbranched polymer core.

Critical physicochemical and biological attributes of nanoemulsions for pulmonary delivery of rifampicin by nebulization technique in tuberculosis treatment

The study investigated aerosolization, pulmonary inhalation, intracellular trafficking potential in macrophages and pharmacokinetics profiles of rifampicin-oleic acid first-generation nanoemulsion and its respective chitosan- and chitosan-folate conjugate-decorated second and third-generation nanoemulsions, delivered via nebulization technique. The nanoemulsions were prepared by conjugate synthesis and spontaneous emulsification techniques. They were subjected to physicochemical, drug release, aerosolization, inhalation, cell culture and pharmacokinetics analysis. The nanoemulsions had average droplet sizes of 40-60 nm, with narrow polydispersity indices. They exhibited desirable pH, surface tension, viscosity, refractive index, density and viscosity attributes for pulmonary rifampicin administration. All nanoemulsions demonstrated more than 95% aerosol output and inhalation efficiency greater than 75%. The aerosol output, aerosolized and inhaled fine particle fractions were primarily governed by the size and surface tension of nanoemulsions in an inverse relationship. The nanoemulsions were found to be safe with third-generation nanoemulsion exhibiting higher cell internalization potential, reduced plasma drug concentration, and higher lung drug content.

Preparation of a dual cored hepatoma-specific star glycopolymer nanogel via arm-first ATRP approach

A reductase-cleavable and thermo-responsive star-shaped polymer nanogel was prepared via an "arm-first" atom transfer radical polymerization approach. The nanogel consists of a thermo- and redox-sensitive core and a zwitterionic copolymer block. The dual sensitive core is composed of poly(N-isopropylacrylamide) that is formed by disulfide crosslinking of N-isopropylacrylamide. The zwitterionic copolymer block contains a poly(sulfobetaine methacrylate) component, a known anti-adsorptive moiety that extends blood circulation time, and a lactose motif of poly(2-lactobionamidoethyl methacrylamide) that specifically targets the asialoglycoprotein receptors (ASGP-Rs) of hepatoma. Doxorubicin (DOX) was encapsulated into the cross-linked nanogels via solvent extraction/evaporation method and dialysis; average diameter of both blank and DOX-loaded nanogels was ~120 nm. The multi-responsiveness of nanogel drug release in different temperatures and redox conditions was assessed. After 24 h, DOX release was only ~20% at 30°C with 0 mM glutathione (GSH), whereas over 90% DOX release was observed at 40°C and 10 mM GSH, evidence of dual responsiveness to temperature and reductase GSH. The IC50 value of DOX-loaded nanogels was much lower in human hepatoma (HepG2) cells compared to non-hepatic HeLa cells. Remarkably, DOX uptake of HepG2 cells differed substantially in the presence and absence of galactose (0.31 vs 1.42 µg/mL after 48 h of incubation). The difference was non-detectable in HeLa cells (1.21 vs 1.57 µg/mL after 48 h of incubation), indicating that the overexpression of ASGP-Rs leads to the DOX-loaded lactosylated nanogels actively targeting hepatoma. Our data indicate that the lactose-decorated star-shaped nanogels are dual responsive and hepatoma targeted, and could be employed as hepatoma-specific anti-cancer drug delivery vehicle for cancer chemotherapy.

Specific and Differential Binding of N-Acetylgalactosamine Glycopolymers to the Human Macrophage Galactose Lectin and Asialoglycoprotein Receptor

A range of glycopolymers composed of N-acetylgalactosamine were prepared via sequential Cu(I)-mediated polymerization and alkyne-azide click (CuAAC). The resulting polymers were shown, via multichannel surface plasmon resonance, to interact specifically with human macrophage galactose lectin (MGL; CD301) with high affinity (K_D = 1.11 μM), but they did not bind to the mannose/fucose-selective human lectin dendritic-cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN; CD209). The effect of sugar ligand valency on the binding (so-called "glycoside cluster effect") of poly(N-acetylgalactosamine) to MGL was investigated by varying first the polymer chain length (DP: 100, 64, 40, 23, 12) and then the architecture (4- and 8-arm star glycopolymers). The chain length did not have a significant effect on the binding to MGL (K_D = 0.17-0.52 μM); however, when compared to a hepatic C-type lectin of a similar monosaccharide specificity, the asialoglycoprotein receptor (ASGPR), the binding affinity was more noticeably affected (K_D = 0.37- 6.65 μM). These data suggest that known differences in the specific configuration/orientation of the carbohydrate recognition domains of MGL and ASGPR are responsible for the differences in binding observed between the different polymers of varied chain length and architecture. In the future, this model has the potential to be employed for the development of tissue-selective delivery systems.

A glucose-targeted mixed micellar formulation outperforms Genexol in breast cancer cells

Breast cancer represents the top cancer among women, accounting 521.000 deaths per year. Development of targeted nanomedicines to breast cancer tissues represents a milestone to reduce chemotherapy side effects. Taking advantage of the over-expression of glucose (Glu) membrane transporters in breast cancer cells, we aim to expand the potential of a paclitaxel (PTX)-loaded mixed micellar formulation based on polyvinyl caprolactam-polyvinylacetate-polyethylene glycol graft copolymer (Soluplus®) and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) by its surface decoration with Glu moieties. The glycopolymer (Soluplus(Glu)) was obtained by microwave-assisted ring opening reaction of δ-gluconolactone initiated by Soluplus®. The glycosylation was confirmed by ¹H NMR and by agglutination assays employing Concanavalin A. The hydrodynamic diameter of Soluplus(Glu) micelles was characterized by dynamic light scattering (100.3±3.8nm) as well as the critical micellar concentration value (0.0151% w/v). Then, a mixed micelle formulation employing Soluplus®, Soluplus(Glu) and TPGS (3:1:1wt ratio) loaded with PTX (4mg/mL) was developed as a multifunctional nanocarrier. Its in vitro anticancer performance in MCF-7 (1.6-fold) and MDA-MB-231 (14.1-fold) was significantly enhanced (p<0.05) versus the unique commercially available micellar-based PTX-nanoformulation (Genexol®). Furthermore, the in vitro PTX cellular uptake assays revealed that the drug intracellular/cell content was significantly (p<0.05) higher for the Glu-containing mixed micelles versus Genexol® after 6h of incubation with MCF-7 (30.5-fold) and MDA-MB-231 (5-fold). Overall, results confirmed the potential of our Glu-decorated mixed colloidal formulation as an intelligent nanocarrier for PTX-targeted breast cancer chemotherapy.

Synthesis of zwitterionic, hydrophobic, and amphiphilic polymers via RAFT polymerization induced self-assembly (PISA) in acetic acid

Hydrophilic, hydrophobic, and combinations of these monomers were directly (co)polymerized via RAFT polymerization induced self-assembly (PISA) in acetic acid.

A biomimicking and electrostatic self-assembly strategy for the preparation of glycopolymer decorated photoactive nanoparticles

A biomimicking and electrostatic self-assembly strategy for the preparation of glycopolymer decorated photoactive nanoparticles.

Polymer nanostructures synthesized by controlled living polymerization for tumor-targeted drug delivery

The development of drug delivery systems based on well-defined polymer nanostructures could lead to significant improvements in the treatment of cancer. The design of these therapeutic nanosystems must account for numerous systemic and circulation obstacles as well as the specific pathophysiology of the tumor. Nanoparticle size and surface charge must also be carefully selected in order to maintain long circulation times, allow tumor penetration, and avoid clearance by the reticuloendothelial system (RES). Targeting ligands such as vitamins, peptides, and antibodies can improve the accumulation of nanoparticle-based therapies in tumor tissue but must be optimized to allow for intratumoral penetration. In this review, we will highlight factors influencing the design of nanoparticle therapies as well as the development of modern controlled "living" polymerization techniques (e.g. ATRP, RAFT, ROMP) that are leading to the creation of sophisticated new polymer architectures with discrete spatially-defined functional modules. These innovative materials (e.g. star polymers, polymer brushes, macrocyclic polymers, and hyperbranched polymers) combine many of the desirable properties of traditional nanoparticle therapies while substantially reducing or eliminating the need for complex formulations.

Glycocalyx-Mimicking Nanoparticles for Stimulation and Polarization of Macrophages via Specific Interactions

Malignant tumors develop multiple mechanisms to impair and escape from antitumor immune responses, of which tumor-associated macrophages that often show immunosuppressive phenotype (M2), play a critical role in tumor-induced immunosuppression. Therefore, strategies that can reverse M2 phenotype and even enhance immune-stimulation function of macrophage would benefit tumor immunotherapy. In this paper, self-assembled glyco-nanoparticles (glyco-NPs), as artificial glycocalyx, have been found to be able to successfully induce the polarization of mouse primary peritoneal macrophages from M2 to inflammatory type (M1). The polarization change was evidenced by the decreased expression of cell surface signaling molecules CD206 and CD23, and the increased expression of CD86. Meanwhile, secretion of cytokines supported this polarization change as well. More importantly, this phenomenon is observed not only in vitro, but also in vivo. As far as we known, this is the first report about macrophage polarization being induced by synthetic nanomaterials. Moreover, preparation, characterization of these glyco-NPs and their interaction with the macrophages are also demonstrated.

Biomedical applications of polymers derived by reversible addition - fragmentation chain-transfer (RAFT)

RAFT- mediated polymerization, providing control over polymer length and architecture as well as facilitating post polymerization modification of end groups, has been applied to virtually every facet of biomedical materials research. RAFT polymers have seen particularly extensive use in drug delivery research. Facile generation of functional and telechelic polymers permits straightforward conjugation to many therapeutic compounds while synthesis of amphiphilic block copolymers via RAFT allows for the generation of self-assembled structures capable of carrying therapeutic payloads. With the large and growing body of literature employing RAFT polymers as drug delivery aids and vehicles, concern over the potential toxicity of RAFT derived polymers has been raised. While literature exploring this complication is relatively limited, the emerging consensus may be summed up in three parts: toxicity of polymers generated with dithiobenzoate RAFT agents is observed at high concentrations but not with polymers generated with trithiocarbonate RAFT agents; even for polymers generated with dithiobenzoate RAFT agents, most reported applications call for concentrations well below the toxicity threshold; and RAFT end-groups may be easily removed via any of a variety of techniques that leave the polymer with no intrinsic toxicity attributable to the mechanism of polymerization. The low toxicity of RAFT-derived polymers and the ability to remove end groups via straightforward and scalable processes make RAFT technology a valuable tool for practically any application in which a polymer of defined molecular weight and architecture is desired.

Facile and Efficient Preparation of Tri-component Fluorescent Glycopolymers via RAFT-controlled Polymerization

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and efficient synthesis of well-controlled fluorescent statistical glycopolymers using reversible addition-fragmentation chain-transfer (RAFT)-based polymerization is demonstrated. The synthesis starts with the preparation of β-galactose-containing glycomonomer 2-lactobionamidoethyl methacrylamide obtained by reaction of lactobionolactone and N-(2-aminoethyl) methacrylamide (AEMA). 2-Gluconamidoethyl methacrylamide (GAEMA) is used as a structural analog lacking a terminal β-galactoside. The following RAFT-mediated copolymerization reaction involves three different monomers: N-(2-hydroxyethyl) acrylamide as spacer, AEMA as target for further fluorescence labeling, and the glycomonomers. Tolerant of aqueous systems, the RAFT agent used in the reaction is (4-cyanopentanoic acid)-4-dithiobenzoate. Low dispersities (≤1.32), predictable copolymer compositions, and high reproducibility of the polymerizations were observed among the products. Fluorescent polymers are obtained by modifying the glycopolymers with carboxyfluorescein succinimidyl ester targeting the primary amine functional groups on AEMA. Lectin-binding specificities of the resulting glycopolymers are verified by testing with corresponding agarose beads coated with specific glycoepitope recognizing lectins. Because of the ease of the synthesis, the tight control of the product compositions and the good reproducibility of the reaction, this protocol can be translated towards preparation of other RAFT-based glycopolymers with specific structures and compositions, as desired.

Aqueous RAFT synthesis of block and statistical copolymers of 2-(α-d-mannopyranosyloxy)ethyl methacrylate with 2-(N,N-dimethylamino)ethyl methacrylate and their application for nonviral gene delivery

Statistical and block glycopolymers presenting d-mannose were prepared by aqueous RAFT polymerization, and the effect of the microstructure on gene delivery was examined.

Carbohydrate-Based Polymers for Immune Modulation

Carbohydrates play prominent roles in immune surveillance and response to infection. Multivalency, molecular weight control, and molecular architecture control are properties that polymer science is well suited to address. Each of these properties has been demonstrated to impact the biological interaction of carbohydrate-bearing chains with their binding partners. This viewpoint highlights synthetic advances and potential applications of carbohydrate-based polymers for immune modulation. It also offers future directions in polymer science necessary for carbohydrate polymers to fulfill their potential as immune modulators.

Glucose-containing diblock polycations exhibit molecular weight, charge, and cell-type dependence for pDNA delivery

A series of diblock glycopolycations were created by polymerizing 2-deoxy-2-methacrylamido glucopyranose (MAG) with either a tertiary amine-containing monomer, N-[3-(N,N-dimethylamino) propyl] methacrylamide (DMAPMA), or a primary amine-containing unit, N-(2-aminoethyl) methacrylamide (AEMA). Seven structures were synthesized via aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization that varied in the block lengths of MAG, DMAPMA, and AEMA along with two homopolymer controls of DMAPMA and AEMA that lacked a MAG block. The polymers were all able to complex plasmid DNA into polyplex structures and to prevent colloidal aggregation of polyplexes in physiological salt conditions. In vitro transfection experiments were performed in both HeLa (human cervix adenocarcinoma) cells and HepG2 (human liver hepatocellular carcinoma) cells to examine the role of charge type, block length, and cell type on transfection efficiency and toxicity. The glycopolycation vehicles with primary amine blocks and PAEMA homopolymers revealed much higher transfection efficiency and lower toxicity when compared to analogs created with DMAPMA. Block length was also shown to influence cellular delivery and toxicity; as the block length of DMAPMA increased in the glycopolycation-based polyplexes, toxicity increased while transfection decreased. While the charge block played a major role in delivery, the MAG block length did not affect these cellular parameters. Lastly, cell type played a major role in efficiency. These glycopolymers revealed higher cellular uptake and transfection efficiency in HepG2 cells than in HeLa cells, while homopolycations (PAEMA and PDMAPMA) lacking the MAG blocks exhibited the opposite trend, signifying that the MAG block could aid in hepatocyte transfection.

Inhibition of influenza virus in vivo by siRNA delivered using ABA triblock copolymer synthesized by reversible addition-fragmentation chain-transfer polymerization

AIM

Influenza virus remains a major threat, with outbreaks continuing to occur. Few treatment options are available and drug resistance can emerge rapidly. New drugs that can quickly be adapted to virus mutations are needed. Several highly effective siRNAs targeting influenza that inhibit virus replication are known; however, effective delivery of these siRNAs remains a challenge. The aim of this study was to demonstrate the safety and efficacy of ABA triblock copolymer-delivered siRNA to inhibit influenza virus replication in vivo.

MATERIALS & METHODS

We report on the delivery of a siRNA targeting the influenza virus in chicken embryos using an ABA triblock copolymer prepared by reversible addition-fragmentation chain-transfer polymerization, containing a central cationic block and two outer hydrophilic polyethylene glycol blocks.

RESULTS

A significant reduction of virus titer was observed with the polymer/anti-influenza siRNA complexes, whereas the control with polymer/control siRNA complexes showed no effect.

CONCLUSION

These data suggest that a reversible addition-fragmentation chain transfer-based siRNA delivery platform may be suitable for combating infectious diseases in vivo.

RAFT-based tri-component fluorescent glycopolymers: synthesis, characterization and application in lectin-mediated bacterial binding study

A group of fluorescent statistical glycopolymers, prepared via reversible addition–fragmentation chain-transfer (RAFT)-based polymerizations, were successfully employed in lectin-mediated bacterial binding studies. The resultant glycopolymers contained three different monomers: N-(2-hydroxyethyl) acrylamide (HEAA), N-(2-aminoethyl) methacrylamide (AEMA) and N-(2-glyconamidoethyl)-methacrylamides possessing different pendant sugars. Low dispersities (≤1.32) and predictable degrees of polymerization were observed among the products. After the polymerization, the glycopolymers were further modified by different succinimidyl ester fluorophores targeting the primary amine groups on AEMA. With their binding specificities being confirmed by testing with lectin coated agarose beads, the glycopolymers were employed in bacterial binding studies, where polymers containing α-galactose or β-galactose as the pendant sugar were specifically bound by two clinically important pathogens Pseudomonas aeruginosa and Staphylococcus aureus, respectively. This is the first report of using RAFT-based glycopolymers in bacterial binding studies, and the ready access to tri-component statistical glycopolymers also warrants further exploration of their utility in other glycobiological applications.