Janus PEG-Based Dendrimers for Use in Combination Therapy: Controlled Multi-Drug Loading and Sequential Release

Anticancer evaluation of new organometallic ruthenium(ii) flavone complexes

Targeting multiple malignancy features such as angiogenesis, proliferation and metastasis with one molecule is an effective strategy in developing potent anticancer agents. Ruthenium metal complexation to bioactive scaffolds is reported to enhance their biological activities. Herein, we evaluate the impact of Ru chelation on the pharmacological activities of two bioactive flavones (1 and 2) as anticancer candidates. The novel Ru complexes (1Ru and 2Ru) caused a loss of their parent molecules' antiangiogenic activities in an endothelial cell tube formation assay. 1Ru enhanced the antiproliferative and antimigratory activities of its 4-oxoflavone 1 on MCF-7 breast cancer cells (IC₅₀ = 66.15 ± 5 μM and 50% migration inhibition, p < 0.01 at 1 μM). 2Ru diminished 4-thioflavone's (2) cytotoxic activity on MCF-7 and MDA-MB-231 yet significantly enhanced 2's migration inhibition (p < 0.05) particularly on the MDA-MB-231 cell line. The test derivatives also showed non-intercalative interaction with VEGF and c-myc i-motif DNA sequences.

Synthesis of Fluorescent, Dumbbell-Shaped Polyurethane Homo- and Heterodendrimers and Their Photophysical Properties

Fluorescent dendrimers have wide applications in biomedical and materials science. Here, we report the synthesis of fluorescent polyurethane homodendrimers and Janus dendrimers, which often pose challenges due to the inherent reactivity of isocyanates. Polyurethane dendrons (G1-G3) were synthesized via a convergent method using a one-pot multicomponent Curtius reaction as a crucial step to establish urethane linkages. The alkyne periphery of the G1-G3 dendrons was modified by a copper catalyzed azide-alkyne click reaction (CuAAC) to form fluorescent dendrons. In the reaction of the surfaces functionalized two different dendrons with a difunctional core, a mixture of three dendrimers consisting of two homodendrimers and a Janus dendrimer were obtained. The Janus dendrimer accounted for a higher proportion in the products' distribution, being as high as 93% for G3. The photophysical properties of Janus dendrimers showed the fluorescence resonance energy transfer (FRET) from one to the other fluorophore of the dendrimer. The FRET observation accompanied by a large Stokes shift make these dendrimers potential candidates for the detection and tracking of interactions between the biomolecules, as well as potential candidates for fluorescence imaging.

Synergistically Enhancing the Therapeutic Effect on Cancer, via Asymmetric Bioinspired Materials

The undesirable side effects of conventional chemotherapy are one of the major problems associated with cancer treatment. Recently, with the development of novel nanomaterials, tumor-targeted therapies have been invented in order to achieve more specific cancer treatment with reduced unfavorable side effects of chemotherapic agents on human cells. However, the clinical application of nanomedicines has some shortages, such as the reduced ability to cross biological barriers and undesirable side effects in normal cells. In this order, bioinspired materials are developed to minimize the related side effects due to their excellent biocompatibility and higher accumulation therapies. As bioinspired and biomimetic materials are mainly composed of a nanometric functional agent and a biologic component, they can possess both the physicochemical properties of nanomaterials and the advantages of biologic agents, such as prolonged circulation time, enhanced biocompatibility, immune modulation, and specific targeting for cancerous cells. Among the nanomaterials, asymmetric nanomaterials have gained attention as they provide a larger surface area with more active functional sites compared to symmetric nanomaterials. Additionally, the asymmetric nanomaterials are able to function as two or more distinct components due to their asymmetric structure. The mentioned properties result in unique physiochemical properties of asymmetric nanomaterials, which makes them desirable materials for anti-cancer drug delivery systems or cancer bio-imaging systems. In this review, we discuss the use of bioinspired and biomimetic materials in the treatment of cancer, with a special focus on asymmetric nanoparticle anti-cancer agents.

Halogenated Flavonoid Derivatives Display Antiangiogenic Activity

Antiangiogenic agents attenuate tumours' growth and metastases and are therefore beneficial as an adjuvant or standalone cancer regimen. Drugs with dual antiproliferative and antiangiogenic activities can achieve anticancer efficacy and overcome acquired resistance. In this study, synthetic flavones (5a,b) with reported anticancer activity, and derivatives (4b and 6a), exhibited significant inhibition of endothelial cell tube formation (40-55%, 12 h) at 1 µM, which is comparable to sunitinib (50% inhibition at 1 µM, 48 h). Flavones (4b, 5a,b and 6a) also showed 25-37% reduction in HUVECs migration at 10 µM. In a Western blotting assay, 5a and 5b subdued VEGFR2 phosphorylation by 37% and 57%, respectively, suggesting that VEGFR2 may be their main antiangiogenic target. 5b displayed the best docking fit with VEGFR2 in an in silico study, followed by 5a, emphasizing the importance of the 7-hydroxyl group accompanied by a 4-C=S for activity. Conversely, derivatives with a 4-carbonyl moiety fitted poorly into the target's binding pocket, suggesting that their antiangiogenic activity depends on a different target. This study provides valuable insight into the Structure Activity Relationships (SAR) and modes of action of halogenated flavones with VEGFR2 and highlights their therapeutic potential as antiangiogenic/anticancer lead compounds.

Embracing nanomaterials' interactions with the innate immune system

Immunotherapy has firmly established itself as a compelling avenue for treating disease. Although many clinically approved immunotherapeutics engage the adaptive immune system, therapeutically targeting the innate immune system remains much less explored. Nanomedicine offers a compelling opportunity for innate immune system engagement, as many nanomaterials inherently interact with myeloid cells (e.g., monocytes, macrophages, neutrophils, and dendritic cells) or can be functionalized to target their cell-surface receptors. Here, we provide a perspective on exploiting nanomaterials for innate immune system regulation. We focus on specific nanomaterial design parameters, including size, form, rigidity, charge, and surface decoration. Furthermore, we examine the potential of high-throughput screening and machine learning, while also providing recommendations for advancing the field. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Construction of Janus dendrimers through a self-assembly approach involving chiral discrimination at a focal point

A strategy to build Janus dendrimers via the chirality-directed self-assembly of heteroleptic Zn(ii) BOX complexes is reported. The method allows quantitative synthesis of Janus dendrimers in situ without the need for purifications. Each dendritic domain of the Janus dendrimers can be recycled upon disassembly at the focal point.

Stimulus-Responsive Sequential Release Systems for Drug and Gene Delivery

In recent years, a range of studies have been conducted with the aim to design and characterize delivery systems that are able to release multiple therapeutic agents in controlled and programmed temporal sequences, or with spatial resolution inside the body. This sequential release occurs in response to different stimuli, including changes in pH, redox potential, enzyme activity, temperature gradients, light irradiation, and by applying external magnetic and electrical fields. Sequential release (SR)-based delivery systems, are often based on a range of different micro- or nanocarriers and may offer a silver bullet in the battle against various diseases, such as cancer. Their distinctive characteristic is the ability to release one or more drugs (or release drugs along with genes) in a controlled sequence at different times or at different sites. This approach can lengthen gene expression periods, reduce the side effects of drugs, enhance the efficacy of drugs, and induce an anti-proliferative effect on cancer cells due to the synergistic effects of genes and drugs. The key objective of this review is to summarize recent progress in SR-based drug/gene delivery systems for cancer and other diseases.

A 3D printed drug delivery implant formed from a dynamic supramolecular polyurethane formulation

Prototype drug eluting implants have been 3D printed using a supramolecular polyurethane-PEG formulation. The implants are capable of releasing a pharmaceutical active with effective drug release over a period of up to 8.5 months.

Scaffold-mediated sequential drug/gene delivery to promote nerve regeneration and remyelination following traumatic nerve injuries

Neural tissue regeneration following traumatic injuries is often subpar. As a result, the field of neural tissue engineering has evolved to find therapeutic interventions and has seen promising outcomes. However, robust nerve and myelin regeneration remain elusive. One possible reason may be the fact that tissue regeneration often follows a complex sequence of events in a temporally-controlled manner. Although several other fields of tissue engineering have begun to recognise the importance of delivering two or more biomolecules sequentially for more complete tissue regeneration, such serial delivery of biomolecules in neural tissue engineering remains limited. This review aims to highlight the need for sequential delivery to enhance nerve regeneration and remyelination after traumatic injuries in the central nervous system, using spinal cord injuries as an example. In addition, possible methods to attain temporally-controlled drug/gene delivery are also discussed for effective neural tissue regeneration.

Synthesis, Characterization andin vivoEvaluation of PEGylated PPI Dendrimer for Safe and Prolonged Delivery of Insulin

Background:

The present study was aimed at developing and exploring the use of PEGylated Poly (propyleneimine) dendrimers for the delivery of an anti-diabetic drug, insulin.

Methods:

For this study, 4.0G PPI dendrimer was synthesized by successive Michael addition and exhaustive amidation reactions, using ethylenediamine as the core and acrylonitrile as the propagating agent. Two different activated PEG moieties were employed for PEGylation of PPI dendrimers. Various physicochemical and physiological parameters UV, IR, NMR, TEM, DSC, drug entrapment, drug release, hemolytic toxicity and blood glucose level studies of both PEGylated and non- PEGylated dendritic systems were determined and compared.

Results:

PEGylation of PPI dendrimers caused increased solubilization of insulin in the dendritic framework as well as in PEG layers, reduced drug release and hemolytic toxicity as well as increased therapeutic efficacy with reduced side effects of insulin. These systems were found to be suitable for sustained delivery of insulin by in vitro and blood glucose-level studies in albino rats, without producing any significant hematological disturbances.

Conclusion:

Thus, surface modification of PPI dendrimers with PEG molecules has been found to be a suitable approach to utilize it as a safe and effective nano-carrier for drug delivery.

Janus nanoparticles in cancer diagnosis, therapy and theranostics

Anisotropic Janus nanoparticles (JNPs), due to their several distinct merits, have been widely investigated for cancer theranostics.

Modular synthesis and modification of novel bifunctional dendrons

The modular synthesis of two generations of highly branched bifunctional dendrons is reported. The first generation dendron–antibody conjugate is shown to selectively detect CD4⁺ T cells in the PBMC culture.

Injectable long-acting human immunodeficiency virus antiretroviral prodrugs with improved pharmacokinetic profiles

While highly active antiretroviral therapy (HAART) has significantly reduced mortality rates in patients with human immunodeficiency virus type 1 (HIV-1), its efficacy may be impeded by emergence of drug resistance caused by lack of patient adherence. A therapeutic strategy that requires infrequent drug administration as a result of sustained release of antiretroviral drugs would put less burden on the patient. Long-acting antiretroviral prodrugs for HIV therapy were synthesized through modification of the active drugs, emtricitabine (FTC) and elvitegravir (EVG), with docosahexaenoic acid (DHA) in one-step, one-pot, high-yielding reactions. The in vitro drug release profiles of these synthetic conjugates demonstrated sustained and controlled release of the active drug over a period of 3-4 weeks attributable to the hydrolysis of the chemical linker in conjunction with the hydrophilicity of the parent drug. Both conjugates exhibited superior antiviral activities in tissue culture models of HIV replication as compared to those of the free drugs, strengthening their role as potent prodrugs for HIV therapy. Pharmacokinetic analysis in CD1 mice further confirmed the long-acting aspect of these conjugates with released drug concentrations in plasma detected at their respective IC₉₀/IC₉₅ values over a period of 2 weeks and discernable amounts of active drug even at 6 weeks. Our findings suggest that the injectable small molecule conjugates could be used as long-acting controlled release of FTC and EVG in attempts to mitigate adherence-related HIV resistance.

Dendronized Systems for the Delivery of Chemotherapeutics

This chapter reviews the use of dendronized systems as nanocarriers for the delivery of chemotherapeutic drugs. Dendronized systems include dendrimers prepared through convergent methods as well as other systems containing dendrons (e.g., polymers, nanoparticles, liposomes). The preparation of such systems is detailed, followed by the various conjugation techniques used for the transport of chemotherapeutic drugs and their specific delivery to tumor cells. In addition, the ability of dendronized systems to provide passive and active targeting to tumors is discussed. The efficacy of drug delivery using dendronized systems is also illustrated through specific examples of kinetic and biological studies. Finally, the newest trends in conjugation of the most common chemotherapeutics to dendronized systems are described. Overall, this chapter highlights dendronized systems as a way to improve the therapeutic efficiency of drugs for the treatment of cancer. All the recent developments in areas, such as biodegradable dendrimers, modifications to enhance biocompatibility, selectively cleavable drug conjugations, ligand-mediated targeting, and the potential for multifunctional properties, show promises for future advances in cancer therapy.

Modular synthesis of self-assembling Janus-dendrimers and facile preparation of drug-loaded dendrimersomes

Materials and methods aimed at the next generation of nanoscale carriers for drugs and other therapeutics are currently in great demand. Yet, creating these precise molecular arrangements in a feasible and straightforward manner represents a remarkable challenge. Herein we report a modular synthetic route for amphiphilic Janus-dendrimers via a copper-catalyzed click reaction (CuAAC) and a facile procedure, using simple injection, to obtain highly uniform dendrimersomes with efficient loading of the model drug compound propranolol. The resulting assemblies were analyzed by dynamic light scattering and cryogenic transmission electron microscopy revealing the formation of unilamellar and multilamellar dendrimersomes. The formation of a bilayer structure was confirmed using cryo-TEM and confocal microscopy visualization of an encapsulated solvatochromic dye (Nile Red). The dendrimersomes reported here are tunable in size, stable over time and display robust thermal stability in aqueous media. Our results expand the scope of dendrimer-based supramolecular colloidal systems and offer the means for one-step fabrication of drug-loaded dendrimersomes in the size range of 90-200 nm, ideal for biomedical applications.

Long-subchain Janus-dendritic copolymers from locally confined click reaction and generation-dependent micro-phase separation

Long-subchain Janus-dendritic copolymers composed of PSt and PtBA half-dendrons, up to the third generation, were prepared under alternating chemical and local confinement. All the Janus-dendritic copolymers exhibited generation-dependent microphase separation.

An emerging class of amphiphilic dendrimers for pharmaceutical and biomedical applications: Janus amphiphilic dendrimers

In recent years, a new class of dendrimer, known as Janus dendrimers (JDs), has attracted much attention due to their different structures and properties to the conventional symmetric forms. The broken symmetry of JDs offers the opportunity to form complex self-assembled materials, and presents new sets of properties that are presently inconceivable for homogeneous or symmetrical dendrimers. Due to their unique features, JDs have a promising future in pharmaceutical and biomedical fields, as seen from the recent interest in their application in conjugating multiple drugs and targeting moieties, forming supramolecular hydrogels, enabling micellar delivery systems, and preparing nano-vesicles, known as dendrimersomes, for drug encapsulation. The present paper is the first review, with an emphasis on various emerging applications of JDs, in the drug delivery and biomedical field reported so far. In addition, the paper describes different synthetic methods for producing JDs that can guide the design of new biocompatible forms with pharmacological activities, and that have the potential to be nano drug delivery vehicles. Furthermore, future studies to optimize the applications of JDs in drug delivery sciences and biomedical field to realize their potential to treat various disease conditions are identified and highlighted. Overall, this review identifies the current status of JDs in terms of their synthesis and applications, as well as the future research for their translation into macromolecules for clinical applications to solve health problems. It highlights the future combined efforts needed to be taken by dendrimer chemists, formulation scientist and microbiologists to develop novel antibacterials and nanomedicines from JDs.

Nanoparticle Based Combination Treatments for Targeting Multiple Hallmarks of Cancer

Treatment of cancer remains one of the most challenging tasks facing the healthcare system. Cancer affects the lives of millions of people and is often fatal. Current treatment methods include surgery, chemotherapy, radiation therapies or some combinations of these. However, recurrence is a major problem. These treatments can be invasive with severe side effects. Inefficacies in treatments are a result of the complex and variable biology of cancerous cells. Malignant tumor cells and normal functioning cells share many of the same biological characteristics but the main difference is that in cancer cells there is in an overuse and over expression of these biological characteristics. These pertinent characteristics can be grouped into eight hallmarks, as illustrated by Hanahan and Weinberg. These characteristics include sustaining proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, activating invasion and metastasis, reprogramming energy metabolism, and evading immune destruction. In order to provide a noninvasive, effective treatment, delivery methods must be explored in order to transport cytotoxic agents used for targeting the hallmarks of cancer in a safer and more effective fashion. The use of nanoparticles as drug delivery carriers provides an effective method in which multiple cytotoxic agents can be safely delivered to cancer tissue to simultaneously target multiple hallmarks. By targeting multiple hallmarks of cancer at once, the efficacy of cancer treatments could be improved drastically. This review explores the uses and efficacy of combination therapies using nanoparticles that can simultaneously target multiple hallmarks of cancer.

Design Advances in Particulate Systems for Biomedical Applications

The search for more efficient therapeutic strategies and diagnosis tools is a continuous challenge. Advances in understanding the biological mechanisms behind diseases and tissues regeneration have widened the field of applications of particulate systems. Particles are no more just protective systems for the encapsulated drugs, but they play an active role in the success of the therapy. Moreover, particles have been explored for innovative purposes as templates for cells growth and as diagnostic tools. Until few years ago the most relevant parameters in particles formulation were the chemistry and the size. Currently, it is known that other physical characteristics can remarkably affect the performance of particulate systems. Particles with non-conventional shapes exhibit advantages due to the increasing circulation time in blood stream, less clearance by the immune system and more efficient cell internalization and trafficking. Creation of compartments has been found useful to control drug release, to tune the transport of substances across biological barriers, to supply the target with more than one bioactive agent or even to act as theranostic systems. It is expected that such complex shaped and compartmentalized systems improve the therapeutic outcomes and also the patient's compliance, acting as advanced devices that serve for simultaneous diagnosis and treatment of the disease, combining agents of very different features, at the same time. In this review, we overview and analyse the most recent advances in particle shape and compartmentalization and applications of newly designed particulate systems in the biomedical field.

Chromatography-free synthesis of monodisperse oligo(ethylene glycol) mono-p-toluenesulfonates and quantitative analysis of oligomer purity

Oligo(ethylene glycol) monotosylates are prepared on a multigram scale and in high purity with a new chromatography-free process.

Recent advances in click chemistry applied to dendrimer synthesis

Dendrimers are monodisperse polymers grown in a fractal manner from a central point. They are poised to become the cornerstone of nanoscale devices in several fields, ranging from biomedicine to light-harvesting. Technical difficulties in obtaining these molecules has slowed their transfer from academia to industry. In 2001, the arrival of the "click chemistry" concept gave the field a major boost. The flagship reaction, a modified Hüisgen cycloaddition, allowed researchers greater freedom in designing and building dendrimers. In the last five years, advances in click chemistry saw a wider use of other click reactions and a notable increase in the complexity of the reported structures. This review covers key developments in the click chemistry field applied to dendrimer synthesis from 2010 to 2015. Even though this is an expert review, basic notions and references have been included to help newcomers to the field.

Controlled Drug Release from Pharmaceutical Nanocarriers

Nanocarriers providing spatiotemporal control of drug release contribute to reducing toxicity and improving therapeutic efficacy of a drug. On the other hand, nanocarriers face unique challenges in controlling drug release kinetics, due to the large surface area per volume ratio and the short diffusion distance. To develop nanocarriers with desirable release kinetics for target applications, it is important to understand the mechanisms by which a carrier retains and releases a drug, the effects of composition and morphology of the carrier on the drug release kinetics, and current techniques for preparation and modification of nanocarriers. This review provides an overview of drug release mechanisms and various nanocarriers with a specific emphasis on approaches to control the drug release kinetics.

Molecular design of a discrete chain-folding polyimide for controlled inkjet deposition of supramolecular polymers

Herein we describe the generation of a well-defined polyimide to afford coloured supramolecular polymer assemblies with electronically complementary pyrenyl terminated polymers which can be inkjet printed.

Janus nanoparticles: materials, preparation and recent advances in drug delivery

INTRODUCTION

The term Janus particles was used to describe particles that are the combination of two distinct sides with differences in chemical nature and/or polarity on each face. Due to the exponential growth of interest on multifunctional nanotechnologies, such anisotropic nanoparticles are promising tools in the field of drug delivery.

AREAS COVERED

The main preparation processes and the materials used have been described first. Then a specific focus has been done on therapeutic and/or diagnostic applications of Janus particles.

EXPERT OPINION

Janus particles are demonstrated as interesting objects with advanced properties that combine features and functionalities of different materials in one single unit. Due to their dual structure, Janus particles are promising candidates for a variety of high-quality applications dealing with drug delivery purposes. Still, the main challenges for the future lie in the development of the preparation of shape-controlled and nano-sized particles with large-scale production processes and approved pharmaceutical excipients.

Potentials and emerging trends in nanopharmacology

Nanopharmacology is a relatively newer branch of pharmacology which investigates interaction of a nanomedicine with living systems at the nanoscale level. Modern medicine is increasingly concerned with various surface modified nanocarriers, such as dendrimers, nanoparticles, carbon based nanomaterials, polymer-drug nanoconjugates, etc., which have immense therapeutic potential by target specific drug delivery, using nanoscaffolding and nanocontainers, owing to the specific physical, chemical and biological properties of these moieties that is related to their nanoscale size range. Nanopharmacology could have potential medical and pharmaceutical benefits via applications of nanotechnology in the delivery of therapeutic and diagnostic agents. Nanomaterials may be expected to find application in the cardiovascular, as well as, renal arena, in the near future.

Biocompatible, multifunctional, and well-defined OEG-based dendritic platforms for biomedical applications

Given the growing importance of drug and gene delivery systems, imaging agents, biosensors, and theranostics, there is a need to develop new multifunctional and biocompatible platforms. Here we synthesized and fully characterized a family of novel multifunctional and completely monodisperse dendritic platforms. Our synthetic methodology, based on compatible protecting groups and the attachment of monodisperse triethylene glycol units, allows the control of the generation and differentiation of terminal groups, thus giving rise to multifunctional and perfectly-defined products. A family of dendrons was synthesized and four distinct dendritic structures were chosen from the family in order to determine the effect of the generation and surface groups on their biocompatibility. The stability in serum, cytotoxicity, and hemocompatibility of these products were studied. Our results indicate that these non-toxic, hemocompatible, non-immunogenic, stable and versatile scaffolds may be very interesting candidates for biomedical applications.

Dendrimersomes with photodegradable membranes for triggered release of hydrophilic and hydrophobic cargo

Amphiphilic Janus dendrimers with fully photodegradable hydrophobic blocks were synthesized and assembled into dendrimersomes in water. Irradiation with UV light triggered the release of hydrophobic and hydrophilic cargo.

Materials innovation for co-delivery of diverse therapeutic cargos

Co-delivery is a rapidly growing sector of drug delivery that aspires to enhance therapeutic efficacy through controlled delivery of diverse therapeutic cargoes with synergistic activities. It requires the design of carriers capable of simultaneously transporting to and releasing multiple therapeutics at a disease site. Co-delivery has arisen from the emerging trend of combination therapy, where treatment with two or more therapeutics at the same time can succeed where single therapeutics fail. However, conventional combination therapy offers little control over achieving an optimized therapeutic ratio at the target site. Co-delivery via inclusion of multiple therapeutic cargos within the same carrier addresses this issue by not only ensuring delivery of both therapeutics to the same cell, but also offering a platform for control of the delivery process, from loading to release. Co-delivery systems have been formulated using a number of carriers previously developed for single-therapeutic delivery. Liposomes, polymeric micelles, PLGA nanoparticles, and dendrimers have all been adapted for co-delivery. Much of the effort focuses on dealing with drugs having dissimilar properties, increasing loading efficiencies, and controlling loading and release ratios. In this review, we highlight the innovations in carrier designs and formulations to deliver combination cargoes of drug/drug, drug/siRNA, and drug/pDNA toward disease therapy. With rapid advances in mechanistic understanding of interrelating molecular pathways and development of molecular medicine, the future of co-delivery will become increasingly promising and prominent.