Recent advances in targeted drug delivery approaches using dendritic polymers

Biohybrid Nanoparticle-Based In Situ Monitoring of In Vivo Drug Delivery

Nanomaterials have gained huge attention worldwide owing to their unique physicochemical characteristics which enable their applications in the field of biomedicine and drug delivery systems. Although nanodrug delivery systems (NDDSs) have better target specificity and bioavailability than traditional drug delivery systems, their behavior and clearance mechanisms in living subjects remain unclear. In this regard, the importance of bioimaging methods has come to the forefront for investigating the biodistribution of nanocarriers and discovering drug release mechanisms in vivo. In this review, we introduce several examples of biohybrid nanoparticles and their clinical applications, focusing on their advantages and limitations. The various bioimaging methods for monitoring the fate of nanodrugs in biological systems and the future perspectives of NDDSs have also been discussed.

Recent updates in curcumin delivery

Curcumin is a natural component extracted from the rhizomes of turmeric (Curcuma longa), a natural plat with known medicinal uses for more than 4000 years. Most turmeric therapeutic effects are attributed to curcumin, a yellow-coloured extract. Curcumin has received considerable attention due to its biological activities, such as its use in arthritis, liver and neurodegenerative diseases, obesity, and several types of cancers. Most of these curcumin therapeutic activities are related to its antioxidant and anti-inflammatory effects. However, the clinical application of curcumin is hampered by some limitations that prevent its extensive clinical application. Curcumin high hydrophobicity of curcumin and limited water solubility are among the most important limitations. This poor solubility will result in low bioavailability due to its poor absorption into plasma and the target tissues. Curcumin also has rapid metabolism, which will significantly lower its bioavailability and shorten its half-life. Moreover, curcumin is photosensitive with limited chemical stability during manufacturing and storage. These limitations have been overcome by applying nanotechnology using several types of nanoparticles (NPs). This includes using NPs such as liposomes, niosomes, gold nanoparticles, and many others to improve the curcumin solubility and bioavailability. This review focuses on the different types of NPs investigated and the outcomes generated by their use in the most recent studies in this field. To follow the latest advances in the field of site-specific drug delivery using nanomaterials, an electronic databases search was conducted using PubMed, Google scholar and Scopus using the following keywords: lipid-based nanoparticles, curcumin delivery, niosomes, and liposomes.

Dendrimers for cancer immunotherapy: Avidity-based drug delivery vehicles for effective anti-tumor immune response

Cancer immunotherapy, or the utilization of a patient's own immune system to treat cancer, has shifted the paradigm of cancer treatment. Despite meaningful responses being observed in multiple studies, currently available immunotherapy platforms have only proven effective to a small subset of patients. To address this, nanoparticles have been utilized as a novel carrier for immunotherapeutic drugs, achieving robust anti-tumor effects with increased adaptive and durable responses. Specifically, dendrimer nanoparticles have attracted a great deal of scientific interest due to their versatility in various therapeutic applications, resulting from their unique physicochemical properties and chemically well-defined architecture. This review offers a comprehensive overview of dendrimer-based immunotherapy technologies, including their formulations, biological functionalities, and therapeutic applications. Common formulations include: (1) modulators of cytokine secretion of immune cells (adjuvants); (2) facilitators of the recognition of tumorous antigens (vaccines); (3) stimulators of immune effectors to selectively attack cells expressing specific antigens (antibodies); and (4) inhibitors of immune-suppressive responses (immune checkpoint inhibitors). On-going works and prospects of dendrimer-based immunotherapies are also discussed. Overall, this review provides a critical overview on rapidly growing dendrimer-based immunotherapy technologies and serves as a guideline for researchers and clinicians who are interested in this field. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Recent advances of zwitterionic based topological polymers for biomedical applications

Zwitterionic polymers, comprising hydrophilic anionic and cationic groups with the same total number of positive and negative charges on the same monomer residue, have received increasing attention due to their...

Size-Dependent Drug Loading, Gene Complexation, Cell Uptake, and Transfection of a Novel Dendron-Lipid Nanoparticle for Drug/Gene Co-delivery

Dendron micelles have shown promising results as a multifunctional delivery system, owing to their unique molecular architecture. Herein, we have prepared a novel poly(amidoamine) (PAMAM) dendron-lipid hybrid nanoparticle (DLNP) as a nanocarrier for drug/gene co-delivery and examined how the dendron generation of DLNPs impacts their cargo-carrying capabilities. DLNPs, formed by a thin-layer hydration method, were internally loaded with chemo-drugs and externally complexed with plasmids. Compared to generation 2 dendron DLNP (D2LNPs), D3LNPs demonstrated a higher drug encapsulation efficiency (31% vs 87%) and better gene complexation (minimal N/P ratio of 20:1 vs 5:1 for complexation) due to their smaller micellar aggregation number and higher charge density, respectively. Furthermore, D3LNPs were able to avoid endocytosis and subsequent lysosomal degradation and demonstrated a higher cellular uptake than D2LNPs. As a result, D3LNPs exhibited significantly enhanced antitumor and gene transfection efficacy in comparison to D2LNPs. These findings provide design cues for engineering multifunctional dendron-based nanotherapeutic systems for effective combination cancer treatment.

Emerging strategies against tumor-associated fibroblast for improved the penetration of nanoparticle into desmoplastic tumor

The therapeutic effect of nanoparticles is limited in solid tumors, especially desmoplastic tumors, because the tumor matrix hinders the delivery of nanoparticles. As the most abundant cells in the tumor stroma, tumor-associated fibroblasts (TAFs) produce a dense extracellular matrix, which leads to higher tissue fluid pressure, thereby creating a physical barrier for nanoparticle delivery. Therefore, researchers focused on eliminating TAFs to combat desmoplastic tumors. In recent years, a series of methods for TAFs have been developed. In this paper, we first introduced the biological mechanism of TAFs hindering the penetration of nanoparticles. Then, the different methods of eliminating TAFs were summarized, and the mechanism of nanomedicine in eliminating TAFs was highlighted. Finally, the problems and future development directions for TAFs treatment were discussed from the perspective of the treatment of desmoplastic tumors.

Current applications and prospects of nanoparticles for antifungal drug delivery

Currently, the significance of fungi as human pathogens is not medically concealed in the world. Consequently, suitable recognition and treatment of such infections are of great importance and necessitate the need for comprehensive information in this regard. The introduction of new antifungals and their use today, especially in the last two decades, have revolutionized the treatment of fungal infections. On the other hand, increasing drug resistance in the world has overshadowed such developments. The use of NPs results in the treatment of fungal infections and owing to their specific properties, these particles, unlike the pure antibiotics, can exert a greater inhibitory power although with less concentration compared with conventional drugs. Important reasons that have led to the use of antifungal drugs in delivery systems include reduced drug efficacy, limited penetration through tissue, poor aqueous solubility, decreased bioavailability, and poor drug pharmacokinetics. It is therefore hoped that unfavorable properties of antifungal drugs be mitigated via their incorporation into different types of NPs. This review summarizes the different types of NPs as delivery systems of antifungal as well as their advantages over pure drugs.

Platinum (II)-coordinated Portulaca oleracea polysaccharides as metal-drug based polymers for anticancer study

Novel polysaccharide-platinum conjugated polymers bearing alendronate on Portulaca oleracea polysaccharides (PPS) were designed and synthesized. Their chemical structures and properties were characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H NMR and ³¹P NMR spectroscopy, Thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), UV-vis spectrophotometer (UV-vis) and other analysis methods. The results demonstrated that alendronate can be used as the linker of Portulaca oleracea polysaccharides and platinum compounds. Portulaca oleracea polysaccharides-alendronate (PPS-ALN) conjugates exhibited stronger antioxidant ability than PPS. The cytotoxicity assay to cancer cells was tested in vitro, and the Portulaca oleracea polysaccharides-alendronate-platinum (PPS-ALN-Pt) conjugates strongly inhibited the proliferation of cancer cells than PPS and PPS-ALN. The evaluation of complexes affinity toward supercoiled plasmid DNA, displayed a high DNA interaction. Interestingly, the platinum conjugates displayed immunological competence in HeLa cells by cellular immunofluorescence assay. Besides, the cellular platinum accumulation of PPS-ALN-Pt conjugates was higher than that of cisplatin in HeLa cells, implying that the polysaccharide-platinum conjugated polymers might have a synergistically therapeutic application in metal anticancer drug delivery.

Nanoapproaches to Modifying Epigenetics of Epithelial Mesenchymal Transition for Treatment of Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a chronically progressive interstitial lung that affects over 3 M people worldwide and rising in incidence. With a median survival of 2-3 years, IPF is consequently associated with high morbidity, mortality, and healthcare burden. Although two antifibrotic therapies, pirfenidone and nintedanib, are approved for human use, these agents reduce the rate of decline of pulmonary function but are not curative and do not reverse established fibrosis. In this review, we discuss the prevailing epithelial injury hypothesis, wherein pathogenic airway epithelial cell-state changes known as Epithelial Mesenchymal Transition (EMT) promotes the expansion of myofibroblast populations. Myofibroblasts are principal components of extracellular matrix production that result in airspace loss and mortality. We review the epigenetic transition driving EMT, a process produced by changes in histone acetylation regulating mesenchymal gene expression programs. This mechanistic work has focused on the central role of bromodomain-containing protein 4 in mediating EMT and myofibroblast transition and initial preclinical work has provided evidence of efficacy. As nanomedicine presents a promising approach to enhancing the efficacy of such anti-IPF agents, we then focus on the state of nanomedicine formulations for inhalable delivery in the treatment of pulmonary diseases, including liposomes, polymeric nanoparticles (NPs), inorganic NPs, and exosomes. These nanoscale agents potentially provide unique properties to existing pulmonary therapeutics, including controlled release, reduced systemic toxicity, and combination delivery. NP-based approaches for pulmonary delivery thus offer substantial promise to modify epigenetic regulators of EMT and advance treatments for IPF.

Superbranched polyglycerol nanostructures as drug delivery and theranostics tools for cancer treatment

Hyperbranched polymers (HBPs), such as hyperbranched polyglycerols (HPGs) with a dendritic configuration, have been recognized for their excellent biocompatibility and multifunctionalization. HPGs have been studied for use in the delivery diagnostic, imaging and therapeutic molecules in the area of nanobiomedicine. They show superior characteristics to linear polymers and dendrimers, such as compact structure, a simple manufacturing process with easy functionalization ability, low viscosity, and high stability. Owing to these advantages, HPGs are now considered promising carriers for drug delivery, diagnostics, imaging, and theranostics applications for cancer treatment. In this review, we also discuss safety aspects of HPG-based nanoformulations in various animal models and the clinical translation status of such polymers for real-time applications.

Fluorescent Dendritic Micro-Hydrogels: Synthesis, Analysis and Use in Single-Cell Detection

Hydrogels are of keen interest for a wide range of medical and biotechnological applications including as 3D substrate structures for the detection of proteins, nucleic acids, and cells. Hydrogel parameters such as polymer wt % and crosslink density are typically altered for a specific application; now, fluorescence can be incorporated into such criteria by specific macromonomer selection. Intrinsic fluorescence was observed at λmax 445 nm from hydrogels polymerized from lysine and aldehyde- terminated poly(ethylene glycol) macromonomers upon excitation with visible light. The hydrogel’s photochemical properties are consistent with formation of a nitrone functionality. Printed hydrogels of 150 μm were used to detect individual cell adherence via a decreased in fluorescence. The use of such intrinsically fluorescent hydrogels as a platform for cell sorting and detection expands the current repertoire of tools available.

Clinical utility of non-EpCAM based circulating tumor cell assays

Methods enabling the isolation, detection, and characterization of circulating tumor cells (CTCs) in blood have clear potential to facilitate precision medicine approaches in patients with cancer, not only for prognostic purposes but also for prediction of the benefits of specific therapies in oncology. However, current CTC assays, which capture CTCs based on expression of epithelial cell adhesion molecule (EpCAM), fail to capture cells from de-differentiated tumors and carcinomas undergoing loss of the epithelial phenotype during the invasion/metastatic process. To address this limitation, many groups are developing non-EpCAM based CTC assays that incorporate nanotechnology to improve test sensitivity for rare but important cells that may otherwise go undetected, and therefore may improve upon clinical utility. In this review, we outline emerging non-EpCAM based CTC assays utilizing nanotechnology approaches for CTC capture or characterization, including dendrimers, magnetic nanoparticles, gold nanoparticles, negative selection chip or software-based on-slide methods, and nano-scale substrates. In addition, we address challenges that remain for the clinical translation of these platforms.

Enhanced Intestinal Permeability of Bufalin by a Novel Bufalin-Peptide-Dendrimer Inclusion through Caco-2 Cell Monolayer

Bufalin (BFL) has excellent physiological activities such as defending tumors, improving cardiac function, and so on. However, due to its poor water-solubility and bioavailability, the clinical application of BFL remains limited. In order to improve bioavailability of BFL, in our previous research, a novel peptide-dendrimer (PD) was synthesized and applied to encapsulate BFL. In the present study, we investigate the absorption property and mechanism of BFL in free form and BFL-peptide-dendrimer inclusion (BPDI) delivery system by using the Caco-2 cell monolayer model in vitro. The apparent permeability coefficient (P_app) values of BFL in free or BPDI form were over 1.0 × 10⁻⁶ cm/s. Meanwhile, their almost equal bi-directional transport and linear transport percentage with time and concentration course indicated that BFL in both forms was absorbed mainly through passive diffusion. The most important result is that the P_app values of BFL increased about three-fold more BPDI than those of its free form, which indicated the intestinal permeability of BFL could be improved while BFL was encapsulated in BPDI form. Therefore, PD encapsulation may be a potential delivery system to increase the bioavailability of BFL.

Nanoscale Investigation of Generation 1 PAMAM Dendrimers Interaction with a Protein Nanopore

Herein, we describe at uni-molecular level the interactions between poly(amidoamine) (PAMAM) dendrimers of generation 1 and the α-hemolysin protein nanopore, at acidic and neutral pH, and ionic strengths of 0.5 M and 1 M KCl, via single-molecule electrical recordings. The results indicate that kinetics of dendrimer-α-hemolysin reversible interactions is faster at neutral as compared to acidic pH, and we propose as a putative explanation the fine interplay among conformational and rigidity changes on the dendrimer structure, and the ionization state of the dendrimer and the α-hemolysin. From the analysis of the dendrimer's residence time inside the nanopore, we posit that the pH- and salt-dependent, long-range electrostatic interactions experienced by the dendrimer inside the ion-selective α-hemolysin, induce a non-Stokesian diffusive behavior of the analyte inside the nanopore. We also show that the ability of dendrimer molecules to adapt their structure to nanoscopic spaces, and control the flow of matter through the α-hemolysin nanopore, depends non-trivially on the pH- and salt-induced conformational changes of the dendrimer.

Charge-reversible and pH-responsive biodegradable micelles and vesicles from linear-dendritic supramolecular amphiphiles for anticancer drug delivery

The linear-dendritic supramolecular amphiphiles could assemble into charge-reversible and pH-responsive biodegradable micelles and vesicles.

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

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

Nano-formulations of drugs: Recent developments, impact and challenges

Nano-formulations of medicinal drugs have attracted the interest of many researchers for drug delivery applications. These nano-formulations enhance the properties of conventional drugs and are specific to the targeted delivery site. Dendrimers, polymeric nanoparticles, liposomes, nano-emulsions and micelles are some of the nano-formulations that are gaining prominence in pharmaceutical industry for enhanced drug formulation. Wide varieties of synthesis methods are available for the preparation of nano-formulations to deliver drugs in biological system. The choice of synthesis methods depend on the size and shape of particulate formulation, biochemical properties of drug, and the targeted site. This article discusses recent developments in nano-formulation and the progressive impact on pharmaceutical research and industries. Additionally, process challenges relating to consistent generation of nano-formulations for drug delivery are discussed.

Eradication of Acute Myeloid Leukemia with FLT3 Ligand-Targeted miR-150 Nanoparticles

Acute myeloid leukemia (AML) is a common and fatal form of hematopoietic malignancy. Overexpression and/or mutations of FLT3 have been shown to occur in the majority of cases of AML. Our analysis of a large-scale AML patient cohort (N = 562) indicates that FLT3 is particularly highly expressed in some subtypes of AML, such as AML with t(11q23)/MLL-rearrangements or FLT3-ITD. Such AML subtypes are known to be associated with unfavorable prognosis. To treat FLT3-overexpressing AML, we developed a novel targeted nanoparticle system: FLT3 ligand (FLT3L)-conjugated G7 poly(amidoamine) (PAMAM) nanosized dendriplex encapsulating miR-150, a pivotal tumor suppressor and negative regulator of FLT3 We show that the FLT3L-guided miR-150 nanoparticles selectively and efficiently target FLT3-overexpressing AML cells and significantly inhibit viability/growth and promote apoptosis of the AML cells. Our proof-of-concept animal model studies demonstrate that the FLT3L-guided miR-150 nanoparticles tend to concentrate in bone marrow, and significantly inhibit progression of FLT3-overexpressing AML in vivo, while exhibiting no obvious side effects on normal hematopoiesis. Collectively, we have developed a novel targeted therapeutic strategy, using FLT3L-guided miR-150-based nanoparticles, to treat FLT3-overexpressing AML with high efficacy and minimal side effects. Cancer Res; 76(15); 4470-80. ©2016 AACR.

Molecular Determinants of the Cellular Entry of Asymmetric Peptide Dendrimers and Role of Caveolae

Caveolae are flask-shaped plasma membrane subdomains abundant in most cell types that participate in endocytosis. Caveola formation and functions require membrane proteins of the caveolin family, and cytoplasmic proteins of the cavin family. Cationic peptide dendrimers are non-vesicular chemical carriers that can transport pharmacological agents or genetic material across the plasma membrane. We prepared a panel of cationic dendrimers and investigated whether they require caveolae to enter into cells. Cell-based studies were performed using wild type or caveola-deficient i.e. caveolin-1 or PTRF gene-disrupted cells. There was a statistically significant difference in entry of cationic dendrimers between wild type and caveola-deficient cells. We further unveiled differences between dendrimers with varying charge density and head groups. Our results show, using a molecular approach, that (i) expression of caveola-forming proteins promotes cellular entry of cationic dendrimers and (ii) dendrimer structure can be modified to promote endocytosis in caveola-forming cells.

Exploring the use of nanocarrier systems to deliver the magical molecule; Curcumin and its derivatives

Curcumin and its derivatives; curcuminoids have been proven as potential remedies in different diseases. However, their delivery carries several challenges owing to their poor aqueous solubility, photodegradation, chemical instability, poor bioavailability and rapid metabolism. This review explores and criticizes the numerous attempts that were adopted through the years to entrap/encapsulate this valuable drug in nanocarriers aiming to reach its most appropriate and successful delivery system.

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.

Recent advances in nanotechnology-based detection and separation of circulating tumor cells

Although circulating tumor cells (CTCs) in blood have been widely investigated as a potential biomarker for diagnosis and prognosis of metastatic cancer, their inherent rarity and heterogeneity bring tremendous challenges to develop a CTC detection method with clinically significant specificity and sensitivity. With advances in nanotechnology, a series of new methods that are highly promising have emerged to enable or enhance detection and separation of CTCs from blood. In this review, we systematically categorize nanomaterials, such as gold nanoparticles, magnetic nanoparticles, quantum dots, graphenes/graphene oxides, and dendrimers and stimuli-responsive polymers, used in the newly developed CTC detection methods. This will provide a comprehensive overview of recent advances in the CTC detection achieved through application of nanotechnology as well as the challenges that these existing technologies must overcome to be directly impactful on human health.