Dendrimer pharmacokinetics: the effect of size, structure and surface characteristics on ADME properties

PAMAM dendrimers as mediators of dermal and transdermal drug delivery: a review

OBJECTIVES

Poly(amidoamine) dendrimers have been widely investigated as potential nanomaterials that can enhance the skin permeation of topically applied drugs. This article reviews the studies that have used dendrimers as penetration enhancers and examines the mechanisms by which enhancement is claimed.

KEY FINDINGS

A wide range of studies have demonstrated that, in certain circumstances and for certain drugs, the incorporation of dendrimers into a topically applied formulation can significantly increase the amount of drug passing into and through the skin. In some cases, dendrimers offered little or no enhancement of skin permeation, suggesting that the drug-dendrimer interaction and the selection of a specific dendrimer were central to ensuring optimal enhancement of skin permeation. Significant interactions between dendrimers and other formulation components were also reported in some cases.

SUMMARY

Dendrimers offer substantial potential for enhancing drug delivery into and across the skin, putatively by mechanisms that include occlusion and changes to surface tension. However, most of these studies are conducted in vitro and limited progress has been made beyond such laboratory studies, some of which are conducted using membranes of limited relevance to humans, such as rodent skin. Thus, the outcomes and claims of such studies should be treated with caution.

Systemically targeting monocytic myloid-derrived suppressor cells using dendrimers and their cell-level biodistribution kinetics

The focus of nanoparticles in vivo trafficking has been mostly on their tissue-level biodistribution and clearance. Recent progress in the nanomedicine field suggests that the targeting of nanoparticles to immune cells can be used to modulate the immune response and enhance therapeutic delivery to the diseased tissue. In the presence of tumor lesions, monocytic-myeloid-derived suppressor cells (M-MDSCs) expand significantly in the bone marrow, egress into peripheral blood, and traffic to the solid tumor, where they help maintain an immuno-suppressive tumor microenvironment. In this study, we investigated the interaction between PAMAM dendrimers and M-MDSCs in two murine models of glioblastoma, by examining the cell-level biodistribution kinetics of the systemically injected dendrimers. We found that M-MDSCs in the tumor and lymphoid organs can efficiently endocytose hydroxyl dendrimers. Interestingly, the trafficking of M-MDSCs from the bone marrow to the tumor contributed to the deposition of hydroxyl dendrimers in the tumor. M-MDSCs showed different capacities of endocytosing dendrimers of different functionalities in vivo. This differential uptake was mediated by the unique serum proteins associated with each dendrimer surface functionality. The results of this study set up the framework for developing dendrimer-based immunotherapy to target M-MDSCs for cancer treatment.

Attenuated polyethylene glycol immunogenicity and overcoming accelerated blood clearance of a fully PEGylated dendrimer

Polyethylene glycol (PEG) is a popular biocompatible polymer and PEGylated nanoparticles passively accumulate in tumor tissues because of their enhanced permeability and retention effects. Recently, the anti-PEG immunity of PEGylated nanoparticles has become an issue that needs to be solved for their clinical applications. Dendrimers are highly branched and well-defined polymers with many terminal groups, which act as potent drug carriers. In this study, we examined the pharmacokinetics, biodistribution, anti-PEG immunity, and tumor accumulation of a fully PEGylated polyamidoamine (PAMAM) dendrimer after the first and second injections and compared them to those of a PEGylated liposome with the same lipid component as Doxil®. The PEGylated dendrimer showed greater blood circulation than that of the PEGylated liposome after the first and second injections in rats. In mice injected with the PEGylated dendrimer, much less anti-PEG immunoglobulin M (IgM) was generated than that in mice injected with the PEGylated liposome. The PEGylated dendrimer accumulated in the tumor after both the first and second injections. Our results indicated that the PEGylated dendrimer with a small size and high PEG density showed attenuated anti-PEG immunity and overcame the accelerated blood clearance phenomenon, which is useful for drug delivery systems for cancer treatment.

Micro- and nanoformulations of antibiotics against Brucella

Brucellosis, a zoonotic intracellular bacterial infection primarily transmitted through the consumption of unpasteurized milk from infected animals, remains a challenging condition to clinically control. This is mainly because of the limited effectiveness of conventional antibiotics in targeting intracellular Brucella. Micro- and nanoformulations of antibiotics, whether used as a mono- or combination therapy, have the potential to reduce the antibiotic doses required and treatment duration. Extensive research has been conducted on various organic, semiorganic, and inorganic nanomaterials with different morphologies, such as nanoparticles (NPs), nanotubes, nanowires, and nanobelts. Metal/metal oxide, lipidic, polymeric, and carbonic NPs have been widely explored to overcome the limitations of traditional formulations. In this review, we discuss the advances and challenges of these novel formulations based on recent investigations.

Research Status of Dendrimer Micelles in Tumor Therapy for Drug Delivery

Dendrimers are a family of polymers with highly branched structure, well-defined composition, and extensive functional groups, which have attracted great attention in biomedical applications. Micelles formed by dendrimers are ideal nanocarriers for delivering anticancer agents due to the explicit study of their characteristics of particle size, charge, and biological properties such as toxicity, blood circulation time, biodistribution, and cellular internalization. Here, the classification, preparation, and structure of dendrimer micelles are reviewed, and the specific functional groups modified on the surface of dendrimers for tumor active targeting, stimuli-responsive drug release, reduced toxicity, and prolonged blood circulation time are discussed. In addition, their applications are summarized as various platforms for biomedical applications related to cancer therapy including drug delivery, gene transfection, nano-contrast for imaging, and combined therapy. Other applications such as tissue engineering and biosensor are also involved. Finally, the possible challenges and perspectives of dendrimer micelles for their further applications are discussed.

Immunotoxicity of engineered nanomaterials and their role in asthma

The toxicity of engineered nanomaterials (ENMs) in vivo and in vitro has formed the basis of most studies. However, the toxicity of ENMs, particularly on the immune system, i.e. immunotoxicity, and their role in manipulating it, are less known. This review addresses the initiation or exacerbation as well as the attenuation of allergic asthma by a variety of ENMs and how they may be used in drug delivery to enhance the treatment of asthma. This review also highlights a few research gaps in the study of the immunotoxicity of ENMs, for example, the potential drawbacks of assays used in immunotoxicity assays; the potential role of hormesis during dosing of ENMs; and the variables that result in discrepancies among different studies, such as the physicochemical properties of ENMs, differences in asthmatic animal models, and different routes of administration.

Visualizing drug-induced lipid accumulation in lysosomes of live cancer cells with stimulated Raman imaging

The low pH of the lysosomal compartment often results in sequestration of chemotherapeutic agents that contain positively charged basic functional groups, leading to anti-cancer drug resistance. To visualize drug localization in lysosomes and its influence on lysosomal functions, we synthesize a group of drug-like compounds that contain both a basic functional group and a bisarylbutadiyne (BADY) group as a Raman probe. With quantitative stimulated Raman scattering (SRS) imaging, we validate that the synthesized lysosomotropic (LT) drug analogs show high lysosomal affinity, which can also serve as a photostable lysosome tracker. We find that long-term retention of the LT compounds in lysosomes leads to the increased amount and colocalization of both lipid droplets (LDs) and lysosomes in SKOV3 cells. With hyperspectral SRS imaging, further studies find that the LDs stuck in lysosomes are more saturated than the LDs staying out of the lysosomes, indicating impaired lysosomal lipid metabolism by the LT compounds. These results demonstrate that SRS imaging of the alkyne-based probes is a promising approach to characterizing the lysosomal sequestration of drugs and its influence on cell functions.

Combination of Drug Delivery Properties of PAMAM Dendrimers and Cytotoxicity of Platinum(IV) Complexes-A More Selective Anticancer Treatment?

Based on their drug delivery properties and activity against tumors, we combined PAMAM dendrimers with various platinum(IV) complexes in order to provide an improved approach of anticancer treatment. Platinum(IV) complexes were linked to terminal NH₂ moieties of PAMAM dendrimers of generation 2 (G2) and 4 (G4) via amide bonds. Conjugates were characterized by ¹H and ¹⁹⁵Pt NMR spectroscopy, ICP-MS and in representative cases by pseudo-2D diffusion-ordered NMR spectroscopy. Additionally, the reduction behavior of conjugates in comparison to corresponding platinum(IV) complexes was investigated, showing a faster reduction of conjugates. Cytotoxicity was evaluated via the MTT assay in human cell lines (A549, CH1/PA-1, SW480), revealing IC₅₀ values in the low micromolar to high picomolar range. The synergistic combination of PAMAM dendrimers and platinum(IV) complexes resulted in up to 200 times increased cytotoxic activity of conjugates in consideration of the loaded platinum(IV) units compared to their platinum(IV) counterparts. The lowest IC₅₀ value of 780 ± 260 pM in the CH1/PA-1 cancer cell line was detected for an oxaliplatin-based G4 PAMAM dendrimer conjugate. Finally, in vivo experiments of a cisplatin-based G4 PAMAM dendrimer conjugate were performed based on the best toxicological profile. A maximum tumor growth inhibition effect of 65.6% compared to 47.6% for cisplatin was observed as well as a trend of prolonged animal survival.

Pharmacokinetics and tumor delivery of nanoparticles

Nanoparticles (NPs) have been widely used in different areas, including consumer products and medicine. In terms of biomedical applications, NPs or NP-based drug formulations have been extensively investigated for cancer diagnostics and therapy in preclinical studies, but the clinical translation rate is low. Therefore, a thorough and comprehensive understanding of the pharmacokinetics of NPs, especially in drug delivery efficiency to the target therapeutic tissue tumor, is important to design more effective nanomedicines and for proper assessment of the safety and risk of NPs. This review article focuses on the pharmacokinetics of both organic and inorganic NPs and their tumor delivery efficiencies, as well as the associated mechanisms involved. We discuss the absorption, distribution, metabolism, and excretion (ADME) processes following different routes of exposure and the mechanisms involved. Many physicochemical properties and experimental factors, including particle type, size, surface charge, zeta potential, surface coating, protein binding, dose, exposure route, species, cancer type, and tumor size can affect NP pharmacokinetics and tumor delivery efficiency. NPs can be absorbed with varying degrees following different exposure routes and mainly accumulate in liver and spleen, but also distribute to other tissues such as heart, lung, kidney and tumor tissues; and subsequently get metabolized and/or excreted mainly through hepatobiliary and renal elimination. Passive and active targeting strategies are the two major mechanisms of tumor delivery, while active targeting tends to have less toxicity and higher delivery efficiency through direct interaction between ligands and receptors. We also discuss challenges and perspectives remaining in the field of pharmacokinetics and tumor delivery efficiency of NPs.

Dendrimer: An update on recent developments and future opportunities for the brain tumors diagnosis and treatment

A brain tumor is an uncontrolled cell proliferation, a mass of tissue composed of cells that grow and divide abnormally and appear to be uncontrollable by the processes that normally control normal cells. Approximately 25,690 primary malignant brain tumors are discovered each year, 70% of which originate in glial cells. It has been observed that the blood-brain barrier (BBB) limits the distribution of drugs into the tumour environment, which complicates the oncological therapy of malignant brain tumours. Numerous studies have found that nanocarriers have demonstrated significant therapeutic efficacy in brain diseases. This review, based on a non-systematic search of the existing literature, provides an update on the existing knowledge of the types of dendrimers, synthesis methods, and mechanisms of action in relation to brain tumours. It also discusses the use of dendrimers in the diagnosis and treatment of brain tumours and the future possibilities of dendrimers. Dendrimers are of particular interest in the diagnosis and treatment of brain tumours because they can transport biochemical agents across the BBB to the tumour and into the brain after systemic administration. Dendrimers are being used to develop novel therapeutics such as prolonged release of drugs, immunotherapy, and antineoplastic effects. The use of PAMAM, PPI, PLL and surface engineered dendrimers has proven revolutionary in the effective diagnosis and treatment of brain tumours.

Delivering on the promise of protein degraders

Over the past 3 years, the first bivalent protein degraders intentionally designed for targeted protein degradation (TPD) have advanced to clinical trials, with an initial focus on established targets. Most of these clinical candidates are designed for oral administration, and many discovery efforts appear to be similarly focused. As we look towards the future, we propose that an oral-centric discovery paradigm will overly constrain the chemical designs that are considered and limit the potential to drug novel targets. In this Perspective, we summarize the current state of the bivalent degrader modality and propose three categories of degrader designs, based on their likely route of administration and requirement for drug delivery technologies. We then describe a vision for how parenteral drug delivery, implemented early in research and supported by pharmacokinetic-pharmacodynamic modelling, can enable exploration of a broader drug design space, expand the scope of accessible targets and deliver on the promise of protein degraders as a therapeutic modality.

Dendrimer Technology in Glioma: Functional Design and Potential Applications

Novel therapeutic and diagnostic methods are sorely needed for gliomas, which contribute yearly to hundreds of thousands of cancer deaths worldwide. Despite the outpouring of research efforts and funding aimed at improving clinical outcomes for patients with glioma, the prognosis for high-grade glioma, and especially glioblastoma, remains dire. One of the greatest obstacles to improving treatment efficacy and destroying cancer cells is the safe delivery of chemotherapeutic drugs and biologics to the tumor site at a high enough dose to be effective. Over the past few decades, a burst of research has leveraged nanotechnology to overcome this obstacle. There has been a renewed interest in adapting previously understudied dendrimer nanocarriers for this task. Dendrimers are small, highly modifiable, branched structures featuring binding sites for a variety of drugs and ligands. Recent studies have demonstrated the potential for dendrimers and dendrimer conjugates to effectively shuttle therapeutic cargo to the correct tumor location, permeate the tumor, and promote apoptosis of tumor cells while minimizing systemic toxicity and damage to surrounding healthy brain tissue. This review provides a primer on the properties of dendrimers; outlines the mechanisms by which they can target delivery of substances to the site of brain pathology; and delves into current trends in the application of dendrimers to drug and gene delivery, and diagnostic imaging, in glioma. Finally, future directions for translating these in vitro and in vivo findings to the clinic are discussed.

Polycationic PAMAM ameliorates obesity-associated chronic inflammation and focal adiposity

As a surging public health crisis, obesity and overweight predispose individuals to various severe comorbidities contributed by the accompanying chronic inflammation. However, few options exist for tackling chronic inflammation in obesity or inhibiting depot-specific adiposity. Here, we report that polycationic polyamidoamine (PAMAM) treatment can improve both aspects of obesity. With the discovery that the plasma cell-free RNA (cfRNA) level is elevated in obese subjects, we applied the cationic PAMAM generation 3 (P-G3) scavenger to treat diet-induced obese (DIO) mice. Intraperitoneal delivery of P-G3 alleviated the chronic inflammation in DIO mice and reduced their body weight, resulting in improved metabolic functions. To further enhance the applicability of P-G3, we complexed P-G3 with human serum albumin (HSA) to attain a sustained release, which showed consistent benefits in treating DIO mice. Local injection of HSA-PG3 into subcutaneous fat completely restricted the distribution of the complex within the targeted depot and reduced focal adiposity. Our study illuminates a promising cationic strategy to ameliorate chronic inflammation in obesity and target local adiposity.

Dendrimers as nanoscale vectors: Unlocking the bars of cancer therapy

Chemotherapy is the first choice in the treatment of cancer and is always preferred to other approaches such as radiation and surgery, but it has never met the need of patients for a safe and effective drug. Therefore, new advances in cancer treatment are now needed to reduce the side effects and burdens associated with chemotherapy for cancer patients. Targeted treatment using nanotechnology are now being actively explored as they could effectively deliver therapeutic agents to tumor cells without affecting normal cells. Dendrimers are promising nanocarriers with distinct physiochemical properties that have received considerable attention in cancer therapy studies, which is partly due to the numerous functional groups on their surface. In this review, we discuss the progress of different types of dendrimers as delivery systems in cancer therapy, focusing on the challenges, opportunities, and functionalities of the polymeric molecules. The paper also reviews the various role of dendrimers in their entry into cells via endocytosis, as well as the molecular and inflammatory pathways in cancer. In addition, various dendrimers-based drug delivery (e.g., pH-responsive, enzyme-responsive, redox-responsive, thermo-responsive, etc.) and lipid-, amino acid-, polymer- and nanoparticle-based modifications for gene delivery, as well as co-delivery of drugs and genes in cancer therapy with dendrimers, are presented. Finally, biosafety concerns and issues hindering the transition of dendrimers from research to the clinic are discussed to shed light on their clinical applications.

Peptides to Overcome the Limitations of Current Anticancer and Antimicrobial Nanotherapies

Biomedical research devotes a huge effort to the development of efficient non-viral nanovectors (NV) to improve the effectiveness of standard therapies. NVs should be stable, sustainable and biocompatible and enable controlled and targeted delivery of drugs. With the aim to foster the advancements of such devices, this review reports some recent results applicable to treat two types of pathologies, cancer and microbial infections, aiming to provide guidance in the overall design of personalized nanomedicines and highlight the key role played by peptides in this field. Additionally, future challenges and potential perspectives are illustrated, in the hope of accelerating the translational advances of nanomedicine.

Polymeric Nanotubes as Drug Delivery Vectors─Comparison of Covalently and Supramolecularly Assembled Constructs

Rod-shaped nanoparticles have been identified as promising drug delivery candidates. In this report, the in vitro cell uptake and in vivo pharmacokinetic/bio-distribution behavior of molecular bottle-brush (BB) and cyclic peptide self-assembled nanotubes were studied in the size range of 36-41 nm in length. It was found that BB possessed the longest plasma circulation time (t_1\2 > 35 h), with the cyclic peptide system displaying an intermediate half-life (14.6 h), although still substantially elevated over a non-assembling linear control (2.7 h). The covalently bound BB underwent substantial distribution into the liver, whereas the cyclic peptide nanotube was able to mostly circumvent organ accumulation, highlighting the advantage of the inherent degradability of the cyclic peptide systems through their reversible aggregation of hydrogen bonding core units.

Baseline and time-updated factors in preclinical development of anionic dendrimers as successful anti-HIV-1 vaginal microbicides

Although a wide variety of topical microbicides provide promising in vitro and in vivo efficacy, most of them failed to prevent sexual transmission of human immunodeficiency virus type 1 (HIV-1) in human clinical trials. In vitro, ex vivo, and in vivo models must be optimized, considering the knowledge acquired from unsuccessful and successful clinical trials to improve the current gaps and the preclinical development protocols. To date, dendrimers are the only nanotool that has advanced to human clinical trials as topical microbicides to prevent HIV-1 transmission. This fact demonstrates the importance and the potential of these molecules as microbicides. Polyanionic dendrimers are highly branched nanocompounds with potent activity against HIV-1 that disturb HIV-1 entry. Herein, the most significant advancements in topical microbicide development, trying to mimic the real-life conditions as closely as possible, are discussed. This review also provides the preclinical assays that anionic dendrimers have passed as microbicides because they can improve current antiviral treatments' efficacy. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Nanoparticle based medicines: approaches for evading and manipulating the mononuclear phagocyte system and potential for clinical translation

For decades, nanomedicines have been reported as a potential means to overcome the limitations of conventional drug delivery systems by reducing side effects, toxicity and the non-ideal pharmacokinetic behaviour typically exhibited by small molecule drugs. However, upon administration many nanoparticles prompt induction of host inflammatory responses due to recognition and uptake by macrophages, eliminating up to 95% of the administered dose. While significant advances in nanoparticle engineering and consequent therapeutic efficacy have been made, it is becoming clear that nanoparticle recognition by the mononuclear phagocyte system (MPS) poses an impassable junction in the current framework of nanoparticle development. Hence, this has negative consequences on the clinical translation of nanotechnology with respect to therapeutic efficacy, systemic toxicity and economic benefit. In order to improve the translation of nanomedicines from bench-to-bedside, there is a requirement to either modify nanomedicines in terms of how they interact with intrinsic processes in the body, or modulate the body to be more accommodating for nanomedicine treatments. Here we provide an overview of the current standard for design elements of nanoparticles, as well as factors to consider when producing nanomedicines that have minimal MPS-nanoparticle interactions; we explore this landscape across the cellular to tissue and organ levels. Further, rather than designing materials to suit the body, a growing research niche involves modulating biological responses to administered nanomaterials. We here discuss how developing strategic methods of MPS 'pre-conditioning' with small molecule or biological drugs, as well as implementing strategic dosing regimens, such as 'decoy' nanoparticles, is essential to increasing nanoparticle therapeutic efficacy. By adopting such a perspective, we hope to highlight the increasing trends in research dedicated to improving nanomedicine translation, and subsequently making a positive clinical impact.

Synthesis and Characterization of Pyrazole-Enriched Cationic Nanoparticles as New Promising Antibacterial Agent by Mutual Cooperation

A pyrazole derivative (CB1) was previously evaluated in vivo for various pharmacological activities (with the exception of antimicrobial effects), using DMSO as the administrative medium, mainly due to its water insolubility. Considering the global necessity for new antimicrobial agents, CB1 attracted our attention as a candidate to meet this need, mainly because the secondary amine group in its structure would make it possible to obtain its hydrochloride salt (CB1H), thus effortlessly solving its water-solubility drawbacks. In preliminary microbiologic investigations on Gram-negative and Gram-positive bacteria, CB1H displayed weak antibacterial effects on MDR isolates of Gram-positive species, nonetheless better than those displayed by the commonly-used available antibiotics. Therefore, aiming at improving such activity and extending the antibacterial spectrum of CB1H to Gram-negative pathogens, in this first work CB1 was strategically formulated in nanoparticles using a cationic copolymer (P7) previously developed by us, possessing potent broad-spectrum bactericidal activity. Using the nanoprecipitation method, CB1H-loaded polymer nanoparticles (CB1H-P7 NPs) were obtained, which were analyzed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy to confirm the successful loading. Additionally, CB1H-P7 NPs were fully characterized in terms of morphology, size, polydispersity indices, surface charge, DL%, and EE%, as well as release and potentiometric profiles.

Therapeutic development of polymers for prion disease

Prion diseases, also known as transmissible spongiform encephalopathies, are caused by the accumulation of abnormal isoforms of the prion protein (scrapie isoform of the prion protein, PrPSc) in the central nervous system. Many compounds with anti-prion activities have been found using in silico screening, in vitro models, persistently prion-infected cell models, and prion-infected rodent models. Some of these compounds include several types of polymers. Although the inhibition or removal of PrPSc production is the main target of therapy, the unique features of prions, namely protein aggregation and assembly accompanied by steric structural transformation, may require different strategies for the development of anti-prion drugs than those for conventional therapeutics targeting enzyme inhibition, agonist ligands, or modulation of signaling. In this paper, we first overview the history of the application of polymers to prion disease research. Next, we describe the characteristics of each type of polymer with anti-prion activity. Finally, we discuss the common features of these polymers. Although drug delivery of these polymers to the brain is a challenge, they are useful not only as leads for therapeutic drugs but also as tools to explore the structure of PrPSc and are indispensable for prion disease research.

An Orthogonal Protection Strategy for Synthesizing Scaffold-Modifiable Dendrons and Their Application in Drug Delivery

Dendrons have well-defined dendritic structures. However, it is a great challenge to preserve their high structural definition after multiple functionalization because the site-selective conjugation of different functional molecules is quite difficult. Scaffold-modifiable dendrons that have orthogonal reactive groups at the scaffold and periphery are ideal for achieving the site-specific bifunctionalization. In this paper, we present a new strategy for synthesizing scaffold-modifiable dendrons via orthogonal amino protection and a solid-phase synthesis method. This strategy renders the reactive sites at the scaffold and periphery of the dendrons a super selectivity, high reactivity, and wide applicability to various reaction types. The fourth-generation dendrons can be facilely synthesized within 2 days without structural defects as demonstrated by mass spectrometry. We conjugated doxorubicin (DOX) and phenylboronic acid (PBA) groups to the scaffold and periphery, respectively. Thanks to the PBA-enhanced lysosome escape, tumor targeting ability, and tumor permeability as well as the high drug loading content larger than 30%, the dendron-based prodrug exhibited extraordinary antitumor efficacy and could eradicate the tumors established in mice by multiple intravenous administration. This work provides a practical strategy for synthesizing scaffold-modifiable dendrons that can be a promising nanoplatform to achieve function integration in a precisely controlled manner.

Journey to the Market: The Evolution of Biodegradable Drug Delivery Systems

Biodegradable polymers have been used as carriers in drug delivery systems for more than four decades. Early work used crude natural materials for particle fabrication, whereas more recent work has utilized synthetic polymers. Applications include the macroscale, the microscale, and the nanoscale. Since pioneering work in the 1960’s, an array of products that use biodegradable polymers to encapsulate the desired drug payload have been approved for human use by international regulatory agencies. The commercial success of these products has led to further research in the field aimed at bringing forward new formulation types for improved delivery of various small molecule and biologic drugs. Here, we review recent advances in the development of these materials and we provide insight on their drug delivery application. We also address payload encapsulation and drug release mechanisms from biodegradable formulations and their application in approved therapeutic products.

Successful Dendrimer and Liposome-Based Strategies to Solubilize an Antiproliferative Pyrazole Otherwise Not Clinically Applicable

Water-soluble formulations of the pyrazole derivative 3-(4-chlorophenyl)-5-(4-nitrophenylamino)-1H-pyrazole-4-carbonitrile (CR232), which were proven to have in vitro antiproliferative effects on different cancer cell lines, were prepared by two diverse nanotechnological approaches. Importantly, without using harmful organic solvents or additives potentially toxic to humans, CR232 was firstly entrapped in a biodegradable fifth-generation dendrimer containing lysine (G5K). CR232-G5K nanoparticles (CR232-G5K NPs) were obtained with high loading (DL%) and encapsulation efficiency (EE%), which showed a complex but quantitative release profile governed by Weibull kinetics. Secondly, starting from hydrogenated soy phosphatidylcholine and cholesterol, we prepared biocompatible CR232-loaded liposomes (CR232-SUVs), which displayed DL% and EE% values increasing with the increase in the lipids/CR232 ratio initially adopted and showed a constant prolonged release profile ruled by zero-order kinetics. When relevant, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS) experiments, as well as potentiometric titrations completed the characterization of the prepared NPs. CR232-G5K NPs were 2311-fold more water-soluble than the pristine CR232, and the CR232-SUVs with the highest DL% were 1764-fold more soluble than the untreated CR232, thus establishing the success of both our strategies.

Dendronization: A practical strategy to improve the performance of molecular systems used in biomedical applications

Nanomedicine is an emerging area that largely influences the efficacy of various therapies through the rational design of new materials exhibiting more targeted behavior. The synthetic effort, the amount of used material, and the cost are critical parameters to bear in mind if the production of the designed material is intended to be scaled for their widespread use. Even though materials science offers diverse options for different types of therapies, it is a difficult task to meet all the parameters mentioned above. The dendronization appears as an insightful approach to incorporate all the known benefits of the dendritic architecture by the attachment of dendrons to therapeutic agents, but in a much more affordable manner in terms of synthetic effort, amount of material, and cost. As will be presented, the most common dendrons used for biomedical applications are polyamide, polyester, carbosilane, polyether, and glycol-type, which are bonded to biological active molecules (BAMs), or molecular nanoplatforms (MPs) by hydrolysable bonds. Also relevant is the fact that the incorporation of dendrons not larger than third generation (G3) is sufficient to improve essential properties of these molecular systems, such as aqueous solubility, stability, and cellular internalization, among others. The type of dendron and its location on the BAMs or MPs, similar to placing a Lego piece on a model, will be decisive for obtaining the desired properties.

Poly(HPMA-co-NIPAM) copolymer as an alternative to polyethylene glycol-based pharmacokinetic modulation of therapeutic proteins

PEGylation is the standard approach for prolonging the plasma exposure of protein therapeutics but has limitations. We explored whether polymers prepared by Reversible Addition-Fragmentation chain-Transfer (RAFT) may provide better alternatives to polyethylene glycol (PEG). Four RAFT polymers were synthesised with varying compositions, molar mass (M_n), and structures, including a homopolymer of N-(2-hydroxypropyl)methacrylamide, (pHPMA) and statistical copolymers of HPMA with poly(ethylene glycol methyl ether acrylate) p(HPMA-co-PEGA); HPMA and N-acryloylmorpholine, p(HPMA-co-NAM); and HPMA and N-isopropylacrylamide, p(HPMA-co-NIPAM). The intravenous pharmacokinetics of the polymers were then evaluated in rats. The in vitro activity and in vivo pharmacokinetics of p(HPMA-co-NIPAM)-conjugated trastuzumab Fab' and full length mAb were then evaluated. p(HPMA-co-NIPAM) prolonged plasma exposure more avidly compared to the other p(HPMA) polymers or PEG, irrespective of molecular weight. When conjugated to trastuzumab-Fab', p(HPMA-co-NIPAM) prolonged plasma exposure of the Fab' similar to PEG-Fab'. The generation of anti-PEG IgM in rats 7 days after intravenous and subcutaneous dosing of p(HPMA-co-NIPAM) conjugated trastuzumab mAb was also examined and was shown to exhibit lower immunogenicity than the PEGylated construct. These data suggest that p(HPMA-co-NIPAM) has potential as a promising copolymer for use as an alternative conjugation strategy to PEG, to prolong the plasma exposure of therapeutic proteins.

Drug delivery to the anterior segment of the eye: A review of current and future treatment strategies

Research in the development of ophthalmic drug formulations and innovative technologies over the past few decades has been directed at improving the penetration of medications delivered to the eye. Currently, approximately 90% of all ophthalmic drug formulations (e.g. liposomes, micelles) are applied as eye drops. The major challenge of topical eye drops is low bioavailability, need for frequent instillation due to the short half-life, poor drug solubility, and potential side effects. Recent research has been focused on improving topical drug delivery devices by increasing ocular residence time, overcoming physiological and anatomical barriers, and developing medical devices and drug formulations to increase the duration of action of the active drugs. Researchers have developed innovative technologies and formulations ranging from sub-micron to macroscopic size such as prodrugs, enhancers, mucus-penetrating particles (MPPs), therapeutic contact lenses, and collagen corneal shields. Another approach towards the development of effective topical drug delivery is embedding therapeutic formulations in microdevices designed for sustained release of the active drugs. The goal is to optimize the delivery of ophthalmic medications by achieving high drug concentration with prolonged duration of action that is convenient for patients to administer.

Nanotechnological Manipulation of Nutraceuticals and Phytochemicals for Healthy Purposes: Established Advantages vs. Still Undefined Risks

Numerous foods, plants, and their bioactive constituents (BACs), named nutraceuticals and phytochemicals by experts, have shown many beneficial effects including antifungal, antiviral, anti-inflammatory, antibacterial, antiulcer, anti-cholesterol, hypoglycemic, immunomodulatory, and antioxidant activities. Producers, consumers, and the market of food- and plant-related compounds are increasingly attracted by health-promoting foods and plants, thus requiring a wider and more fruitful exploitation of the healthy properties of their BACs. The demand for new BACs and for the development of novel functional foods and BACs-based food additives is pressing from various sectors. Unfortunately, low stability, poor water solubility, opsonization, and fast metabolism in vivo hinder the effective exploitation of the potential of BACs. To overcome these issues, researchers have engineered nanomaterials, obtaining food-grade delivery systems, and edible food- and plant-related nanoparticles (NPs) acting as color, flavor, and preservative additives and natural therapeutics. Here, we have reviewed the nanotechnological transformations of several BACs implemented to increase their bioavailability, to mask any unpleasant taste and flavors, to be included as active ingredients in food or food packaging, to improve food appearance, quality, and resistance to deterioration due to storage. The pending issue regarding the possible toxic effect of NPs, whose knowledge is still limited, has also been discussed.

First-in-class and best-in-class dendrimer nanoplatforms from concept to clinic: Lessons learned moving forward

Research to develop active dendrimers by themselves or as nanocarriers represents a promising approach to discover new biologically active entities that can be used to tackle unmet medical needs including difficult diseases. These developments are possible due to the exceptional physicochemical properties of dendrimers, including their biocompatibility, as well as their therapeutic activity as nanocarriers and drugs themselves. Despite a large number of academic studies, very few dendrimers have crossed the 'valley of death' between. Only a few number of pharmaceutical companies have succeeded in this way. In fact, only Starpharma (Australia) and Orpheris, Inc. (USA), an Ashvattha Therapeutics subsidiary, can fill all the clinic requirements to have in the market dendrimers based drugs/nancocarriers. After evaluating the main physicochemical properties related to the respective biological activity of dendrimers classified as first-in-class or best-in-class in nanomedicine, this original review analyzes the advantages and disavantages of these two strategies as well the concerns to step in clinical phases. Various solutions are proposed to advance the use of dendrimers in human health.

Different hydration states and passive tumor targeting ability of polyethylene glycol-modified dendrimers with high and low PEG density

It has been reported that the amount of intermediate water, defined as water molecules loosely bound to a material, is a useful index of the material's bio-inert properties. Polyethylene glycol (PEG) is a well-known biocompatible polymer with a large amount of intermediate water. Many researchers have showed that PEGylated nanoparticles are passively accumulated in tumor tissues owing to their enhanced permeability and retention (EPR) effects. Dendrimers are regularly branched polymers with highly controllable size and structure, which can be exploited as potent drug carriers. In this study, we investigated the tripartite relationship among the PEG density, the hydration state, and the passive tumor targeting property, using PEGylated dendrimers. The fully PEGylated dendrimer, PEG64-den, showed similar hydration behavior to PEG and a passive tumor targeting property. In contrast, the hydration state of the partly PEGylated dendrimer, PEG5-den, was different from that of PEG64-den, and the passive tumor targeting property was not observed. This is the first report to show the hydration state of a drug carrier as well as discuss a relationship between the hydration state and biodistribution.

Dermal delivery and follicular targeting of adapalene using PAMAM dendrimers

Acne is a chronic dermatological disease of pilosebaceous units existing in the form of hair follicles (HFs) and accompanying sebaceous glands. In topical acne treatment, localisation of drug substance at the target site, in pilosebaceous units, especially in HFs is essential. The aims of this study were to develop and optimise adapalene (ADA)-loaded PAMAM dendrimer-based nanocarriers for topical acne treatment and to prepare gel formulations of the selected nanocarriers and to characterise their rheological properties and spreadability. ADA accumulation in HFs and in the skin from PAMAM dendrimers' aqueous colloidal formulations and their gel formulations were quantitatively determined using punch biopsy technique. Follicular targeting efficiency from PAMAM dendrimers and their gel formulation was compared with the commercial gel product, Differin^® Gel. The localisation of fluorescently labelled PAMAM dendrimers was visualised using a confocal microscope, which confirmed a successful delivery of the carrier system to the HFs. It was also quantified that PAMAM dendrimers improved follicular localisation and skin deposition of ADA. PAMAM dendrimers' gel formulation including lower ADA doses compared with the commercial product exhibited efficient performance in terms of drug accumulation in HFs. In vitro cell viability studies showed the relative safety of G2-PAMAM dendrimers which could be considered to possibly be well tolerated by the skin. Overall, PAMAM dendrimers' potential to selectively target drugs to the site of action, reduce dose administrated, therefore minimise side effects and provide efficiency in topical treatment of dermatological diseases such as acne was shown.

Spatiotemporal Concurrent Liberation of Cytotoxins from Dual-Prodrug Nanomedicine for Synergistic Antitumor Therapy

Nanomedicine developed to date by means of directly encapsulating cytotoxins suffers from crucial drawbacks, including premature release and detoxification prior to arrival at pharmaceutics targets. To these respects, redox-responsive polymeric prodrugs of platinum (Pt) and camptothecin (CPT), selectively and concomitantly activated in the cytoplasm, were elaborated in manufacture of dual prodrug nanomedicine. Herein, multiple CPTs were conjugated to poly(lysine) (PLys) segments of block copolymeric poly(ethylene glycol) (PEG)-PLys through the redox responsive disulfide linkage [PEG-PLys(ss-CPT)] followed by reversible conversion of amino groups from PLys into carboxyl groups based on their reaction with cis-aconitic anhydride [PEG-PLys(ss-CPT&CAA)]. On the other hand, Pt(IV) in conjugation with dendritic polyamindoamine [(G3-PAMAM-Pt(IV)] was synthesized for electrostatic complexation with PEG-PLys(ss-CPT&CAA) into dual prodrug nanomedicine. Subsequent investigations proved that the elaborated nanomedicine could sequentially respond to intracellular chemical potentials to overcome a string of predefined biological barriers and facilitate intracellular trafficking. Notably, PEG-PLys(ss-CPT&CAA) capable of responding to the acidic endosomal microenvironment for transformation into endosome-disruptive PEG-PLys(ss-CPT), as well as release of G3-PAMAM-Pt(IV) from nanomedicine, prompted transclocation of therapeutic payloads from endosomes into cytosols. Moreover, concurrent activation and liberation of cytotoxic CPT and Pt(II) owing to their facile responsiveness to the cytoplasmic reducing microenvironment have demonstrated overwhelming cytotoxic potencies. Eventually, systemic administration of the dual prodrug construct exerted potent tumor suppression efficacy in treatment of intractable solid breast adenocarcinoma, as well as an appreciable safety profile. The present study illustrated the first example of nanomedicine with a dual prodrug motif, precisely and concomitantly activated by the same subcellular stimuli before approaching pharmaceutic action targets, thus shedding important implication in development of advanced nanomedicine to seek maximized pharmaceutic outcomes.

PEGylation of Dendronized Gold Nanoparticles Affects Their Interaction with Thrombin and siRNA

The use of nonviral carriers based on nanomaterials is a promising strategy for modern gene therapy aimed at protecting the genetic material against degradation and enabling its efficient cellular uptake. To improve the effectiveness of nanocarriers in vivo, they are often modified with poly(ethylene glycol) (PEG) to reduce their toxicity, limit nonspecific binding by proteins in the bloodstream, and extend blood half-life. Thus, the selection of an appropriate degree of surface PEGylation is crucial to preserve the interaction of nanoparticles with the genetic material and to ensure its efficient transport to the site of action. Our research focuses on the use of innovative gold nanoparticles (AuNPs) coated with cationic carbosilane dendrons as carriers of siRNA. In this study, using dynamic light scattering and zeta potential measurements, circular dichroism, and gel electrophoresis, we investigated dendronized AuNPs modified to varying degrees with PEG in terms of their interactions with siRNA and thrombin to select the most promising PEGylated carrier for further research.

Design and optimisation of dendrimer-conjugated Bcl-2/xL inhibitor, AZD0466, with improved therapeutic index for cancer therapy

Dual Bcl-2/Bcl-x_L inhibitors are expected to deliver therapeutic benefit in many haematological and solid malignancies, however, their use is limited by tolerability issues. AZD4320, a potent dual Bcl-2/Bcl-x_L inhibitor, has shown good efficacy however had dose limiting cardiovascular toxicity in preclinical species, coupled with challenging physicochemical properties, which prevented its clinical development. Here, we describe the design and development of AZD0466, a drug-dendrimer conjugate, where AZD4320 is chemically conjugated to a PEGylated poly-lysine dendrimer. Mathematical modelling was employed to determine the optimal release rate of the drug from the dendrimer for maximal therapeutic index in terms of preclinical anti-tumour efficacy and cardiovascular tolerability. The optimised candidate is shown to be efficacious and better tolerated in preclinical models compared with AZD4320 alone. The AZD4320-dendrimer conjugate (AZD0466) identified, through mathematical modelling, has resulted in an improved therapeutic index and thus enabled progression of this promising dual Bcl-2/Bcl-x_L inhibitor into clinical development.

Claire Patterson et al. present the design and development of AZD0466, a drug-dendrimer conjugate, and use preclinical and mathematical models to determine the optimal release rate of the drug from the dendrimer carrier for maximal therapeutic index in terms of anti-tumour efficacy and cardiovascular tolerability. This study identifies this promising dual Bcl-2/Bcl-x_L inhibitor for progression to clinical development.

Lipophilic Peptide Dendrimers for Delivery of Splice-Switching Oligonucleotides

Non-viral transfection reagents are continuously being developed in attempt to replace viral vectors. Among those non-viral vectors, dendrimers have gained increasing interest due to their unique molecular structure and multivalency. However, more improvements are still needed to achieve higher efficacy and lower toxicity. In this study, we have examined 18 peptide dendrimers conjugated to lipophilic moieties, such as fatty acids or hydrophobic amino acids, that were previously explored for siRNA. Reporter cells were employed to investigate the transfection of single strand splice-switching oligonucleotides (ONs) using these peptide dendrimers. Luciferase level changes reflecting efficiency varied with amino acid composition, stereochemistry, and complexation media used. 3rd generation peptide dendrimers with D-amino acid configuration were superior to L-form. Lead formulations with 3rd generation, D-amino acid peptide dendrimers increased the correction level of the delivered ON up to 93-fold over untreated HeLa Luc/705 cells with minimal toxicity. To stabilize the formed complexes, Polyvinyl alcohol 18 (PVA18) polymer was added. Although PVA18 addition increased activity, toxicity when using our best candidates G 2,3KL-(Leu)₄ (D) and G 2,3KL-diPalmitamide (D) was observed. Our findings demonstrate the potential of lipid-conjugated, D-amino acid-containing peptide dendrimers to be utilized as an effective and safe delivery vector for splice-switching ONs.

Dendrimers against fungi - A state of the art review

Fungal based diseases currently affect nearly a quarter of the population around the world, which diseases are usually limited to superficial infections. Perversely, along with the development of modern medicine, cases of life-threatening systemic fungi are more and more often encountered. Compared to antibacterial drugs, significantly fewer fungicides are tested and introduced to clinical practice. At the same time, the drug resistance of pathological fungi is constantly growing. In addition to obtaining new derivatives of already-established classes of drugs, such as azoles, there is a growing interest in new compounds with potentially new mechanisms and application possibilities. Polymers are included in the flow of these studies, and among them - dendrimers. Dendrimers are a special type of polymers with a strictly defined structure and a plethora of functionalization possibilities. This allows them to not only be used as effective antifungal drug carriers but also enables them to exhibit antifungal activity per se. In this review, we have introduced to the epidemiology of fungal infections and summarized the aspects related to their control and therapy. Various polymers and dendrimers with antifungal activity were presented. In the subsequent sections antifungal acting dendrimers were discussed within three subchapters, based on their chemical structure: (i) amino acid-based dendrimers, (ii) amino based dendrimers, and (iii) other, which do not share similarities in structure. We have gathered and summarized the reports regarding the direct action of dendrimers on infectious fungi, as well as their effect when used as solubilizers, carriers or adjuvants with currently used antifungals. Use of dendrimers for the sensing of fungi or their metabolites are also considered. Special attention was also paid to the applications of dendrimers together with photosensitizers in antimicrobial photodynamic therapy.

The Impact of Polymer Size and Cleavability on the Intravenous Pharmacokinetics of PEG-Based Hyperbranched Polymers in Rats

A better understanding of the impact of molecular size and linkers is important for PEG-based hyperbranched polymers (HBPs) intended as tailored drug delivery vehicles. This study aimed to evaluate the effects of crosslinker chemistry (cleavable disulphide versus non-cleavable ethylene glycol methacrylate (EGDMA) linkers) and molecular weight within the expected size range for efficient renal elimination (22 vs. 48 kDa) on the intravenous pharmacokinetic and biodistribution properties of 89Zr-labelled HBPs in rats. All HBPs showed similar plasma pharmacokinetics over 72 h, despite differences in linker chemistry and size. A larger proportion of HBP with the cleavable linker was eliminated via the urine and faeces compared to a similar-sized HBP with the non-cleavable linker, while size had no impact on the proportion of the dose excreted. The higher molecular weight HBPs accumulated in organs of the mononuclear phagocyte system (liver and spleen) more avidly than the smaller HBP. These results suggest that HBPs within the 22 to 48 kDa size range show no differences in plasma pharmacokinetics, but distinct patterns of organ biodistribution and elimination are evident.

Dendritic Nanotheranostic for the Delivery of Infliximab: A Potential Carrier in Rheumatoid Arthritis Therapy

Antibodies are macromolecules that specifically recognize their target, making them good candidates to be employed in various therapies. The possibility of attaching a drug to an immunoglobulin makes it possible to release it specifically into the affected tissue as long as it overexpresses the target. However, chemical coupling could affect the functionality (specificity and affinity) of the antibody. It has been observed that the use of intermediaries, such as dendrimers, could resolve this issue. Because carbosilane dendrimers have aroused great interest in the field of biomedicine, this report describes the synthesis of an anionic carbosilane dendrimer with a fluorochrome on its surface that then forms a conjugate with an antibody. It has been used as immunoglobulin and infliximab, whose target is TNF-α, which is a cytokine that is overexpressed in the inflamed area or even in the blood of patients with autoimmune diseases, such as rheumatoid arthritis. In addition, the integrity and functionality of the antibody has been studied to see if they have been affected after the chemical coupling process.

Pharmacokinetic Research Progress of Anti-tumor Drugs Targeting for Pulmonary Administration

BACKGROUND

Cancer is a major problem that threatens human survival and has a high mortality rate. The traditional chemotherapy methods are mainly intravenous injection and oral administration, but have obvious toxic and side effects. Anti-tumor drugs for pulmonary administration can enhance drug targeting, increase local drug concentration, and reduce the damage to systemic organs, especially for the treatment of lung cancer.

METHODS

The articles on the pharmacokinetics of anti-tumor drugs targeting pulmonary administration were retrieved from the Pub Med database. This article mainly took lung cancer as an example and summarized the pharmacokinetic characteristics of anti-tumor drugs targeting for pulmonary administration contained in nanoparticles, dendrimers, liposomes and micelles.

RESULTS

The review shows that the pharmacokinetics process of pulmonary administration is associated with a drug carrier by increasing the deposition and release of drugs in the lung, and retarding the lung clearance rate. Among them, the surface of dendrimers could be readily modified, and polymer micelles have favorable loading efficiency. In the case of inhalation administration, liposomes exhibit more excellent lung retention properties compared to other non-lipid carriers. Therefore, the appropriate drug carrier is instrumental to increase the curative effect of anti-tumor drugs and reduce the toxic effect on surrounding healthy tissues or organs.

CONCLUSION

In the process of pulmonary administration, the carrier-embedded antitumor drugs have the characteristics of targeted and sustained release compared with non-packaging drugs, which provides a theoretical basis for the clinical rational formulation of chemotherapy regimens. However, there is currently a lack of comparative research between drug packaging materials, and more importantly, the development of safe and effective anti-tumor drugs targeting for pulmonary administration requires more data.

A Dendron-Based Fluorescence Turn-On Probe for Tumor Detection

Specifically amplifying the emission signals of optical probes in tumors is an effective way to improve the tumor-imaging sensitivity and contrast. In this paper, the first case of dendron-based fluorescence turn-on probes mediated by a Förster resonance energy transfer (FRET) mechanism is reported. Dendrons up to the fourth generation with a hydrophilic oligo(ethylene glycol) scaffold are synthesized by a solid-phase synthesis strategy, and show precise and defect-free chemical structures. To construct the fluorescence turn-on probe, one Cy5.5 molecule is conjugated to the focal of a G3 dendron through a robust linkage and eight Black Hole Quencher 3 (BHQ-3) molecules are conjugated to its periphery through a PEG chain bearing a reductively cleavable disulfide linkage. By in vitro and in vivo experiments, it is demonstrated that the fluorescence of the dendron-based probe can be activated effectively and rapidly in the reductive environments of tumor cells and tissues, and the probe thus exhibits amplified tumor signals and weak normal tissue signals. Compared with the reported nanoscale turn-on probes, the dendron-based probe has several significant advantages, such as well-defined chemical structure, precisely controllable fluorophore/quencher conjugation sites and ratio, desirable chemical stability, and reproducible pharmacokinetic and pharmacological profiles, and is very promising in tumor detection.

Biodegradable and biocompatible spherical dendrimer nanoparticles with a gallic acid shell and a double-acting strong antioxidant activity as potential device to fight diseases from "oxidative stress"

Gallic acid (GA) is a natural polyphenol with remarkable antioxidant power present in several vegetables and fruits. A normal feeding regime leads to a daily intake of GA which is reasonably regarded as "natural" and "safe" for humans. It owns strong potentials as alternative to traditional drugs to treat several diseases triggered by oxidative stress (OS), but poor gastrointestinal absorbability, pharmacokinetic drawbacks, and fast metabolism limit its clinical application. In this work, a fifth-generation polyester-based dendrimer was firstly prepared as a better absorbable carrier to protect and deliver GA. Then, by its peripheral esterification with GA units, a GA-enriched delivering system (GAD) with remarkable antioxidant power and high potential against diseases from OS was achieved. Scanning electron microscopy results and dynamic light scattering analysis revealed particles with an average size around 387 and 375 nm, respectively, and an extraordinarily spherical morphology. These properties, by determining a large particles surface area, typically favour higher systemic residence time and bio-efficiency. Z-potential of - 25 mV suggests satisfactory stability in solution with tendency to form megamers and low polydispersity index. GAD showed intrinsic antioxidant power, higher than GA by 4 times and like prodrugs, and it can carry contemporary several bioactive GA units versus cells. In physiological condition, the action of pig liver esterase (PLE), selected as a model of cells esterase, hydrolyses GAD to non-cytotoxic small molecules, thus setting free the bioactive GA units, for further antioxidant effects. Cytotoxicity studies performed on two cell lines demonstrated a high cell viability. Graphical Abstract Graphical Abstract.

Dendrimers toward Translational Nanotherapeutics: Concise Key Step Analysis

The goal of nanomedicine is to address specific clinical problems optimally, to fight human diseases, and to find clinical relevance to change clinical practice. Nanomedicine is poised to revolutionize medicine via the development of more precise diagnostic and therapeutic tools. The field of nanomedicine encompasses numerous features and therapeutic disciplines. A plethora of nanomolecular structures have been engineered and developed for therapeutic applications based on their multitasking abilities and the wide functionalization of their core scaffolds and surface groups. Within nanoparticles used for nanomedicine, dendrimers as well polymers have demonstrated strong potential as nanocarriers, therapeutic agents, and imaging contrast agents. In this review, we present and discuss the different criteria and parameters to be addressed to prepare and develop druggable nanoparticles in general and dendrimers in particular. We also describe the major requirements, included in the preclinical and clinical roadmap, for NPs/dendrimers for the preclinical stage to commercialization. Ultimately, we raise the clinical translation of new nanomedicine issues.

Synthesis and Characterization of Dendrimer-Based Polysarcosine Star Polymers: Well-Defined, Versatile Platforms Designed for Drug-Delivery Applications

This paper describes the synthesis of star polymers designed for future drug-delivery applications. A generation-5 lysine dendrimer was used as a macroinitiator for the ring-opening polymerization of the sarcosine N-carboxyanhydride monomer to produce 32-arm star polymers with narrow molar mass distributions and desirable hydrodynamic size control. Fluorescent dye-labeled polymers were dosed in mice to measure plasma pharmacokinetics. Long circulation times were observed, representing ideal properties for biophysical targeting of tumors. In vivo efficacy of one of these star polymers conjugated to the therapeutic molecule SN-38 was evaluated in mice bearing SW620 xenografted tumors to demonstrate high antitumor activity and low body weight loss compared to the SN-38 prodrug irinotecan and this shows the potential of these delivery systems. As a further build, we demonstrated that these star polymers can be easily chain-end-functionalized with useful chemical moieties, giving opportunities for future receptor-targeting strategies. Finally, we describe the synthetic advantages of these star polymers that make them attractive from a pharmaceutical manufacturing perspective and report characterization of the polymers with a variety of techniques.