Simplifying the synthesis of dendrimers: accelerated approaches

Recent Research Progress on Polyamidoamine-Engineered Hydrogels for Biomedical Applications

Hydrogels are three-dimensional crosslinked functional materials with water-absorbing and swelling properties. Many hydrogels can store a variety of small functional molecules to structurally and functionally mimic the natural extracellular matrix; hence, they have been extensively studied for biomedical applications. Polyamidoamine (PAMAM) dendrimers have an ethylenediamine core and a large number of peripheral amino groups, which can be used to engineer various polymer hydrogels. In this review, an update on the progress of using PAMAM dendrimers for multifunctional hydrogel design was given. The synthesis of these hydrogels, which includes click chemistry reactions, aza-Michael addition, Schiff base reactions, amidation reactions, enzymatic reactions, and radical polymerization, together with research progress in terms of their application in the fields of drug delivery, tissue engineering, drug-free tumor therapy, and other related fields, was discussed in detail. Furthermore, the biomedical applications of PAMAM-engineered nano-hydrogels, which combine the advantages of dendrimers, hydrogels, and nanoparticles, were also summarized. This review will help researchers to design and develop more functional hydrogel materials based on PAMAM dendrimers.

Abelairas A, Criado A, Gómez IJ, Mosquera J. Dendrimers: Exploring Their Wide Structural Variety and Applications

Dendrimers constitute a distinctive category of synthetic materials that bear resemblance to proteins in various aspects, such as discrete structural organization, globular morphology, and nanoscale dimensions. Remarkably, these attributes coexist with the capacity for facile large-scale production. Due to these advantages, the realm of dendrimers has undergone substantial advancement since their inception in the 1980s. Numerous reviews have been dedicated to elucidating this subject comprehensively, delving into the properties and applications of quintessential dendrimer varieties like PAMAM, PPI, and others. Nevertheless, the contemporary landscape of dendrimers transcends these early paradigms, witnessing the emergence of a diverse array of novel dendritic architectures in recent years. In this review, we aim to present a comprehensive panorama of the expansive domain of dendrimers. As such, our focus lies in discussing the key attributes and applications of the predominant types of dendrimers existing today. We will commence with the conventional variants and progressively delve into the more pioneering ones, including Janus, supramolecular, shape-persistent, and rotaxane dendrimers.

Cationic Materials for Gene Therapy: A Look Back to the Birth and Development of 2,2-Bis-(hydroxymethyl)Propanoic Acid-Based Dendrimer Scaffolds

Gene therapy is extensively studied as a realistic and promising therapeutic approach for treating inherited and acquired diseases by repairing defective genes through introducing (transfection) the "healthy" genetic material in the diseased cells. To succeed, the proper DNA or RNA fragments need efficient vectors, and viruses are endowed with excellent transfection efficiency and have been extensively exploited. Due to several drawbacks related to their use, nonviral cationic materials, including lipidic, polymeric, and dendrimer vectors capable of electrostatically interacting with anionic phosphate groups of genetic material, represent appealing alternative options to viral carriers. Particularly, dendrimers are highly branched, nanosized synthetic polymers characterized by a globular structure, low polydispersity index, presence of internal cavities, and a large number of peripheral functional groups exploitable to bind cationic moieties. Dendrimers are successful in several biomedical applications and are currently extensively studied for nonviral gene delivery. Among dendrimers, those derived by 2,2-bis(hydroxymethyl)propanoic acid (b-HMPA), having, unlike PAMAMs, a neutral polyester-based scaffold, could be particularly good-looking due to their degradability in vivo. Here, an overview of gene therapy, its objectives and challenges, and the main cationic materials studied for transporting and delivering genetic materials have been reported. Subsequently, due to their high potential for application in vivo, we have focused on the biodegradable dendrimer scaffolds, telling the history of the birth and development of b-HMPA-derived dendrimers. Finally, thanks to a personal experience in the synthesis of b-HMPA-based dendrimers, our contribution to this field has been described. In particular, we have enriched this work by reporting about the b-HMPA-based derivatives peripherally functionalized with amino acids prepared by us in recent years, thus rendering this paper original and different from the existing reviews.

Enhanced Interface Compatibility by Ionic Dendritic Molecules To Achieve Efficient and Stable Perovskite Solar Cells

Poly(3-hexylthiophene) (P3HT) represents a promising hole transport material for emerging perovskite solar cells (PSCs) due to its appealing merits of high thermal stability and appropriate hydrophobicity. Nonetheless, large energy losses at the P3HT/perovskite interface lead to unsatisfied efficiency and stability of the devices. Herein, two ionic dendritic molecules, 3,3'-(2,7-bis(3,6-bis(bis(4-methoxyphenyl)amino)-9H-carbazol-9-yl)-9H-fluorene-9,9-diyl)bis(N,N,N-trimethylpropan-1-aminium) iodide and 3,3'-(2,7-bis(bis(4-(bis(4-methoxyphenyl)amino)phenyl)amino)-9H-fluorene-9,9-diyl)bis(N,N,N-trimethylpropan-1-aminium) iodide, namely, MPA-Cz-FAI and MPA-PA-FAI, are rationally designed as the interlayer to enhance interfacial compatibility. The dendritic backbone with conjugated structure endows the hole transport layer with high conductivity, derived from the more ordered microstructure with larger crystallization and higher connectivity of domain zones. Besides, a better energy level alignment is established between P3HT and perovskite, which enhances the charge extraction and transport yield. In addition, the peripheral methoxy groups enable effective defect passivation at the interface to suppress nonradiative recombination and the quaternary ammonium iodide serving as side chains enable efficient interfacial hole extraction contributing to enhanced charge collection yield. As a result, the dopant-free P3HT-based PSCs modified with MPA-Cz-PAI deliver a champion efficiency of 19.7%, significantly higher than that of the control devices (15.4%). More encouragingly, the unencapsulated devices demonstrate competitive environmental stability by retaining over 85% of its initial efficiency after 1500 h of storage under humid conditions (70% relative humidity). This work provides an effective molecular design strategy for interface engineering, envisaging a bright prospect for the further development of efficient and stable perovskite solar cells.

Molecularly or atomically precise nanostructures for bio-applications: how far have we come?

A huge variety of nanostructures are promising for biomedical applications, but only a few have been practically applied. Among the various reasons, the limited structural preciseness is a critical one, as it increases the difficulty in product quality control, accurate dosing, and ensuring the repeatability of material performance. Constructing nanoparticles with molecule-like preciseness is becoming a new research field. In this review, we focus on the artificial nanomaterials that can currently be molecularly or atomically precise, including DNA nanostructures, some metallic nanoclusters, dendrimer nanoparticles and carbon nanostructures, describing their syntheses, bio-applications and limitations, in view of up-to-date studies. A perspective on their potential for clinical translation is also given. This review is expected to provide a particular rationale for the future design of nanomedicines.

Target-Specific Delivery and Bioavailability of Pharmaceuticals via Janus and Dendrimer Particles

Nanosized Janus and dendrimer particles have emerged as promising nanocarriers for the target-specific delivery and improved bioavailability of pharmaceuticals. Janus particles, with two distinct regions exhibiting different physical and chemical properties, provide a unique platform for the simultaneous delivery of multiple drugs or tissue-specific targeting. Conversely, dendrimers are branched, nanoscale polymers with well-defined surface functionalities that can be designed for improved drug targeting and release. Both Janus particles and dendrimers have demonstrated their potential to improve the solubility and stability of poorly water-soluble drugs, increase the intracellular uptake of drugs, and reduce their toxicity by controlling the release rate. The surface functionalities of these nanocarriers can be tailored to specific targets, such as overexpressed receptors on cancer cells, leading to enhanced drug efficacy The design of these nanocarriers can be optimized by tuning the size, shape, and surface functionalities, among other parameters. The incorporation of Janus and dendrimer particles into composite materials to create hybrid systems for enhancing drug delivery, leveraging the unique properties and functionalities of both materials, can offer promising outcomes. Nanosized Janus and dendrimer particles hold great promise for the delivery and improved bioavailability of pharmaceuticals. Further research is required to optimize these nanocarriers and bring them to the clinical setting to treat various diseases. This article discusses various nanosized Janus and dendrimer particles for target-specific delivery and bioavailability of pharmaceuticals. In addition, the development of Janus-dendrimer hybrid nanoparticles to address some limitations of standalone nanosized Janus and dendrimer particles is discussed.

Target-Specific Delivery and Bioavailability of Pharmaceuticals via Janus and Dendrimer Particles

Nanosized Janus and dendrimer particles have emerged as promising nanocarriers for the target-specific delivery and improved bioavailability of pharmaceuticals. Janus particles, with two distinct regions exhibiting different physical and chemical properties, provide a unique platform for the simultaneous delivery of multiple drugs or tissue-specific targeting. Conversely, dendrimers are branched, nanoscale polymers with well-defined surface functionalities that can be designed for improved drug targeting and release. Both Janus particles and dendrimers have demonstrated their potential to improve the solubility and stability of poorly water-soluble drugs, increase the intracellular uptake of drugs, and reduce their toxicity by controlling the release rate. The surface functionalities of these nanocarriers can be tailored to specific targets, such as overexpressed receptors on cancer cells, leading to enhanced drug efficacy The design of these nanocarriers can be optimized by tuning the size, shape, and surface functionalities, among other parameters. The incorporation of Janus and dendrimer particles into composite materials to create hybrid systems for enhancing drug delivery, leveraging the unique properties and functionalities of both materials, can offer promising outcomes. Nanosized Janus and dendrimer particles hold great promise for the delivery and improved bioavailability of pharmaceuticals. Further research is required to optimize these nanocarriers and bring them to the clinical setting to treat various diseases. This article discusses various nanosized Janus and dendrimer particles for target-specific delivery and bioavailability of pharmaceuticals. In addition, the development of Janus-dendrimer hybrid nanoparticles to address some limitations of standalone nanosized Janus and dendrimer particles is discussed.

Dendrimers in Corneal Drug Delivery: Recent Developments and Translational Opportunities

Dendrimers are biocompatible organic nanomaterials with unique physicochemical properties, making them the focus of recent research in drug delivery. The cornea of the human eye presents a challenge for drug transit due to its inherently impenetrable nature, requiring nanocarrier-mediated targeted drug delivery. This review intends to examine recent advancements in the use of dendrimers for corneal drug delivery, including their properties and their potential for treating various ocular diseases. The review will also highlight the benefit of the novel technologies that have been developed and applied in the field, such as corneal targeting, drug release kinetics, treatments for dry eye disease, antibacterial drug delivery, corneal inflammation, and corneal tissue engineering. The review seeks to provide a comprehensive overview of the current state of research in this field, along with the translational developments in the field of dendrimer-based therapeutics and imaging agents and inspire the potential for future developments and translational opportunities in dendrimers based corneal drug delivery.

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.

Polymeric Nanoparticles for Delivery of Natural Bioactive Agents: Recent Advances and Challenges

In the last few decades, several natural bioactive agents have been widely utilized in the treatment and prevention of many diseases owing to their unique and versatile therapeutic effects, including antioxidant, anti-inflammatory, anticancer, and neuroprotective action. However, their poor aqueous solubility, poor bioavailability, low GIT stability, extensive metabolism as well as short duration of action are the most shortfalls hampering their biomedical/pharmaceutical applications. Different drug delivery platforms have developed in this regard, and a captivating tool of this has been the fabrication of nanocarriers. In particular, polymeric nanoparticles were reported to offer proficient delivery of various natural bioactive agents with good entrapment potential and stability, an efficiently controlled release, improved bioavailability, and fascinating therapeutic efficacy. In addition, surface decoration and polymer functionalization have opened the door to improving the characteristics of polymeric nanoparticles and alleviating the reported toxicity. Herein, a review of the state of knowledge on polymeric nanoparticles loaded with natural bioactive agents is presented. The review focuses on frequently used polymeric materials and their corresponding methods of fabrication, the needs of such systems for natural bioactive agents, polymeric nanoparticles loaded with natural bioactive agents in the literature, and the potential role of polymer functionalization, hybrid systems, and stimuli-responsive systems in overcoming most of the system drawbacks. This exploration may offer a thorough idea of viewing the polymeric nanoparticles as a potential candidate for the delivery of natural bioactive agents as well as the challenges and the combating tools used to overcome any hurdles.

Synthesis and Characterization of Amino-Functional Polyester Dendrimers Based On Bis-MPA with Enhanced Hydrolytic Stability and Inherent Antibacterial Properties

Polyester dendrimers based on 2,2 bis(hydroxymethyl)propionic acid have been reported to be degradable, non-toxic, and exhibit good antimicrobial activity when decorated with cationic charges. However, these systems exhibit rapid depolymerization, from the outer layer inwards in physiological neutral pHs, which potentially restricts their use in biomedical applications. In this study, we present a new generation of amine functional bis-MPA polyester dendrimers with increased hydrolytic stability as well as antibacterial activity for Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) planktonic bacteria strains. These new derivatives show generally good cytocompatibility for the concentrations they are active toward bacteria, in monocyte/macrophage-like cells (Raw 264.7), and human dermal fibroblasts. Fluoride - promoted esterification chemistry, anhydride chemistry, and click reactions were utilized to produce a library from generations 1-3 and with cationic peripheral groups ranging from 6 to 24 groups, respectively. The dendrimers were successfully purified using conventional purification techniques as well as characterized by matrix-assisted laser desorption ionization time-of-flight mass spectroscopy, nuclear magnetic resonance, and size exclusion chromatography. As proof of synthetic versatility, dendritic-linear-dendritic block copolymer were successfully synthesized to display cysteamine peripheral functionalities as well as the scaffolding ability with biomedically relevant lipoic acid and methoxy polyethylene glycol.

Properties and Bioapplications of Amphiphilic Janus Dendrimers: A Review

Amphiphilic Janus dendrimers are arrangements containing both hydrophilic and hydrophobic units, capable of forming ordered aggregates by intermolecular noncovalent interactions between the dendrimer units. Compared to conventional dendrimers, these molecular self-assemblies possess particular and effective attributes i.e., the presence of different terminal groups, essential to design new elaborated materials. The present review will focus on the pharmaceutical and biomedical application of amphiphilic Janus dendrimers. Important information for the development of novel optimized pharmaceutical formulations, such as structural classification, synthetic pathways, properties and applications, will offer the complete characterization of this type of Janus dendrimers. This work will constitute an up-to-date background for dendrimer specialists involved in designing amphiphilic Janus dendrimer-based nanomaterials for future innovations in this promising field.

Multivalent glycocyclopeptides: conjugation methods and biological applications

Click chemistry was extensively used to decorate synthetic multivalent scaffolds with glycans to mimic the cell surface glycocalyx and to develop applications in glycosciences. Conjugation methods such as oxime ligation, copper(I)-catalyzed alkyne-azide cycloaddition, thiol-ene coupling, squaramide coupling or Lansbury aspartylation proved particularly suitable to achieve this purpose. This review summarizes the synthetic strategies that can be used either in a stepwise manner or in an orthogonal one-pot approach, to conjugate multiple copies of identical or different glycans to cyclopeptide scaffolds (namely multivalent glycocyclopeptides) having different size, valency, geometry and molecular composition. The second part of this review will describe the potential of these structures to interact with various carbohydrate binding proteins or to stimulate immunity against tumor cells.

Synthesis and Characterization of Dendronized Gold Nanoparticles Bearing Charged Peripheral Groups with Antimicrobial Potential

Dendronized gold nanoparticles (AuNPs) were synthesized bearing charged peripheral groups. Two novel AB3-type dendrons were synthesized with a thiol group at the focal point followed by their attachment to AuNPs. Dendrons were designed to have nine charged peripheral groups (carboxyl or amine), glycol solubilizing, units and one thiol moiety at the focal point. Both dendrons and all intermediates were synthesized in high yields and characterized by nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS). The amine- and carboxyl-terminated dendrons were used to functionalize gold nanoparticles (AuNPs) previously stabilized with citrate. The nanoparticles’ diameters and their colloidal stability were investigated using dynamic light scattering (DLS). The size and morphology of the dendronized AuNPs were evaluated by scanning electron microscopy (SEM), which revealed individual particles with no aggregation after replacement of citrate by the dendrons, in agreement with the DLS data. The absorption spectroscopy reveals a prominent plasmonic band at 560 nm for all AuNPs. The zeta potential further confirmed the expected charged structures of the dendronized AuNPs. Considering all the physical–chemical properties of the charged dendronized AuNPs developed in this work, these AuNPs might be used as a weapon against multi-drug resistant bacterial infections.

Advanced Polymeric Nanocomposites for Water Treatment Applications: A Holistic Perspective

Water pollution remains one of the greatest challenges in the modern era, and water treatment strategies have continually been improved to meet the increasing demand for safe water. In the last few decades, tremendous research has been carried out toward developing selective and efficient polymeric adsorbents and membranes. However, developing non-toxic, biocompatible, cost-effective, and efficient polymeric nanocomposites is still being explored. In polymer nanocomposites, nanofillers and/or nanoparticles are dispersed in polymeric matrices such as dendrimer, cellulose, resins, etc., to improve their mechanical, thermophysical, and physicochemical properties. Several techniques can be used to develop polymer nanocomposites, and the most prevalent methods include mixing, melt-mixing, in-situ polymerization, electrospinning, and selective laser sintering techniques. Emerging technologies for polymer nanocomposite development include selective laser sintering and microwave-assisted techniques, proffering solutions to aggregation challenges and other morphological defects. Available and emerging techniques aim to produce efficient, durable, and cost-effective polymer nanocomposites with uniform dispersion and minimal defects. Polymer nanocomposites are utilized as filtering membranes and adsorbents to remove chemical contaminants from aqueous media. This study covers the synthesis and usage of various polymeric nanocomposites in water treatment, as well as the major criteria that influence their performance, and highlights challenges and considerations for future research.

Nanodelivery of nucleic acids

There is growing need for a safe, efficient, specific and non-pathogenic means for delivery of gene therapy materials. Nanomaterials for nucleic acid delivery offer an unprecedented opportunity to overcome these drawbacks; owing to their tunability with diverse physico-chemical properties, they can readily be functionalized with any type of biomolecules/moieties for selective targeting. Nucleic acid therapeutics such as antisense DNA, mRNA, small interfering RNA (siRNA) or microRNA (miRNA) have been widely explored to modulate DNA or RNA expression Strikingly, gene therapies combined with nanoscale delivery systems have broadened the therapeutic and biomedical applications of these molecules, such as bioanalysis, gene silencing, protein replacement and vaccines. Here, we overview how to design smart nucleic acid delivery methods, which provide functionality and efficacy in the layout of molecular diagnostics and therapeutic systems. It is crucial to outline some of the general design considerations of nucleic acid delivery nanoparticles, their extraordinary properties and the structure-function relationships of these nanomaterials with biological systems and diseased cells and tissues.

New Acetamidine Cu(II) Schiff base complex supported on magnetic nanoparticles pectin for the synthesis of triazoles using click chemistry

In this project, the new catalyst copper defines as Fe₃O₄@Pectin@(CH₂)₃-Acetamide-Cu(II) was successfully manufactured and fully characterized by different techniques, including FT-IR, XRD, TEM, FESEM, EDX, VSM, TGA, and ICP analysis. All results showed that copper was successfully supported on the polymer‐coated magnetic nanoparticles. One of the most important properties of a catalyst is the ability to be prepared from simple materials such as pectin that’s a biopolymer that is widely found in nature. The catalytic activity of Fe₃O₄@Pectin@(CH₂)₃-Acetamide-Cu(II) was examined in a classical, one pot, and the three-component reaction of terminal alkynes, alkyl halides, and sodium azide in water and observed, proceeding smoothly and completed in good yields and high regioselectivity. The critical potential interests of the present method include high yields, recyclability of catalyst, easy workup, using an eco-friendly solvent, and the ability to sustain a variety of functional groups, which give economical as well as ecological rewards. The capability of the nanocomposite was compared with previous works, and the nanocomposite was found more efficient, economical, and reproducible. Also, the catalyst can be easily removed from the reaction solution using an external magnet and reused for five runs without reduction in catalyst activity.

Critical parameters for design and development of multivalent nanoconstructs: recent trends

A century ago, the groundbreaking concept of the magic bullet was given by Paul Ehrlich. Since then, this concept has been extensively explored in various forms to date. The concept of multivalency is among such advancements of the magic bullet concept. Biologically, the concept of multivalency plays a critical role in significantly huge numbers of biochemical interactions. This concept is the sole reason behind the higher affinity of biological molecules like viruses to more selectively target the host cell surface receptors. Multivalent nanoconstructs are a promising approach for drug delivery by the active targeting principle. Designing and developing effective and target-specific multivalent drug delivery nanoconstructs, on the other hand, remain a challenge. The underlying reason for this is a lack of understanding of the crucial interactions between ligands and cell surface receptors, as well as the design of nanoconstructs. This review highlights the need for a better theoretical understanding of the multivalent effect of what happens to the receptor-ligand complex after it has been established. Furthermore, the critical parameters for designing and developing robust multivalent systems have been emphasized. We have also discussed current advances in the design and development of multivalent nanoconstructs for drug delivery. We believe that a thorough knowledge of theoretical concepts and experimental methodologies may transform a brilliant idea into clinical translation.

Review of photoresponsive and glycoside dendrimers in biomaterials and sensors applications

Dendrimers are branched molecules with well-defined lengths, shapes, molecular weights, and monodispersity in comparison to linear polymers.

The advanced synthetic modifications and applications of multifunctional PAMAM dendritic composites

The profound advances in dendrimer chemistry have led to new horizons in polymer science.

Size-tunable fluorescent dendrimersomes via aggregation-induced emission

Tetraphenylethylene-functionalized amphiphilic Janus dendrimers of up to third generation are synthesized. Their self-assembly has been studied under kinetic and thermodynamic control. By varying the dendrimer generation number and the self-assembly condition, fluorescent dendrimersomes of tunable size (∼60-200 nm) and quantum yield (5.7-17.4%) are obtained in aqueous medium.

Dendrimers in vaccine delivery: Recent progress and advances

Dendrimers are well-defined, highly branched, multivalent and monodisperse molecules which host a range of attractive, yet functional, chemical and biological characteristics. A dendrimers accessible surface groups enable coupling to different functional moieties (e.g., antibodies, peptides, proteins, etc), which is further assisted by the dendrimers tailored size and surface charge. This adaptability allows for the preparation of molecularly precise vaccines with highly specific and predictable properties, and in conjunction with a dendrimers immune stimulating (adjuvanting) property, makes dendrimers attractive substrates for biomedical applications, including vaccines. This review highlights the structural and synthetic evolution of dendrimers throughout history, detailing the dendrimers role as both an adjuvant and carrier system for vaccine antigens, in addition to reviewing the development of commercially available vaccines for use in humans.

Modular amphiphilic poly(aryl ether)-based supramolecular nanomicelles: an efficient endocytic drug carrier

A rationally designed amphiphilic poly(aryl ether)-based dendrimer self-assembles into nanomicelles and exhibits tunable morphology upon varying the hydrophilic chain length. The 30 nm-sized dendrimer nanomicelles successfully entrapped Doxorubicin, demonstrated the sustained release of Doxorubicin and can successfully penetrate cancer cells through caveolae-dependent endocytosis, compared to the free drug.

Dendritic Hydrogels Induce Immune Modulation in Human Keratinocytes and Effectively Eradicate Bacterial Pathogens

Infections caused by antibiotic-resistant bacteria are globally a major threat, leading to high mortality rates and increased economic burden. Novel treatment strategies are therefore urgently needed by healthcare providers to protect people. Biomaterials that have inherent antibacterial properties and do not require the use of antibiotics present an attractive and feasible avenue to achieve this goal. Herein, we demonstrate the effect of a new class of cationic hydrogels based on amino-functional hyperbranched dendritic-linear-dendritic copolymers (HBDLDs) exhibiting excellent antimicrobial activity toward a wide range of clinical Gram-positive and Gram-negative bacteria, including drug-resistant strains isolated from wounds. Intriguingly, the hydrogels can induce the expression of the antimicrobial peptides RNase 7 and psoriasin, promoting host-mediated bacterial killing in human keratinocytes (HaCaT). Moreover, treatment with the hydrogels decreased the proinflammatory cytokine IL-1β, reactive nitrogen species (NO), and mitochondrial reactive oxygen species (ROS) in S. aureus-infected HaCaT cells, conjunctively resulting in reduced inflammation.

Nano-vehicles give new lease of life to existing antimicrobials

Antibiotic resistance has become one of the greatest challenges for modern medicine, and new approaches for the treatment of bacterial infections are urgently needed to avoid widespread vulnerability again to infections that have so far been easily treatable with existing drugs. Among the many approaches investigated to overcome this challenge is the use of engineered nanostructures for the precise and targeted delivery of existing antimicrobial agents in a fashion that will potentiate their effect. This idea leans on lessons learned from pioneering research in cancer, where the targeted delivery of anti-cancer drugs to mammalian cells has been a topic for some time. In particular, new research has demonstrated that nanomaterials can be functionalised with active antimicrobials and, in some cases, with targeting molecules that potentiate the efficiency of the antimicrobials. In this mini-review, we summarise results that demonstrate the potential for nanoparticles, dendrimers and DNA nanostructures for use in antimicrobial delivery. We consider material aspects of the delivery vehicles and ways in which they can be functionalised with antibiotics and antimicrobial peptides, and we review evidence for their efficacy to kill bacteria both in vitro and in vivo. We also discuss the advantages and limitations of these materials and highlight the benefits of DNA nanostructures specifically for their versatile potential in the present context.

Rationally Designed Galactose Dendrimer for Hepatocyte-Specific Targeting and Intracellular Drug Delivery for the Treatment of Liver Disorders

Over two million people die of liver disorders every year globally. Hepatocytes are the key cells affected in several acute and chronic liver diseases. The current clinical outcomes of liver-targeted nanoparticles are limited, necessitating the need to develop smart hepatocyte-targeted drug delivery systems. Here, we present the rational design and development of a hepatocyte-targeting glycodendrimer (GAL-24) built from biocompatible building blocks, using expedite and facile chemical methodology. GAL-24 is designed to inherently target asialoglycoprotein receptor 1 (ASGP-R) on hepatocytes and shows significant accumulation in the liver (20% of injected dose), just 1 h after systemic administration. This is highly specific to hepatocytes, with over 80% of hepatocytes showing GAL-24-Cy5 signal at 24 h. GAL-24-Cy5 maintains hepatocyte-targeting capabilities in both a mouse model of severe acetaminophen poisoning-induced hepatic necrosis and a rat model of nonalcoholic steatohepatitis (NASH). This GAL-24 nanoplatform holds great promise for improved drug delivery to hepatocytes to combat many liver disorders.

Electrochemical and Electrochemiluminescence Dendrimer-based Nanostructured Immunosensors for Tumor Marker Detection: A Review

The usage of dendrimers or cascade molecules in the biomedical area has recently attracted much attention worldwide. Furthermore, dendrimers are interesting in clinical and pre-clinical applications due to their unique characteristics. Cancer is one of the most widespread challenges and important diseases, which has the highest mortality rate. In this review, the recent advances and developments (from 2009 up to 2019) in the field of electrochemical and electroluminescence immunosensors for detection of the cancer markers are presented. Moreover, this review covers the basic fabrication principles and types of electrochemical and electrochemiluminescence dendrimer-based immunosensors. In this review, we have categorized the current dendrimer based-electrochemical/ electroluminescence immunosensors into five groups: dendrimer/ magnetic particles, dendrimer/ferrocene, dendrimer/metal nanoparticles, thiol-containing dendrimer, and dendrimer/quantum dots based-immunosensors.

First-in-Class Phosphorus Dendritic Framework, a Wide Surface Functional Group Palette Bringing Noteworthy Anti-Cancer and Anti-Tuberculosis Activities: What Lessons to Learn?

Based on phenotypic screening, the major advantages of phosphorus dendrimers and dendrons as drugs allowed the discovery of new therapeutic applications, for instance, as anti-cancer and anti-tuberculosis agents. These biological activities depend on the nature of the chemical groups (neutral or cationic) on their surface as well as their generation. As lessons to learn, in the oncology domain, the increase in the generation of metallo-dendrimers is in the same direction as the anti-proliferative activities, in contrast to the development of polycationic dendrimers, where the most potent anti-tuberculosis phosphorus dendrimer was observed to have the lowest generation (G0). The examples presented in this original analysis of phosphorus dendrimers and dendrons provide support for the lessons learned and for the development of new nanoparticles in nanomedicine.

Developments in Treatment Methodologies Using Dendrimers for Infectious Diseases

Dendrimers comprise a specific group of macromolecules, which combine structural properties of both single molecules and long expanded polymers. The three-dimensional form of dendrimers and the extensive possibilities for use of additional substrates for their construction creates a multivalent potential and a wide possibility for medical, diagnostic and environmental purposes. Depending on their composition and structure, dendrimers have been of interest in many fields of science, ranging from chemistry, biotechnology to biochemical applications. These compounds have found wide application from the production of catalysts for their use as antibacterial, antifungal and antiviral agents. Of particular interest are peptide dendrimers as a medium for transport of therapeutic substances: synthetic vaccines against parasites, bacteria and viruses, contrast agents used in MRI, antibodies and genetic material. This review focuses on the description of the current classes of dendrimers, the methodology for their synthesis and briefly drawbacks of their properties and their use as potential therapies against infectious diseases.

Dendrimer Architectonics to Treat Cancer and Neurodegenerative Diseases with Implications in Theranostics and Personalized Medicine

Integration of diagnostic and therapeutic functions in a single platform namely theranostics has become a cornerstone for personalized medicine. Theranostics platform facilitates noninvasive detection and treatment while allowing the monitoring of disease progression and therapeutic efficacy in case of chronic conditions of cancer and Alzheimer's disease (AD). Theranostic tools function by themselves or with the aid of carrier, viz. liposomes, micelles, polymers, or dendrimers. The dendrimer architectures (DA) are well-characterized molecular nanoobjects with a large number of terminal functional groups to enhance solubility and offer multivalency and multifunctional properties. Various noninvasive diagnostic tools like magnetic resonance imaging (MRI), computed tomography (CT), gamma scintigraphy, and optical techniques have been accomplished utilizing DAs for simultaneous imaging and drug delivery. Obstacles in the formulation design, drug loading, payload delivery, biocompatibility, overcoming cellular membrane and blood-brain barrier (BBB), and systemic circulation remain a bottleneck in translational efforts. This review focuses on the diagnostic, therapeutic and theranostic potential of DA-based nanocarriers in treating cancer and neurodegenerative disorders like AD and Parkinson's disease (PD), among others. In view of the inverse relationship between cancer and AD, designing suitable DA-based theranostic nanodrug with high selectivity has tremendous implications in personalized medicine to treat cancer and neurodegenerative disorders.

Supramolecular dendrimer-containing layer-by-layer nanoassemblies for bioapplications: current status and future prospects

This review provides a comprehensive and critical overview of the supramolecular dendrimer-containing multifunctional layer-by-layer nanoassemblies driven by a multitude of intermolecular interactions for biological and biomedical applications.

Solution size variation of linear and dendritic bis-MPA analogs using DOSY-1H NMR

The size and size variability of bis-MPA dendrimers is shown to be smaller by DOSY-¹H NMR than their linear analog, PBBM. This was accomplished using five different solvents and for the first time confirms, experimentally, what has been theorized.

Slightly congested amino terminal dendrimers. The synthesis of amide-based stable structures on a large scale

Preparation of a new family of stable and aqueous soluble high-generation aliphatic polyamide amino terminal dendrimers. Promising scaffolds for applications where the combination of stability, multivalence and efficient conjugation is required.

Defects and defect engineering in Soft Matter

Soft matter covers a wide range of materials based on linear or branched polymers, gels and rubbers, amphiphilic (macro)molecules, colloids, and self-assembled structures. These materials have applications in various industries, all highly important for our daily life, and they control all biological functions; therefore, controlling and tailoring their properties is crucial. One way to approach this target is defect engineering, which aims to control defects in the material's structure, and/or to purposely add defects into it to trigger specific functions. While this approach has been a striking success story in crystalline inorganic hard matter, both for mechanical and electronic properties, and has also been applied to organic hard materials, defect engineering is rarely used in soft matter design. In this review, we present a survey on investigations on defects and/or defect engineering in nine classes of soft matter composed of liquid crystals, colloids, linear polymers with moderate degree of branching, hyperbranched polymers and dendrimers, conjugated polymers, polymeric networks, self-assembled amphiphiles and proteins, block copolymers and supramolecular polymers. This overview proposes a promising role of this approach for tuning the properties of soft matter.

Self-Assembling Supramolecular Dendrimers for Biomedical Applications: Lessons Learned from Poly(amidoamine) Dendrimers

Dendrimers, notable for their well-defined radial structures with numerous terminal functionalities, hold great promise for biomedical applications such as drug delivery, diagnostics, and therapeutics. However, their translation into clinical use has been greatly impeded by their challenging stepwise synthesis and difficult purification.To circumvent these obstacles, we have pioneered a self-assembly approach to constructing noncovalent supramolecular dendrimers using small amphiphilic dendrimer building units which can be easily synthesized and purified. By virtue of their amphipathic nature, the small amphiphilic dendrimers are able to self-assemble and generate large supramolecular dendrimers via noncovalent weak interactions such as van der Waals forces, H bonds, and electrostatic interactions. The so-created noncovalent dendrimers can mimic covalent dendrimers not only in terms of the radial structural feature emanating from a central core but also in their capacity to deliver drugs and imaging agents for biomedical applications. The noncovalent supramolecular dendrimers can be easily synthesized and modulated with regard to size, shape, and properties by varying the nature of the hydrophobic and hydrophilic entities as well as the dendrimer generation and terminal functionalities, ensuring their adaptability to specific applications. In particular, the dendritic structure of the amphiphilic building units permits the creation of large void spaces within the formed supramolecular dendrimers for the physical encapsulation of drugs, while the large number of surface functionalities can be exploited for both physical and chemical conjugation of pharmaceutic agents for drug delivery.Poly(amidoamine) (PAMAM) dendrimers are the most intensively studied for biomedical applications by virtue of their excellent biocompatibility imparted by their peptide-mimicking amide backbones and numerous interior and terminal amine functionalities. We present a short overview of our self-assembly strategy for constructing supramolecular PAMAM dendrimers for biomedical applications. Specifically, we start with the introduction of dendrimers and their synthesis, focusing on the innovative self-assembly synthesis of supramolecular dendrimers. We then detail the representative examples of the noncovalent supramolecular PAMAM dendrimers established in our group for the delivery of anticancer drugs, nucleic acid therapeutics, and imaging agents, either within the dendrimer interior or at the dendrimer terminals on the surface. Some of the supramolecular dendrimer nanosystems exhibit outstanding performance, excelling the corresponding clinical anticancer therapeutics and imaging agents. This self-assembly approach to creating supramolecular dendrimers is completely novel in concept yet easy to implement in practice, offering a fresh perspective for exploiting the advantageous features of dendrimers in biomedical applications.

Sulfonimide-Based Dendrimers: Progress in Synthesis, Characterization, and Potential Applications

There are more than 50 families of dendrimers, and some of which, such as polyamidoamine PAMAM, are well studied, and some are just starting to attract the attention of researchers. One promising type of dendrimers is sulfonimide-based dendrimers (SBDs). To date, SBDs are used in organic synthesis as starting reagents for the convergent synthesis of higher generations dendrimers, in materials science as alternative electrolyte solutions for fuel cells, and in medicinal chemistry as potential substances for drug transfer procedures. Despite the fact that most dendrimers are amorphous substances among the SBDs, several structures are distinguished that are prone to the formation of crystalline solids with melting points in the range of 120-250 °C. Similar to those of other dendrimers, the chemical and physical properties of SBDs depend on their outer shell, which is formed by functional groups. To date, SBDs decorated with end groups such as naphthyl, nitro, methyl, and methoxy have been successfully synthesized, and each of these groups gives the dendrimers specific properties. Analysis of the structure of SBD, their synthesis methods, and applications currently available in the literature reveals that these dendrimers have not yet been fully explored.

Self-Assembled Polyester Dendrimer/Cellulose Nanofibril Hydrogels with Extraordinary Antibacterial Activity

Cationic dendrimers are intriguing materials that can be used as antibacterial materials; however, they display significant cytotoxicity towards diverse cell lines at high generations or high doses, which limits their applications in biomedical fields. In order to decrease the cytotoxicity, a series of biocompatible hybrid hydrogels based on cationic dendrimers and carboxylated cellulose nanofibrils were easily synthesized by non-covalent self-assembly under physiological conditions without external stimuli. The cationic dendrimers from generation 2 (G2) to generation 4 (G4) based on trimethylolpronane (TMP) and 2,2-bis (methylol)propionic acid (bis-MPA) were synthesized through fluoride promoted esterification chemistry (FPE chemistry). FTIR was used to show the presence of the cationic dendrimers within the hybrid hydrogels, and the distribution of the cationic dendrimers was even verified using elemental analysis of nitrogen content. The hybrid hydrogels formed from G3 and G4 showed 100% killing efficiency towards Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) with bacterial concentrations ranging from 10⁵ CFU/mL to 10⁷ CFU/mL. Remarkably, the hybrid hydrogels also showed good biocompatibility most probably due to the incorporation of the biocompatible CNFs that slowed down the release of the cationic dendrimers from the hybrid hydrogels, hence showing great promise as an antibacterial material for biomedical applications.

Recent advances in development of dendritic polymer-based nanomedicines for cancer diagnosis

Dendritic polymers have highly branched three-dimensional architectures, the fourth type apart from linear, cross-linked, and branched one. They possess not only a large number of terminal functional units and interior cavities, but also a low viscosity with weak or no entanglement. These features endow them with great potential in various biomedicine applications, including drug delivery, gene therapy, tissue engineering, immunoassay and bioimaging. Most review articles related to bio-related applications of dendritic polymers focus on their drug or gene delivery, while very few of them are devoted to their function as cancer diagnosis agents, which are essential for cancer treatment. In this review, we will provide comprehensive insights into various dendritic polymer-based cancer diagnosis agents. Their classification and preparation are presented for readers to have a precise understanding of dendritic polymers. On account of physical/chemical properties of dendritic polymers and biological properties of cancer, we will suggest a few design strategies for constructing dendritic polymer-based diagnosis agents, such as active or passive targeting strategies, imaging reporters-incorporating strategies, and/or internal stimuli-responsive degradable/enhanced imaging strategies. Their recent applications in in vitro diagnosis of cancer cells or exosomes and in vivo diagnosis of primary and metastasis tumor sites with the aid of single/multiple imaging modalities will be discussed in great detail. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > in vivo Nanodiagnostics and Imaging Diagnostic Tools > in vitro Nanoparticle-Based Sensing.

Guijarro L, García-Honduvilla N, Álvarez-Mon M, Buján J, García-Gallego S. Dendrimers and Dendritic Materials: From Laboratory to Medical Practice in Infectious Diseases

Infectious diseases are one of the main global public health risks, predominantly caused by viruses, bacteria, fungi, and parasites. The control of infections is founded on three main pillars: prevention, treatment, and diagnosis. However, the appearance of microbial resistance has challenged traditional strategies and demands new approaches. Dendrimers are a type of polymeric nanoparticles whose nanometric size, multivalency, biocompatibility, and structural perfection offer boundless possibilities in multiple biomedical applications. This review provides the reader a general overview about the uses of dendrimers and dendritic materials in the treatment, prevention, and diagnosis of highly prevalent infectious diseases, and their advantages compared to traditional approaches. Examples of dendrimers as antimicrobial agents per se, as nanocarriers of antimicrobial drugs, as well as their uses in gene transfection, in vaccines or as contrast agents in imaging assays are presented. Despite the need to address some challenges in order to be used in the clinic, dendritic materials appear as an innovative tool with a brilliant future ahead in the clinical management of infectious diseases and many other health issues.