Toxicity And Surface Modification Of Dendrimers: A Critical Review

Nanocarrier-based targeted drug delivery for Alzheimer's disease: addressing neuroinflammation and enhancing clinical translation

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, amyloid-beta (Aβ) aggregation, tau pathology, and chronic neuroinflammation. Among these, neuroinflammation plays a crucial role in exacerbating disease progression, making it an attractive therapeutic target. However, the presence of the blood-brain barrier (BBB) significantly limits the effective delivery of therapeutic agents to the brain, necessitating novel drug delivery strategies. Nanocarrier-based delivery systems have emerged as a promising solution to these challenges, offering targeted drug transport, enhanced BBB penetration, and improved bioavailability while minimizing systemic toxicity. This review explores the current advancements in nanocarrier-mediated drug delivery for AD, focusing on the mechanisms of neuroinflammation, the role of nanocarriers in overcoming the BBB, and their ability to modulate inflammatory pathways. Furthermore, the review discusses preclinical validation strategies and key challenges, including safety concerns, large-scale production limitations, and regulatory hurdles that must be addressed to enable clinical translation. Future perspectives emphasize the integration of nanotechnology with precision medicine, gene therapy, and artificial intelligence to optimize nanocarrier design for individualized AD treatment. By overcoming these obstacles, nanocarriers hold the potential to revolutionize therapeutic approaches for AD and other neurodegenerative diseases.

Deuterated Nanopolymers for Renal and Lymphatic Imaging via Quantitative Deuterium MRI

Deuterium (2H) MRI is an emerging tool for noninvasive imaging. We explore the integration of 2H MRI with deuterated multifunctional nanopolymers for deuterated particle imaging (DPI). To this end, amine-terminated G5-polyamidoamine (PAMAM) dendrimers were labeled with deuterated acetyl surface groups, leading to highly 2H-loaded bioparticles, making them ideal for imaging studies. The accumulation of ∼5 nm PAMAM dendrimers in the kidneys could then be seen by 2H MRI with high submillimeter resolution. The natural abundance HDO signal provided an internal concentration reference to these measurements, leading to quantitative dynamic maps showing distinct nanopolymer uptakes within the renal compartments. Further, these nanopolymers allowed us to obtain in vivo maps of activity in the lymph nodes in an inflammatory rodent leg model, demonstrating these deuterated nanopolymers' potential as a novel class of contrast agents for the quantitative mapping of physiological processes.

Ferritin-Based Supramolecular Assembly Drug Delivery System for Aminated Fullerene Derivatives to Enhance Tumor-Targeted Therapy

Owing to their attractive antitumor effects, aminated fullerene derivatives are emerging as promising therapeutic drugs for cancer. However, their in vivo applications are severely limited due to cation toxicity. To address this problem, human heavy chain ferritin (HFn), possessing natural biocompatibility is utilized, to develop a novel supramolecular assembly drug delivery system. Specifically, tetra[4-(amino)piperidin-1-yl]-C60 (TAPC) is selected as the representative aminated fullerene, and a layer-by-layer assembly strategy is designed to controllably assemble TAPC with the negatively charged HFn into a hierarchical coassembly (H@T@H) via electrostatic interactions and hydrogen bonds. In this ordered multilayer structure, the surface displayed HFn endows the inner TAPC with biocompatibility, tumor-targeting and blood-brain barrier crossing ability. Additionally, the electrostatic assembly mode enables the acid-responsive disassembly of H@T@H to release TAPC in lysosomes. In the orthotopic glioma mouse model, the HFn-assembled TAPC (H@T@H) shows higher brain accumulation and a stronger inhibitory effect on glioma than polyethylene glycol (PEG)-coated TAPC. Moreover, in an experimental metastasis mouse model, H@T@H have significant preventive and therapeutic effects on tumor metastasis. Encouragingly, the ferritin-based supramolecular assembly strategy has been proven to have broad applicability for various aminated fullerene derivatives, showing promising potential for tackling the in vivo delivery challenges of cationic drugs.

PAMAM-Calix-Dendrimers: Third Generation Synthesis and Impact of Generation and Macrocyclic Core Conformation on Hemotoxicity and Calf Thymus DNA Binding

Background/Objectives: Current promising treatments for many diseases are based on the use of therapeutic nucleic acids, including DNA. However, the list of nanocarriers is limited due to their low biocompatibility, high cost, and toxicity. The design of synthetic building blocks for creating universal delivery systems for genetic material is an unsolved problem. In this work, we propose PAMAM dendrimers with rigid thiacalixarene core in various conformations, i.e., PAMAM-calix-dendrimers, as a platform for a supramolecular universal constructor for nanomedicine. Results: Third generation PAMAM dendrimers with a macrocyclic core in three conformations (cone, partial cone, and 1,3-alternate) were synthesized for the first time. The obtained dendrimers were capable of binding and compacting calf thymus DNA, whereby the binding efficiency improved with increasing generation, while the influence of the macrocyclic core was reduced. A dramatic effect of the macrocyclic core conformation on the hemolytic activity of PAMAM-calix-dendrimers was observed. Specifically, a notable reduction in hemotoxicity was associated with a decrease in compound amphiphilicity. Conclusions: We hope the results will help reduce financial and labor costs in developing new drug delivery systems based on dendrimers.

Injectable polyamide-amine dendrimer-crosslinked meloxicam-containing poly-γ-glutamic acid hydrogel for prevention of postoperative tissue adhesion through inhibiting inflammatory responses and balancing the fibrinolytic system

Establishing a physical barrier between the peritoneum and the cecum is an effective method to reduce the risk of postoperative abdominal adhesions. Meloxicam (MX), a nonsteroidal anti-inflammatory drug has also been applied to prevent postoperative adhesions. However, its poor water solubility has led to low bioavailability. Herein, we developed an injectable hydrogel as a barrier and drug carrier for simultaneous postoperative adhesion prevention and treatment. A third-generation polyamide-amine dendrimer (G3) was exploited to dynamically combine with MX to increase the solubility and the bioavailability. The formed G3@MX was further used to crosslink with poly-γ-glutamic acid (γ-PGA) to prepare a hydrogel (GP@MX hydrogel) through the amide bonding. In vitro and in vivo experiments evidenced that the hydrogel had good biosafety and biodegradability. More importantly, the prepared hydrogel could control the release of MX, and the released MX is able to inhibit inflammatory responses and balance the fibrinolytic system in the injury tissues in vivo. The tunable rheological and mechanical properties (compressive moduli: from ∼ 57.31 kPa to ∼ 98.68 kPa;) and high anti-oxidant capacity (total free radical scavenging rate of ∼ 94.56 %), in conjunction with their syringeability and biocompatibility, indicate possible opportunities for the development of advanced hydrogels for postoperative tissue adhesions management.

Research Progress of Drug Delivery Systems Targeting the Kidneys

Chronic kidney disease (CKD) affects more than 10% of the global population, and its incidence is increasing, partially due to an increase in the prevalence of disease risk factors. Acute kidney injury (AKI) is an independent risk factor for CKD and end-stage renal disease (ESRD). The pathogenic mechanisms of CKD provide several potential targets for its treatment. However, due to off-target effects, conventional drugs for CKD typically require high doses to achieve adequate therapeutic effects, leading to long-term organ toxicity. Therefore, ideal treatments that completely cure the different types of kidney disease are rarely available. Several approaches for the drug targeting of the kidneys have been explored in drug delivery system research. Nanotechnology-based drug delivery systems have multiple merits, including good biocompatibility, suitable degradability, the ability to target lesion sites, and fewer non-specific systemic effects. In this review, the development, potential, and limitations of low-molecular-weight protein-lysozymes, polymer nanomaterials, and lipid-based nanocarriers as drug delivery platforms for treating AKI and CKD are summarized.

Navigating the landscape of RNA delivery systems in cardiovascular disease therapeutics

Cardiovascular diseases (CVDs) stand as the leading cause of death worldwide, posing a significant global health challenge. Consequently, the development of innovative therapeutic strategies to enhance CVDs treatment is imperative. RNA-based therapies, encompassing non-coding RNAs, mRNA, aptamers, and CRISPR/Cas9 technology, have emerged as promising tools for addressing CVDs. However, inherent challenges associated with RNA, such as poor cellular uptake, susceptibility to RNase degradation, and capture by the reticuloendothelial system, underscore the necessity of combining these therapies with effective drug delivery systems. Various non-viral delivery systems, including extracellular vesicles, lipid-based carriers, polymeric and inorganic nanoparticles, as well as hydrogels, have shown promise in enhancing the efficacy of RNA therapeutics. In this review, we offer an overview of the most relevant RNA-based therapeutic strategies explored for addressing CVDs and emphasize the pivotal role of delivery systems in augmenting their effectiveness. Additionally, we discuss the current status of these therapies and the challenges that hinder their clinical translation.

In Vivo Applications of Dendrimers: A Step toward the Future of Nanoparticle-Mediated Therapeutics

Over the last few years, the development of nanotechnology has allowed for the synthesis of many different nanostructures with controlled sizes, shapes, and chemical properties, with dendrimers being the best-characterized of them. In this review, we present a succinct view of the structure and the synthetic procedures used for dendrimer synthesis, as well as the cellular uptake mechanisms used by these nanoparticles to gain access to the cell. In addition, the manuscript reviews the reported in vivo applications of dendrimers as drug carriers for drugs used in the treatment of cancer, neurodegenerative diseases, infections, and ocular diseases. The dendrimer-based formulations that have reached different phases of clinical trials, including safety and pharmacokinetic studies, or as delivery agents for therapeutic compounds are also presented. The continuous development of nanotechnology which makes it possible to produce increasingly sophisticated and complex dendrimers indicates that this fascinating family of nanoparticles has a wide potential in the pharmaceutical industry, especially for applications in drug delivery systems, and that the number of dendrimer-based compounds entering clinical trials will markedly increase during the coming years.

Influence of the linkage between long alkyl tails and cationic groups on membrane activity of nano-sized hyperbranched polyquaterniums

The recurrent emergence of serious pathogens necessitates novel insights and highly efficient antibacterial agents. However, the innate inability of metal ions and reactive oxygen species (ROS) to differentiate between bacteria and mammalian cells presents a challenge, limiting the selectivity crucial for an ideal antimicrobial solution. Herein, we present a systematic exploration involving two variants of nano-sized hyperbranched polyquaterniums (NHBPQs) - one featuring a lengthy alkyl tail linked to the ammonium unit at the N-atom center (NHBPQ-A), and the other in a segregated configuration (NHBPQ-B). The exterior alkyl chain chains act as a barrier to the cationic group's non-specific adsorption due to spatial site resistance, causing NHBPQ-A in broad-spectrum cytotoxicity. Conversely, the distinct molecular configuration of NHBPQ-B in the segregated state affords greater flexibility, allowing the cationic groups to be released and interact non-specifically, finally resulting in selective bactericidal activity. Leveraging this selectivity, the optimized NHBPQ-B exhibits robust anti-infectious performance in a model of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds. This work establishes a promising avenue for biocompatible NHBPQs, holding significant potential in addressing MRSA infections and ameliorating both genetically encoded and phenotypic antibiotic resistance mechanisms.

Delivery of nucleic acids using nanomaterials

The increasing number of approved nucleic acid therapeutics demonstrates the potential for the prevention and treatment of a broad spectrum of diseases. This trend underscores the significant impact and promise of nucleic acid-based treatments in the field of medicine. Nevertheless, employing nucleic acids as therapeutics is challenging due to their susceptibility to degradation by nucleases and their unfavorable physicochemical characteristics that hinder delivery into cells. Appropriate vectors play a pivotal role in improving nucleic acid stability and delivering nucleic acids into specific cells. The maturation of delivery systems has led to breakthroughs in the development of therapeutics based on nucleic acids such as DNA, siRNA, and mRNA. Non-viral vectors have gained prominence among the myriad of nanomaterials due to low immunogenicity, ease of manufacturing, and simplicity of cost-effective, large-scale production. Here, we provide an overview of the recent advancements in nanomaterials for nucleic acid delivery. Specifically, we give a detailed introduction to the characteristics of polymers, lipids, and polymer-lipid hybrids, and provide comprehensive descriptions of their applications in nucleic acid delivery. Also, biological barriers, administration routes, and strategies for organ-selective delivery of nucleic acids are discussed. In summary, this review offers insights into the rational design of next-generation delivery vectors for nucleic acid delivery.

Methotrexate and Sulforaphane loaded PBA-G5-PAMAM dendrimers as a combination therapy for anti-inflammatory response in an intra-articular joint arthritic animal model

L-sulforaphane (LSF), a natural product developed from cruciferous vegetables, have shown potent anti-inflammatory effect in cancer as well as arthritis. However, the stable delivery of LSF remains a major challenge. Methotrexate (MTX) is currently the first line treatment for managing RA and is most effective in patients when used in combination with other anti-inflammatory or anti-rheumatic drugs. Here we developed phenylboronic acid-PAMAM dendrimer (PBA-G5D) nanoparticles conjugated MTX (MTX-PBA-G5D), and L-sulforaphane (LSF/PBA-G5D) loaded dendrimers. The MTX and LSF drug loading and release kinetics was analyzed using HPLC. The lipopolysaccharide (LPS) stimulated macrophages were treated with the formulations to study the inflammatory response in vitro. For in vivo studies, arthritis was induced in five-week-old female Wistar rats, and the MTX- and LSF/PBA-G5-D were injected via intra-articular injection for treatment and the arthritis reduction was scored by weight, knee diameter, and serum cytokine level measurement. The average size of the drug-nanoparticle conjugates ranged from 135-250 nm, with mostly cationic surface charges. The encapsulation efficiency of the drugs to the modified dendrimer was more than 60% with a slow release of drugs from the nanoparticles within 24 h at pH 7.4. Drugs in the nanoparticle formulation were biocompatible, with promising anti-inflammatory effects in vitro against LPS-activated murine macrophages. Further in vivo studies on arthritis induced female Wistar rats, revealed significant anti-arthritic effects based on the arthritic scoring from the knee diameter reading, and anti-inflammatory effects based on the serum cytokine levels. This study provides a promising strategy for utilizing PAMAM dendrimers as a nanocarrier for LSF delivery for RA therapy.

Safety Challenges and Application Strategies for the Use of Dendrimers in Medicine

Dendrimers are used for a variety of applications in medicine but, due to their host–guest and entrapment characteristics, are particularly used for the delivery of genes and drugs. However, dendrimers are intrinsically toxic, thus creating a major limitation for their use in biological systems. To reduce such toxicity, biocompatible dendrimers have been designed and synthesized, and surface engineering has been used to create advantageous changes at the periphery of dendrimers. Although dendrimers have been reviewed previously in the literature, there has yet to be a systematic and comprehensive review of the harmful effects of dendrimers. In this review, we describe the routes of dendrimer exposure and their distribution in vivo. Then, we discuss the toxicity of dendrimers at the organ, cellular, and sub-cellular levels. In this review, we also describe how technology can be used to reduce dendrimer toxicity, by changing their size and surface functionalization, how dendrimers can be combined with other materials to generate a composite formulation, and how dendrimers can be used for the diagnosis of disease. Finally, we discuss future challenges, developments, and research directions in developing biocompatible and safe dendrimers for medical purposes.

A siRNA targets and inhibits a broad range of SARS-CoV-2 infections including Delta variant

The emergence of severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) variants has altered the trajectory of the COVID‐19 pandemic and raised some uncertainty on the long‐term efficiency of vaccine strategy. The development of new therapeutics against a wide range of SARS‐CoV‐2 variants is imperative. We, here, have designed an inhalable siRNA, C6G25S, which covers 99.8% of current SARS‐CoV‐2 variants and is capable of inhibiting dominant strains, including Alpha, Delta, Gamma, and Epsilon, at picomolar ranges of IC₅₀in vitro. Moreover, C6G25S could completely inhibit the production of infectious virions in lungs by prophylactic treatment, and decrease 96.2% of virions by cotreatment in K18‐hACE2‐transgenic mice, accompanied by a significant prevention of virus‐associated extensive pulmonary alveolar damage, vascular thrombi, and immune cell infiltrations. Our data suggest that C6G25S provides an alternative and effective approach to combating the COVID‐19 pandemic.