Amphiphilic Polyphenylene Dendron Conjugates for Surface Remodeling of Adenovirus 5

The application advances of dendrimers in biomedical field

Dendrimers are a family of nano‐sized three‐dimensional polymers with unique dendritic branching structures and compact spherical geometries. In recent years, dendrimers have made a series of breakthroughs in the biomedical field. In this review, we introduce the synthesis principles, modification methods, and new materials designed based on dendrimers; discuss the importance of cytotoxicity of dendrimers for applications; and elaborate on their applications in the field of molecular assembly and cancer diagnosis and treatment. We speculate that in the near future, more new materials based on dendrimers will be applied in the biomedical field.

Lung-Targeted Transgene Expression of Nanocomplexed Ad5 Enhances Immune Response in the Presence of Preexisting Immunity

Recombinant adenovirus serotype 5 (Ad5) vector has been widely applied in vaccine development targeting infectious diseases, such as Ebola virus disease and coronavirus disease 2019 (COVID-19). However, the high prevalence of preexisting anti-vector immunity compromises the immunogenicity of Ad5-based vaccines. Thus, there is a substantial unmet need to minimize preexisting immunity while improving the insert-induced immunity of Ad5 vectors. Herein, we address this need by utilizing biocompatible nanoparticles to modulate Ad5-host interactions. We show that positively charged human serum albumin nanoparticles ((+)HSAnp), which are capable of forming a complex with Ad5, significantly increase the transgene expression of Ad5 in both coxsackievirus-adenovirus receptor-positive and -negative cells. Furthermore, in charge- and dose-dependent manners, Ad5/(+)HSAnp complexes achieve robust (up to 227-fold higher) and long-term (up to 60 days) transgene expression in the lungs of mice following intranasal instillation. Importantly, in the presence of preexisting anti-Ad5 immunity, complexed Ad5-based Ebola and COVID-19 vaccines significantly enhance antigen-specific humoral response and mucosal immunity. These findings suggest that viral aggregation and charge modification could be leveraged to engineer enhanced viral vectors for vaccines and gene therapies.

Nanographenes and Graphene Nanoribbons as Multitalents of Present and Future Materials Science

As cut-outs from a graphene sheet, nanographenes (NGs) and graphene nanoribbons (GNRs) are ideal cases with which to connect the world of molecules with that of bulk carbon materials. While various top-down approaches have been developed to produce such nanostructures in high yields, in the present perspective, precision structural control is emphasized for the length, width, and edge structures of NGs and GNRs achieved by modern solution and on-surface syntheses. Their structural possibilities have been further extended from "flatland" to the three-dimensional world, where chirality and handedness are the jewels in the crown. In addition to properties exhibited at the molecular level, self-assembly and thin-film structures cannot be neglected, which emphasizes the importance of processing techniques. With the rich toolkit of chemistry in hand, NGs and GNRs can be endowed with versatile properties and functions ranging from stimulated emission to spintronics and from bioimaging to energy storage, thus demonstrating their multitalents in present and future materials science.

Photostable polymorphic organic cages for targeted live cell imaging

Fluorescent microscopy is a powerful tool for studying the cellular dynamics of biological systems. Small-molecule organic fluorophores are the most commonly used for live cell imaging; however, they often suffer from low solubility, limited photostability and variable targetability. Herein, we demonstrate that a tautomeric organic cage, OC1, has high cell permeability, photostability and selectivity towards the mitochondria. We further performed a structure–activity study to investigate the role of the keto–enol tautomerization, which affords strong and consistent fluorescence in dilute solutions through supramolecular self-assembly. Significantly, OC1 can passively diffuse through the cell membrane directly targeting the mitochondria without going through the endosomes or the lysosomes. We envisage that designing highly stable and biocompatible self-assembled fluorophores that can passively diffuse through the cell membrane while selectively targeting specific organelles will push the boundaries of fluorescent microscopy to visualize intricate cellular processes at the single molecule level in live samples.

In this article, we demonstrate the relatively unexplored potential of organic cages for use in targeted live cell imaging and highlight the importance of inter- and intramolecular interactions to stabilize and improve the performance of fluorophores.

Polymeric Systems for Cancer Immunotherapy: A Review

Immunotherapy holds enormous promise to create a new outlook of cancer therapy by eliminating tumors via activation of the immune system. In immunotherapy, polymeric systems play a significant role in improving antitumor efficacy and safety profile. Polymeric systems possess many favorable properties, including magnificent biocompatibility and biodegradability, structural and component diversity, easy and controllable fabrication, and high loading capacity for immune-related substances. These properties allow polymeric systems to perform multiple functions in immunotherapy, such as immune stimulants, modifying and activating T cells, delivery system for immune cargos, or as an artificial antigen-presenting cell. Among diverse immunotherapies, immune checkpoint inhibitors, chimeric antigen receptor (CAR) T cell, and oncolytic virus recently have been dramatically investigated for their remarkable success in clinical trials. In this report, we review the monotherapy status of immune checkpoint inhibitors, CAR-T cell, and oncolytic virus, and their current combination strategies with diverse polymeric systems.

Synthesis of Giant Dendritic Polyphenylenes with 366 and 546 Carbon Atoms and their High-vacuum Electrospray Deposition

Dendritic polyphenylenes (PPs) can serve as precursors of nanographenes (NGs) if their structures represent 2D projections without overlapping benzene rings. Here, we report the synthesis of two giant dendritic PPs fulfilling this criteria with 366 and 546 carbon atoms by applying a “layer‐by‐layer” extension strategy. Although our initial attempts on their cyclodehydrogenation toward the corresponding NGs in solution were unsuccessful, we achieved their deposition on metal substrates under ultrahigh vacuum through the electrospray technique. Scanning probe microscopy imaging provides valuable information on the possible thermally induced partial planarization of such giant dendritic PPs on a metal surface.

Reversing Aβ Fibrillation and Inhibiting Aβ Primary Neuronal Cell Toxicity Using Amphiphilic Polyphenylene Dendrons

Uncontrolled amyloid-beta (Aβ) fibrillation leads to the deposition of neurotoxic amyloid plaques and is associated with Alzheimer's disease. Inhibiting Aβ monomer fibrillation and dissociation of the formed fibers is regarded as a promising therapeutic strategy. Here, amphiphilic polyphenylene dendrons (APDs) are demonstrated to interrupt Aβ assembly and reduce Aβ-cell interactions. Containing alternating negatively charged sulfonic acid and hydrophobic n-propyl peripheral groups, APDs bind to the secondary structure of the Aβ aggregates, inhibiting fibrillation and disassemble the already formed Aβ fibrils. APDs reveal vesicular cellular uptake in endosomes as well as cell compatibility for endothelial and neuronal cells, and significantly reduce Aβ-induced neuron cytotoxicity in vitro. Moreover, they are transported into the brain and successfully cross the blood-brain barrier after systemic application in mice, indicating their high potential to inhibit Aβ fibrillation in vivo, which can be beneficial for developing therapeutic strategy for Alzheimer's disease.

Engineering surface patterns on nanoparticles: New insights on nano-bio interactions

The surface properties of nanoparticles affect their fates in biological systems. Based on nanotechnology and methodology, pioneering works have explored the effects of chemical surface patterns on the behavior of...

Blood Compatibility of Amphiphilic Phosphorous Dendrons-Prospective Drug Nanocarriers

Dendrons are branched synthetic polymers suitable for preparation of nanosized drug delivery systems. Their interactions with biological systems are mainly predetermined by their chemical structure, terminal groups, surface charge, and the number of branched layers (generation). Any new compound intended to be used, alone or in combination, for medical purposes in humans must be compatible with blood. This study combined results from in vitro experiments on human blood and from laboratory experiments designed to assess the effect of amphiphilic phosphorous dendrons on blood components and model membranes, and to examine the presence and nature of interactions leading to a potential safety concern. The changes in hematological and coagulation parameters upon the addition of dendrons in the concentration range of 2–10 µM were monitored. We found that only the combination of higher concentration and higher generation of the dendron affected the selected clinically relevant parameters: it significantly decreased platelet count and plateletcrit, shortened thrombin time, and increased activated partial thromboplastin time. At the same time, occasional small-sized platelet clumps in blood films under the light microscope were observed. We further investigated aggregation propensity of the positively charged dendrons in model conditions using zwitterionic and negatively charged liposomes. The observed changes in size and zeta potential indicated the electrostatic nature of the interaction. Overall, we proved that the low-generation amphiphilic phosphorous dendrons were compatible with blood within the studied concentration range. However, interactions between high-generation dendrons at bulk concentrations above 10 µM and platelets and/or clotting factors cannot be excluded.

Subcellular Targeted Nanohoop for One- and Two-Photon Live Cell Imaging

Fluorophores are powerful tools for interrogating biological systems. Carbon nanotubes (CNTs) have long been attractive materials for biological imaging due to their near-infrared excitation and bright, tunable optical properties. The difficulty in synthesizing and functionalizing these materials with precision, however, has hampered progress in this area. Carbon nanohoops, which are macrocyclic CNT substructures, are carbon nanostructures that possess ideal photophysical characteristics of nanomaterials, while maintaining the precise synthesis of small molecules. However, much work remains to advance the nanohoop class of fluorophores as biological imaging agents. Herein, we report an intracellular targeted nanohoop. This fluorescent nanostructure is noncytotoxic at concentrations up to 50 μM, and cellular uptake investigations indicate internalization through endocytic pathways. Additionally, we employ this nanohoop for two-photon fluorescence imaging, demonstrating a high two-photon absorption cross-section (65 GM) and photostability comparable to a commercial probe. This work further motivates continued investigations into carbon nanohoop photophysics and their biological imaging applications.

Functionalized Dendrimer Platforms as a New Forefront Arsenal Targeting SARS-CoV-2: An Opportunity

The novel human coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) has caused a pandemic. There are currently several marketed vaccines and many in clinical trials targeting SARS-CoV-2. Another strategy is to repurpose approved drugs to decrease the burden of the COVID-19 (official name for the coronavirus disease) pandemic. as the FDA (U.S. Food and Drug Administration) approved antiviral drugs and anti-inflammatory drugs to arrest the cytokine storm, inducing the production of pro-inflammatory cytokines. Another view to solve these unprecedented challenges is to analyze the diverse nanotechnological approaches which are able to improve the COVID-19 pandemic. In this original minireview, as promising candidates we analyze the opportunity to develop biocompatible dendrimers as drugs themselves or as nanocarriers against COVID-19 disease. From the standpoint of COVID-19, we suggest developing dendrimers as shields against COVID-19 infection based on their capacity to be incorporated in several environments outside the patients and as important means to stop transmission of SARS-CoV-2.

Gene therapy strategies for rare monogenic disorders with nuclear or mitochondrial gene mutations

Rare monogenic disorders are a group of single-gene-mutated diseases that have a low incidence rate (less than 0.5‰) and eventually lead to patient disability and even death. Due to the relatively low number of people affected, these diseases typically fail to attract a great deal of commercial investment and research interest, and the affected patients thus have unmet medical needs. Advances in genomics biology, gene editing, and gene delivery can now offer potentially effective options for treating rare monogenic diseases. Herein, we review the application of gene therapy strategies (traditional gene therapy and gene editing) against various rare monogenic diseases with nuclear or mitochondrial gene mutations, including eye, central nervous system, pulmonary, systemic, and blood cell diseases. We summarize their pathologic features, address the barriers to gene delivery for these diseases, discuss available therapies in the clinic and in clinical trials, and sum up in-development gene delivery systems for various rare monogenic disorders. Finally, we elaborate the possible directions and outlook of gene therapy for rare monogenic disorders.

Materials promoting viral gene delivery

Therapeutic viral gene delivery is an emerging technology which aims to correct genetic mutations by introducing new genetic information to cells either to correct a faulty gene or to initiate cell death in oncolytic treatments. In recent years, significant scientific progress has led to several clinical trials resulting in the approval of gene therapies for human treatment. However, successful therapies remain limited due to a number of challenges such as inefficient cell uptake, low transduction efficiency (TE), limited tropism, liver toxicity and immune response. To adress these issues and increase the number of available therapies, additives from a broad range of materials like polymers, peptides, lipids, nanoparticles, and small molecules have been applied so far. The scope of this review is to highlight these selected delivery systems from a materials perspective.

Interactions of Surface-Functionalized Starch Nanoparticles with Pepsin and Trypsin in Simulated Gastrointestinal Fluids

Nanoparticles (NPs) can form a protein corona (PC) with proteins in biological fluids. We examined whether starch nanoparticles (SNPs) form a PC and interact with digestive enzymes in simulated gastric and intestinal fluids. We investigated the adsorption of pepsin and trypsin on unmodified, carboxyl-, and amino-modified SNPs (SNPs, COOH-SNPs, and NH₂-SNPs, respectively). Quartz crystal microbalance data showed that a tight and irreversible pepsin corona formed on the NH₂-SNPs, pepsin had little or no binding to the SNPs and COOH-SNPs, and trypsin had weak binding to all three kinds of NPs. Dynamic light scattering data showed that pepsin significantly increased the size of the NH₂-SNPs from 120 ± 2.6 to 203 ± 12.2 nm and decreased their surface potential from 23.2 ± 1.0 to 12.7 ± 0.2 mV. NH₂-SNPs could induce the fluorescence quenching of pepsin and change its secondary structures without affecting its activity.

Amphiphilic Polyphenylene Dendron Conjugates for Surface Remodeling of Adenovirus 5

Amphiphilic surface groups play an important role in many biological processes. The synthesis of amphiphilic polyphenylene dendrimer branches (dendrons), providing alternating hydrophilic and lipophilic surface groups and one reactive ethynyl group at the core is reported. The amphiphilic surface groups serve as biorecognition units that bind to the surface of adenovirus 5 (Ad5), which is a common vector in gene therapy. The Ad5/dendron complexes showed high gene transduction efficiencies in coxsackie-adenovirus receptor (CAR)-negative cells. Moreover, the dendrons offer incorporation of new functions at the dendron core by in situ post-modifications, even when bound to the Ad5 surface. Surfaces coated with these dendrons were analyzed for their blood-protein binding capacity, which is essential to predict their performance in the blood stream. A new platform for introducing bioactive groups to the Ad5 surface without chemically modifying the virus particles is provided.

Amphiphilic dendrimers control protein binding and corona formation on liposome nanocarriers

Amphiphilic polyphenylene dendrimers adsorbed to liposomes alter the protein corona dependent on their charge and hydrophobicity.