Effect of Dendrimer Generation and Aglyconic Linkers on the Binding Properties of Mannosylated Dendrimers Prepared by a Combined Convergent and Onion Peel Approach

Clickable APEX2 Probes for Enhanced RNA Proximity Labeling in Live Cells

Although APEX2-mediated proximity labeling has been extensively implemented for studying RNA subcellular localization in live cells, the biotin-phenoxyl radical used for labeling RNAs has a relatively low efficiency, which can limit its compatibility with other profiling methods. Herein, a set of phenol derivatives were designed as APEX2 probes through balancing reactivity, hydrophilicity, and lipophilicity. Among these derivatives, Ph_N3 exhibited reliable labeling ability and enabled two biotinylation routes for downstream analysis. As a proof of concept, we used APEX2/Ph_N3 labeling with high-throughput sequencing analysis to examine the transcriptomes in the mitochondrial matrix, demonstrating high sensitivity and specificity. To further expand the utility of Ph_N3, we employed mechanistically orthogonal APEX2 and singlet oxygen (1O2)-mediated strategies for dual location labeling in live cells. Specifically, DRAQ5, a DNA-intercalating photosensitizer, was applied for nucleus-restricted 1O2 labeling. We validated the orthogonality of APEX2/Ph_N3 and DRAQ5-1O2 at the imaging level, providing an attractive and feasible approach for future studies of RNA translocation in live cells.

A Review on Recent Advances in Mannose-Functionalized Targeted Nanocarrier Delivery Systems in Cancer and Infective Therapeutics

Unmodified nanocarriers used in the chemotherapy of cancers and various infectious diseases exhibit prolonged blood circulation time, prevent enzymatic degradation and increase chemical stability of encapsulated therapeutics. However, off-target effect and lack of specificity associated with unmodified nanoparticles (NPs) limit their applications in the health care system. Mannose (Man) receptors with significant overexpression on antigen-presenting cells and macrophages are among the most admired targets for cancer and anti-infective therapeutics. Therefore, development of Man functionalized nanocarriers targeting Man receptors, for target specific drug delivery in the chemotherapy have been extensively studied. Present review expounds diverse Man-conjugated NPs with their potential for targeted drug delivery, improved biodistribution profiles and localization. Additionally, the review gives detailed account of the interactions of mannosylated NPs with various biological systems and their characterization not discussed in earlier published reports is discussed.

Aza-Michael promoted glycoconjugation of PETIM dendrimers and selectivity in mycobacterial growth inhibitions

The benign nature of aza-Michael addition reaction in aqueous solutions is demonstrated herein to conduct a direct glycoconjugation of amine-terminated poly(ether imine) (PETIM) dendrimers. Zero to three generations of dendrimers, possessing up to 16 amine functionalities at their peripheries, undergo aza-Michael reaction with unsaturated sugar vinyl sulfoxide in aq. MeOH solutions and afford the corresponding dendrimers modified with multiple glycosyl moieties at the periphery. First order kinetics of the glycoconjugation is monitored at varying temperatures and the rate constants are observed to be 60-508 s-1, for zero and first generation dendrimers. The antibacterial effects of amine-terminated dendrimers and the corresponding glycoconjugates are studied across Gram-positive, Gram-negative and acid-fast bacteria. Among the species, M. smegmatis and M. tuberculosis showed the greatest growth inhibition effect at micromolar concentrations, for the native amine-terminated and the corresponding glycoconjugated dendrimers. Quantitative assays are performed to adjudge the inhibition efficacies of dendrimers and the glycoconjugates. Selectivity to inhibit M. smegmatis and M. tuberculosis growth, and minimal effects on other bacterial species by dendrimers and glycoconjugates are emphasized.

Validation of Selective Capture of Fimbriated Uropathogenic Escherichia coli by a Label-free Engineering Detection System Using Mannosylated Surfaces

Label-free detection of pathogens is of major concern to the microbiologist community. Most procedures require several steps and amplification techniques. Carbohydrates are well-established receptors for host-pathogen interactions, which can be amplified using glycodendritic architectures on the basis of multivalent binding interactions. Given that uropathogenic Escherichia coli bacterial FimH is based on such mannopyranoside-binding interactions, we demonstrate herein that synthetic monomeric and trimeric thiolated α-d-mannosides can be effectively bound to gold substrate-functionalized self-assembled monolayers (SAMs) preactivated with maleimide functionalities. Mannosides grafted onto SAMs were followed using Quartz Crystal Microbalance with Dissipation (QCM-D). Binding recognition efficiency was first evaluated using the plant lectin from Canavalia ensiformis (ConA) also using QCM-D. We showed a direct correlation between the amount of mannoside bound and the lectin attachment. Even though there was less trimer bound (nM/cm²) to the surface, we observed a 7-fold higher amount of lectin anchoring, thus further demonstrating the value of the multivalent interactions. We next examined the relative fimbriated E. coli selective adhesion/capture to either the monomeric or the trimeric mannoside bound to the surface. Our results established the successful engineering of the surfaces to show E. coli adhesion via specific mannopyranoside binding but unexpectedly, the monomeric derivative was more efficient than the trimeric analog, which could be explained by steric hindrance. This approach strongly suggests that it could be broadly applicable to other Gram-negative bacteria sharing analogous carbohydrate-dependent binding interactions.

Applications of mannose-binding lectins and mannan glycoconjugates in nanomedicine

Glycosylated nanoparticles (NPs) have drawn a lot of attention in the biomedical field over the past few decades, particularly in applications like targeted drug delivery. Mannosylated NPs and mannan-binding lectins/proteins (MBL/MBP) are emerging as promising tools for delivery of drugs, medicines, and enzymes to targeted tissues and cells as nanocarriers, enhancing their therapeutic benefits while avoiding the adverse effects of the drug. The occurrence of plenty of lectin receptors and their mannan ligands on cell surfaces makes them multifaceted carriers appropriate for specific delivery of bioactive drug materials to their targeted sites. Thus, the present review describes the tethering of mannose (Man) to several nanostructures, like micelles, liposomes, and other NPs, applicable for drug delivery systems. Bioadhesion through MBL-like receptors on cells has involvements applicable to additional arenas of science, for example gene delivery, tissue engineering, biomaterials, and nanotechnology. This review also focuses on the role of various aspects of drug/antigen delivery using (i) mannosylated NPs, (ii) mannosylated lectins, (iii) amphiphilic glycopolymer NPs, and (iv) natural mannan-containing polysaccharides, with most significant applications of MBL-based NPs as multivalent scaffolds, using different strategies.

GRAPHICAL ABSTRACT

Mannosylated NPs and/or MBL/MBP are coming up as viable and versatile tools as nanocarriers to deliver drugs and enzymes precisely to their target tissues or cells. The presence of abundant number of lectin receptors and their mannan ligands on cell surfaces makes them versatile carriers suitable for the targeted delivery of bioactive drugs.

Glycoconjugate Nanoparticle-Based Systems in Cancer Immunotherapy: Novel Designs and Recent Updates

For many years, cell-surface glycans (in particular, Tumor-Associated Carbohydrate Antigens, TACAs) have been the target of both passive and active anticancer immunotherapeutic design. Recent advances in immunotherapy as a treatment for a variety of malignancies has revolutionized anti-tumor treatment regimens. Checkpoint inhibitors, Chimeric Antigen Receptor T-cells, Oncolytic virus therapy, monoclonal antibodies and vaccines have been developed and many approvals have led to remarkable outcomes in a subset of patients. However, many of these therapies are very selective for specific patient populations and hence the search for improved therapeutics and refinement of techniques for delivery are ongoing and fervent research areas. Most of these agents are directed at protein/peptide epitopes, but glycans-based targets are gaining in popularity, and a handful of approved immunotherapies owe their activity to oligosaccharide targets. In addition, nanotechnology and nanoparticle-derived systems can help improve the delivery of these agents to specific organs and cell types based on tumor-selective approaches. This review will first outline some of the historical beginnings of this research area and subsequently concentrate on the last 5 years of work. Based on the progress in therapeutic design, predictions can be made as to what the future holds for increasing the percentage of positive patient outcomes for optimized systems.

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.

Thiol-Ene Click-Inspired Late-Stage Modification of Long-Chain Polyurethane Dendrimers

The construction of well-defined polyurethane dendrimers is challenging due to the high reactivity of externally added or in situ formed isocyanates leading to the formation of side products. With a primary focus of dendrimer research being the interaction of the periphery and the core, we report the synthesis of a common polyurethane dendron, which allows for the late-stage variation of both the periphery and the core. The periphery can be varied simply by installing a clickable unit in the dendron and then attaching to the core and vice-versa. Thus, a common dendron allows for varying periphery and core in the final two steps. To accomplish this, a protecting group-free, one-pot multicomponent Curtius reaction was utilized to afford a robust and versatile AB2 type polyurethane dendron employing commercially available simple molecules: 5-hydroxyisophthalic acid, 11-bromoundecanol, and 4-penten-1-ol. Subsequent late-stage modifications of either dendrons or dendrimers via a thiol-ene click reaction gave surface-functionalized alternating aromatic-aliphatic polyurethane homodendrimers to generation-three (G3). The dendrons and the dendrimers were characterized by NMR, mass spectrometry, and FT-IR analysis. A bifunctional AB2 type dendritic monomer demonstrated this approach’s versatility that can either undergo a thiol-ene click or attachment to the core. This approach enables the incorporation of functionalities at the periphery and the core that may not withstand the dendrimer growth for the synthesis of polyurethane dendrimers and other dendritic macromolecules.

Nanoparticles for Directed Immunomodulation: Mannose-Functionalized Glycodendrimers Induce Interleukin-8 in Myeloid Cell Lines

New therapeutic strategies for personalized medicine need to involve innovative pharmaceutical tools, for example, modular nanoparticles designed for direct immunomodulatory properties. We synthesized mannose-functionalized poly(propyleneimine) glycodendrimers with a novel architecture, where freely accessible mannose moieties are presented on poly(ethylene glycol)-based linkers embedded within an open-shell maltose coating. This design enhanced glycodendrimer bioactivity and led to complex functional effects in myeloid cells, with specific induction of interleukin-8 expression by mannose glycodendrimers detected in HL-60 and THP-1 cells. We concentrated on explaining the molecular mechanism of this phenomenon, which turned out to be different in both investigated cell lines: in HL-60 cells, transcriptional activation via AP-1 binding to the promoter predominated, while in THP-1 cells (which initially expressed less IL-8), induction was mediated mainly by mRNA stabilization. The success of directed immunomodulation, with synthetic design guided by assumptions about mannose-modified dendrimers as exogenous regulators of pro-inflammatory chemokine levels, opens new possibilities for designing bioactive nanoparticles.

On-cell saturation transfer difference NMR for the identification of FimH ligands and inhibitors

We describe the development of an on-cell NMR method for the rapid screening of FimH ligands and the structural identification of ligand binding epitopes. FimH is a mannose-binding bacterial adhesin expressed at the apical end of type 1 pili of uropathogenic bacterial strains and responsible for their d-mannose sensitive adhesion to host mammalian epithelial cells. Because of these properties, FimH is a key virulence factor and an attractive therapeutic target for urinary tract infection. We prepared synthetic d-mannose decorated dendrimers, we tested their ability to prevent the FimH-mediated yeast agglutination, and thus we used the compounds showing the best inhibitory activity as models of FimH multivalent ligands to set up our NMR methodology. Our experimental protocol, based on on-cell STD NMR techniques, is a suitable tool for the screening and the epitope mapping of FimH ligands aimed at the development of new antiadhesive and diagnostic tools against urinary tract infection pathogens. Notably, the study is carried out in a physiological environment, i.e. at the surface of living pathogen cells expressing FimH.

Nanomaterials for the Diagnosis and Treatment of Urinary Tract Infections

The diagnosis and treatment of urinary tract infections (UTIs) remain challenging due to the lack of convenient assessment techniques and to the resistance to conventional antimicrobial therapy, showing the need for novel approaches to address such problems. In this regard, nanotechnology has a strong potential for both the diagnosis and therapy of UTIs via controlled delivery of antimicrobials upon stable, effective and sustained drug release. On one side, nanoscience allowed the production of various nanomaterial-based evaluation tools as precise, effective, and rapid procedures for the identification of UTIs. On the other side, nanotechnology brought tremendous breakthroughs for the treatment of UTIs based on the use of metallic nanoparticles (NPs) for instance, owing to the antimicrobial properties of metals, or of surface-tailored nanocarriers, allowing to overcome multidrug-resistance and prevent biofilm formation via targeted drug delivery to desired sites of action and preventing the development of cytotoxic processes in healthy cells. The goal of the current study is therefore to present the newest developments for the diagnosis and treatment of UTIs based on nanotechnology procedures in relation to the currently available techniques.

FimH and Anti-Adhesive Therapeutics: A Disarming Strategy Against Uropathogens

Chaperone-usher fimbrial adhesins are powerful weapons against the uropathogens that allow the establishment of urinary tract infections (UTIs). As the antibiotic therapeutic strategy has become less effective in the treatment of uropathogen-related UTIs, the anti-adhesive molecules active against fimbrial adhesins, key determinants of urovirulence, are attractive alternatives. The best-characterized bacterial adhesin is FimH, produced by uropathogenic Escherichia coli (UPEC). Hence, a number of high-affinity mono- and polyvalent mannose-based FimH antagonists, characterized by different bioavailabilities, have been reported. Given that antagonist affinities are firmly associated with the functional heterogeneities of different FimH variants, several FimH inhibitors have been developed using ligand-drug discovery strategies to generate high-affinity molecules for successful anti-adhesion therapy. As clinical trials have shown d-mannose's efficacy in UTIs prevention, it is supposed that mannosides could be a first-in-class strategy not only for UTIs, but also to combat other Gram-negative bacterial infections. Therefore, the current review discusses valuable and effective FimH anti-adhesive molecules active against UTIs, from design and synthesis to in vitro and in vivo evaluations.