Biology subjects

Stellacci, F.

Publications and source records attributed to Stellacci, F..

13 recordsLinked to original sources

bioRxiv2025

A pan-respiratory virus attachment inhibitor with high potency in human airway models and in vivo

Respiratory viruses can cause severe infections, including bronchiolitis and pneumonia, often leading to hospitalization or death. Due to their ease of transmission, they are also scrutinized for their pandemic potential. No broad-spectrum antiviral is currently available. However most respiratory viruses use sialic acid or heparan sulfates as attachment receptors. Here, we report the identification of a pan-respiratory antiviral strategy based on mimicking both glycans. We synthesized and characterized a unique modified cyclodextrin that simultaneously mimics heparan sulfate and sialic acid. This novel compound demonstrated broad-spectrum antiviral activity against important human pathogens: parainfluenza virus 3, respiratory syncytial virus, influenza virus H1N1, SARS-CoV-2. Additionally, the compound is active against different avian strains of influenza virus, revealing its importance for pandemic preparedness. The compound retains broad- spectrum activity in ex vivo models of respiratory tissues and in vivo experiments against RSV and Influenza virus, using both prophylactic and therapeutic strategies. These findings represent a significant step forward in the development of future treatments and preventive measures for respiratory viral infections. Significance StatementFollowing the SARS-CoV-2 pandemic, Influenza A H5N1 has become widespread in poultry and has already begun to spill over into mammals, posing a potential risk for the next pandemic. Indeed, respiratory viruses represent a major threat for future global health crises. Unfortunately, there is a significant lack of broad-spectrum antivirals available for such scenarios. To address this gap, our study developed a single molecule with the capacity to inhibit a wide range of clinically relevant human respiratory viruses including avian strains of influenza virus. This antiviral demonstrated verified efficacy not only in cellular systems but also in human-derived respiratory tissues and animal models.

microbiology↗

bioRxiv2024

Long-term protein synthesis with PURE in a mesoscale dialysis system

Cell-free systems are powerful tools in synthetic biology with versatile and wide-ranging applications. However, a significant bottleneck for these systems, particularly the PURE cell-free system, is their limited reaction lifespan and yield. Dialysis offers a promising approach to prolong reaction lifetimes and increase yields, yet most custom dialysis systems require access to sophisticated equipment like 3D printers or microfabrication tools. In this study, we utilized an easy-to-assemble, medium-scale dialysis system for cell-free reactions using commercially available components. By employing dialysis with periodic exchange of the feeding solution, we achieved a protein yield of 1.16 mg/mL GFP in the PURE system and extended protein synthesis for at least 12.5 consecutive days, demonstrating the systems excellent stability.

synthetic biology↗

bioRxiv2024

Development of Broad-spectrum β-cyclodextrins-Based Nanomaterials Against Influenza Viruses

In recent decades, epidemics and pandemics have multiplied throughout the world, with viruses generally being the primary agents responsible. Among these, influenza viruses play a key role, as they cause severe respiratory distress, representing a major threat to public health. To enhance the response to viral disease outbreaks, there is a need for ready-to-use broad-spectrum antivirals. We have engineered macromolecules (named CD-SA) consisting of a {beta}-cyclodextrin (CD) scaffold modified with hydrophobic linkers in the primary face, onto which unitary sialic acid (SA) epitopes are covalently grafted, this to mimic influenza virus host receptors. In this study, we demonstrated that CD-SA, with a unitary SA, without extensive polysaccharides or specific connectivity, acts as a potent virucidal antiviral against several variants of human influenza type A and type B viruses. We also assessed the genetic barrier to resistance of CD-SA in vitro and successfully delayed emergence of resistance by combining CD-SA with interferon-{lambda}1 (IFN {lambda}1). Finally, we completed the characterization of the antiviral activity by conducting both ex vivo and in vivo studies, demonstrating a potent antiviral effect in human airway epithelia and in a mouse model of infection, higher than that of Oseltamivir, a currently approved anti-influenza antiviral.

microbiology↗

bioRxiv2022

Cholesterol-containing liposomes decorated with Au nanoparticles as minimal tunable fusion machinery

Membrane fusion is essential for the basal functionality of eukaryotic cells. In physiological conditions, fusion events are regulated by a wide range of specialized proteins, as well as by a finely tuned local lipid composition and ionic environment. SNARE proteins, for example, provide the mechanical energy necessary to achieve vesicle fusion in neuromediator release, and their action is assisted by other soluble proteins, membrane cholesterol, and calcium ions. Similar cooperative effects must be explored when considering synthetic approaches to achieve controlled and selective membrane fusion. Here we show that liposomes decorated with amphiphilic Au nanoparticles (AuLips) can act as minimal tunable fusion machinery. AuLips fusion is triggered by divalent ions, while the number of fusion events dramatically depends on, and can be finely tuned by, the liposome cholesterol content. Our results, obtained via a combination of experimental (Quartz-Crystal-Microbalance with Dissipation monitoring, Fluorescence assays, Small-Angle X-ray Scattering) and computational techniques (Molecular Dynamics with coarse-grained resolution), reveal new mechanistic details on the fusogenic activity of amphiphilic Au nanoparticles in synergy with membrane cholesterol, and demonstrate the ability of these synthetic nanomaterials to induce fusion regardless of the divalent ion used (Ca2+ or Mg2+). This evidence provides a novel contribution to the development of new artificial fusogenic agents for next-generation biomedical applications that require tight control of the rate of fusion events (e.g., targeted drug delivery).

biophysics↗

bioRxiv2022

Trapping virus-loaded aerosols using granular protein nanofibrils and iron oxyhydroxides nanoparticles

The ongoing COVID-19 pandemic has revealed that developing effective therapeutics against viruses might be outpaced by emerging variants,1-5 waning immunity,6-9 vaccine skepticism/hesitancy,10-12 lack of resources,13-16 and the time needed to develop virus-specific therapeutics,17,18 emphasizing the importance of non-pharmaceutical interventions as the first line of defense against virus outbreaks and pandemics.19-23 However, fighting the spread of airborne viruses has proven extremely challenging,23-28 much more if this needs to be achieved on a global scale and in an environmentally-friendly manner.29,30 Here, we introduce an aerosol filter made of granular material based on whey protein nanofibrils and iron oxyhydroxides nanoparticles. The material is environmentally-friendly, biodegradable, and composed mainly of a dairy industry byproduct.31 It features remarkable filtration efficiencies between 95.91% and 99.99% for both enveloped and non-enveloped viruses, including SARS-CoV-2, the influenza A virus strain H1N1, enterovirus 71, bacteriophage {Phi}6, and bacteriophage MS2. The developed material is safe to handle and recycle, with a simple baking step sufficient to inactivate trapped viruses. The high filtration efficiency, virtually-zero environmental impact, and low cost of the material illuminate a viable role in fighting current and future pandemics on a global scale.

microbiology↗

bioRxiv2022

Recycling of Polymerase Chain Reaction (PCR) kits

During the outbreak of the SARS-CoV-2 pandemic, PCR (polymerase chain reaction) kits have been used as a common diagnosing method, with daily worldwide usage in the millions. It is well known that at the beginning of the pandemic there was a shortage of PCR kits. So far, the ecosystem of PCR kit is linear use, that is kits are produced, used one-time, and disposed in biolab wastes. Here we show that, to mitigate the risk of future shortages, it is possible to envision recyclable PCR kits, based on a more sustainable use of nucleic acid resources. A PCR kit is mainly composed of primers, nucleotides, and enzymes. In the case of a positive test, the free nucleotides are polymerized onto the primers to form longer DNA strands. Our approach depolymerizes such strands keeping the primers and regenerating the nucleotides, i.e., returning the nucleic acid materials to the original state. The polymerized long DNA strands are hydrolyzed into nucleotides monophosphates that are then phosphorylated in triphosphates using a method that is a development of a recently published one. We used oligonucleotides with 3-terminal phosphorothioate (PS) backbone modification as non-hydrolysable PCR primers, so to undergo the recycling process unchanged. We have successfully recycled both PCR primers ([~]65% yield for 4-PS modification, and [~]40% yield for 2-PS modification) and nucleotides ([~]75% yield). We demonstrate that the method allows for direct re-use of the PCR kits. We also show that the recycled primers can be isolated and then added to end point or quantitative PCR. This recycling approach provides a new path for circularly reusing PCR nucleic acids.

biochemistry↗

bioRxiv2021

Ions and lipids drive aggregation of surface-functionalized gold nanoparticles on lipid membranes

The control of the aggregation of biomedical nanoparticles (NP) in physiological conditions is crucial as clustering may change completely the way they interact with the biological environment. Here we show that Au nanoparticles, functionalized by an anionic, amphiphilic shell, spontaneously aggregate in fluid zwitterionic lipid bilayers. We use Molecular Dynamics and enhanced sampling techniques to disentangle the short-range and long-range driving forces of aggregation. At short inter-particle distances, ion-mediated, charge-charge interactions (ion bridging) stabilize the formation of large NP aggregates, as confirmed by cryo-electron microscopy. Lipid depletion and membrane curvature are the main membrane deformations driving long-range NP-NP attraction. Ion bridging, lipid depletion, and membrane curvature stem from the configurational flexibility of the nanoparticle shell. Our simulations show, more in general, that the aggregation of same-charge membrane inclusions can be expected as a result of intrinsically nanoscale effects taking place at the NP-NP and NP-bilayer soft interfaces.

biophysics↗

bioRxiv2021

DNA as a Recyclable Natural Polymer

Nature has the ability of circularly re-using its components to produce molecules and materials it needs. An example is the ability of most living organisms of digesting proteins they feed off into amino acids and then using such amino acids in the ribosomal synthesis of new proteins. Recently, we have shown that such recycling of proteins can be reproduced outside living organisms. The key proteins feature that allows for this type of recycling is their being sequence-defined polymers. Arguably, Natures most famous sequence-defined polymer is DNA. Here we show that it is possible starting from sheared calf-DNA to obtain all the four nucleotides as monophosphate-nucleotides (dNMPs). These dNMPs were phosphorylated in a one-pot, multi-enzymes, phosphorylation reaction to generate triphosphate-nucleotides (dNTPs). Finally, we used the dNTPs so achieved (with a global yield of [~]60%) as reagents for PCR (polymerase chain reaction) to produce target DNA strands, and for the diagnose of targeted DNA by quantitative PCR (qPCR). This approach is an efficient, convenient, and environmentally friendly way to produce dNTPs and DNA through recycling according to the paradigm of circular economy.

biochemistry↗

bioRxiv2021

A novel anti-influenza combined therapy assessed by single cell RNA-sequencing

Influenza makes millions of people ill every year, placing a large burden on the healthcare system and the economy. To develop a novel treatment against influenza, we combined virucidal sialylated cyclodextrins with interferon lambda and demonstrated, in human airway epithelia, that the two compounds inhibit the replication of a clinical H1N1 strain more efficiently when administered together rather than alone. We investigated the mechanism of action of the combined treatment by single cell RNA sequencing analysis and found that both the single and combined treatments impair viral replication to different extents across distinct epithelial cell types. We also showed that each cell type comprises multiple sub-types, whose proportions are altered by H1N1 infection, and assess the ability of the treatments to restore them. To the best of our knowledge this is the first study investigating the effectiveness of an antiviral therapy by transcriptomic studies at the single cell level.

genomics↗

bioRxiv2020

Nature-inspired Circular-economy Recycling (NaCRe) for Proteins: Proof of Concept

The billion tons of synthetic polymer-based materials (i.e. plastics) produced every year are one of the greatest challenges that humanity has to face. Nature produces even more natural polymers, yet they are sustainable. For example, proteins are sequence-defined natural polymers, that are constantly recycled when living systems feed. Indeed, digestion is the protein depolymerization into amino acids (i.e. the monomers) followed by their re-assembly into new proteins of arbitrarily different sequence and function. This process breaks a common recycling paradigm where a material is recycled into itself. Organisms feed of random protein mixtures that are recycled into new proteins whose identity depends on the cells needs at the time of protein synthesis. Currently, advanced materials are increasingly made of proteins, but the abovementioned ideal recyclability of such materials has yet to be recognized and established. In this study mixtures of several (up to >30) peptides and/or proteins were depolymerized into their amino acid constituents, and these amino acids were used to synthesize new fluorescent, and bio-active proteins extra-cellularly by using an amino acid-free cell-free transcription-translation system. Proteins with high relevance in materials engineering ({beta}-lactoglobulin films, used for water filtration, or silk fibroin solutions) were successfully recycled into biotechnologically relevant proteins (green, and red fluorescent proteins, catechol 2,3-dioxygenase). The potential long-term impact of this approach to recycling lies in its compatibility with circular-economy models where raw materials remain in use as long as possible, thus reducing the burden on the planet.

biochemistry↗

bioRxiv2020

Non-Toxic Virucidal Macromolecules Show High Efficacy Against Influenza Virus Ex Vivo and In Vivo

Influenza is one of the most widespread viral infections worldwide and represents a major public health problem. The risk that one of the next pandemics is caused by an influenza strain is very high. It is very important to develop broad-spectrum influenza antivirals to be ready for any possible vaccine shortcomings. Anti-influenza drugs are available but they are far from ideal. Arguably, an ideal antiviral should target conserved viral domains and be virucidal, i.e. irreversibly inhibit viral infectivity. Here, we describe a new class of broad-spectrum anti-influenza macromolecules that meets these criteria and displays exceedingly low toxicity. These compounds are based on a cyclodextrin core modified on its primary face with long hydrophobic linkers terminated in 6sialyl-N-acetyllactosamine (6SLN) or 3SLN. SLN enables nanomolar inhibition of the viruses while the hydrophobic linkers confer irreversibility to the inhibition. The combination of these two properties allows for efficacy in vitro against several human or avian influenza strains, as well as against a 2009 pandemic influenza strain ex vivo. Importantly, we show that, in mice, the compounds provide therapeutic efficacy when administered 24h post-infection allowing 90% survival as opposed to no survival for the placebo and oseltamivir..

microbiology↗

bioRxiv2019

Reproducibility warning: The curious case of Polyethylene glycol 6000 and spheroid cell culture

In this study we report about the reproducibility of three-dimensional cell culture of floating cell spheroids on PEG6000 treated cell culture dishes. Three-dimensional tumour spheroids or organoids present an interesting test platform for nanoparticulated drug delivery or nanoparticle toxicity. We tested the reproducibility of spheroid formation induced by the PEG coated surface. Interestingly we found that the results were different in a reproducible manner depending on the distributors of PEG6000.\n\nDespite the nearly identical physicochemical properties of PEG6000 (MALDI-MS, NMR, FTIR, Triple SEC) with only minor differences, we observed only for one PEG6000 a highly reproducible formation of spheroids with different cell lines such as HT-29, HeLa, Caco2, and PANC-1. The surface coating with the different PEG6000 was studied by AFM. The surface coating as well as the physicochemical characterization showed only small differences in mass and hydrodynamic radius between the different PEGs. A direct coating of the cells with PEG from two distributors indicate that the spheroid formation in due to direct interaction of the polymer with the cell rather than by interaction of cells with the coated surface.\n\nThe experiments point out that for biological entities, such as cells or tissues, even very small differences such as impurities or batch-to-batch variations in the purchased product can have a very strong impact.

scientific communication and education↗

bioRxiv2019

Unraveling the Complexity of Amyloid Polymorphism Using Gold Nanoparticles and Cryo-EM

The misfolding and self-assembly of proteins into {beta}-sheet-rich amyloid fibrils of various structures and morphologies is a hallmark of several neurodegenerative and systemic diseases. Increasing evidence suggests that amyloid polymorphism gives rise to different strains of amyloids with distinct toxicity and pathology-spreading properties. Validating this hypothesis is challenging due to a lack of tools and methods that allow for the direct characterization of amyloid polymorphism in hydrated and complex biological samples. Here, we report on the use of 11-mercapto-1-undecanesulfonate-coated gold nanoparticles (NPs) to label the edges of synthetic, recombinant and native amyloid fibrils to assess amyloid morphological polymorphism using cryogenic transmission electron microscopy (cryo-EM). The fibrils studied were derived from amyloid proteins involved in disorders of the central nervous system (amyloid-{beta}, tau, -synuclein) and in systemic amyloidosis (a fragment of an immunoglobulin {lambda} light chain). The labeling efficiency enabled imaging and characterization of amyloid fibrils of different morphologies under hydrated conditions using cryo-EM. These NPs allowed for the visualization of morphological features that are not directly observed using standard imaging techniques, including TEM with use of the negative stain or cryo-EM imaging. We also demonstrate the use of these NPs to label native paired helical filaments (PHFs) from the postmortem brain of an Alzheimers disease patient, as well as amyloid fibrils extracted from the heart tissue of a patient suffering from systemic amyloid light-chain (AL) amyloidosis. Analysis of the cryo-EM images of amyloids decorated with NPs shows exceptional homogeneity across the fibrils derived from human tissue in comparison to fibrils aggregated in vitro. The use of these NPs enabled us to gain novel insight into the structural features that distinguish amyloid fibrils formed in vivo from those formed in cell-free in vitro systems. Our findings demonstrate that these NPs represent a powerful tool for rapid imaging and profiling of amyloid morphological polymorphism in different types of samples, including those derived from complex biological aggregates found in human tissue and animal models of amyloid diseases. These advances should not only facilitate the profiling and characterization of amyloids for structural studies by cryo-EM but also pave the way to elucidate the structural basis of amyloid strains and toxicity and possibly the correlation between the pathological and clinical heterogeneity of amyloid diseases.

neuroscience↗