Effects of surface nanopatterning on internalization and amyloid aggregation of the fragment 264-277 of Nucleophosmin 1

Multiparametric in vitro and in vivo analysis of the safety profile of self-assembling peptides

Self-assembling peptides (SAPs) have gained significant attention in biomedicine because of their unique properties and ability to undergo molecular self-assembly driven by non-covalent interactions. By manipulating their composition and structure, SAPs can form well-ordered nanostructures with enhanced selectivity, stability and biocompatibility. SAPs offer advantages such as high chemical and biological diversity and the potential for functionalization. However, studies concerning its potentially toxic effects are very scarce, a limitation that compromises its potential translation to humans. This study investigates the potentially toxic effects of six different SAP formulations composed of natural amino acids designed for nervous tissue engineering and amenable to ready cross-linking boosting their biomechanical properties. All methods were performed in accordance with the relevant guidelines and regulations. A wound-healing assay was performed to evaluate how SAPs modify cell migration. The results in vitro demonstrated that SAPs did not induce genotoxicity neither skin sensitization. In vivo, SAPs were well-tolerated without any signs of acute systemic toxicity. Interestingly, SAPs were found to promote the migration of endothelial, macrophage, fibroblast, and neuronal-like cells in vitro, supporting a high potential for tissue regeneration. These findings contribute to the development and translation of SAP-based biomaterials for biomedical applications.

Nanomanipulation of Ligand Nanogeometry Modulates Integrin/Clathrin-Mediated Adhesion and Endocytosis of Stem Cells

Nanosubstrate engineering can be a biomechanical approach for modulating stem cell differentiation in tissue engineering. However, the study of the effect of clathrin-mediated processes on manipulating this behavior is unexplored. Herein, we develop integrin-binding nanosubstrates with confined nanogeometries that regulate clathrin-mediated adhesion- or endocytosis-active signaling pathways for modulating stem fates. Isotropically presenting ligands on the nanoscale enhances the expression of clathrin in cells, thereby facilitating uptake of dexamethasone-loaded nanoparticles (NPs) to boost osteogenesis of stem cells. In contrast, anisotropic ligand nanogeometry suppresses this clathrin-mediated NP entry by strengthening the association between clathrin and adhesion spots to reinforce mechanotransduced signaling, which can be abrogated by the pharmacological inhibition of clathrin. Meanwhile, inhibiting focal adhesion formation hinders cell spreading and enables a higher endocytosis efficiency. Our findings reveal the crucial roles of clathrin in both endocytosis and mechanotransduction of stem cells and provide the parameter of ligand nanogeometry for the rational design of biomaterials for tissue engineering.

PLGA microparticle formulations for tunable delivery of a nano-engineered filamentous bacteriophage-based vaccine: in vitro and in silico-supported approach

Bacteriophages have attracted great attention in the bioengineering field in diverse research areas from tissue engineering to therapeutic and clinical applications. Recombinant filamentous bacteriophage, carrying multiple copies of foreign peptides on protein capsid has been successfully used in the vaccine delivery setting, even if their plasma instability and degradation have limited their use on the pharmaceutical market. Encapsulation techniques in polymeric materials can be applied to preserve bacteriophage activity, extend its half-life, and finely regulate their release in the target environment. The main goal of this study was to provide tunable formulations of the bacteriophage encapsulated in polymeric microparticles (MPs). We used poly (lactic-co-glycolic-acid) as a biocompatible and biodegradable polymer with ammonium bicarbonate as a porogen to encapsulate bacteriophage expressing OVA (257-264) antigenic peptide. We demonstrate that nano-engineered fdOVA bacteriophages encapsulated in MPs preserve their structure and are immunologically active, inducing a strong immune response towards the delivered peptide. Moreover, MP encapsulation prolongs bacteriophage stability over time also at room temperature. Additionally, in this study, we show the ability of in silico-supported approach to predict and tune the release of bacteriophages. These results lay the framework for a versatile bacteriophage-based vaccine delivery system that could successfully generate robust immune responses in a sustained manner, to be used as a platform against cancer and new emerging diseases.

Graphical abstract

Synopsis: administration of recombinant bacteriophage-loaded PLGA microparticles for antigen delivery. PLGA microparticles release the bacteriophages, inducing activation of dendritic cells and enhancing antigen presentation and specific T cell response. Bacteriophage-encapsulated microneedles potentially can be administered into human body and generate robust immune responses.

Insights into Network of Hot Spots of Aggregation in Nucleophosmin 1

In a protein, point mutations associated with diseases can alter the native structure and provide loss or alteration of functional levels, and an internal structural network defines the connectivity among domains, as well as aggregate/soluble states' equilibria. Nucleophosmin (NPM)1 is an abundant nucleolar protein, which becomes mutated in acute myeloid leukemia (AML) patients. NPM1-dependent leukemogenesis, which leads to its aggregation in the cytoplasm (NPMc+), is still obscure, but the investigations have outlined a direct link between AML mutations and amyloid aggregation. Protein aggregation can be due to the cooperation among several hot spots located within the aggregation-prone regions (APR), often predictable with bioinformatic tools. In the present study, we investigated potential APRs in the entire NPM1 not yet investigated. On the basis of bioinformatic predictions and experimental structures, we designed several protein fragments and analyzed them through typical aggrsegation experiments, such as Thioflavin T (ThT), fluorescence and scanning electron microscopy (SEM) experiments, carried out at different times; in addition, their biocompatibility in SHSY5 cells was also evaluated. The presented data clearly demonstrate the existence of hot spots of aggregation located in different regions, mostly in the N-terminal domain (NTD) of the entire NPM1 protein, and provide a more comprehensive view of the molecular details potentially at the basis of NPMc+-dependent AML.

Engineered Bacterial Cellulose Nanostructured Matrix for Incubation and Release of Drug-Loaded Oil in Water Nanoemulsion

Bacterial cellulose (BC) is a highly pure form of cellulose produced by bacteria, which possesses numerous advantages such as good mechanical properties, high chemical flexibility, and the ability to assemble in nanostructures. Thanks to these features, it achieved a key role in the biomedical field and in drug delivery applications. BC showed its ability to modulate the release of several drugs and biomolecules to the skin, thus improving their clinical outcomes. This work displays the loading of a 3D BC nanonetwork with an innovative drug delivery nanoemulsion system. BC was optimized by static culture of SCOBY (symbiotic colony of bacteria and yeast) and characterized by morphological and ultrastructural analyses, which indicate a cellulose fiber diameter range of 30–50 nm. BC layers were then incubated at different time points with a nanocarrier based on a secondary nanoemulsion (SNE) previously loaded with a well-known antioxidant and anti-inflammatory agent, namely, coenzyme-Q10 (Co-Q10). Incubation of Co-Q10–SNE in the BC nanonetwork and its release were analyzed by fluorescence spectroscopy.

Glucosyl Platinum(II) Complexes Inhibit Aggregation of the C-Terminal Region of the Aβ Peptide

Neurodegenerative diseases are often caused by uncontrolled amyloid aggregation. Hence, many drug discovery processes are oriented to evaluate new compounds that are able to modulate self-recognition mechanisms. Herein, two related glycoconjugate pentacoordinate Pt(II) complexes were analyzed in their capacity to affect the self-aggregation processes of two amyloidogenic fragments, Aβ_21-40 and Aβ_25-35, of the C-terminal region of the β-amyloid (Aβ) peptide, the major component of Alzheimer's disease (AD) neuronal plaques. The most water-soluble complex, 1Pt_dep, is able to bind both fragments and to deeply influence the morphology of peptide aggregates. Thioflavin T (ThT) binding assays, electrospray ionization mass spectrometry (ESI-MS), and ultraviolet-visible (UV-vis) absorption spectroscopy indicated that 1Pt_dep shows different kinetics and mechanisms of inhibition toward the two sequences and demonstrated that the peptide aggregation inhibition is associated with a direct coordinative bond of the compound metal center to the peptides. These data support the in vitro ability of pentacoordinate Pt(II) complexes to inhibit the formation of amyloid aggregates and pave the way for the application of this class of compounds as potential neurotherapeutics.

Self-Assembling Peptides: From Design to Biomedical Applications

Self-assembling peptides could be considered a novel class of agents able to harvest an array of micro/nanostructures that are highly attractive in the biomedical field. By modifying their amino acid composition, it is possible to mime several biological functions; when assembled in micro/nanostructures, they can be used for a variety of purposes such as tissue regeneration and engineering or drug delivery to improve drug release and/or stability and to reduce side effects. Other significant advantages of self-assembled peptides involve their biocompatibility and their ability to efficiently target molecular recognition sites. Due to their intrinsic characteristics, self-assembled peptide micro/nanostructures are capable to load both hydrophobic and hydrophilic drugs, and they are suitable to achieve a triggered drug delivery at disease sites by inserting in their structure's stimuli-responsive moieties. The focus of this review was to summarize the most recent and significant studies on self-assembled peptides with an emphasis on their application in the biomedical field.

Fate of CdSe/ZnS quantum dots in cells: Endocytosis, translocation and exocytosis

Semiconductor quantum dots (QDs) have been extensively explored for extensive bioapplications, yet their cellular fate, especially exocytosis, has not been thoroughly investigated. Herein, we systematically investigated the whole cellular process from the endocytosis, intercellular trafficking, to the exocytosis of a typical QD, core/shell CdSe/ZnS QD. Using confocal laser scanning microscopy and flow cytometry, and after carefully eliminating the effect of cell division, we found that the QDs were internalized by HeLa cells with a time-, dose-, and serum-dependent manner. The cellular uptake was inhibited by serum, but eventually peaked after 4-6 h incubation with or without serum. The primary endocytosis pathway was clathrin-mediated, and actin- and microtubule-dependent in the medium with serum, while the caveolae-mediated endocytosis and macropinocytosis were more important for the QDs in the serum-free medium. Inside cells, most QDs distributed in lysosomes, and some entered mitochondria, endoplasmic reticulum, and Golgi apparatus. The translocation of the QDs from other organelles to Golgi apparatus was observed. The exocytosis of QDs was faster than the endocytosis, reaching the maximum in about one hour after cultured in fresh culture medium, with around 60% of the internalized QDs remained undischarged. The exocytosis process was energy- and actin-dependent, and the lysosome exocytosis and endoplasmic reticulum/Golgi pathway were the main routes. This study provides a full picture of behavior and fate of QDs in cells, which may facilitate the design of ideal QDs applied in biomedical and other fields.

Type F mutation of nucleophosmin 1 Acute Myeloid Leukemia: A tale of disorder and aggregation

Protein aggregation is suggested as a reversible, wide-spread physiological process used by cells to regulate their growth and adapt to different stress conditions. Nucleophosmin 1(NPM1) protein is an abundant multifunctional nucleolar chaperone and its gene is the most frequently mutated in Acute Myeloid Leukemia (AML) patients. So far, the role of NPM1 mutations in leukemogenesis has remained largely elusive considering that they have the double effect of unfolding the C-terminal domain (CTD) and delocalizing the protein in the cytosol (NPM1c+). This mislocalization heavily impacts on cell cycle regulation. Our recent investigations unequivocally demonstrated an amyloid aggregation propensity introduced by AML mutations. Herein, employing complementary biophysical assays, we have characterized a N-terminal extended version of type F AML mutation of CTD and proved that it is able to form assemblies with amyloid character and fibrillar morphology. The present study represents an additional phase of knowledge to deepen the roles exerted by different types of cytoplasmatic NPM1c+ forms to develop in the future potential therapeutics for their selective targeting.

Cell Membrane-Coated Oil in Water Nano-Emulsions as Biomimetic Nanocarriers for Lipophilic Compounds Conveyance

Recently, we developed ultra-stable oil in water nano-emulsions (O/W NEs), able to carry both internal and external cargos (Somes), such as lipophilic compounds and hydrophilic coatings, respectively, that we call here NEsoSomes. O/W NEs are an excellent bioengineering tool for drug and molecules delivery, due to their ability to dissolve a large number of hydrophobic compounds and protect them from hydrolysis and degradation under biological conditions. At present, no report is available on the combination of cell membrane coatings with such nanocarriers, probably due to their typical instability feature. Since then, we have reported, for the first time, a new cell membrane (CM)-coated nanomaterial composed of membranes extracted from glioblastoma cancer cells (U87-MG) deposited on NEsoSomes, through a liquid-liquid interface method, to produce highly controllable membrane caked nano-capsules, namely CM-NEsoSomes. CM-NEsoSomes were physically characterized by dynamic light scattering (DLS) over time and their correct morphology was analyzed by confocal and transmission electron microscopy (TEM) microscopy. Moreover, CM-NEsoSomes biocompatibility was tested on the healthy model cell line, performing cell cytotoxicity and uptake assay, showing nanocarriers uptake by cells with no induced cytotoxicity.

Electroanalytical Sensor Based on Gold-Nanoparticle-Decorated Paper for Sensitive Detection of Copper Ions in Sweat and Serum

The growth of (bio)sensors in analytical chemistry is mainly attributable to the development of affordable, effective, portable, and user-friendly analytical tools. In the field of sensors, paper-based devices are gaining a relevant position for their outstanding features including foldability, ease of use, and instrument-free microfluidics. Herein, a multifarious use of filter paper to detect copper ions in bodily fluids is reported by exploiting this eco-friendly material to (i) synthesize AuNPs without the use of reductants and/or external stimuli, (ii) print the electrodes, (iii) load the reagents for the assay, (iv) filter the gross impurities, and (v) preconcentrate the target analyte. Copper ions were detected down to 3 ppb with a linearity up to 400 ppb in standard solutions. The applicability in biological matrices, namely, sweat and serum, was demonstrated by recovery studies and by analyzing these biofluids with the paper-based platform and the reference method (atomic absorption spectroscopy), demonstrating satisfactory accuracy of the novel eco-designed analytical tool.

Computational Evolution of Beta-2-Microglobulin Binding Peptides for Nanopatterned Surface Sensors

The bottom-up design of smart nanodevices largely depends on the accuracy by which each of the inherent nanometric components can be functionally designed with predictive methods. Here, we present a rationally designed, self-assembled nanochip capable of capturing a target protein by means of pre-selected binding sites. The sensing elements comprise computationally evolved peptides, designed to target an arbitrarily selected binding site on the surface of beta-2-Microglobulin (β2m), a globular protein that lacks well-defined pockets. The nanopatterned surface was generated by an atomic force microscopy (AFM)-based, tip force-driven nanolithography technique termed nanografting to construct laterally confined self-assembled nanopatches of single stranded (ss)DNA. These were subsequently associated with an ssDNA-peptide conjugate by means of DNA-directed immobilization, therefore allowing control of the peptide's spatial orientation. We characterized the sensitivity of such peptide-containing systems against β2m in solution by means of AFM-based differential topographic imaging and surface plasmon resonance (SPR) spectroscopy. Our results show that the confined peptides are capable of specifically capturing β2m from the surface-liquid interface with micromolar affinity, hence providing a viable proof-of-concept for our approach to peptide design.