Multilayered silica-biopolymer nanocapsules with a hydrophobic core and a hydrophilic tunable shell thickness

Biomimetic Oil-in-Water Nanoemulsions as a Suitable Drug Delivery System to Target Inflamed Endothelial Cells

Currently, the biomimetic approach of drawing inspiration from nature has frequently been employed in designing drug nanocarriers (NCs) of actively target various diseases, ranging from cancer to neuronal and inflammation pathologies. The cell-membrane coating can confer upon the inner nanomaterials a biological identity and the functions exhibited by the cells from which the membrane is derived. Monocyte- and macrophage-membrane-coated nanomaterials have emerged as an ideal delivery system to target inflamed vasculature. Herein, we developed two biomimetic NCs using a human-derived leukaemia monocytic cell line (THP-1), either undifferentiated or differentiated by phorbol 12-myristate 13-acetate (PMA) into adherent macrophage-like cells as membrane sources for NC coating. We employed a secondary oil-in-water nano-emulsion (SNE) as the inner core, which served as an optimal NC for high payloads of lipophilic compounds. Two different biomimetic systems were produced, combining the biomimetic features of biological membranes with the physicochemical and nano-sized characteristics of SNEs. These systems were named Monocyte NEsoSome (M-NEsoSome) and Macrophage NEsoSome (M0-NEsoSome). Their uptake ability was investigated in tumour necrosis factor alfa (TNFα)-treated human umbilical vein endothelial cells (HUVECs), selected as a model of inflamed endothelial cells. The M0 membrane coating demonstrated accelerated internalisation compared with the monocyte coating and notably surpassed the uptake rate of bare NCs. In conclusion, M0-NEsoSome NCs could be a therapeutic system for targeting inflamed endothelial cells and potentially delivering anti-inflammatory drugs in vascular inflammation.

"Smart" nanosensors for early detection of corrosion: Environmental behavior and effects on marine organisms

Corrosion is an environmental and economic global problem. "Smart" or stimuli-responsive colorimetric nanosensors for maritime coatings have been proposed as an asset to overcome the limitations of the current monitoring techniques by changing color in the presence of triggers associated with the early stages of corrosion. Layered double hydroxides (Zn-Al LDH; Mg-Al LDH) and silica mesoporous nanocapsules (SiNC) were used as precursor nanocarriers of active compounds: hexacyanoferrate ions ([Fe(CN)₆]^3-) and phenolphthalein (PhPh), respectively. Additionally, the safer-by-design principles were employed to optimize the nanosensors in an eco-friendly perspective (e.g., regular vs. warm-washed SiNC-PhPh; immobilization using different carriers: Zn-Al LDH-[Fe(CN)₆]^3- vs. Mg-Al LDH-[Fe(CN)₆]^3-). Therefore, the present study aims to assess the environmental behavior in saltwater and the toxic effects of the nanosensors, their nanocarriers, and the active compounds on the marine microalgae Tetraselmis chuii and the crustacean Artemia salina. Briefly, tested compounds exhibited no acute toxic effects towards A. salina (NOEC = 100 mg/L), apart from SiNC-PhPh (LC₅₀ = 2.96 mg/L) while tested active compounds and nanosensors caused significant growth inhibition on T. chuii (lowest IC₅₀ = 0.40 mg/L for SiNC-PhPh). The effects of [Fe(CN)₆]^3- were similar regardless of the nanocarrier choice. Regarding SiNC-PhPh, its toxicity can be decreased at least twice by simply reinforcing the nanocapsules washing, which contributes to the removal (at least partially) of the surfactants residues. Thus, implementing safe-by-design strategies in the early stages of research proved to be critical, although further progress is still needed towards the development of truly eco-friendly nanosensors.

Synthesis and Characterization of Polyethylenimine-Silica Nanocomposite Microparticles

A novel procedure for the synthesis of polyethylenimine (PEI)-silica nanocomposite particles with high adsorption capacities has been developed based on an emulsion templating concept. The exceptional chelating properties of PEI as the parent polymer for the particle core promote the binding abilities of the resulting composite for charged species. Further, the subsequent introduction of silica via the self-catalyzed hydrolysis of tetraethoxysilane facilitates production of robust composite particles with smooth surfaces, enabling potential use in multiphase environments. To enable tailored application in solid/liquid porous environments, the production of particles with reduced sizes was attempted by modulating the shear rates and surfactant concentrations during emulsification. The use of high-speed homogenization resulted in a substantial decrease in average particle size, while increasing surfactant loading only had a limited effect. All types of nanocomposites produced demonstrated excellent binding capacities for copper ions as a test solute. The maximum binding capacities of the PEI-silica nanocomposites of 210-250 mg/g are comparable to or exceed those of other copper binding materials, opening up great application potential in resources, chemical processing, and remediation industries.

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.

Facile fabrication of self-reporting micellar and vesicular structures based on an etching-ion exchange strategy of photonic composite spheres of poly(ionic liquid)

Micellar and vesicular structures capable of sensing and reporting the chemical environment as well as facilely introducing user-defined functions make a vital contribution to constructing versatile compartmentalized systems. Herein, by combining poly(ionic liquid)-based photonic spheres and an etching-ion exchange strategy we fabricate micellar and vesicular photonic compartments that can not only mimic the structure and function of conventional micelles and vesicles, but also sense and report the chemical environment as well as introducing user-defined functions. Photonic composite spheres composed of a SiO2 template and poly(ionic liquid) are employed to selectively etch outer-shell SiO2 followed by ion exchange and removal of the residual SiO2 to afford micellar photonic compartments (MPCs). The MPCs can selectively absorb solvents from the oil/water mixtures together with sensing and reporting the adsorbed solvents by the self-reporting optical signal associated with the uniform porous structure of photonic spheres. Vesicular photonic compartments (VPCs) are fabricated via selective infiltration and polymerization of ionic liquids followed by etching of the SiO2 template. Subsequent ion exchange introduces desirable functions to the VPCs. Furthermore, we demonstrate that the thickness and the anisotropic functions of VPCs can be facilely modulated. Overall, we anticipate that the micellar and vesicular photonic compartments with self-reporting optical signals and user-defined functions could serve as novel platforms towards multifunctional compartmentalized systems.

Aqueous core and hollow silica nanocapsules for confined enzyme modules

The development of enzyme modules by coupling several enzymes in confinement is of paramount importance to artificial biological reaction systems for efficient enzymatic reactions. Silica nanocapsules are ideal candidates for loading enzymes. Aqueous core silica nanocapsules have relatively been rarely reported due to the crux of difficulty in forming dense silica shells by interfacial sol-gel reactions. Herein we suggest a one-step synthesis of hollow silica nanocapsules with an aqueous core containing enzymes via a template-free and interfacial condensation method for developing enzyme modules with coupled enzymatic reactions. As a proof-of-concept, we developed enzyme modules for three useful purposes by encapsulating a couple of enzymes: (i) development of a miniature glucose sensor, (ii) protection of living cells, and (iii) regeneration of nicotinamide adenine dinucleotides (NADs). By the modulation of enzymes using silica nanocapsules, more efficient coupled reactions, separation of enzymatic reactions from surroundings, and easy handling of several enzymes by using a single module could be achieved. Therefore, our silica nanocapsules for enzyme modules can be promoted as general platforms for developing artificial nanoreactors.

Regulating Payload Release from Hybrid Nanocapsules with Dual Silica/Polycaprolactone Shells

We describe a facile strategy to synthesize hybrid nanocapsules with an oil core for hindering interactions between payloads and silica shell. Polycaprolactone/silica nanocapsules are synthesized by an interfacial sol-gel process occurring simultaneously with internal phase separation of the polymer produced by a miniemulsion-solvent evaporation technique. The localization of the polycaprolactone in the nanocapsules is depending on the ratio between polymer and silica. Formation of hybrid nanocapsules is found to significantly hinder interactions of drugs such as ibuprofen and carbamazepine with the silica surface.

Degradable, thermo-, pH- and redox-sensitive hydrogel microcapsules for burst and sustained release of drugs

Polymer microcapsules offer a possibility of storing increased amounts of drugs. Appropriate design and composition of the microcapsules allow tuning of the drug-release process. In this paper, we report on synthesis of hydrogel microcapsules sensitive to temperature and pH and degradable by glutathione and hydrogen peroxide. Microcapsules were based on thermo-responsive poly(N-isopropylacrylamide) and degradable cystine crosslinker, and were synthesized by applying precipitation polymerization. Such way of polymerization was appropriately modified to limit the crosslinking in the microcapsule center. This led to a possibility of washing out the pNIPA core at room temperature and the formation of a capsule. Microcapsules revealed rather high drug-loading capacity of ca. 17%. The degradation of the microcapsules by the reducing agent (GSH) and the oxidizing agent (H₂O₂) was confirmed by using the DLS, UV-Vis, SEM and TEM techniques. Depending on pH and concentration of the reducing/oxidizing agents a fast or slow degradation of the microcapsules and a burst or long-term release of doxorubicin (DOX) were observed. The DOX loaded microcapsules appeared to be cytotoxic against A2780 cancer cells similarly to DOX alone, while unloaded microcapsules did not inhibit proliferation of the cells.

Silver-nanoparticles as plasmon-resonant enhancers for eumelanin's photoacoustic signal in a self-structured hybrid nanoprobe

Developing safe and high efficiency contrast tools is an urgent need to allow in vivo applications of photoacoustics (PA), an emerging biomolecular imaging methodology, with poor invasiveness, deep penetration, high spatial resolution and excellent endogenous contrast. Eumelanins hold huge promise as biocompatible, endogenous photoacoustic contrast agents. However, their huge potential is still unexplored due to the difficulty to achieve at the same time poor aggregation in physiologic environment and high PA contrast. This study addresses both issues through the design of a biocompatible photoacoustic nanoprobe, named MelaSil_Ag-NPs, relying on silica-templated eumelanin formation as well as eumelanins redox and metal chelating properties to reduce Ag⁺ ions and control the growth of generated metal nanoparticles. This strategy allowed self-structuring of the system into a core-shell architecture, where the Ag core was found to boost PA signal, despite the poor eumelanin content. Obtained hybrid nanoplatforms, showed stable photoacoustic properties even under long irradiation. Furthermore, conjugation with rhodamine isothiocyanate allowed particles detection through fluorescent imaging proving their multifunctional potentialities. In addition, they were stable towards aggregation and efficiently endocytosed by human pancreatic cancer cells (BxPC3 and Panc-1) displaying no significant cytotoxicity. Such numerous features prove huge potential of those nanoparticles as a multifunctional platform for biomedical applications.

Oil Core-PEG Shell Nanocarriers for In Vivo MRI Imaging

Oil-in-water emulsions represent a promising carrier for in vivo imaging because of the possibility to convey poorly water-soluble species. To promote accumulation at the tumor site and prolong circulation time, reduction of carrier size and surface PEGylation plays a fundamental role. In this work a novel, simple method to design an oil-core/PEG-shell nanocarrier is reported. A PEG-shell is grown around a monodisperse oil-in-water nanoemulsion with a one-pot method, using the radical polymerization of poly(ethylene glycol)diacrylate. PEG polymerization is triggered by UV, obtaining a PEG-shell with tunable thickness. This core-shell nanosystem combines the eluding feature of the PEG with the ability to confine high payloads of lipophilic species. Indeed, the core is successfully loaded with a lipophilic contrast agent, namely super paramagnetic iron oxide nanocubes. Interestingly, it is demonstrated an in vitro and an in vivo MRI response of the nanocapsules. Additionally, when the nanosystem loaded with nanocubes is mixed with a fluorescent contrast agent, indo-cyanine green, a relevant in vitro photoacoustic effect is observed. Moreover, viability and cellular uptake studies show no significant cell cytotoxicity. These results, together with the choice of low cost materials and the scale up production, make this nanocarrier a potential platform for in vivo imaging.

Chlorogenic Acid Entrapped in Hybrid Materials with High PEG Content: A Strategy to Obtain Antioxidant Functionalized Biomaterials?

The formation of pro-oxidant species after implantation of biomaterials could be responsible for the failure of the implant itself, because of oxidative stress-induced damage. In this work, the SiO₂/polyethylene glycol (PEG)/chlorogenic acid (CGA) hybrids synthesized by the sol⁻gel method with 50 wt% of the polymer and different amounts of CGA (5, 10, 15 and 20 wt%) were studied. The hybrids soaked in simulated body fluid (SBF) showed the formation of hydroxyapatite layers on their surface, suggesting that the hybrids are bioactive. Their radical scavenging capacity towards DPPH· and ABTS·+ (2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), evaluated at three different doses (0.5, 1 and 2 mg), showed probe- and dose-dependent behavior. In addition, the antioxidant properties of CGA were not affected by the presence of high amounts of the polymer. The in vitro biocompatibility in three cell lines (NIH 3T3, HaCaT and SH-SY5Y) was assessed by using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Apart from SH-SY5Y, the cell viability-expressed as mitochondrial redox activity percentage of cells directly exposed to powders-and morphology was not affected, suggesting that the hybrids have the ability to interfere and act selectively against tumor cells. The antibacterial properties of the different materials against Escherichia coli and Enterococcus faecalis were affected by different amounts of the natural antioxidant component.

Cardioprotective Effects of Nanoemulsions Loaded with Anti-Inflammatory Nutraceuticals against Doxorubicin-Induced Cardiotoxicity

Doxorubicin is a highly active antineoplastic agent, but its clinical use is limited because of its cardiotoxicity. Although nutraceuticals endowed with anti-inflammatory properties exert cardioprotective activity, their bioavailability and stability are inconsistent. In an attempt to address this issue, we evaluated whether bioavailable nanoemulsions loaded with nutraceuticals (curcumin and fresh and dry tomato extracts rich in lycopene) protect cardiomyoblasts (H9C2 cells) from doxorubicin-induced toxicity. Nanoemulsions were produced with a high-pressure homogenizer. H9C2 cells were incubated with nanoemulsions loaded with different nutraceuticals alone or in combination with doxorubicin. Cell viability was evaluated with a modified MTT method. The levels of the lipid peroxidation products malondialdehyde (MDA) and 4-hydroxy-2-butanone (4-HNA), and of the cardiotoxic-related interleukins IL-6, IL-8, IL-1β and IL-10, tumor necrosis factor-alpha (TNF-α), and nitric oxide were analyzed in cardiomyoblasts. The hydrodynamic size of nanoemulsions was around 100 nm. Cell viability enhancement was 35⁻40% higher in cardiomyoblasts treated with nanoemulsion + doxorubicin than in cardiomyoblasts treated with doxorubicin alone. Nanoemulsions also protected against oxidative stress as witnessed by a reduction of MDA and 4-HNA. Notably, nanoemulsions inhibited the release of IL-6, IL-8, IL-1β, TNF-α and nitric oxide by around 35⁻40% and increased IL-10 production by 25⁻27% versus cells not treated with emulsions. Of the nutraceuticals evaluated, lycopene-rich nanoemulsions had the best cardioprotective profile. In conclusion, nanoemulsions loaded with the nutraceuticals described herein protect against cardiotoxicity, by reducing inflammation and lipid oxidative stress. These results set the stage for studies in preclinical models.

Understanding the Effects of Nanocapsular Mechanical Property on Passive and Active Tumor Targeting

The physicochemical properties of nanoparticles (size, charge, and surface chemistry, etc.) influence their biological functions often in complex and poorly understood ways. This complexity is compounded when the nanostructures involved have variable mechanical properties. Here, we report the synthesis of liquid-filled silica nanocapsules (SNCs, ∼ 150 nm) having a wide range of stiffness (with Young's moduli ranging from 704 kPa to 9.7 GPa). We demonstrate a complex trade-off between nanoparticle stiffness and the efficiencies of both immune evasion and passive/active tumor targeting. Soft SNCs showed 3 times less uptake by macrophages than stiff SNCs, while the uptake of PEGylated SNCs by cancer cells was independent of stiffness. In addition, the functionalization of stiff SNCs with folic acid significantly enhanced their receptor-mediated cellular uptake, whereas little improvement for the soft SNCs was conferred. Further in vivo experiments confirmed these findings and demonstrated the critical role of nanoparticle mechanical properties in regulating their interactions with biological systems.

Probing the Eumelanin-Silica Interface in Chemically Engineered Bulk Hybrid Nanoparticles for Targeted Subcellular Antioxidant Protection

We disclose herein the first example of stable monodispersed hybrid nanoparticles (termed MelaSil-NPs) made up of eumelanin biopolymer intimately integrated into a silica nanoscaffold matrix and endowed with high antioxidant and cytoprotective effects associated with a specific subcellular localization. MelaSil-NPs have been fabricated by an optimized sol-gel methodology involving ammonia-induced oxidative polymerization of a covalent conjugate of the eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA) with 3-aminopropyltriethoxysilanes (APTS). They displayed a round-shaped (ca. 50-80 nm) morphology, exhibited the typical electron paramagnetic resonance signal of eumelanin biopolymers, and proved effective in promoting decomposition of hydrogen peroxide under physiologically relevant conditions. When administered to human ovarian cancer cells (A2780) or cervical cancer cells (HeLa), MelaSil-NPs were rapidly internalized and colocalized with lysosomes and exerted efficient protecting effects against hydrogen peroxide-induced oxidative stress and cytotoxicity.

Enhanced Drug Delivery into Cell Cytosol via Glycoprotein H-Derived Peptide Conjugated Nanoemulsions

The key role of nanocarriers in improving the pharmacological properties of commonly used drugs is recognized worldwide. It is also known that in the development of new effective nanocarriers the use of targeting moieties integrated on their surface is essential. Herein, we propose a nanocarrier based on an oil in water nanoemulsion coated with a membranotropic peptide derived from the glycoprotein H of Herpes simplex virus 1, known as gH625, in order to reduce endolysosomal accumulation and to enhance cytosolic localization. In addition, we show an enhanced anti-inflammatory activity of curcumin, a bioactive compound isolated from the Curcuma longa plant, when loaded into our engineered nanocarriers. This effect is a consequence of a higher uptake combined with a high curcumin preservation exerted by the active nanocapsules compared to control ones. When loaded into our nanocapsules, indeed, curcumin molecules are directly internalized into the cytosol rather than into lysosomes. Further, in order to extend the in vitro experimental setting with a more complex model and to explore the possibility to use our nanocarriers for further biological applications, we tested their performance in a 3D sprouting angiogenesis model. Finally, we show promising preliminary in vivo results by assessing the anti-inflammatory properties of the proposed nanocarrier.

Nanoparticle-based strategy for personalized B-cell lymphoma therapy

B-cell lymphoma is associated with incomplete response to treatment, and the development of effective strategies targeting this disease remains challenging. A new personalized B-cell lymphoma therapy, based on a site-specific receptor-mediated drug delivery system, was developed in this study. Specifically, natural silica-based nanoparticles (diatomite) were modified to actively target the antiapoptotic factor B-cell lymphoma/leukemia 2 (Bcl2) with small interfering RNA (siRNA). An idiotype-specific peptide (Id-peptide) specifically recognized by the hypervariable region of surface immunoglobulin B-cell receptor was exploited as a homing device to ensure specific targeting of lymphoma cells. Specific nanoparticle uptake, driven by the Id-peptide, was evaluated by flow cytometry and confocal microscopy and was increased by approximately threefold in target cells compared with nonspecific myeloma cells and when a random control peptide was used instead of Id-peptide. The specific internalization efficiency was increased by fourfold when siRNA was also added to the modified nanoparticles. The modified diatomite particles were not cytotoxic and their effectiveness in downregulation of gene expression was explored using siRNA targeting Bcl2 and evaluated by quantitative real-time polymerase chain reaction and Western blot analyses. The resulting gene silencing observed is of significant biological importance and opens new possibilities for the personalized treatment of lymphomas.

Oil/water nano-emulsion loaded with cobalt ferrite oxide nanocubes for photo-acoustic and magnetic resonance dual imaging in cancer: in vitro and preclinical studies

Dual imaging dramatically improves detection and early diagnosis of cancer. In this work we present an oil in water (O/W) nano-emulsion stabilized with lecithin and loaded with cobalt ferrite oxide (Co_0.5Fe_2.5O₄) nanocubes for photo-acoustic and magnetic resonance dual imaging. The nanocarrier is responsive in in vitro photo-acoustic and magnetic resonance imaging (MRI) tests. A clear and significant time-dependent accumulation in tumor tissue is shown in in vivo photo-acoustic studies on a murine melanoma xenograft model. The proposed O/W nano-emulsion exhibits also high values of r₂/r₁ (ranging from 45 to 85, depending on the magnetic field) suggesting a possible use as T₂ weighted image contrast agents. In addition, viability and cellular uptake studies show no significant cytotoxicity on the fibroblast cell line. We also tested the O/W nano-emulsion loaded with curcumin against melanoma cancer cells demonstrating a significant cytotoxicity and thus showing possible therapeutic effects in addition to the in vivo imaging.