Interactions between silica nanoparticles and phospholipid membranes

Modification of Living Diatom, Thalassiosira weissflogii, with a Calcium Precursor through a Calcium Uptake Mechanism: A Next Generation Biomaterial for Advanced Delivery Systems

The diatom's frustule, characterized by its rugged and porous exterior, exhibits a remarkable biomimetic morphology attributable to its highly ordered pores, extensive surface area, and unique architecture. Despite these advantages, the toxicity and nonbiodegradable nature of silica-based organisms pose a significant challenge when attempting to utilize these organisms as nanotopographically functionalized microparticles in the realm of biomedicine. In this study, we addressed this limitation by modulating the chemical composition of diatom microparticles by modulating the active silica metabolic uptake mechanism while maintaining their intricate three-dimensional architecture through calcium incorporation into living diatoms. Here, the diatom Thalassiosira weissflogii was chemically modified to replace its silica composition with a biodegradable calcium template, while simultaneously preserving the unique three-dimensional (3D) frustule structure with hierarchical patterns of pores and nanoscale architectural features, which was evident by the deposition of calcium as calcium carbonate. Calcium hydroxide is incorporated into the exoskeleton through the active mechanism of calcium uptake via a carbon-concentrating mechanism, without altering the microstructure. Our findings suggest that calcium-modified diatoms hold potential as a nature-inspired delivery system for immunotherapy through antibody-specific binding.

A novel system to determine activity of individual uridine 5'-diphospho-glucuronosyltransferase (UGT) isoforms: Recombinant UGT-beads

Previous work demonstrated that human liver microsomes (HLMs) can spontaneously bind to silica-coated magnetizable beads (HLM-beads) and that these HLM-beads retain uridine 5'-diphospho-glucuronosyltransferase (UGT) activity. However, the contributions of individual UGT isoforms are not directly assessable in this system except through use of model inhibitors. Thus, a preparation wherein recombinant UGT (rUGT) microsomes bound to these same beads to form rUGT-beads of individual UGT isoforms would provide a novel system for measuring the contribution of individual UGT isoforms in a direct manner. To this end, the enzyme activities and kinetic parameter estimates of various rUGT isoforms in rUGT-beads were investigated, as well as the impact of fatty acids (FAs) on enzyme activity. The catalytic efficiencies (Vmax/Km) of the tested rUGTs were twofold to sevenfold higher in rUGT-beads compared with rUGT microsomes, except for rUGT1A6, where Vmax is the maximum product formation rate normalized to milligram of microsomal protein (pmol/min/mg protein). Interestingly, in contrast to traditional rUGT preparations, the sequestration of UGT-inhibitory FA using bovine serum albumin did not alter the catalytic efficiency (Vmax/Km) of the rUGTs in rUGT-beads. Moreover, the increase in catalytic efficiency of rUGT-beads over rUGT microsomes was similar to increases in catalytic efficiency noted with rUGT microsomes (not bound to beads) incubated with bovine serum albumin, suggesting the beads in some way altered the potential for FAs to inhibit activity. The rUGT-bead system may serve as a useful albumin-free tool to determine kinetic constants for UGT substrates, particularly those that exhibit high binding to albumin.

Quantitative determination of the intracellular uptake of silica nanoparticles using asymmetric flow field flow fractionation coupled with ICP mass spectrometry and their cytotoxicity in HepG2 cells

We established a size separation method for silica nanoparticles (SiNPs) measuring 10, 30, 50, 70, and 100 nm in diameter using asymmetric flow field flow fractionation hyphenated with inductively coupled plasma mass spectrometry (AF4-ICP-MS), and evaluated the cytotoxicity of SiNPs in human hepatoma HepG2 cells. Analysis of the mixture sample revealed that nanoparticles of different sizes were eluted at approximately 2-min intervals, with no effect on each elution time or percentage recovery. Compared with larger SiNPs, smaller SiNPs exhibited high cytotoxicity when the volume of SiNPs exposed to the cells was the same. We measured SiNPs in culture medium and inside cells by AF4-ICP-MS and found that approximately 17% of SiNPs in the mixture of five differently sized particles were absorbed by the cells. Transmission electron microscopy revealed that 10 nm SiNPs formed aggregates and accumulated in the cells. Based on AF4-ICP-MS analysis, there is no clear difference in the particle volume absorbed by the cells among different sizes. Therefore, the high toxicity of small SiNPs can be explained by the fact that their large surface area relative to particle volume efficiently induces toxicological influences. Indeed, the large surface area of 10 nm SiNPs significantly contributed to the production of reactive oxygen species.

Formation of Giant Unilamellar Vesicles Assisted by Fluorinated Nanoparticles

In the quest to produce artificial cells, one key challenge that remains to be solved is the recreation of a complex cellular membrane. Among the existing models, giant unilamellar vesicles (GUVs) are particularly interesting due to their intrinsic compartmentalisation ability and their resemblance in size and shape to eukaryotic cells. Many techniques have been developed to produce GUVs all having inherent advantages and disadvantages. Here, the authors show that fluorinated silica nanoparticles (FNPs) used to form Pickering emulsions in a fluorinated oil can destabilise lipid nanosystems to template the formation of GUVs. This technique enables GUV production across a broad spectrum of buffer conditions, while preventing the leakage of the encapsulated components into the oil phase. Furthermore, a simple centrifugation process is sufficient for the release of the emulsion-trapped GUVs, bypassing the need to use emulsion-destabilising chemicals. With fluorescent FNPs and transmission electron microscopy, the authors confirm that FNPs are efficiently removed, producing contaminant-free GUVs. Further experiments assessing the lateral diffusion of lipids and unilamellarity of the GUVs demonstrate that they are comparable to GUVs produced via electroformation. Finally, the ability of incorporating transmembrane proteins is demonstrated, highlighting the potential of this method for the production of GUVs for artificial cell applications.

Redistribution of hydrophobic hypericin from nanoporous particles of SBA-15 silica in vitro, in cells and in vivo

Nanoporous silica is nowadays used in various fields of nano- and micro-materials research. The advantage of nanoporous material is that it can be filled with various hydrophilic and hydrophobic molecules, which are then delivered to the target cells and tissues. In the present study, we have studied the interaction of nanoporous silica with hydrophobic and photodynamically active molecule - hypericin. Hypericin was adsorbed on/in SBA-15 silica, which led to the disappearance of its fluorescence due to hypericin aggregate formation. However, it was observed here that hypericin can be easily redistributed from these particles towards proteins and lipids in serum and cells in vitro and in vivo. Moreover, the charged surface character of SBA-15 pores forced the creation of protein/lipid corona on particles. Such complex enabled monomerization of hypericin on the surface of particles presented by fluorescence in the corona and singlet oxygen production suitable for photodynamic therapy (PDT). The PDT efficacy achieved by introducing the new construct into the PDT protocol was comparable to the efficacy of hypericin PDT. In conclusion, this study demonstrates a promising approach for the delivery of hydrophobic photosensitizers to cancer cells by nanoporous silica using fluorescence techniques.

Key Role of Choline Head Groups in Large Unilamellar Phospholipid Vesicles for the Interaction with and Rupture by Silica Nanoparticles

For highly abundant silica nanomaterials, detrimental effects on proteins and phospholipids are postulated as critical molecular initiating events that involve hydrogen-bonding, hydrophobic, and/or hydrophilic interactions. Here, large unilamellar vesicles with various well-defined phospholipid compositions are used as biomimetic models to recapitulate membranolysis, a process known to be induced by silica nanoparticles in human cells. Differential analysis of the dominant phospholipids determined in membranes of alveolar lung epithelial cells demonstrates that the quaternary ammonium head groups of phosphatidylcholine and sphingomyelin play a critical and dose-dependent role in vesicle binding and rupture by amorphous colloidal silica nanoparticles. Surface modification by either protein adsorption or by covalent coupling of carboxyl groups suppresses the disintegration of these lipid vesicles, as well as membranolysis in human A549 lung epithelial cells by the silica nanoparticles. Furthermore, molecular modeling suggests a preferential affinity of silanol groups for choline head groups, which is also modulated by the pH value. Biomimetic lipid vesicles can thus be used to better understand specific phospholipid-nanoparticle interactions at the molecular level to support the rational design of safe advanced materials.

Physico-Chemical Approaches to Investigate Surface Hydroxyls as Determinants of Molecular Initiating Events in Oxide Particle Toxicity

The study of molecular recognition patterns is crucial for understanding the interactions between inorganic (nano)particles and biomolecules. In this review we focus on hydroxyls (OH) exposed at the surface of oxide particles (OxPs) which can play a key role in molecular initiating events leading to OxPs toxicity. We discuss here the main analytical methods available to characterize surface OH from a quantitative and qualitative point of view, covering thermogravimetry, titration, ζ potential measurements, and spectroscopic approaches (NMR, XPS). The importance of modelling techniques (MD, DFT) for an atomistic description of the interactions between membranes/proteins and OxPs surfaces is also discussed. From this background, we distilled a new approach methodology (NAM) based on the combination of IR spectroscopy and bioanalytical assays to investigate the molecular interactions of OxPs with biomolecules and membranes. This NAM has been already successfully applied to SiO₂ particles to identify the OH patterns responsible for the OxPs' toxicity and can be conceivably extended to other surface-hydroxylated oxides.

ISOTHERMAL TITRATION CALORIMETRY (ITC) AS A PROMISING TOOL IN PHARMACEUTICAL NANOTECHNOLOGY

Isothermal titration calorimetry (ITC) is a technique for evaluating the thermodynamic profiles of connection between two molecules, allowing the experimental design of nanoparticles systems with drugs and/or biological molecules. Taking into account the relevance of ITC, we conducted, therefore, an integrative revision of the literature, from 2000 to 2023, on the main purposes of using this technique in pharmaceutical nanotechnology. The search were carried out in the Pubmed, Sciencedirect, Web of Science, and Scifinder databases using the descriptors "Nanoparticles", "Isothermal Titration Calorimetry", and "ITC". We have observed that the ITC technique has been increasingly used in pharmaceutical nanotechnology, seeking to understand the interaction mechanisms in the formation of nanoparticles. Additionally, to understand the behavior of nanoparticles with biological materials (proteins, DNA, cell membranes, among others), thereby helping to understand the behavior of nanocarriers in vivo studies. As a contribution, we intended to reveal the importance of ITC in the laboratory routine, which is itself a quick and easy technique to obtain relevant results that help to optimize the nanosystems formulation process.

Therapeutic Applications of Mesenchymal Stem Cell Loaded with Gold Nanoparticles for Regenerative Medicine

In the present study, the various concentrations of AuNP (1.25, 2.5, 5, 10 ppm) were prepared to investigate the biocompatibility, biological performances and cell uptake efficiency via Wharton's jelly mesenchymal stem cells and rat model. The pure AuNP, AuNP combined with Col (AuNP-Col) and FITC conjugated AuNP-Col (AuNP-Col-FITC) were characterized by Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR) and Dynamic Light Scattering (DLS) assays. For in vitro examinations, we explored whether the Wharton's jelly MSCs had better viability, higher CXCR4 expression, greater migration distance and lower apoptotic-related proteins expression with AuNP 1.25 and 2.5 ppm treatments. Furthermore, we considered whether the treatments of 1.25 and 2.5 ppm AuNP could induce the CXCR4 knocked down Wharton's jelly MSCs to express CXCR4 and reduce the expression level of apoptotic proteins. We also treated the Wharton's jelly MSCs with AuNP-Col to investigate the intracellular uptake mechanisms. The evidence demonstrated the cells uptake AuNP-Col through clathrin-mediated endocytosis and the vacuolar-type H+-ATPase pathway with good stability inside the cells to avoid lysosomal degradation as well as better uptake efficiency. Additionally, the results from in vivo examinations elucidated the 2.5 ppm of AuNP attenuated foreign body responses and had better retention efficacy with tissue integrity in animal model. In conclusion, the evidence demonstrates that AuNP shows promise as a biosafe nanodrug delivery system for development of regenerative medicine coupled with Wharton's jelly MSCs.

Comparative Evaluation of the Effects of Amorphous Silica Nanoparticles on the Erythrocytes of Wistar Normotensive and Spontaneously Hypertensive Rats

Silica nanoparticles (SiNPs) are one of the most widely used nanomaterials. SiNPs can encounter erythrocytes and hypertension is strongly linked to abnormalities in the functional and structural characteristics of erythrocytes. As little is known about the combinatorial effect of SiNP-hypertension interactions on erythrocytes, the aim of this work was to study the effects triggered by hypertension on SiNPs induced hemolysis and the pathophysiological mechanism underlying it. We compared the interaction of amorphous 50 nm SiNPs at various concentrations (0.2, 1, 5 and 25 µg/mL) with erythrocytes of normotensive (NT) and hypertensive (HT) rats in vitro. Following incubation of the erythrocytes, SiNPs induced significant and dose-dependent increase in hemolysis. Transmission electron microscopy revealed erythrocyte deformity in addition to SiNPs taken up by erythrocytes. The erythrocyte susceptibility to lipid peroxidation was significantly increased. The concentration of reduced glutathione, and activities of superoxide dismutase, and catalase were significantly increased. SiNPs significantly increased intracellular Ca²⁺. Likewise, the concentration of the cellular protein annexin V and calpain activity was enhanced by SiNPs. Concerningly, all the tested parameters were significantly enhanced in erythrocytes from HT rats compared to NT rats. Our results collectively demonstrate that hypertension can potentially exacerbate the in vitro effect induced by SiNPs.

Cholesterol content regulates silica-induced lysosomal membrane permeability

Inhalation of crystalline silica has been well documented to cause pulmonary inflammation and lung disease such as silicosis. Respirable silica particles deposit in the lungs and are phagocytosed by alveolar macrophages. Subsequently, phagocytosed silica remains undegraded within lysosomes causing lysosomal damage known as phagolysosomal membrane permeability (LMP). LMP can trigger the assembly of the NLRP3 inflammasome resulting in release of inflammatory cytokines that contribute to disease. In order to better understand the mechanisms of LMP this study used murine bone marrow derived macrophages (BMdM) as a cellular model to investigate the mechanism of silica-induced LMP. Reduction of lysosomal cholesterol in bone marrow derived macrophages with 18:1 phosphatidylglycerol (DOPG) liposome treatment increased silica-induced LMP and IL-1β release. Conversely, increasing lysosomal and cellular cholesterol with U18666A reduced IL-1β release. Co-treatment of bone marrow derived macrophages with 18:1 phosphatidylglycerol and U18666A resulted in a significant reduction of the effects of U18666A on lysosomal cholesterol. Phosphatidylcholine 100-nm liposome model systems were used to examine the effects of silica particles on lipid membrane order. Time-resolved fluorescence anisotropy of the membrane probe, Di-4-ANEPPDHQ, was used to determine changes to membrane order. Silica increased lipid order that was attenuated by inclusion of cholesterol in the phosphatidylcholine liposomes. These results demonstrate that increased cholesterol can attenuate silica-induced membrane changes in liposomes and cell models, while decreasing cholesterol exacerbates silica-induced membrane changes. Selective manipulation of lysosomal cholesterol may be a way of attenuating lysosomal disruption and preventing silica-induced chronic inflammatory disease progression.

Fluorescent silica nanoparticles as an internal marker in fruit flies and their effects on survivorship and fertility

Tracking and differentiating small insects at the individual levels requires appropriate marking materials because of their small size. This study proposes and investigates the use of fluorescent silica nanoparticles (FSNPs) as an internal marker owing to their good optical properties and biocompatibility. FSNPs were prepared using the water-in-oil reverse microemulsion technique with Rubpy dye as a fluorophore. The obtained particles were spherical, monodispersed in nanosize and exhibited bright orange luminescence under ultraviolet (UV) light. Internal marking was accomplished in fruit flies (Drosophila melanogaster) through feeding. The result shows that the fruit flies exhibit bright luminescence in their abdomen when exposed to UV light. The marking persistence duration of FSNPs in the fruit fly bodies is longer than those of other fluorescent dyes. Fruit flies fed with FSNPs have a longer lifespan than those fed with Rubpy dye. There was no difference in fertility and negative geotaxis response among the treatment and control groups. These findings demonstrate that FSNPs can be used as an internal marker in fruit flies, and are possibly applied with other small insects with a translucent abdomen.

Heterogeneous Rate Constant for Amorphous Silica Nanoparticle Adsorption on Phospholipid Monolayers

The interaction of amorphous silica nanoparticles with phospholipid monolayers and bilayers has received a great deal of interest in recent years and is of importance for assessing potential cellular toxicity of such species, whether natural or synthesized for the purpose of nanomedical drug delivery and other applications. This present communication studies the rate of silica nanoparticle adsorption on to phospholipid monolayers in order to extract a heterogeneous rate constant from the data. This rate constant relates to the initial rate of growth of an adsorbed layer of nanoparticles as SiO2 on a unit area of the monolayer surface from unit concentration in dispersion. Experiments were carried out using the system of dioleoyl phosphatidylcholine (DOPC) monolayers deposited on Pt/Hg electrodes in a flow cell. Additional studies were carried out on the interaction of soluble silica with these layers. Results show that the rate constant is effectively constant with respect to silica nanoparticle size. This is interpreted as indicating that the interaction of hydrated SiO2 molecular species with phospholipid polar groups is the molecular initiating event (MIE) defined as the initial interaction of the silica particle surface with the phospholipid layer surface promoting the adsorption of silica nanoparticles on DOPC. The conclusion is consistent with the observed significant interaction of soluble SiO2 with the DOPC layer and the established properties of the silica-water interface.

Tear of lipid membranes by nanoparticles

Health concerns associated with the advent of nanotechnologies have risen sharply when it was found that particles of nanoscopic dimensions reach the cell lumina. Plasma and organelle lipid membranes, which are exposed to both the incoming and the engulfed nanoparticles, are the primary targets of possible disruptions. However, reported adhesion, invagination and embedment of nanoparticles (NPs) do not compromise the membrane integrity, precluding direct bilayer damage as a mechanism for toxicity. Here it is shown that a lipid membrane can be torn by small enough nanoparticles, thus unveiling mechanisms for how lipid membrane can be compromised by tearing from nanoparticles. Surprisingly, visualization by cryo transmission electron microscopy (cryo-TEM) of liposomes exposed to nanoparticles revealed also that liposomal laceration is prevented by particle abundance. Membrane destruction results thus from a subtle particle-membrane interplay that is here elucidated. This brings into a firmer molecular basis the theorized mechanisms of nanoparticle effects on lipid bilayers and paves the way for a better assessment of nanoparticle toxicity.

Preparation of Natural Rubber Composites with High Silica Contents Using a Wet Mixing Process

A wet mixing process is proposed for filled rubber composites with a high silica loading to overcome the drawbacks of high energy consumption and workplace contamination of the conventional dry mixing process. Ball milling was adopted for preparing the silica dispersion because it has a simple structure, is easy to operate, and is a low-cost process that can be easily scaled up for industrial production. The response surface methodology was used to optimize the making of the silica dispersion. The optimum conditions for a well-dispersed silica suspension with the smallest silica particle size of 4.9 mm were an about 22% silica content and 62 h of ball milling. The effects of dry and wet mixing methods on the properties of silica-filled rubber composites were investigated in a broad range of silica levels from low to high loadings. The mixing method choice had little impact on the properties of rubber composites with low silica loadings. The silica-filled rubber demonstrated in this study, however, shows superior characteristics over the rubber composite prepared with conventional dry mixing, particularly with high silica loadings. When compared to silica-filled natural rubbers prepared by dry mixing (dry silica rubber, DSR), the wet mixing (for WSR) produced smaller silica aggregates with better dispersion. Due to the shorter heat history, the WSR exhibits superior curing characteristics such as a longer scorch time (2.2-3.3 min for WSR and 1.0-2.1 min for DSR) and curing time (4.1-4.5 min for WSR and 2.2-3.1 min for DSR). Additionally, the WSR has superior mechanical properties (hardness, modulus, tensile strength, and especially the elongation at break (420-680% for WSR and 360-620% DSR)) over the DSR. The rolling resistance of WSR is lower than that of DSR. However, the reversed trend on the wet skid resistance is observed.

Controlled adhesion, membrane pinning and vesicle transport by Janus particles

The interactions between biomembranes and particles are key to many applications, but the lack of controllable model systems to study them limits the progress in their research. Here, we describe how Janus polystyrene microparticles, half coated with iron, can be partially engulfed by artificial cells, namely giant vesicles, with the goals to control and investigate their adhesion and degree of encapsulation. The interaction between the Janus particles and these model cell membrane systems is mediated by electrostatic charge, offering a further mode of modulation in addition to the iron patches. The ferromagnetic particle coatings also enable manipulation and transport of the vesicles by magnetic fields.

Nano-sized zeolite-like metal-organic frameworks induced hematological effects on red blood cell

Understanding the toxicity of metal-organic frameworks (MOFs) is important for improving their biocompatibility in further applications, especially the hematotoxicity of MOFs due to the unavoidable contact of MOFs with blood in biomedical science. Here we report the hematotoxicity and underlying mechanisms of nano-sized zeolite-like MOFs ZIF-8 and ZIF-67 because of their wide applications in biomedical science. ZIF-67 induced significant hemolysis of red blood cell (Rb) through breaking the structure of membrane due to the generation of free radicals, whereas ZIF-8 was hematocompatible. ZIF-67 was thus internalized by Rb and then bound with hemoglobin via hydrogen bond and van der Waals force, which influenced the structure and function of hemoglobin in accompany with heme release. These findings reveal the detailed mechanism of the hematological effects of MOFs on Rb and are helpful to the assessment of the toxicity and potential health risks of MOFs and the design of biosafe MOFs for biomedical applications.

Role of scavenger receptors in silica nanoparticle-induced cytokine responses in bronchial epithelial cells

A major challenge in nanoparticle (NP) research is to elucidate how NPs activate initial targets in cells, leading to cytotoxicity and inflammation. We have previously shown that silica (Si)NPs induce pro-inflammatory responses in bronchial epithelial cells (BEAS-2B) via mechanisms involving transforming growth factor (TGF)-α release, and activation of MAP-kinase p38 and JNK besides NF-κB (p65). In the present study, the roles of scavenger receptors (SRs) in SiNP-induced cytokine responses in BEAS-2B cells were examined by siRNA silencing. Cells exposed to Si10 and Si50 (nominal sizes 10 and 50 nm) showed marked interleukin (IL)-6, CXCL8, IL-1α, IL-1β responses. Transient knockdown of SR-B1, LOX-1 and CXCL16 reduced the Si10- and Si50-induced cytokine responses, to a different magnitude dependent on the particle size, SR and cytokine. Si10-induced TGF-α responses were also markedly reduced by knockdown of SR-B1 and CXCL16. Furthermore, the role of SR-B1 in Si10-induced phosphorylations of p65 and MAP-kinases p38 and JNK were examined, and no significant reductions were observed upon knockdown of SR-B1. In conclusion, LOX-1 and CXCL16 and especially SR-B1 seem to have important roles in mediating cytokine responses and TGF-α release due to SiNP exposure in BEAS-2B cells, without a down-stream role of MAP-kinase and NF-κB.

Anticlogging Hemofiltration Device for Mass Collection of Circulating Tumor Cells by Ligand-Free Size Selection

A new hemofiltration system was developed to continuously capture circulating tumor cells (CTCs) from a large volume of whole blood using a column that was packed with antifouling zwitterionized silica microspheres. The silica microspheres were modified with sulfobetaine silane (SBSi) to inhibit fouling, resist clogging, and give a high surface wettability and prolonged operation time. Packed microspheres with different diameters formed size-controllable interstitial pores that effectively captured CTCs by ligand-free size selection. For optimized performance of the hemofiltration system, operational factors, including the size of microspheres, flow rate, and cross-sectional area of the column, were considered with respect to the removal rate for colorectal cancer cells and the retention rate for white blood cells and red blood cells. The captured CTCs were collected from the column by density sedimentation. A large quantity of colorectal cancer cells was spiked into sheep blood, and the sample was circulated for 5 h with a total operational volume of 2 L followed by collection and culture in vitro. The results showed that the proposed hemofiltration device selectively removed abundant CTCs from in vitro circulatory blood. The viable cells were harvested for amplification and potential applications for precision medicine.

Adsorption Kinetics of Oppositely Charged Hard and Soft Nanoparticles with Phospholipid Membranes

Nanoparticles (NPs) have great potential for biological applications as typically they exhibit strongly size-dependent properties. Specifically, the interaction of NPs with phospholipid membranes is significantly relevant to nanomedicine and the related field of nanotoxicology. Therefore, the investigation of interactions of NPs with model membranes is not only fundamentally important but also practically valuable to understand interactions of NPs with more complex cell membranes. Here, we report on the interaction of anionic vesicles of different charge densities and cationic SiO₂ NPs, either covered by a bare surface functionalized with amino moieties (-NH₂) or covered by poly[2-(dimethylamino) ethyl methacrylate]. We studied the kinetics of binding of NPs to the vesicle surface by time-resolved scattering experiments. A key result of the study is that binding is favored in the presence of electrostatic attraction, but the polymer layer decreases the binding rate drastically.

Protein corona meets freeze-drying: overcoming the challenges of colloidal stability, toxicity, and opsonin adsorption

Freeze-drying of nanoparticle suspensions is capable of generating stable nanoformulations with improved storage times and easier transportation. Nonetheless, nanoparticle aggregation is likely induced during freeze-drying, which reduces its redispersibility upon reconstitution and leads to undesirable effects such as non-specific toxicity and impaired efficacy. In this work, bovine serum albumin (BSA) is described as a suitable protectant for silica nanoparticles (SNPs), which result in solid structures with excellent redispersibility and negligible signs of aggregation even when longer storage times are considered. We experimentally demonstrated that massive system aggregation can be prevented when a saturated BSA corona around the nanoparticle is formed before the lyophilization process. Furthermore, the BSA corona is able to suppress non-specific interactions between these nanoparticles and biological systems, as evidenced by the lack of residual cytotoxicity, hemolytic activity and opsonin adsorption. Hence, BSA can be seriously considered for industry as an additive for nanoparticle freeze-drying since it generates solid and redispersible nanoformulations with improved biocompatibility.

A novel vertical aligned mesoporous silica coated nanohydroxyapatite particle as efficient dexamethasone carrier for potential application in osteogenesis

Bone defect is a common problem and inducing osteoblasts differentiation is the key process for the regenerative repair. Recently, the mesoporous silica (MS) coated nanohydroxyapatite particles nHA (nHA-MS) has shown enhanced intrinsic potency for bone regeneration, whereas whether the osteogenesis potency can be further enhanced after drug delivery has not been investigated. In this study, the nHA-MS was fabricated by a novel biphase stratification growth way. The cytotoxicity in MC3T3-E1 was validated by MTT assay, apoptosis analysis and cell cycle examination. The cell uptake was observed by confocal laser scanning microscope and transmission electron microscope respectively. After adsorption with dexamethasone (DEX), the osteogenic differentiation was determined both in vitro and in vivo. The synthesized nHA-MS showed a core-shell structure that the nanorod-like nHA was coated by a porous MS shell (~5 nm pores diameter, ~50 nm thickness). A dose-dependent cytotoxicity was observed and below 10 µg/ml was a safe concentration. The nHA-MS also showed efficient cell uptake efficiency and more efficient in DEX loading and release. After DEX adsorption, the nanoparticles exhibited enhanced osteogenic induction in MC3T3-E1 and rat calvarial bone defect regeneration. In conclusion, the nHA-MS is a favorable platform for drug delivery to obtain more enhanced osteogenesis capabilities.

Bortezomib-Loaded Mesoporous Silica Nanoparticles Selectively Alter Metabolism and Induce Death in Multiple Myeloma Cells

Simple Summary

Multiple myeloma (MM) is the second most common hematological malignancy and, despite the great advances made in its management, the development of novel therapeutic strategies are still needed in order to extend patients’ survival and to improve their quality of life. Here we show the striking ability of a mesoporous silica-based device to selectively deliver the antineoplastic drug bortezomib to Folate Receptor (FR) overexpressing MM cells, without causing injury nor perturbing the metabolic homeostasis of FR-negative healthy cells. Our data highlight the high efficacy and extraordinary safety of the tested nanodevice, paving the way for its future exploitation in the treatment of MM.

Abstract

A mesoporous silica-based nanodevice bearing the antineoplastic drug bortezomib (BTZ), whose release is triggered in acidic environment and grafted with folic acid (FOL) as a targeting function (FOL-MSN-BTZ) was tested on folate receptor overexpressing (FR+) multiple myeloma (MM) cells and on FR negative (FR−) normal cells. FOL-MSN-BTZ efficacy studies were conducted by means of growth experiments, TEM, TUNEL assay and Western Blotting analysis (WB). Metabolic investigations were performed to assess cells metabolic response to MSNs treatments. FOL-MSN-BTZ exclusively killed FR+ MM cells, leading to an apoptotic rate that was comparable to that induced by free BTZ, and the effect was accompanied by metabolic dysfunction and oxidative stress. Importantly, FOL-MSN-BTZ treated FR− normal cells did not show any significant sign of injury or metabolic perturbation, while free BTZ was still highly toxic. Notably, the vehicle alone (MSN-FOL) did not affect any biological process in both tested cell models. These data show the striking specificity of FOL-MSN-BTZ toward FR+ tumor cells and the outstanding safety of the MSN-FOL vehicle, paving the way for a future exploitation of FOL-MSN-BTZ in MM target therapy.

Human Liver Microsomes Immobilized on Magnetizable Beads: A Novel Approach to Study In Vitro Drug Metabolism

Human liver microsomes (HLM) are a commonly used tool to study drug metabolism in vitro. Typical experiments conducted using suspensions of HLM can be challenging to separate from the incubation solution without lengthy ultracentrifugation steps. Magnetizable beads coated with silica (MGBS) were found to bind strongly to HLM, which could then be isolated and purified using a magnet. Binding of HLM to the MGBS (HLM-MGBS) was demonstrated to be mediated by strong interactions between microsomal phospholipids and MGBS, as artificially prepared phosphatidylcholine (PC) liposomes could be more efficiently captured by the MGBS. HLM-MGBS complexes retained functional cytochrome P450 and uridine-diphosphate-glucuronosyltransferase (UGT) activity as indicated by CYP2C8-mediated amodiaquine de-ethylation, CYP3A4-mediated midazolam 1'hydroxylation, UGT1A1-mediated glucuronidation of estradiol, UGT1A9-mediated glucuronidation of propofol, and UGT2B7-mediated glucuronidation of zidovudine. When comparing suspension HLM alone with HLM-MGBS complexes containing equivalent amounts of HLM, the intrinsic clearance (CLint) of CYP450 substrates was comparable; however, CLint of UGT1A1, UGT1A9, and UGT2B7 was increased in the HLM-MGBS system between 1.5- and 6-fold. HLM-MGBS used in an incubation could also be readily replaced with fresh HLM-MGBS to maintain the presence of active enzymes. Thus, HLM-MGBS demonstrate increased in vitro metabolic efficiency and manipulability, providing a new platform for determination of accurate metabolic parameters. SIGNIFICANCE STATEMENT: The following work describes the strong binding of HLM to magnetizable beads. In addition, the preservation of enzyme activity on the bound HLM provides a novel means to conduct preclinical metabolism studies.

Effect of Sintering Temperature of Bioactive Glass Nanoceramics on the Hemolytic Activity and Oxidative Stress Biomarkers in Erythrocytes

INTRODUCTION

The nature of the surface is critical in determining the biological activity of silica powders. A novel correlation between toxicity and surface properties of bioactive glass ceramics (BGCs) synthesized via the sol-gel method was attempted in this study.

METHODS

The behavior of BGCs after their attachment to the surface of red blood cells (RBCs) was evaluated and their toxic effects were determined based on hemolysis, membrane injury via anti-phosphotyrosine immunoblot of Band 3, lipid peroxidation, potential to generate reactive oxygen species, and antioxidant enzyme production. In particular, three BGCs were synthesized and treated at three sintering temperatures (T1 = 835 °C, T2 = 1000 °C and T3 = 1100 °C) to investigate possible relation between surface charge or structure and hemolytic potential.

RESULTS

Their toxicity based on hemolysis was dose dependent, while BGC-T2 had the best hemocompatibility in compare with the other BGCs.No BGCs in dosages lower than 0.125 mg/mL could damage erythrocytes. On the other hand, all BGCs promoted the production of reactive oxygen species in certain concentrations, with the BGC-T2 producing the lowest ROS and increasing the glutathione levels in RBCs protecting their damage.

CONCLUSIONS

The results suggest that various factors such as size, a probable different proportion of surface silanols, a balanced mechanism between calcium and magnesium cellular uptake or the different crystalline nature may have contributed to this finding; however, future research is needed to clarify the underlying mechanisms.

Lipid Chemical Structure Modulates the Disruptive Effects of Nanomaterials on Membrane Models

Understanding the mechanisms by which engineered nanomaterials disrupt the cell plasma membrane is crucial in advancing the industrial and biomedical applications of nanotechnology. While the role of nanoparticle properties in inducing membrane damage has received significant attention, the role of the lipid chemical structure in regulating such interactions is less explored. Here, we investigated the role of the lipid chemical structure in the disruption of lipid vesicles by unmodified silica, carboxyl-modified silica, and unmodified polystyrene nanoparticles (50 nm). The role of the lipid headgroup was examined by comparing nanoparticle effects on vesicles composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) vs an inverse phosphocholine (PC) with the same acyl chain structure. The role of acyl chain saturation was examined by comparing nanoparticle effects on saturated vs unsaturated PCs and sphingomyelins. Nanoparticle effects on PCs (glycerol backbone) vs sphingomyelins (sphingosine backbone) were also examined. Results showed that the lipid headgroup, backbone, and acyl chain saturation affect nanoparticle binding to and disruption of the membranes. A low headgroup tilt angle and the presence of a trimethylammonium moiety at the vesicle surface are required for unmodified nanoparticles to induce membrane disruption. Lipid backbone structure significantly affects nanoparticle-membrane interactions, with carboxyl-modified particles only disrupting lipids containing cis unsaturation and a sphingosine backbone. Acyl chain saturation makes vesicles more resistant to particles by increasing lipid packing in vesicles, impeding molecular interactions. Finally, nanoparticles were capable of changing the lipid packing, resulting in pore formation in the process. These observations are important in interpreting nanoparticle toxicity to biological membranes.

Nanocarriers for the Delivery of Medical, Veterinary, and Agricultural Active Ingredients

Nanocarrier-based delivery systems can be used to increase the safety and efficacy of active ingredients in medical, veterinary, or agricultural applications, particularly when such ingredients are unstable, sparingly soluble, or cause off-target effects. In this review, we highlight the diversity of nanocarrier materials and their key advantages compared to free active ingredients. We discuss current trends based on peer-reviewed research articles, patent applications, clinical trials, and the nanocarrier formulations already approved by regulatory bodies. Although most nanocarriers have been engineered to combat cancer, the number of formulations developed for other purposes is growing rapidly, especially those for the treatment of infectious diseases and parasites affecting humans, livestock, and companion animals. The regulation and prohibition of many pesticides have also fueled research to develop targeted pesticide delivery systems based on nanocarriers, which maximize efficacy while minimizing the environmental impact of agrochemicals.

The effect of size and surface ligands of iron oxide nanoparticles on blood compatibility

Superparamagnetic iron oxide nanoparticles (SPIONs) have been widely used and have attracted increased attention for their unique physicochemical properties, especially in biomedical sciences as contrast agents following intravenous administration. However, only few studies have systematically reported the blood compatibility of iron oxide nanoparticles with different physicochemical properties such as different sizes and surface ligands. Therefore, we selected three widely used organic ligands (polyacrylic acid, hyaluronic acid, and chitosan) with modified SPIONs at the same size of 5-6 nm, and polyacrylic acid-modified SPIONs with different sizes (5, 10, and 30 nm) at different concentrations to evaluate their haemocompatibility. Our results revealed that SPIONs modified with polyacrylic acid demonstrated size-dependent destruction of red blood cells and complement activation. Interestingly, 5 nm SPIONs prolonged blood clotting time as compared with 10 nm and 30 nm SPIONs in vitro. Compared with polyacrylic acid-modified SPIONs, hyaluronic acid- and chitosan-modified SPIONs least affected red blood cells, platelets, coagulation, and complement activation. Hence, hyaluronic acid- and chitosan-coated SPIONs are more suitable for nanomedicine applications than polyacrylic acid-coated SPIONs. Furthermore, the interaction between SPIONs and blood components strongly correlated with the administered concentration of nanoparticles. These results will provide some experimental information for safe-by-design SPIONs.

Urate crystals trigger B-cell receptor signal transduction and induce B-cell proliferation

Background Urate in its crystal form is a known danger-associated molecular pattern, which after its internalization activates cells of the innate immune system. However, by inducing lipid raft sequestration and clustering of membrane-bound proteins with immunoreceptor tyrosine-based activation motifs, urate crystals can also activate cells of the innate immune system without previous internalization. Also, urate crystals trigger T-cell receptor signal transduction and induce T-cell proliferation. In this study, we evaluated whether urate crystals can also initiate B-cell receptor (BCR) signal transduction and promote B-cell proliferation. Methods B cells were isolated from the blood of 10 individuals and cultured with or without urate at a concentration of 10 mg/dL, at which crystallization occurs. Phosphorylated Igα (CD79A) and c-Myc were assessed by Western blotting and B-cell proliferation with BrdU assay. Results Urate increased the level of phosphorylated Igα, a component of the BCR complex. Phosphorylation of Igα is the very proximal event in BCR signal transduction. Also, urate increased the expression of c-Myc, an essential transcription factor for BCR-induced B-cell proliferation. Finally, urate induces B-cell proliferation. Conclusions Urate crystals trigger BCR signal transduction and induce B-cell proliferation. The clinical significance of urate-induced B-cell activation remains to be elucidated.

Oxidative stress, inflammation, and glycometabolism disorder-induced erythrocyte hemolysis in selenium-deficient exudative diathesis broilers

Selenium (Se) deficiency causes injury of diversified tissues and cells, including livers, hearts, skeletal muscles, and erythrocytes. The aim of the present study is to explore the molecular mechanism of erythrocyte hemolysis due to Se deficiency in broilers. One hundred and eighty broilers (male/female, 1 day old) were randomly divided into two groups and fed with either a normal Se content diet (C group, 0.2 mg Se/kg) or a Se-deficient diet (ED group, 0.008 mg Se/kg) for 45 days. During the trial period of 15-30 days, biological properties such as osmotic fragility, fluidity, phospholipid components of cell membrane, adenosine triphosphatase activities, and antioxidant function of erythrocytes in broilers were examined. Moreover, the messenger RNA (mRNA) expressions of genes associated with inflammation, glycometabolism, and avian uncoupling protein (avUCP) were detected. We found that compared with the C group, hemolysis rate, degree of polarization, and microviscosity of erythrocytes were increased in broilers of the ED group. The composition of erythrocyte membrane lipids was changed. Meanwhile, the antioxidant function of erythrocytes was weakened and mRNA levels of inflammatory genes were stimulated by Se deficiency (p < 0.05). In addition, mRNA expressions of rate-limiting enzymes in glycometabolism were effected and avUCP mRNA level was downregulated (p < 0.05) in the ED group. It has been concluded from the results that oxidative stress, inflammatory response, and glycometabolism disorder lead to erythrocyte hemolysis by changing the structure and function of erythrocyte membrane in ED broilers suffered from Se deficiency.

The puzzling issue of silica toxicity: are silanols bridging the gaps between surface states and pathogenicity?

BACKGROUND

Silica continues to represent an intriguing topic of fundamental and applied research across various scientific fields, from geology to physics, chemistry, cell biology, and particle toxicology. The pathogenic activity of silica is variable, depending on the physico-chemical features of the particles. In the last 50 years, crystallinity and capacity to generate free radicals have been recognized as relevant features for silica toxicity. The 'surface' also plays an important role in silica toxicity, but this term has often been used in a very general way, without defining which properties of the surface are actually driving toxicity. How the chemical features (e.g., silanols and siloxanes) and configuration of the silica surface can trigger toxic responses remains incompletely understood.

MAIN BODY

Recent developments in surface chemistry, cell biology and toxicology provide new avenues to improve our understanding of the molecular mechanisms of the adverse responses to silica particles. New physico-chemical methods can finely characterize and quantify silanols at the surface of silica particles. Advanced computational modelling and atomic force microscopy offer unique opportunities to explore the intimate interactions between silica surface and membrane models or cells. In recent years, interdisciplinary research, using these tools, has built increasing evidence that surface silanols are critical determinants of the interaction between silica particles and biomolecules, membranes, cell systems, or animal models. It also has become clear that silanol configuration, and eventually biological responses, can be affected by impurities within the crystal structure, or coatings covering the particle surface. The discovery of new molecular targets of crystalline as well as amorphous silica particles in the immune system and in epithelial lung cells represents new possible toxicity pathways. Cellular recognition systems that detect specific features of the surface of silica particles have been identified.

CONCLUSIONS

Interdisciplinary research bridging surface chemistry to toxicology is progressively solving the puzzling issue of the variable toxicity of silica. Further interdisciplinary research is ongoing to elucidate the intimate mechanisms of silica pathogenicity, to possibly mitigate or reduce surface reactivity.

Crystalline silica activates the T-cell and the B-cell antigen receptor complexes and induces T-cell and B-cell proliferation

Silicosis is an occupational fibrotic lung disease, which is associated with an increased incidence of autoimmune diseases. The effect of crystalline silica on the immune system is thought to be mediated by the antigen presenting cells. However, the direct effect of silica on T-cells and B-cells has not been evaluated adequately. For this purpose, CD4(+)T-cells and B-cells from 10 healthy individuals were isolated and cultured with or without Min-U-Sil 5. Cell proliferation was assessed with BrdU assay. In cell proliferation experiments, tacrolimus, an inhibitor of the signal transduction derived from the activation of the T-cell or the B-cell antigen receptor (BCR) complex, was also used. The levels of phosphorylated zeta and phosphorylated Igα, indicative of the T-cell and BCR complex activation respectively, and of the transcription factor c-Myc, required for cell proliferation, were assessed by Western blotting. Crystalline silica triggered CD4(+)T-cell and B-cell proliferation, while tacrolimus significantly decreased the silica-induced proliferation in both cell types. Crystalline silica enhanced the level of phosphorylated zeta and phosphorylated Igα in CD4(+)T-cells and B-cells, respectively. In both cell types, treatment with silica increased c-Myc expression. Thus, crystalline silica may induce T-cell and B-cell proliferation by activating T-cell and BCR complexes. It is likely that the direct activation of CD4(+)T-cells and B-cells by silica crystals detected in this study circumvents many self-tolerance check-points and offers a mechanistic explanation for the crystalline silica-induced autoimmune diseases.

Poly(Ionic Liquid) Nanoparticles Selectively Disrupt Biomembranes

Polymer-based nanoparticles have an increasing presence in research due to their attractive properties, such as flexible surface functionality design and the ability to scale up production. Poly(ionic liquid) (PIL) nanoparticles of size below 50 nm are very unique in terms of their high charge density and internal onion-like morphology. The interaction between PIL nanoparticles and giant unilamellar vesicles (GUVs) of various surface charge densities is investigated. GUVs represent a convenient model system as they mimic the size and curvature of plasma membranes, while simultaneously offering direct visualization of the membrane response under the microscope. Incubating PIL nanoparticles with GUVs results in poration of the lipid membrane in a concentration- and charge-dependent manner. A critical poration concentration of PILs is located and the interactions are found to be analogous to those of antimicrobial peptides. Microbial mimetic membranes are already affected at submicromolar PIL concentrations where contrast loss is observed due to sugar exchange across the membrane, while at high concentrations the collapse of vesicles is observed. Finally, a confocal microscopy-based approach assessing the particle permeation through the membrane is reported and a mechanism based on bilayer frustration and pore stabilization via particle integration in the membrane is proposed.

Functionalized mesoporous silica nanoparticles and biomedical applications

Since the first report in early 1990s, mesoporous silica nanoparticles (MSNs) have progressively attracted the attention of scientists due to their potential applications in physic, energy storage, imaging, and especially in biomedical engineering. Owning the unique physiochemical properties, such as highly porosity, large surface area and pore volume, functionalizable, tunable pore and particle sizes and biocompatibility, and high loading cavity, MSNs offer efficient encapsulation and then controlled release, and in some cases, intracellular delivery of bioactive molecules for biomedical applications. During the last decade, functionalized MSNs that show respond upon the surrounding stimulus changes, such as temperature, pH, redox, light, ultrasound, magnetic or electric fields, enzyme, redox, ROS, glucose, and ATP, or their combinations, have continuously revolutionized their potential applications in biomedical engineering. Therefore, this review focuses on discussion the recent fabrication of functionalized MSNs and their potential applications in drug delivery, therapeutic treatments, diagnostic imaging, and biocatalyst. In addition, some potential clinical applications and challenges will also be discussed.

Inhaled nanomaterials and the respiratory microbiome: clinical, immunological and toxicological perspectives

Our development and usage of engineered nanomaterials has grown exponentially despite concerns about their unfavourable cardiorespiratory consequence, one that parallels ambient ultrafine particle exposure from vehicle emissions. Most research in the field has so far focused on airway inflammation in response to nanoparticle inhalation, however, little is known about nanoparticle-microbiome interaction in the human airway and the environment. Emerging evidence illustrates that the airway, even in its healthy state, is not sterile. The resident human airway microbiome is further altered in chronic inflammatory respiratory disease however little is known about the impact of nanoparticle inhalation on this airway microbiome. The composition of the airway microbiome, which is involved in the development and progression of respiratory disease is dynamic, adding further complexity to understanding microbiota-host interaction in the lung, particularly in the context of nanoparticle exposure. This article reviews the size-dependent properties of nanomaterials, their body deposition after inhalation and factors that influence their fate. We evaluate what is currently known about nanoparticle-microbiome interactions in the human airway and summarise the known clinical, immunological and toxicological consequences of this relationship. While associations between inhaled ambient ultrafine particles and host immune-inflammatory response are known, the airway and environmental microbiomes likely act as intermediaries and facilitate individual susceptibility to inhaled nanoparticles and toxicants. Characterising the precise interaction between the environment and airway microbiomes, inhaled nanoparticles and the host immune system is therefore critical and will provide insight into mechanisms promoting nanoparticle induced airway damage.

Interactions between Metal Oxides and Biomolecules: from Fundamental Understanding to Applications

Metallo-oxide (MO)-based bioinorganic nanocomposites promise unique structures, physicochemical properties, and novel biochemical functionalities, and within the past decade, investment in research on materials such as ZnO, TiO₂, SiO₂, and GeO₂ has significantly increased. Besides traditional approaches, the synthesis, shaping, structural patterning, and postprocessing chemical functionalization of the materials surface is inspired by strategies which mimic processes in nature. Would such materials deliver new technologies? Answering this question requires the merging of historical knowledge and current research from different fields of science. Practically, we need an effective defragmentation of the research area. From our perspective, the superficial accounting of material properties, chemistry of the surfaces, and the behavior of biomolecules next to such surfaces is a problem. This is particularly of concern when we wish to bridge between technologies in vitro and biotechnologies in vivo. Further, besides the potential practical technological efficiency and advantages such materials might exhibit, we have to consider the wider long-term implications of material stability and toxicity. In this contribution, we present a critical review of recent advances in the chemistry and engineering of MO-based biocomposites, highlighting the role of interactions at the interface and the techniques by which these can be studied. At the end of the article, we outline the challenges which hamper progress in research and extrapolate to developing and promising directions including additive manufacturing and synthetic biology that could benefit from molecular level understanding of interactions occurring between inanimate (abiotic) and living (biotic) materials.

Cytotoxic consequences of Halloysite nanotube/iron oxide nanocomposite and iron oxide nanoparticles upon interaction with bacterial, non-cancerous and cancerous cells

Cytotoxic effects of iron oxide (Fe₃O₄) nanoparticles and Halloysite nanotube/iron oxide (HNT/Fe₃O₄) nanocomposite are compared based on their interaction with Gram-negative bacteria Escherichia coli and Gram-positive bacteria Bacillus subtilis. Similarly, the action of these two nanomaterials on non-cancerous Vero cell lines and human lung cancerous (A-549) cell lines are compared. The cytotoxicity studies on Fe₃O₄ nanoparticles and HNT/Fe₃O₄ nanocomposite showed difference in the rate of killing of bacterial cells. This is reflected in differential cell growth, cell membrane integrity loss, lactate dehydrogenase (LDH) release and reactive oxygen species (ROS) production. These factors are measured over a range of concentrations of Fe₃O₄ nanoparticles and HNT/Fe₃O₄ nanocomposite and at specified time intervals, to test if there is any statistically significant difference between the toxicity of the two nanomaterials. Between the two nanomaterials, HNT/Fe₃O₄ nanocomposite is found to be less toxic to bacterial cells than Fe₃O₄ nanoparticles. HNT, when attached to the Fe₃O₄ nanoparticles, changes their surface characteristics and suppresses their inherent toxicity on bacteria. In the study on the effect on cell lines, Fe₃O₄ nanoparticles and HNT/Fe₃O₄ nanocomposite are both seen to be biocompatible with Vero cell lines. However, HNT/Fe₃O₄ nanocomposite showed more cytotoxicity than Fe₃O₄ nanoparticles on A-549 cell lines.

Neutron Reflectometry reveals the interaction between functionalized SPIONs and the surface of lipid bilayers

The safe application of nanotechnology devices in biomedicine requires fundamental understanding on how they interact with and affect the different components of biological systems. In this respect, the cellular membrane, the cell envelope, certainly represents an important target or barrier for nanosystems. Here we report on the interaction between functionalized SuperParamagnetic Iron Oxide Nanoparticles (SPIONs), promising contrast agents for Magnetic Resonance Imaging (MRI), and lipid bilayers that mimic the plasma membrane. Neutron Reflectometry, supported by Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) experiments, was used to characterize this interaction by varying both SPION coating and lipid bilayer composition. In particular, the interaction of two different SPIONs, functionalized with a cationic surfactant and a zwitterionic phospholipid, and lipid bilayers, containing different amount of cholesterol, were compared. The obtained results were further validated by Dynamic Light Scattering (DLS) measurements and Cryogenic Transmission Electron Microscopy (Cryo-TEM) images. None of the investigated functionalized SPIONs were found to disrupt the lipid membrane. However, in all case we observed the attachment of the functionalized SPIONs onto the surface of the bilayers, which was affected by the bilayer rigidity, i.e. the cholesterol concentration.