Biomembrane disruption by silica-core nanoparticles: effect of surface functional group measured using a tethered bilayer lipid membrane

Nanoparticle elicitation: A promising strategy to modulate the production of bioactive compounds in hairy roots

Hairy root culture is one of the promising biotechnological tools to obtain the stable and sustainable production of specialized metabolites from plants under controlled environment conditions. Various strategies have been adopted to enhance the accumulation of bioactive compounds in hairy roots yet their utilization at the commercial scale is restricted to only a few products. Recently, nanotechnology has been emerged as an active technique that has revolutionized the many sectors in an advantageous way. Elicitation using nanoparticles has been recognized as an effective strategy for enhancing the bioactive compounds of interest in plants. Nanoparticles elicit the activity of defense-related compounds through activation of the specific transcription factors involved in specialized metabolites production. This review discusses the recent progress in using nanoparticles to enhance specialized metabolite biosynthesis using hairy root culture system and the significant achievements in this area of research. Biotic and abiotic elicitors to improve the production of bioactive compounds in hairy roots, different types of nanoparticles as eliciting agents, their properties as dependent on shape, most widely used nanoparticles in plant hairy root systems are described in detail. Further challenges involved in application of nanoparticles, their toxicity in plant cells and risks associated to human health are also envisaged. No doubt, nanoparticle elicitation is a remarkable approach to obtain phytochemicals from hairy roots to be utilized in various sectors including food, medicines, cosmetics or agriculture but it is quite essential to understand the inter-relationships between the nanoparticles and the plant systems in terms of specifics such as type, dosage and time of exposure as well as other important parameters.

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.

Mechanical and Electrical Interaction of Biological Membranes with Nanoparticles and Nanostructured Surfaces

In this review paper, we theoretically explain the origin of electrostatic interactions between lipid bilayers and charged solid surfaces using a statistical mechanics approach, where the orientational degree of freedom of lipid head groups and the orientational ordering of the water dipoles are considered. Within the modified Langevin Poisson–Boltzmann model of an electric double layer, we derived an analytical expression for the osmotic pressure between the planar zwitterionic lipid bilayer and charged solid planar surface. We also show that the electrostatic interaction between the zwitterionic lipid head groups of the proximal leaflet and the negatively charged solid surface is accompanied with a more perpendicular average orientation of the lipid head-groups. We further highlight the important role of the surfaces’ nanostructured topography in their interactions with biological material. As an example of nanostructured surfaces, we describe the synthesis of TiO₂ nanotubular and octahedral surfaces by using the electrochemical anodization method and hydrothermal method, respectively. The physical and chemical properties of these nanostructured surfaces are described in order to elucidate the influence of the surface topography and other physical properties on the behavior of human cells adhered to TiO₂ nanostructured surfaces. In the last part of the paper, we theoretically explain the interplay of elastic and adhesive contributions to the adsorption of lipid vesicles on the solid surfaces. We show the numerically predicted shapes of adhered lipid vesicles corresponding to the minimum of the membrane free energy to describe the influence of the vesicle size, bending modulus, and adhesion strength on the adhesion of lipid vesicles on solid charged surfaces.

Hydrogel-Induced Cell Membrane Disruptions Enable Direct Cytosolic Delivery of Membrane-Impermeable Cargo

Intracellular delivery of membrane-impermeable cargo offers unique opportunities for biological research and the development of cell-based therapies. Despite the breadth of available intracellular delivery tools, existing protocols are often suboptimal and alternative approaches that merge delivery efficiency with both biocompatibility, as well as applicability, remain highly sought after. Here, a comprehensive platform is presented that exploits the unique property of cationic hydrogel nanoparticles to transiently disrupt the plasma membrane of cells, allowing direct cytosolic delivery of uncomplexed membrane-impermeable cargo. Using this platform, which is termed Hydrogel-enabled nanoPoration or HyPore, the delivery of fluorescein isothiocyanate (FITC)-dextran macromolecules in various cancer cell lines and primary bovine corneal epithelial cells is convincingly demonstrated. Of note, HyPore demonstrates efficient FITC-dextran delivery in primary human T cells, outperforming state-of-the-art electroporation-mediated delivery. Moreover, the HyPore platform enables cytosolic delivery of functional proteins, including a histone-binding nanobody as well as the enzymes granzyme A and Cre-recombinase. Finally, HyPore-mediated delivery of the MRI contrast agent gadobutrol in primary human T cells significantly improves their T₁ -weighted MRI signal intensities compared to electroporation. Taken together, HyPore is proposed as a straightforward, highly versatile, and cost-effective technique for high-throughput, ex vivo manipulation of primary cells and cell lines.

Improved tropane alkaloid production and changes in gene expression in hairy root cultures of two Hyoscyamus species elicited by silicon dioxide nanoparticles

Species of Hyoscyamus are rich sources of medicinally important tropane alkaloids, which have anticholinergic, antispasmodic and sedative effects and are competitive inhibitors of acetylcholine. The application of nanotechnology and nanomaterials for elicitation is rapidly expanding and recent research indicates that silicon dioxide nanoparticles (SiO₂ NPs) can be used as an efficient elicitor to increase the production of hyoscyamine and scopolamine in Hyoscyamus species. Thus, in this work, the effect of SiO₂ NPs (0, 25, 50, 100 and 200 mg L^-1) with two treatment times (24 and 48 h) on the growth rate, total phenol and flavonoid content (TPC, TFC), antioxidant enzyme activity, tropane alkaloid yield and pmt (putrescine N-methyltransferase) and h6h (hyoscyamine 6<beta>-hydroxylase) gene expression levels in hairy roots of two Hyoscyamus species (H. reticulatus and H. pusillus) was investigated. The highest TPC and TFC accumulation was obtained in H. reticulatus elicited by SiO₂ NPs (100 and 200 mg L^-1), respectively, at 24 h of treatment. High-performance liquid chromatography (HPLC) revealed the highest amount of hyoscyamine (140.15 μg g^-1 FW) and scopolamine (67.71 μg g^-1 FW) accumulated in H. reticulatus transformed roots treated with 100 mg L^-1 SiO₂ NPs at 24 h, with a respective increase of 1212% and 272% compared to non-treated roots. In H. pusillus, the highest hyoscyamine (7.42 μg g^-1 FW) and scopolamine (15.56 μg g^-1 FW) production (about 82% and 241% higher, respectively, compared to the lowest amounts) was achieved with 25 and 100 mg L^-1 SiO₂ NPs, respectively, at 48 h of treatment. Semi-quantitative RT-PCR analysis determined the highest expression level of pmt and h6h genes in H. reticulatus transformed roots supplemented with 100 mg L^-1 SiO₂ NPs.

Promising opportunities and potential risk of nanoparticle on the society

The ever-promising opportunities and the uses of NP in our life are increasing but their present and future potential risks on the animals, plants and microorganisms are not well discussed elsewhere. In this review, the authors have systematically discussed the toxic effect of the uses of NP on animals, plants and microorganisms including human health. They have also discussed about the bioaccumulation of these NP in the food chain. Finally, they have provided some possible suggestions for the uses of NP to reduce the detrimental effect on the environment.

Direct translocation of nanoparticles across a model cell membrane by nanoparticle-induced local enhancement of membrane potential

Nanoparticles directly translocate across a cell membrane by a locally enhanced membrane potential at the NP/cell-membrane contact interface.

Nano-silicon alters antioxidant activities of soybean seedlings under salt toxicity

Materials with a particle size less than 100 nm are classified as nano-materials. The physical and chemical properties of nano-materials can vary considerably from those of bulk materials of the same composition. Silicon (Si) still fails to get recognized as an essential nutrient for plant growth and development, however the beneficial effects in terms of growth, biotic and abiotic stress resistance have been indicated in a variety of plant species for their growth. The aim of this study was to investigate the effects of different nano-silicon rates on the growth and antioxidant activities of soybean (Glycine max L. cv. M7) under salt stress. The results showed that salinity decreased shoot and root dry weight, potassium (K+) concentration in the root and leaf; however, increased sodium (Na+) concentration, catalase, peroxidase, ascorbate peroxidase and superoxide dismutase activities, phenolic components, ascorbic acid and α-tocopherol contents, lipid peroxidation, hydrogen peroxide, and oxygen radical's concentration. Between the treatments, 0.5 and 1 mM of nanosilicon oxide (nano-SiO2) improved shoot and root growth of seedlings. In contrast, a foliar application of SiO2 at 2 mM reduced the soybean growth. Overall, exogenous nano-silicon alleviated the salt stress by increase in K+ concentration, antioxidant activities, non-enzymatic compounds and decreasing of Na+ concentration, lipid peroxidation, and reactive oxygen species production.

Tethered bilayer membranes as a complementary tool for functional and structural studies: The pyolysin case

We demonstrate the use of tethered bilayer lipid membranes (tBLMs) as an experimental platform for functional and structural studies of membrane associated proteins by electrochemical techniques. The reconstitution of the cholesterol-dependent cytolysin (CDC) pyolysin (PLO) from Trueperella pyogenes into tBLMs was followed in real-time by electrochemical impedance spectroscopy (EIS). Changes of the EIS parameters of the tBLMs upon exposure to PLO solutions were consistent with the dielectric barrier damage occurring through the formation of water-filled pores in membranes. Parallel experiments involving a mutant version of PLO, which is able to bind to the membranes but does not form oligomer pores, strengthen the reliability of this methodology, since no change in the electrochemical impedance was observed. Complementary atomic force microscopy (AFM) and neutron reflectometry (NR) measurements revealed structural details of the membrane bound PLO, consistent with the structural transformations of the membrane bound toxins found for other cholesterol dependent cytolysins. In this work, using the tBLMs platform we also observed a protective effect of the dynamin inhibitor Dynasore against pyolysin as well as pneumolysin. An effect of Dynasore in tBLMs, which was earlier observed in experiments with live cells, confirms the biological relevance of the tBLMs models, as well as demonstrates the potential of the electrochemical impedance spectroscopy to quantify membrane damage by the pore forming toxins. In conclusion, tBLMs are a reliable and complementary method to explore the activity of CDCs in eukaryotic cells and to develop strategies to limit the toxic effects of CDCs.

The relevance of membrane models to understand nanoparticles-cell membrane interactions

Over the past two decades, numerous types of nanoparticles (NPs) have been developed for medical applications; however only a few nanomedicines are actually available on the market. One reason is the lack of understanding and data concerning the NP fate and their behavior upon contact with biological media and cell membranes. Biomimetic membrane models are interesting tools to approach and understand NPs-cell membrane interactions. The use of these models permits one to control physical and chemical parameters and to rapidly compare membrane types and the influence of different media conditions. The interactions between NPs and cell membranes can be qualified and quantified using analytical and modeling methods. In this review, the major studies concerning NPs-cell membrane models and associated methods are described. The advantages and drawbacks for each method are compared for the different models. The key mechanisms of interactions between NPs and cell membranes are revealed using cell membrane models and are interrogated in comparison with the NP behavior in cellulo or in vivo. Investigating the interactions between NPs and cell membrane models is now proposed as an intermediate step between physicochemical characterization of NPs and biological assays.

The influence of fluorescent silica nanoparticle surface chemistry on the energy transfer processes with lipid bilayers

A study of 3D and 2D intracellular FRET processes at the interface between surface tailored silica nanoparticles and lipid bilayers.

Understanding the mechanism of replacement of citrate from the surface of gold nanoparticles by amino acids: a theoretical and experimental investigation and their biological application

The present study explores the physicochemical aspects needed for the appropriate in vitro synthesis and surface modification behavior of gold nanoparticles (AuNPs) in the presence of amino acids (AA).

Recent developments in methodology employed to study the interactions between nanomaterials and model lipid membranes

With the boom of nanotechnology, nanomaterials (NMs) have been widely utilized in diverse applications, especially in biological and biomedical fields. Understanding how NMs interact with biomolecules, including proteins, DNA, and lipids, is of great importance for revealing the limitations posed and opportunities offered. Model lipid membrane, as a simplified cell membrane model, has been widely used to study the nanomaterial-lipid membrane interactions. In this article, current and emerging techniques, both experimental and theoretical, to investigate the interactions between NMs and model lipid membrane are summarized with each tool's capacities and limitations, along with future directions and challenges in this exciting area. This critical information will provide methodological guidance for researchers in this field.

Alteration of Membrane Compositional Asymmetry by LiCoO2 Nanosheets

Given the projected massive presence of redox-active nanomaterials in the next generation of consumer electronics and electric vehicle batteries, they are likely to eventually come in contact with cell membranes, with biological consequences that are currently not known. Here, we present nonlinear optical studies showing that lithium nickel manganese cobalt oxide nanosheets carrying a negative ζ-potential have no discernible consequences for lipid alignment and interleaflet composition in supported lipid bilayers formed from zwitterionic and negatively charged lipids. In contrast, lithiated and delithiated LiCoO2 nanosheets having positive and neutral ζ-potentials, respectively, alter the compositional asymmetry of the two membrane leaflets, and bilayer asymmetry remains disturbed even after rinsing. The insight that some cobalt oxide nanoformulations induce alterations to the compositional asymmetry in idealized model membranes may represent an important step toward assessing the biological consequences of their predicted widespread use.

Interaction of silver nanoparticles with tethered bilayer lipid membranes

Silver nanoparticles are well-known for their antibacterial properties. However, the detailed mechanism describing the interaction between the nanoparticles and a cell membrane is not fully understood, which can impede the use of the particles in biomedical applications. Here, a tethered bilayer lipid membrane has been used as a model system to mimic a natural membrane and to study the effect of exposure to small silver nanoparticles with diameters of about 2 nm. The solid supported membrane architecture allowed for the application of surface analytical techniques such as electrochemical impedance spectroscopy and atomic force microscopy. Exposure of the membrane to solutions of the silver nanoparticles led to a small but completely reversible perturbation of the lipid bilayer.

Native silica nanoparticles are powerful membrane disruptors

Silica nanoparticles permeabilize liposomal membranes as a function of nanoparticle size, surface chemistry and biocoating as well as membrane charge.