Interaction of silica nanoparticles with tau proteins and PC12 cells: Colloidal stability, thermodynamic, docking, and cellular studies

https://doi.org/10.1016/j.ijbiomac.2018.07.041Get rights and content

Abstract

Study on the side effects of the nanoparticles (NPs) can provide useful information regarding their biological and medical applications. Herein, the colloidal stability of the silicon dioxide NPs (SiO2 NPs) in the absence and presence of tau was investigated by TEM and DLS techniques. Afterwards, the thermodynamic parameters of interaction between SiO2 NPs and tau were determined by fluorescence spectroscopy and docking studies. Finally, the cytotoxic effects of SiO2 NPs on the viability of PC12 cells were investigated by MTT, AO/EB staining and flow cytometry assays. TEM, DLS, and zeta potential investigations revealed that tau can reduce the colloidal stability of SiO2 NPs. Fluorescence spectroscopy study indicated that SiO2 NPs bound to the tau with high affinity through hydrogen bonds and van der Waals interactions. Docking study also determined that Ser, Thr and Tyr residues provide a polar microenvironment for SiO2 NPs/tau interaction. Cellular studies demonstrated that SiO2 NPs can induce cell mortality through both apoptosis and necrosis mechanisms. Therefore, it may be concluded that the biological systems such as nervous system proteins can affect the colloidal stability of NPs and vice versa NPs in the biological systems can bind to proteins and cell membranes non-specifically and may induce toxicity.

Introduction

Nanomaterials are potentially helpful particles in the biomedicine and biotechnology as they are of comparable size to main biological components such as DNA and proteins. This almost identical size can increase the probability of interaction between nanomaterials and biological systems [1,2]. Recently, a number of considerable applications of NPs have been reported in the drug delivery systems, nanobiotechnology, biomedical imaging, and enzyme immobilization [[3], [4], [5], [6], [7]]. Therefore, the interaction of NPs with biological systems is unavoidable and the interaction mechanism between NPs, cells and proteins has emerged as a key area of research [[8], [9], [10]]. Most nanomaterials, after interaction with biological systems, are coated by proteins causing to the formation of a protein corona that mainly specify the biological identity of the NPs [11,12]. This protein NP interaction may change the protein structure, expose new residues on the protein surface and disturb the normal protein function [13]. Adsorption of proteins onto the NP surfaces has been shown to induce protein conformational changes, aggregation, and corresponding deactivation [14,15]. The urgency to reveal the toxicological effect and the design of early indicators to detect potential adverse health effects deriving from the application of nanomaterials is most obvious and some well-known toxicity assays should be carried out prior to release to the public. The comparison of cytotoxic effects from various NPs has indicated diverse responses [16].

Because, the adsorbed proteins onto the NP surface control the route of internalization into the cell, distribution, and delivery to the targeted tissues, therefore the interaction of NPs with protein and cell play a considerable role in the designing and development of NPs for therapeutic applications. Currently, the mechanism of protein absorption and interaction of cells onto/with the NPs is not well characterized.

SiO2 NPs have been applied for various biomedical applications. For example, mesoporous SiO2-coated iron oxide NPs have been used for predictable heating and positive MRI contrast agent [17]. Also, effective delivery of immunosuppressive drug molecules has been done by SiO2coated iron oxide NPs [18]. In the other study, tumor vascular-targeted co-delivery of anti-angiogenesis and chemotherapeutic agents by mesoporous SiO2 NPs-based drug delivery system has been carried out [19]. They have also been used for controlled release and intracellular protein delivery systems [20].

Upon administration and inhalation of SiO2 NPs, they can enter into the nervous system and interact with common human brain proteins and neurons [21].

Tau presents largely in the axons of the central nervous system (CNS) and is known as microtubule associated proteins (MAPs). Tau shows a natively unfolded structure with three different domains of amino-terminal, carboxyl-terminal, and repeat domains and represents a hydrophilic conformation [22,23]. In fact, data from a number of biophysical methods like Raman spectroscopy and nuclear magnetic resonance (NMR) demonstrate that the tau molecule is intrinsically unfolded [24,25]. This means that the polypeptide chain has only a low content of secondary structures such as α-helix and β-sheets, and high content of random coil structure. Tau could establish transient interactions with a various proteins and ions, and maybe NPs in the crowded environment of a cell. In spite of the unfolded structure, tau may shows a folded and aggregated structure upon interactions with ligands, where the amino-terminal, carboxyl-terminal, and repeat domains approach each other.

Because, neurons do not divide, they are not usually used for the cytotoxic studies of NPs on the CNS in vitro. Therefore, neuronal-like cells with a high proliferative capacity are commonly utilized for cellular and molecular studies to monitor the NP-related CNS cytotoxicity. Up-to-date, a sparse number of in vitro studies have been reported using neural-like cell lines for testing the cytotoxicity effect of SiO2 NPs. Some reports have demonstrated cytotoxicity effect of copper oxide NPs, silver NPs, iron NPs, graphene NPs, single-wall carbon nanotubes and multi-wall carbon nanotubes against PC12 cells (a rat cell line with a neuronal-like phenotype) [1,[26], [27], [28], [29]].

Here, we analyzed the colloidal stability of SiO2 NPs in the absence and presence of tau by transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. Also, the effect of different concentrations of SiO2 NPs on the intrinsic fluorescence intensity of tau was investigated to calculate the thermodynamic parameters. Molecular docking study was also carried out to explore more detailed data regarding the SiO2 NPs interaction with tau at the binding site. Also, the growth characteristics of PC12 cells as neuronal-like cells line in the presence of SiO2 NPs were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5diphenyltetrazolium bromide (MTT), acridine orange/ethidium bromide (AO/EB) dual staining and flow cytometry assays.

Section snippets

Materials

SiO2 NPs (15–20 nm, spherical, nonporous and amorphous was purchased from US Research Nanomaterials, Inc., US3436). The cell culture medium (DMEM), penicillin–streptomycin, fetal bovine serum (FBS) were obtained from Gibco BRL (Life technology, Paisley, Scotland). AB, AO, MTT, and dimethyl sulfoxide (DMSO) were purchased from Merck Co. (Darmstadt, Germany). PC12 cell line (rat adrenal pheochromocytoma cells) was obtained from Pasture institute of Tehran, Tehran Iran. All other chemicals were of

TEM and DLS measurements

TEM observation was carried out to monitor the diameter distribution and morphology of SiO2 NPs in the absence and presence of tau. Fig. 1(a) exhibited that SiO2 NPs have a diameter of around 20 nm with a semi rounded shape. However, after addition of tau protein to the SiO2 NPs sample, the proteins are adsorbed onto the NP surface and result in the agglomeration of NPs [Fig. 1(b)].

To explore the size and distribution of SiO2 NP in the solution, DLS technique was also carried out. As shown in

Conclusion

The behavior of SiO2 NPs in the nervous system was evaluated by biophysical, docking and cellular studies. The colloidal stability of the SiO2 NPs in the presence of tau was reduced. SiO2 NPs formed a static complex with tau and bound to the tau with high affinity by means of hydrogen bonds and van der Waals interactions. Ser, Thr and Tyr residues established hydrogen bonds with the surface of SiO2 NPs. Cellular assays reveled that SiO2 NPs can trigger cytotoxicity through apoptosis and

Acknowledgment

The financial support of Islamic Azad University, Pharmaceutical Science branch (IAUPS) is greatly acknowledged. Tau protein was gifted by Dr. Koorosh Shahpasand from Royan Institute for Stem Cell Biology and Technology, Tehran, Iran.

Conflict of interest

The author declare no conflict of interest.

References (58)

  • B.A. Asl et al.

    Probing the interaction of zero valent iron nanoparticles with blood system by biophysical, docking, cellular, and molecular studies

    Int. J. Biol. Macromol.

    (2018 Apr 1)
  • S. Marouzi et al.

    Study on effect of lomefloxacin on human holo-transferrin in the presence of essential and nonessential amino acids: spectroscopic and molecular modeling approaches

    Int. J. Biol. Macromol.

    (2017 Apr 1)
  • N. Moradi et al.

    Separate and simultaneous binding of tamoxifen and estradiol to human serum albumin: spectroscopic and molecular modeling investigations

    J. Mol. Liq.

    (2018 Jan 1)
  • N.A. Al-Shabib et al.

    Exploring the mode of binding between food additive “butylated hydroxytoluene (BHT)” and human serum albumin: spectroscopic as well as molecular docking study

    J. Mol. Liq.

    (2017 Mar 1)
  • J.M. Khan et al.

    Cationic gemini surfactant (16-4-16) interact electrostatically with anionic plant lectin and facilitates amyloid fibril formation at neutral pH

    Colloids Surf. A Physicochem. Eng. Asp.

    (2017 Jun 5)
  • M. Bar-Zeev et al.

    Targeted nanomedicine for cancer therapeutics: towards precision medicine overcoming drug resistance

    Drug Resist. Updat.

    (2017 Mar 1)
  • Y. Ye et al.

    Nano-SiO2 induces apoptosis via activation of p53 and Bax mediated by oxidative stress in human hepatic cell line

    Toxicol. in Vitro

    (2010 Apr 1)
  • A.T. Bauer et al.

    Cytotoxicity of silica nanoparticles through exocytosis of von Willebrand factor and necrotic cell death in primary human endothelial cells

    Biomaterials

    (2011 Nov 1)
  • A. Tarantini et al.

    Toxicity, genotoxicity and proinflammatory effects of amorphous nanosilica in the human intestinal Caco-2 cell line

    Toxicol. in Vitro

    (2015 Mar 1)
  • H.A. Zeinabad et al.

    Interaction of single and multi-wall carbon nanotubes with the biological systems: tau protein and PC12 cells as targets

    Sci. Rep.

    (2016)
  • H.A. Zeinabad et al.

    Thermodynamic and conformational changes of protein toward interaction with nanoparticles: a spectroscopic overview

    RSC Adv.

    (2016)
  • D. Ling et al.

    A general strategy for site-directed enzyme immobilization by using NiO nanoparticle decorated mesoporous silica

    Chem. Eur. J.

    (2014 Jun 23)
  • L. Momeni et al.

    Spectroscopic analysis of the interaction between NiO nanoparticles and bovine trypsin

    J. Biomol. Struct. Dyn.

    (2016 Jul 30)
  • F. Pasbanziyarat et al.

    Probing the interaction of lysozyme with ciprofloxacin in the presence of different-sized Ag nano-particles by multispectroscopic techniques and isothermal titration calorimetry

    J. Biomol. Struct. Dyn.

    (2014 Apr 3)
  • O. Vilanova et al.

    Understanding the kinetics of protein–nanoparticle corona formation

    ACS Nano

    (2016 Dec 27)
  • S. Tenzer et al.

    Rapid formation of plasma protein corona critically affects nanoparticle pathophysiology

    Nat. Nanotechnol.

    (2013 Oct 1)
  • C.D. Walkey et al.

    Protein corona fingerprinting predicts the cellular interaction of gold and silver nanoparticles

    ACS Nano

    (2014 Feb 25)
  • I. Radauer-Preiml et al.

    Nanoparticle-allergen interactions mediate human allergic responses: protein corona characterization and cellular responses

    Part. Fibre Toxicol.

    (2016 Jan 16)
  • C. Gunawan et al.

    Nanoparticle–protein corona complexes govern the biological fates and functions of nanoparticles

    J. Mater. Chem. B

    (2014)
  • Cited by (15)

    • Tin oxide nanoparticles trigger the formation of amyloid β oligomers/protofibrils and underlying neurotoxicity as a marker of Alzheimer's diseases

      2022, International Journal of Biological Macromolecules
      Citation Excerpt :

      Then, a protein corona forms on the surface of the NPs [4–6]. For example, previously, it was found that that silver NPs [6], single-wall and multi-walls carbon nanotubes [7], titanium oxide NPs [8], aluminum NPs [9], silica NPs [10], and nickel oxide NPs [11] are able to interact with central nervous systems' proteins leading to some structural changes. Amyloid β (Aβ) has an important role in short, long-term memory and learning [12,13], with a random coil structure [14].

    • The application of multifunctional nanomaterials in Alzheimer's disease: A potential theranostics strategy

      2021, Biomedicine and Pharmacotherapy
      Citation Excerpt :

      Furthermore, Al2O3 NPs elicited cell death via membrane leakage, caspase-9/-3 activation, and induction of both apoptosis and necrosis [169]. SiO2-NPs bound to Tau with high affinity through hydrogen bonds and van der Waals interactions and caused PC12 cell death via apoptosis as well as necrosis [170]. Silica nanoparticles (Si-NPs) induced intrinsic apoptosis in SH-SY5Y cells via the CytC/Apaf-1 pathway [171].

    • The dual effect of natural organic matter on the two-step internalization process of Au@Sio<inf>2</inf> in freshwater

      2020, Water Research
      Citation Excerpt :

      Au@SiO2 has a large number of silanol functional groups on its surface, which can act as both a hydrogen bond donor and a hydrogen bond acceptor (Delle Piane et al. 2018). This gives the outer SiO2 layer the propensity to interact with the surface-exposed functional groups such as phosphates, carboxylic acids and amines in the cell membrane through van der Waals forces and hydrogen bonding (Delle Piane et al. 2018; Mathelie-Guinlet et al., 2017; Shariati et al., 2018). β-lactoglobulin, BSA and HA reduced the amount of Au@SiO2 which adhered onto the cell membrane by 84.7%, 80.1% and 55.6%, respectively (Fig.S4).

    View all citing articles on Scopus
    1

    These authors contributed equally to this work.

    View full text