Skip to main content

Advertisement

SpringerLink
Log in

Evaluation interaction of graphene oxide with heparin for antiviral blockade: a study of ab initio simulations, molecular docking, and experimental analysis

  • Original Paper
  • Published:
Journal of Molecular Modeling Aims and scope Submit manuscript

Abstract

Context

Heparin, one of the drugs reused in studies with antiviral activity, was chosen to investigate a possible blockade of the SARS-CoV-2 spike protein for viral entry through computational simulations and experimental analysis. Heparin was associated to graphene oxide to increase in the binding affinity in biological system. First, the electronic and chemical interaction between the molecules was analyzed through ab initio simulations. Later, we evaluate the biological compatibility of the nanosystems, in the target of the spike protein, through molecular docking. The results show that graphene oxide interacts with the heparin with an increase in the affinity energy with the spike protein, indicating a possible increment in the antiviral activity. Experimental analysis of synthesis and morphology of the nanostructures were carried out, indicating heparin absorption by graphene oxide, confirming the results of the first principle simulations. Experimental tests were conducted on the structure and surface of the nanomaterial, confirming the heparin aggregation on the synthesis with a size between the GO layers of 7.44 Å, indicating a C–O type bond, and exhibiting a hydrophilic surface characteristic (36.2°).

Methods

Computational simulations of the ab initio with SIESTA code, LDA approximations, and an energy shift of 0.05 eV. Molecular docking simulations were performed in the AutoDock Vina software integrated with the AMDock Tools Software using the AMBER force field. GO, GO@2.5Heparin, and GO@5Heparin were synthesized by Hummers and impregnation methods, respectively, and characterized by X-ray diffraction and surface contact angle.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12

Similar content being viewed by others

References

  1. Hopkins J (2022) Coronavirus Resource Center. https://coronavirus.jhu.edu/map.html

  2. Wang D, Li Z, Liu Y (2020) An overview of the safety, clinical application and antiviral research of the COVID-19 therapeutics. J Infect Public Health 13:1405–1414. https://doi.org/10.1016/j.jiph.2020.07.004

    Article  PubMed  PubMed Central  Google Scholar 

  3. Rhazouani A, Aziz K, Gamrani H et al (2021) Can the application of graphene oxide contribute to the fight against COVID-19? Antiviral activity, diagnosis and prevention. Curr Res Pharmacol Drug Discov 2:100062. https://doi.org/10.1016/j.crphar.2021.100062

    Article  PubMed  PubMed Central  Google Scholar 

  4. Gupta I, Azizighannad S, Farinas ET, Mitra S (2021) Antiviral properties of select carbon nanostructures and their functionalized analogs. Mater Today Commun 29:102743. https://doi.org/10.1016/j.mtcomm.2021.102743

    Article  CAS  Google Scholar 

  5. Seifi T, Reza Kamali A (2021) Antiviral performance of graphene-based materials with emphasis on COVID-19: a review. Med Drug Discov 11:100099. https://doi.org/10.1016/j.medidd.2021.100099

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. Shafiee A, Iravani S, Varma RS (2022) Graphene and graphene oxide with anticancer applications: challenges and future perspectives. MedComm (Beijing) 3. https://doi.org/10.1002/mco2.118

  7. Dacrory S (2021) Antimicrobial Activity, DFT Calculations, and molecular docking of dialdehyde cellulose/graphene oxide film against Covid-19. J Polym Environ 29:2248–2260. https://doi.org/10.1007/s10924-020-02039-5

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  8. Fukuda M, Islam MS, Shimizu R et al (2021) Lethal interactions of SARS-CoV-2 with graphene oxide: implications for COVID-19 treatment. ACS Appl Nano Mater 4:11881–11887. https://doi.org/10.1021/acsanm.1c02446

    Article  CAS  Google Scholar 

  9. Unal MA, Bayrakdar F, Nazir H et al (2021) Graphene oxide nanosheets interact and interfere with SARS-CoV-2 surface proteins and cell receptors to inhibit infectivity. Small 17:2101483. https://doi.org/10.1002/smll.202101483

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Wang J, Yu Y, Leng T et al (2022) The inhibition of SARS-CoV-2 3CL Mpro by graphene and its derivatives from molecular dynamics simulations. ACS Appl Mater Interfaces 14:191–200. https://doi.org/10.1021/acsami.1c18104

    Article  CAS  PubMed  Google Scholar 

  11. Seabra AB, Paula AJ, de Lima R et al (2014) Nanotoxicity of graphene and graphene oxide. Chem Res Toxicol 27:159–168. https://doi.org/10.1021/tx400385x

    Article  CAS  PubMed  Google Scholar 

  12. Clausen TM, Sandoval DR, Spliid CB et al (2020) SARS-CoV-2 Infection depends on cellular heparan sulfate and ACE2. Cell 183:1043–1057.e15. https://doi.org/10.1016/j.cell.2020.09.033

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  13. Gupta Y, Maciorowski D, Zak SE et al (2021) Heparin: a simplistic repurposing to prevent SARS-CoV-2 transmission in light of its in-vitro nanomolar efficacy. Int J Biol Macromol 183:203–212. https://doi.org/10.1016/j.ijbiomac.2021.04.148

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  14. Mycroft-West CJ, Su D, Pagani I et al (2020) Heparin inhibits cellular invasion by SARS-CoV-2: structural dependence of the interaction of the Spike S1 receptor-binding domain with heparin. Thromb Haemost 120:1700–1715. https://doi.org/10.1055/s-0040-1721319

    Article  PubMed  PubMed Central  Google Scholar 

  15. Tandon R, Sharp JS, Zhang F et al (2021) Effective inhibition of SARS-CoV-2 entry by heparin and enoxaparin derivatives. J Virol 95. https://doi.org/10.1128/JVI.01987-20

  16. Alzain AA, Elbadwi FA, Alsamani FO (2022) Discovery of novel TMPRSS2 inhibitors for COVID-19 using in silico fragment-based drug design, molecular docking, molecular dynamics, and quantum mechanics studies. Inform Med Unlocked 29:100870. https://doi.org/10.1016/j.imu.2022.100870

    Article  PubMed  PubMed Central  Google Scholar 

  17. Ridgway H, Moore GJ, Mavromoustakos T et al (2022) Discovery of a new generation of angiotensin receptor blocking drugs: receptor mechanisms and in silico binding to enzymes relevant to SARS-CoV-2. Comput Struct Biotechnol J 20:2091–2111. https://doi.org/10.1016/j.csbj.2022.04.010

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  18. Ghosh K, SkA A, Gayen S, Jha T (2021) Chemical-informatics approach to COVID-19 drug discovery: exploration of important fragments and data mining based prediction of some hits from natural origins as main protease (Mpro) inhibitors. J Mol Struct 1224:129026. https://doi.org/10.1016/j.molstruc.2020.129026

    Article  CAS  PubMed  Google Scholar 

  19. Ongtanasup T, Wanmasae S, Srisang S et al (2022) In silico investigation of ACE2 and the main protease of SARS-CoV-2 with phytochemicals from Myristica fragrans (Houtt.) for the discovery of a novel COVID-19 drug. Saudi. J Biol Sci 29:103389. https://doi.org/10.1016/j.sjbs.2022.103389

    Article  CAS  Google Scholar 

  20. Gangadharan S, Ambrose JM, Rajajagadeesan A et al (2022) Repurposing of potential antiviral drugs against RNA-dependent RNA polymerase of SARS-CoV-2 by computational approach. J Infect Public Health 15:1180–1191. https://doi.org/10.1016/j.jiph.2022.09.007

    Article  PubMed  PubMed Central  Google Scholar 

  21. Santos AF dos, Ortiz MM, Montagner GE, et al (2022) In-silico study of antivirals and non-antivirals for the treatment of SARS-COV-2. Disciplinarum Scientia 23:57–83. https://doi.org/10.37779/nt.v23i2.4200

  22. Schultz JV, Tonel MZ, Martins MO, Fagan SB (2023) Graphene oxide and flavonoids as potential inhibitors of the spike protein of SARS-CoV-2 variants and interaction between ligands: a parallel study of molecular docking and DFT. Struct Chem. https://doi.org/10.1007/s11224-023-02135-x

  23. Hohenberg P, Kohn W (1964) Inhomogeneous electron gas. Phys Rev 136:B864–B871. https://doi.org/10.1103/PhysRev.136.B864

    Article  Google Scholar 

  24. Perdew JP, Zunger A (1981) Self-interaction correction to density-functional approximations for many-electron systems. Phys Rev B 23:5048–5079. https://doi.org/10.1103/PhysRevB.23.5048

    Article  CAS  Google Scholar 

  25. ICMAB (2020) Instituto de Ciência de Materiais de Barcelona. https://departments.icmab.es/leem/siesta/

  26. Soler JM, Artacho E, Gale JD et al (2002) The SIESTA method for ab initio order- N materials simulation. J Phys : Condensed Matter 14:2745–2779. https://doi.org/10.1088/0953-8984/14/11/302

    Article  CAS  Google Scholar 

  27. García A, Papior N, Akhtar A et al (2020) Siesta : recent developments and applications. J Chem Phys 152:204108. https://doi.org/10.1063/5.0005077

    Article  CAS  PubMed  Google Scholar 

  28. Jauris IM, Matos CF, Saucier C et al (2016) Adsorption of sodium diclofenac on graphene: a combined experimental and theoretical study. Phys Chemist Chem Phys 18:1526–1536. https://doi.org/10.1039/C5CP05940B

    Article  CAS  Google Scholar 

  29. Machado FM, Carmalin SA, Lima EC et al (2016) Adsorption of alizarin Red S dye by carbon nanotubes: an experimental and theoretical investigation. J Phys Chem C 120:18296–18306. https://doi.org/10.1021/acs.jpcc.6b03884

    Article  CAS  Google Scholar 

  30. Jauris IM, Fagan SB, Adebayo MA, Machado FM (2016) Adsorption of acridine orange and methylene blue synthetic dyes and anthracene on single wall carbon nanotubes: a first principle approach. Comput Theor Chem 1076:42–50. https://doi.org/10.1016/j.comptc.2015.11.021

    Article  CAS  Google Scholar 

  31. Hernández Rosas JJ, Ramírez Gutiérrez RE, Escobedo-Morales A, Chigo Anota E (2011) First principles calculations of the electronic and chemical properties of graphene, graphane, and graphene oxide. J Mol Model 17:1133–1139. https://doi.org/10.1007/s00894-010-0818-1

    Article  CAS  PubMed  Google Scholar 

  32. de Moraes EE, Tonel MZ, Fagan SB, Barbosa MC (2019) Density functional theory study of π-aromatic interaction of benzene, phenol, catechol, dopamine isolated dimers and adsorbed on graphene surface. J Mol Model 25:302. https://doi.org/10.1007/s00894-019-4185-2

    Article  CAS  PubMed  Google Scholar 

  33. Tournus F, Charlier J-C (2005) Ab initio study of benzene adsorption on carbon nanotubes. Phys Rev B 71:165421. https://doi.org/10.1103/PhysRevB.71.165421

    Article  CAS  Google Scholar 

  34. Tournus F, Latil S, Heggie MI, Charlier J-C (2005) π-stacking interaction between carbon nanotubes and organic molecules. Phys Rev B 72:075431. https://doi.org/10.1103/PhysRevB.72.075431

    Article  CAS  Google Scholar 

  35. Li B, Ou P, Wei Y et al (2018) Polycyclic aromatic hydrocarbons adsorption onto graphene: a DFT and AIMD study. Materials 11:726. https://doi.org/10.3390/ma11050726

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  36. Arrigoni M, Madsen GKH (2019) Comparing the performance of LDA and GGA functionals in predicting the lattice thermal conductivity of III-V semiconductor materials in the zincblende structure: the cases of AlAs and BAs. Comput Mater Sci 156:354–360. https://doi.org/10.1016/j.commatsci.2018.10.005

    Article  CAS  Google Scholar 

  37. Cresti A, Lopez-Bezanilla A, Ordejón P, Roche S (2011) Oxygen surface functionalization of graphene nanoribbons for transport gap engineering. ACS Nano 5:9271–9277. https://doi.org/10.1021/nn203573y

    Article  CAS  PubMed  Google Scholar 

  38. Trott O, Olson AJ (2009) AutoDock Vina: improving the speed and accuracy of docking with a new scoring function, efficient optimization, and multithreading. J Comput Chem NA-NA. https://doi.org/10.1002/jcc.21334

  39. Martins MO, Silva IZ da, Fagan SB, Santos AF dos (2021) Docking fundamentals for simulation in nanoscience. Disciplinarum Scientia 22:67–76. https://doi.org/10.37779/nt.v22i3.4106

  40. Bell EW, Zhang Y (2019) DockRMSD: an open-source tool for atom mapping and RMSD calculation of symmetric molecules through graph isomorphism. J Cheminform 11:40. https://doi.org/10.1186/s13321-019-0362-7

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  41. Humphrey W, Dalke A, Schulten K (1996) VMD: visual molecular dynamics. J Mol Graph 14:33–38. https://doi.org/10.1016/0263-7855(96)00018-5

    Article  CAS  PubMed  Google Scholar 

  42. Dassault Systèmes (2023) Biovia Discovery Studio

  43. Valdés-Tresanco MS, Valdés-Tresanco ME, Valiente PA, Moreno E (2020) AMDock: a versatile graphical tool for assisting molecular docking with Autodock Vina and Autodock4. Biol Direct 15:12. https://doi.org/10.1186/s13062-020-00267-2

    Article  PubMed  PubMed Central  Google Scholar 

  44. van Dijk ADJ, Bonvin AMJJ (2006) Solvated docking: introducing water into the modelling of biomolecular complexes. Bioinformatics 22:2340–2347. https://doi.org/10.1093/bioinformatics/btl395

    Article  PubMed  Google Scholar 

  45. Pubchem (2022) Pubchem. https://pubchem.ncbi.nlm.nih.gov/compound/5288499. Accessed 2 Oct 2022

    Google Scholar 

  46. Chemcraft (2022) Chemcraft - graphical software for visualization of quantum chemistry computationsy. . https://www.chemcraftprog.com. Accessed 5 Dec 2022

    Google Scholar 

  47. PDB Protein Data Bank (2020) SARS-CoV-2 spike ectodomain structure (open state). https://www.rcsb.org/structure/6VYB

  48. PDB Protein Data Bank (2022) SARS-CoV-2 Omicron BA.4 variant spike. https://www.rcsb.org/structure/7XNQ

  49. Hummers WS, Offeman RE (1958) Preparation of graphitic oxide. J Am Chem Soc 80:1339–1339. https://doi.org/10.1021/ja01539a017

    Article  CAS  Google Scholar 

  50. Moraes FC, Rossi B, Donatoni MC et al (2015) Sensitive determination of 17β-estradiol in river water using a graphene based electrochemical sensor. Anal Chim Acta 881:37–43. https://doi.org/10.1016/j.aca.2015.04.043

    Article  CAS  PubMed  Google Scholar 

  51. Ahmad W, Mehmood U, Al-Ahmed A et al (2016) Synthesis of zinc oxide/titanium dioxide (ZnO/TiO2) nanocomposites by wet incipient wetness impregnation method and preparation of ZnO/TiO2 paste using poly(vinylpyrrolidone) for efficient dye-sensitized solar cells. Electrochim Acta 222:473–480. https://doi.org/10.1016/j.electacta.2016.10.200

    Article  CAS  Google Scholar 

  52. Le GTT, Chanlek N, Manyam J et al (2019) Insight into the ultrasonication of graphene oxide with strong changes in its properties and performance for adsorption applications. Chem Eng J 373:1212–1222. https://doi.org/10.1016/j.cej.2019.05.108

    Article  CAS  Google Scholar 

  53. Silva CC, Graça MPF, Valente MA, Sombra ASB (2007) Crystallite size study of nanocrystalline hydroxyapatite and ceramic system with titanium oxide obtained by dry ball milling. J Mater Sci 42:3851–3855. https://doi.org/10.1007/s10853-006-0474-0

    Article  CAS  Google Scholar 

  54. De Rosa C, Auriemma F (2013) Crystals and crystallinity in polymers: diffraction analysis of ordered and disordered crystals. Wiley

    Book  Google Scholar 

  55. Bursulaya BD, Totrov M, Abagyan R, Brooks III CL (2003) Comparative study of several algorithms for flexible ligand docking. J Comput Aided Mol Des 17:755–763. https://doi.org/10.1023/B:JCAM.0000017496.76572.6f

    Article  CAS  PubMed  Google Scholar 

  56. Krishnamoorthy K, Veerapandian M, Yun K, Kim S-J (2013) The chemical and structural analysis of graphene oxide with different degrees of oxidation. Carbon N Y 53:38–49. https://doi.org/10.1016/j.carbon.2012.10.013

    Article  CAS  Google Scholar 

  57. Siburian R, Sihotang H, Lumban Raja S et al (2018) New route to synthesize of graphene nano sheets. Oriental Journal of Chemistry 34:182–187. https://doi.org/10.13005/ojc/340120

    Article  CAS  Google Scholar 

  58. Bureau MN, Denault J, Cole KC, Enright GD (2002) The role of crystallinity and reinforcement in the mechanical behavior of polyamide-6/clay nanocomposites. Polym Eng Sci 42:1897–1906. https://doi.org/10.1002/pen.11082

    Article  CAS  Google Scholar 

  59. Kim B-H, Lee S-H, Han S-W et al (2016) Anatomy of high recyclability of graphene oxide based palladium nanocomposites in the Sonogashira reaction: on the nature of the catalyst deactivation. Mater Express 6:61–68. https://doi.org/10.1166/mex.2016.1280

    Article  CAS  Google Scholar 

  60. Kang W-S, Rhee KY, Park S-J (2017) Influence of surface energetics of graphene oxide on fracture toughness of epoxy nanocomposites. Compos B Eng 114:175–183. https://doi.org/10.1016/j.compositesb.2017.01.032

    Article  CAS  Google Scholar 

  61. Fu J, Ji J, Yuan W, Shen J (2005) Construction of anti-adhesive and antibacterial multilayer films via layer-by-layer assembly of heparin and chitosan. Biomaterials 26:6684–6692. https://doi.org/10.1016/j.biomaterials.2005.04.034

    Article  CAS  PubMed  Google Scholar 

  62. Pietsch T, Gindy N, Fahmi A (2009) Nano- and micro-sized honeycomb patterns through hierarchical self-assembly of metal-loaded diblock copolymer vesicles. Soft Matter 5:2188–2197. https://doi.org/10.1039/B814061H

    Article  CAS  Google Scholar 

  63. Zheng Y, Zaoui A (2017) Wetting and nanodroplet contact angle of the clay 2:1 surface: the case of Na-montmorillonite (001). Appl Surf Sci 396:717–722. https://doi.org/10.1016/j.apsusc.2016.11.015

    Article  CAS  Google Scholar 

  64. Tang K, Yu J, Zhao Y et al (2006) Fabrication of super-hydrophobic and super-oleophilic boehmite membranes from anodic alumina oxide film via a two-phase thermal approach. J Mater Chem 16:1741. https://doi.org/10.1039/b600733c

    Article  CAS  Google Scholar 

Download references

Acknowledgements

Acknowledgment for computational support from CENAPAD-SP (National Center for High-Performance Processing in São Paulo).

Funding

This work was carried out with the support of the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-Brazil (CAPES) Financing Code 001, TELEMEDICINA 1690389P, INCT Nanomateriais de Carbono (CNPq).

Author information

Authors and Affiliations

  1. Postgraduate Program in Nanoscience: Laboratory of Simulation and Modeling of Nanomaterials-LASIMON, Franciscan University-UFN, Andradas Street, 1614, Santa Maria, RS, 97010-030, Brazil

    André Flores dos Santos, Mirkos Ortiz Martins, Sérgio Roberto Mortari, Daniel Moro Druzian, Mariana Zancan Tonel, Ivana Zanella da Silva & Solange Binotto Fagan

  2. Institute of Biological Sciences, Federal University of Pará-UFPA, Belém, PA, Brazil

    Jerônimo Lameira & Jéssica de Oliveira Araújo

  3. Postgraduate Program in Chemical Engineering-PosENQ, Federal University of Santa Catarina-UFSC, Florianopolis, SC, Brazil

    Marcela Sagrilo Frizzo

  4. Postgraduate Program in Nanosciences: Laboratory of Cell Culture and Bioactive Effects, Franciscan University-UFN, Santa Maria, RS, Brazil

    Carolina Bordin Davidson, Diulie Valente de Souza & Alencar Kolinski Machado

Authors
  1. André Flores dos Santos
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Mirkos Ortiz Martins
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Jerônimo Lameira
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Jéssica de Oliveira Araújo
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Marcela Sagrilo Frizzo
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Carolina Bordin Davidson
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Diulie Valente de Souza
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Alencar Kolinski Machado
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Sérgio Roberto Mortari
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Daniel Moro Druzian
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Mariana Zancan Tonel
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Ivana Zanella da Silva
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. Solange Binotto Fagan
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

AFS, MOM, DMD, JSL, CBD, and MZT developed the conception and design of the study. AKM, CBD, and DVL developed the methodology and are conducting safety and efficacy tests with cells. DMD, SRM, and MSF developed the methodology and performed compound characterization tests. AFS, MOM, MZT, JSL, and JOA performed computer simulations. AFS, MZT, JOA, CBD, AKM, and DVS reviewed the images and wrote the article under the supervision of IZS, SF, and SRM. AFS, JOA, JSL, and DMD reviewed the results. All authors reviewed and commented on the manuscript. All authors approved the final manuscript.

Corresponding author

Correspondence to André Flores dos Santos.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

This paper belongs to the Topical Collection IX Symposium on Electronic Structure and Molecular Dynamics – IX SeedMol

Supplementary Material

Video 1 of version 01 of the ab initio simulation results. (MPG 1339 kb)

Video 2 of version 02 of the ab initio simulation results. (MPG 3968 kb)

Video 3 of version 03 of the ab initio simulation results. (MPG 870 kb)

Video 4 of version 04 of the ab initio simulation results. (MPG 4700 kb)

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

dos Santos, A.F., Martins, M.O., Lameira, J. et al. Evaluation interaction of graphene oxide with heparin for antiviral blockade: a study of ab initio simulations, molecular docking, and experimental analysis. J Mol Model 29, 235 (2023). https://doi.org/10.1007/s00894-023-05645-x

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s00894-023-05645-x

Keywords

Search

Navigation