Elucidating Protein Involvement in the Stabilization of the Biogenic Silver Nanoparticles

Author(s)

Ballottin, Daniela ^{[1, 2]} ; Fulaz, Stephanie ^[1] ; Souza, Michele L. ^{[3, 4]} ; Corio, Paola ^[3] ; Rodrigues, Alexandre G. ^[5] ; Souza, Ana O. ^[5] ; Gaspari, Priscyla M. ^[6] ; Gomes, Alexandre F. ^[7] ; Gozzo, Fabio ^[7] ; Tasic, Ljubica ^{[1, 2]}

Affiliation

^[1] Univ Estadual Campinas, Inst Quim, Lab Quim Biol, Campinas, SP - Brazil

^[2] Univ Estadual Campinas, SisNano, NanoBioss, Campinas, SP - Brazil

^[3] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Sao Paulo, SP - Brazil

^[4] Univ Fed Fluminense, Inst Ciencias Exatas, Volta Redonda, RJ - Brazil

^[5] Inst Butantan, Lab Bioquim & Biofis, Sao Paulo, SP - Brazil

^[6] Univ Sao Paulo, Fa Ciencias Farmaceaut, Lab Nanobiotecnol, Ribeirao Preto, SP - Brazil

^[7] Univ Estadual Campinas, Inst Quim, Lab Dalton, Campinas, SP - Brazil

• Document type: Journal article
• Source: NANOSCALE RESEARCH LETTERS; v. 11, JUN 29 2016.
• Web of Science Citations: 14

Abstract

Silver nanoparticles (AgNPs) have been broadly used as antibacterial and antiviral agents. Further, interests for green AgNP synthesis have increased in recent years and several results for AgNP biological synthesis have been reported using bacteria, fungi and plant extracts. The understanding of the role and nature of fungal proteins, their interaction with AgNPs and the subsequent stabilization of nanosilver is yet to be deeply investigated. Therefore, in an attempt to better understand biogenic AgNP stabilization with the extracellular fungal proteins and to describe these supramolecular interactions between proteins and silver nanoparticles, AgNPs, produced extracellularly by Aspergillus tubingensis-isolated as an endophytic fungus from Rizophora mangle-were characterized in order to study their physical characteristics, identify the involved proteins, and shed light into the interactions among protein-NPs by several techniques. AgNPs of around 35 nm in diameter as measured by TEM and a positive zeta potential of +8.48 mV were obtained. These AgNPs exhibited a surface plasmon resonance (SPR) band at 440 nm, indicating the nanoparticles formation, and another band at 280 nm, attributed to the electronic excitations in tryptophan, tyrosine, and/or phenylalanine residues in fungal proteins. Fungal proteins were covalently bounded to the AgNPs, mainly through S-Ag bonds due to cysteine residues (HS-) and with few N-Ag bonds from H2N-groups, as verified by Raman spectroscopy. Observed supramolecular interactions also occur by electrostatic and other protein-protein interactions. Furthermore, proteins that remain free on AgNP surface may perform hydrogen bonds with other proteins or water increasing thus the capping layer around the AgNPs and consequently expanding the hydrodynamic diameter of the particles (similar to 264 nm, measured by DLS). FTIR results enabled us to state that proteins adsorbed to the AgNPs did not suffer relevant secondary structure alteration upon their physical interaction with the AgNPs or when covalently bonded to them. Eight proteins in the AgNP dispersion were identified by mass spectrometry analyses. All these proteins are involved in metabolic pathways of the fungus and are important for carbon, phosphorous and nitrogen uptake, and for the fungal growth. Thereby, important proteins for fungi are also involved in the formation and stabilization of the biogenic AgNPs. (AU)

• FAPESP's process: 12/13119-3 - Vibrational spectroscopy in condensed phases
• Grantee: Mauro Carlos Costa Ribeiro
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 11/00222-8 - CHARACTERIZATION OF SILVER NANOPARTICLES AND THEIR APPLICATION IN THE PRODUCTION OF ANTIMICROBIAL FABRIC
• Grantee: Daniela Pott Marinho Ballottin
• Support Opportunities: Scholarships in Brazil - Doctorate