Anisotropic Gold Nanostructures: Optimization via in Silico Modeling for Hyperthermia Ajay Vikram Singh,* ,†,#,∥ Timotheus Jahnke, §,∥ Shuo Wang, †,§,∥ Yang Xiao, †,§ Yunus Alapan, † Soheila Kharratian, ⊥ Mehmet Cengiz Onbasli, ¶ Kristen Kozielski, † Hilda David, ‡ Gunther Richter, ‡ Joachim Bill, § Peter Laux, # Andreas Luch, # and Metin Sitti † † Physical Intelligence Department and ‡ CSF Thin Films Group, Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany § Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany ⊥ Department of Materials Science and Engineering and ¶ Department of Electrical and Electronics Engineering, Koç University, Sarıyer, 34450 Istanbul, Turkey # Department of Chemical and Product Safety, German Federal Institute for Risk Assessment (BfR), Max-Dohrn-Strasse 8-10, 10589 Berlin, Germany * S Supporting Information ABSTRACT: Protein- and peptide-based manufacturing of self-assembled supramolecular functional materials has been a formidable challenge for biomedical applications, being complex in structure and immunogenic in nature. In this context, self- assembly of short amino acid sequences as simplified building blocks to design metal−biomolecule frameworks (MBioFs) is an emerging field of research. Here, we report a facile, bioinspired route of anisotropic nanostructure synthesis using gold binding peptides (10−15mers) secreted by cancer cells. The bioinformatics tool i-TASSER predicts the effect of amino acid sequences on metal binding sites and the secondary structures of the respective peptide sequence. Electron microscopy, X-ray, infrared, and Raman spectroscopy validated the versatile anisotropic gold nanostructures and the metal−bioorganic nature of this biomineralization. We studied the influence of precursor salt, pH, and peptide concentration on the evolution of nanoleaf, nanoflower, nanofiber, and dendrimer-like anisotropic MBioFs. Characterization of photothermal properties using infrared laser (785 nm) revealed excellent conversion of light into heat. Exposure of bacterial cells in culture exhibits high rate of photothermal death using lower laser power (1.9 W/cm 2 ) compared with recent reports. The MBioF’s self-assembly process shown here can readily be extended and adapted to superior plasmonic material synthesis with a promising photothermal effect for in vivo biofilm destruction and cancer hyperthermia applications. KEYWORDS: metal−biomolecule frameworks, biomineralization, i-TASSER, photothermal effect, surface plasmon resonance M etal and polymeric nanoparticles (NPs) can be utilized in a wide range of biomedical applications due to their size- and shape-dependent biophysical and optoelectronic proper- ties. 1,2 Particularly, nanoparticles fabricated by using peptides containing short sequences of amino acids can synthesize spe- cific types of nanomaterials via controlled self-assembly. The physical and biochemical properties of these peptides are strongly dependent on constituent amino acids, which can be tailored for hydrophobicity, size, charge, and polarity. Non- covalent interactions such as π−π orbital interactions, van der Waals forces, ionic interactions, hydrogen bonding, and hydrophobicity predominantly control the self-assembly process of these short amino acid sequences. Manipulation of the environmental conditions as a function of covalent interactions has been used to fabricate versatile anisotropic protein/peptide nanostructures (e.g., nanocages, 3 nanogels, 4 nanovesicles, 5 nanoplates, 6 nanofibers, 7 nanotubes 8 ). Using this approach of fabricating self-assembled metal hybrid nanomaterials, novel properties can also emerge as a collective function of individual amino acid sequences. 9 Biological functionality and stability of these self-assembled peptides can be further improved via ligand Received: August 14, 2018 Accepted: October 26, 2018 Published: October 26, 2018 Article www.acsanm.org Cite This: ACS Appl. Nano Mater. XXXX, XXX, XXX-XXX © XXXX American Chemical Society A DOI: 10.1021/acsanm.8b01406 ACS Appl. Nano Mater. XXXX, XXX, XXX−XXX Downloaded via 142.147.106.27 on November 10, 2018 at 14:48:08 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.