Comparison of α-Helix and β-Sheet Structure Adaptation to a Quantum Dot Geometry: Toward the Identification of an Optimal Motif for a Protein Nanoparticle Cover

Katarzyna Kopeć; Marta Pędziwiatr; Dominik Gront; Olga Sztatelman; Jakub Sławski; Magdalena Łazicka; Remigiusz Worch; Katarzyna Zawada; Katerina Makarova; Marcin Nyk; Joanna Grzyb

doi:10.1021/acsomega.9b00505

Comparison of α-Helix and β-Sheet Structure Adaptation to a Quantum Dot Geometry: Toward the Identification of an Optimal Motif for a Protein Nanoparticle Cover

ACS Omega. 2019 Aug 5;4(8):13086-13099. doi: 10.1021/acsomega.9b00505. eCollection 2019 Aug 20.

Authors

Affiliations

¹ Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, PL02668 Warsaw, Poland.
² Faculty of Chemistry, University of Warsaw, Pasteura 1, PL02093 Warsaw, Poland.
³ Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, PL02106 Warsaw, Poland.
⁴ Department of Biophysics, Faculty of Biotechnology, University of Wrocław, F. Joliot-Curie Street 14a, PL50383 Wrocław, Poland.
⁵ Department of Metabolic Regulation, Institute of Biochemistry, Faculty of Biology, University of Warsaw, Miecznikowa 1, PL02096 Warsaw, Poland.
⁶ Department of Physical Chemistry, Faculty of Pharmacy with the Laboratory Medicine Division, The Medical University of Warsaw, Banacha 1 Street, PL02097 Warsaw, Poland.
⁷ Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, PL50370 Wrocław, Poland.

Abstract

While quantum dots (QDs) are useful as fluorescent labels, their application in biosciences is limited due to the stability and hydrophobicity of their surface. In this study, we tested two types of proteins for use as a cover for spherical QDs, composed of cadmium selenide. Pumilio homology domain (Puf), which is mostly α-helical, and leucine-rich repeat (LRR) domain, which is rich in β-sheets, were selected to determine if there is a preference for one of these secondary structure types for nanoparticle covers. The protein sequences were optimized to improve their interaction with the surface of QDs. The solubilization of the apoproteins and their assembly with nanoparticles required the application of a detergent, which was removed in subsequent steps. Finally, only the Puf-based cover was successful enough as a QD hydrophilic cover. We showed that a single polypeptide dimer of Puf, PufPuf, can form a cover. We characterized the size and fluorescent properties of the obtained QD:protein assemblies. We showed that the secondary structure of the Puf proteins was not destroyed upon contact with the QDs. We demonstrated that these assemblies do not promote the formation of reactive oxygen species during illumination of the nanoparticles. The data represent advances in the effort to obtain a stable biocompatible cover for QDs.