Switchable length nanotubes from a self-assembling pH and thermosensitive linear l,d-peptide-polymer conjugate

Serena De Santis; Federica Novelli; Fabio Sciubba; Stefano Casciardi; Simona Sennato; Stefano Morosetti; Anita Scipioni; Giancarlo Masci

doi:10.1016/j.jcis.2019.03.093

Switchable length nanotubes from a self-assembling pH and thermosensitive linear l,d-peptide-polymer conjugate

J Colloid Interface Sci. 2019 Jul 1:547:256-266. doi: 10.1016/j.jcis.2019.03.093. Epub 2019 Mar 29.

Authors

Serena De Santis¹, Federica Novelli¹, Fabio Sciubba¹, Stefano Casciardi², Simona Sennato³, Stefano Morosetti¹, Anita Scipioni¹, Giancarlo Masci⁴

Affiliations

¹ Dipartimento di Chimica, Sapienza Università di Roma, P.le A. Moro, 5, I-00185 Rome, Italy.
² National Institute for Insurance against Accidents at Work (INAIL Research), Department of Occupational and Environmental Medicine, Epidemiology and Hygiene, Rome, Italy.
³ Institute for Complex Systems, National Research Council (ISC-CNR), Dipartimento di Fisica, Sapienza Università di Roma, P.le A. Moro, 2 00185 Rome, Italy.
⁴ Dipartimento di Chimica, Sapienza Università di Roma, P.le A. Moro, 5, I-00185 Rome, Italy. Electronic address: giancarlo.masci@uniroma1.it.

PMID: 30954769
DOI: 10.1016/j.jcis.2019.03.093

Abstract

Preparation and characterization of a pH and thermosensitive linear l,d-octapeptide-poly(dimethylamino ethyl methacrylate) ((l-Val-d-Val)₄-PDMAEMA) conjugate is reported. The hydrophobic uncharged linear (l-Val-d-Val)₄ octapeptide was designed to self-assemble in nanotubes by exploiting the tubular self-assembling properties of linear peptides with regularly alternating enantiomeric sequences. pH and thermosensitive PDMAEMA was obtained by atom transfer radical polymerization (ATRP). The conjugate was prepared by click-chemistry on the solid phase synthetized peptide. Because of the strong interactions between the peptide moieties, long single channel nanotubes (0.2-1.5 μm) are formed also at acidic pH with the fully charged polymer. At 25 °C and basic pH the size of the nanotubes did not change significantly. In basic conditions and temperature above the PDMAEMA lower critical solution temperature (LCST) a significant increase of the length of the nanotubes up to several micrometers is observed. The size is retained for several days after cooling back to room temperature. Sonication significantly reduces the nanotube length (0.2-0.5 μm) forming low polydisperse nanotubes. The elongation of the nanotubes is fully reversible by restoring acidic pH. This is the first example, to our knowledge, of thermosensitive peptide-polymer single channel nanotubes with length that can be varied from hundreds of nanometers to several micrometers.

Keywords: Linear l,d-octapeptide; Nanotubes; Poly(dimethylamino ethyl methacrylate) (PDMAEMA); Self–assembly; Thermosensitive; pH-sensitive.