title: Thermoresponsive and Mechanical Properties of Poly(L-proline) Gels.
abstract: Gelation of the left helical N-substituted homopolypeptide poly(L-proline) (PLP) in water was explored, employing rheological and small-angle scattering studies at different temperatures and concentrations in order to investigate the network structure and its mechanical properties. Stiff gels were obtained at 10 wt % or higher at 5 °C, the first time gelation has been observed for homopolypeptides. The secondary structure and helical rigidity of PLP has large structural similarities to gelatin but as gels the two materials show contrasting trends with temperature. With increasing temperature in D2O, the network stiffens, with broad scattering features of similar correlation length for all concentrations and molar masses of PLP. A thermoresponsive transition was also achieved between 5 and 35 °C, with moduli at 35 °C higher than gelatin at 5 °C. The brittle gels could tolerate strains of 1% before yielding with a frequency-independent modulus over the observed range, similar to natural proline-rich proteins, suggesting the potential for thermoresponsive or biomaterial-based applications.
authors.affiliation: Department of Chemical Engineering and ‡Department of Biological Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Manos
authors.initials: M
authors.lastname: Gkikas
authors.affiliation: Department of Chemical Engineering and ‡Department of Biological Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Reginald K
authors.initials: RK
authors.lastname: Avery
authors.affiliation: Department of Chemical Engineering and ‡Department of Biological Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Bradley D
authors.initials: BD
authors.lastname: Olsen
mesh_terms: D055119:Elastic Modulus; D005782:Gels; D006860:Hydrogen Bonding; D007700:Kinetics; D033363:Neutron Diffraction; D010455:Peptides / Q000737:chemistry*; D058105:Polymerization; D017433:Protein Structure, Secondary; D053838:Scattering, Small Angle; D012996:Solutions; D044366:Transition Temperature; D014783:Viscosity
chemical_list: D005782:Gels; D010455:Peptides; D012996:Solutions; C011083:polyproline