Organophilic, Superparamagnetic, and Reversibly Thermoresponsive Silica-Polypeptide Core–Shell Particles

Journal Article · 22 October 2019 · Langmuir

DOI: https://doi.org/10.1021/acs.langmuir.9b01931 · OSTI ID:1632688

Turksen-Selcuk, Sibel ^[1]; Rosu, Cornelia  ^[2]; Blake, Alyssa ^[3]; Soto-Cantu, Erick ^[4]; Qiu, Jianhong ^[4]; Wu, Yan ^[4]; DiTusa, J. F. ^[4]; Steffens, Amanda ^[4]; Russo, Paul S.  ^[2]

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1. Louisiana State Univ., Baton Rouge, LA (United States); Louisiana State University
2. Louisiana State Univ., Baton Rouge, LA (United States); Georgia Inst. of Technology, Atlanta, GA (United States)
3. Georgia Inst. of Technology, Atlanta, GA (United States)
4. Louisiana State Univ., Baton Rouge, LA (United States)

Particles with a superparamagnetic cobalt inner core, silica outer core, and covalently bound homopolypeptide shell were investigated under thermal and magnetic stimuli. The homopolypeptide was poly(ε-carbobenzyloxy-l-lysine), PCBL, which is known to exhibit a thermoreversible coil ⇔ helix transition when dissolved as a pure polymer in m-cresol. Tethering to a core particle did not prevent PCBL from undergoing this conformational transition, as confirmed by dynamic light scattering and optical rotation, but the transition was broadened compared to that of the untethered polymer. The Co@SiO₂-PCBL hybrid particles retained the superparamagnetic properties of the cobalt inner nougat. Indeed, some response remains even after aging for >5 years. The aged PCBL shell also preserved its responsiveness to temperature, although differences in the shape of the size vs temperature transition curve were determined compared to the freshly made particles. A reversible coil ⇔ helix transition for a particle-bound polypeptide in a pure organic solvent is rare. Further to providing a convenient tool for characterizing coil ⇔ helix transitions for surface-bound polypeptides without interference from pH or the strong ionic forces that dominate behavior in aqueous systems, the Co@SiO₂-PCBL/m-cresol system may prove useful in studies of the effect of shell polymer conformation on colloid interactions. The stability of the magnetic core and polypeptide shell suggest a long shelf life for Co@SiO₂-PCBL, which can, in principle, be deprotected to yield positively charged Co@SiO₂-poly(l-lysine) particles for possible transfection or antimicrobial applications or chained magnetically to produce responsive poly(colloids).

• Research Organization: Louisiana State Univ., Baton Rouge, LA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
• Grant/Contract Number: SC0012432
• OSTI ID: 1632688
• Alternate ID(s): OSTI ID: 1676368
• Journal Information: Langmuir, Journal Name: Langmuir Journal Issue: 44 Vol. 35; ISSN 0743-7463
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English