TY - JOUR
T1 - Influence of Protamine Functionalization on the Colloidal Stability of 1D and 2D Titanium Oxide Nanostructures
AU - Rouster, Paul
AU - Pavlovic, Marko
AU - Horváth, Endre
AU - Forró, László
AU - Dey, Sandwip
AU - Szilagyi, Istvan
N1 - Funding Information:
This research was supported by the Swiss Secretariat for Education, Research and Innovation (C15.0024), Swiss National Science Foundation (150162), and COST Action CM1303. We thank Professor Michal Borkovec for the access to the light scattering instruments in the Laboratory of Colloid and Surface Chemistry. The technical help of Mr. Olivier Vassalli during the time-resolved measurements is gratefully acknowledged.
PY - 2017/9/26
Y1 - 2017/9/26
N2 - The colloidal stability of titanium oxide nanosheets (TNS) and nanowires (TiONW) was studied in the presence of protamine (natural polyelectrolyte) in aqueous dispersions, where the nanostructures possessed negative net charge, and the protamine was positively charged. Regardless of their shape, similar charging and aggregation behaviors were observed for both TNS and TiONW. Electrophoretic experiments performed at different protamine loadings revealed that the adsorption of protamine led to charge neutralization and charge inversion depending on the polyelectrolyte dose applied. Light scattering measurements indicated unstable dispersions once the surface charge was close to zero or slow aggregation below and above the charge neutralization point with negatively or positively charged nanostructures, respectively. These stability regimes were confirmed by the electron microscopy images taken at different polyelectrolyte loadings. The protamine dose and salt-dependent colloidal stability confirmed the presence of DLVO-type interparticle forces, and no experimental evidence was found for additional interactions (e.g., patch-charge, hydrophobic, or steric forces), which are usually present in similar polyelectrolyte-particle systems. These findings indicate that the polyelectrolyte adsorbs on the TNS and TiONW surfaces in a flat and extended conformation giving rise to the absence of surface heterogeneities. Therefore, protamine is an excellent biocompatible candidate to form smooth surfaces, for instance in multilayers composed of polyelectrolytes and particles to be used in biomedical applications.
AB - The colloidal stability of titanium oxide nanosheets (TNS) and nanowires (TiONW) was studied in the presence of protamine (natural polyelectrolyte) in aqueous dispersions, where the nanostructures possessed negative net charge, and the protamine was positively charged. Regardless of their shape, similar charging and aggregation behaviors were observed for both TNS and TiONW. Electrophoretic experiments performed at different protamine loadings revealed that the adsorption of protamine led to charge neutralization and charge inversion depending on the polyelectrolyte dose applied. Light scattering measurements indicated unstable dispersions once the surface charge was close to zero or slow aggregation below and above the charge neutralization point with negatively or positively charged nanostructures, respectively. These stability regimes were confirmed by the electron microscopy images taken at different polyelectrolyte loadings. The protamine dose and salt-dependent colloidal stability confirmed the presence of DLVO-type interparticle forces, and no experimental evidence was found for additional interactions (e.g., patch-charge, hydrophobic, or steric forces), which are usually present in similar polyelectrolyte-particle systems. These findings indicate that the polyelectrolyte adsorbs on the TNS and TiONW surfaces in a flat and extended conformation giving rise to the absence of surface heterogeneities. Therefore, protamine is an excellent biocompatible candidate to form smooth surfaces, for instance in multilayers composed of polyelectrolytes and particles to be used in biomedical applications.
UR - http://www.scopus.com/inward/record.url?scp=85029929344&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85029929344&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.7b01815
DO - 10.1021/acs.langmuir.7b01815
M3 - Article
C2 - 28829607
AN - SCOPUS:85029929344
SN - 0743-7463
VL - 33
SP - 9750
EP - 9758
JO - Langmuir
JF - Langmuir
IS - 38
ER -