TY - JOUR A1 - Robinson, J.W. A1 - Secker, C. A1 - Weidner, Steffen A1 - Schlaad, H. T1 - Thermoresponsive poly(N-C3 glycine)s N2 - Ring-opening polymerization of N-substituted glycine N-carboxyanhydrides (NCAs) was applied to prepare a series of well-defined poly(N-C3 glycine)s (C3 = n-propyl, allyl, propargyl, and isopropyl), polypeptoids, with molecular weights in the range of 1.8–6.6 kg mol–1. Poly(N-isopropyl glycine), a previously unreported polypeptoid, could be obtained by bulk polymerization of the corresponding NCA in the melt. The samples were characterized by spectroscopy (NMR and FT-IR), size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI–ToF MS). The polymers could be dispersed in water up to 20–40 g L–1; the poly(N-propargyl glycine) was not soluble in water. Turbidity measurements of the three water-soluble polypeptoids illustrated cloud point temperatures dependent on structural and electronic properties of the side chain. The cloud point temperatures were found to increase in the order C3 = n-propyl (15–25 °C) < allyl (27–54 °C) < isopropyl (47–58 °C). Long-term annealing of the aqueous solution of poly(N-{n-propyl} glycine) and poly(N-allyl glycine) above the cloud point temperature resulted in the formation of crystalline microparticles with melting points of 188–198 and 157–165 °C (differential scanning calorimetry, DSC), respectively, and rose bud type morphology (scanning electron microscopy, SEM). PY - 2013 U6 - https://doi.org/10.1021/ma302412v SN - 0024-9297 SN - 1520-5835 VL - 46 IS - 3 SP - 580 EP - 587 PB - American Chemical Society CY - Washington, DC AN - OPUS4-27696 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Koshkina, Olga A1 - Lang, Thomas A1 - Thiermann, R. A1 - Docter, D. A1 - Stauber, R.H. A1 - Secker, C. A1 - Schlaad, H. A1 - Weidner, Steffen A1 - Mohr, B. A1 - Maskos, M. A1 - Bertin, Annabelle T1 - Temperature-triggered protein adsorption on polymer-coated nanoparticles in serum N2 - The protein corona, which forms on the nanoparticle's surface in most biological media, determines the nanoparticle’s physicochemical characteristics. The formation of the protein corona has a significant impact on the biodistribution and clearance of nanoparticles in vivo. Therefore, the ability to influence the formation of the protein corona is essential to most biomedical applications, including drug delivery and imaging. In this study, we investigate the protein adsorption on nanoparticles with a hydrodynamic radius of 30 nm and a coating of thermoresponsive poly(2-isopropyl-2-oxazoline) in serum. Using multiangle dynamic light scattering (DLS) we demonstrate that heating of the nanoparticles above their phase separation temperature induces the formation of agglomerates, with a hydrodynamic radius of 1 µm. In serum, noticeably stronger agglomeration occurs at lower temperatures compared to serum-free conditions. Cryogenic transmission electron microscopy (cryo-TEM) revealed a high packing density of agglomerates when serum was not present. In contrast, in the presence of serum, agglomerated nanoparticles were loosely packed, indicating that proteins are intercalated between them. Moreover, an increase in protein content is observed upon heating, confirming that protein adsorption is induced by the alteration of the surface during phase separation. After cooling and switching the surface back, most of the agglomerates were dissolved and the main fraction returned to the original size of approximately 30 nm as shown by asymmetrical flow-field flow fractionation (AF-FFF) and DLS. Furthermore, the amounts of adsorbed proteins are similar before and after heating the nanoparticles to above their phase-separation temperature. Overall, our results demonstrate that the thermoresponsivity of the polymer coating enables turning the corona formation on nanoparticles on and off in situ. As the local heating of body areas can be easily done in vivo, the thermoresponsive coating could potentially be used to induce the agglomeration of nanoparticles and proteins and the accumulation of nanoparticles in a targeted body region. PY - 2015 U6 - https://doi.org/10.1021/acs.langmuir.5b00537 SN - 0743-7463 SN - 1520-5827 VL - 31 IS - 32 SP - 8873 EP - 8881 PB - American Chemical Society CY - Washington, DC AN - OPUS4-34163 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -