Universally Applicable Encapsulation and Functionalization Method for Preparing Functional Nanocomposites and Hybrids for Biomedical Applications

By synthesizing homogenous magneto-responsive nanocomposites and functional nanohybrids, we demonstrate the universal applicability of our advanced encapsulation technique.^1-3<br/><br/>Our encapsulation technique is based on the micellar encapsulation of various nanocrystals in a polyisoprene-block-poly(ethylene oxide) (PI-b-PEO) diblock copolymer shell with subsequent thiol-ene click reaction initiated cross-linking of the PI block. This leads to a robust and functionalizable polymer shell that provides maximum stability to the nanocrystal in both water and host matrix. These even offer the possibility to perform copper(I) catalyzed click reactions while keeping the fluorescence of the quantum dots. We demonstrate the robustness of the shell by synthesizing a magneto-responsive nanocomposite with homogeneously dispersed superparamagnetic iron oxide nanocrystals in a poly(ethylene oxide) matrix. We present an extensive step-by-step characterization during the different stages of preparation by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), with both methods perfectly complementing each other.¹<br/><br/>Biocompatibility and functionalizability were demonstrated by a systemic study with human alveolar epithelial cells (A549) and murine macrophage leukemia cell (RAW-264.7). Thereby, we could show that using different polymer architectures besides the variation of the polymers' molecular weight allows us to control the size of the resulting constructs and the permeability of the shell. As a general trend, it can be stated that those coatings, which were most stable against quenchers, also showed the best resistivity concerning unspecific cellular uptake.²<br/><br/>All these results underline the vast variability and controllability of the PI-b-PEO diblock copolymer system for the encapsulation and functionalization of nanoparticles for biological applications and magneto-rheological nanocomposites.<br/><br/>1. Feld, A.; Koll, R.; Fruhner, L. S.; Krutyeva, M.; Pyckhout-Hintzen, W.; Weiß, C.; Heller, H.; Weimer, A.; Schmidtke, C.; Appavou, M.-S.; et al. <i>ACS Nano</i> 2017, <i>11</i> (4), 3767–3775.<br/><br/>2. Ostermann, J.; Merkl, J.-P.; Flessau, S.; Wolter, C.; Kornowksi, A.; Schmidtke, C.; Pietsch, A.; Kloust, H.; Feld, A.; Weller, H. Controlling the Physical and Biological Properties of Highly Fluorescent Aqueous Quantum Dots Using Block Copolymers of Different Size and Shape. <i>ACS Nano</i> 2013, <i>7</i> (10), 9156–9167.<br/><br/>3. Feld, A.; Merkl, J.-P.; Kloust, H.; Flessau, S.; Schmidtke, C.; Wolter, C.; Ostermann, J.; Kampferbeck, M.; Eggers, R.; Mews, A.; et al. A Universal Approach to Ultrasmall Magneto-Fluorescent Nanohybrids. <i>Angew. Chemie Int. Ed.</i> 2015, <i>54</i> (42), 12468–12471.