The site-specific surface modification of colloidal substrates, yielding "patchy" nanoparticles, is a rapidly expanding area of research as a result of the new complex structural hierarchies that are becoming accessible to chemists and materials scientists through colloidal self-assembly. The inherent directionality of cellulose chains, which feature a non-reducing and a reducing end, within individual cellulose nanocrystals (CNCs) renders them an interesting experimental platform for the synthesis of asymmetric nanorods with end-tethered polymer chains. Here, we present water-tolerant reaction pathways toward patchy and uniformly modified CNC hybrids based on atom transfer radical polymerization (ATRP) and initiators that were linked to the CNCs with carbodiimide-mediated coupling and Fischer esterification, respectively. Various monomers, including Nisopropylacrylamide (NIPAM), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), and sodium 4vinylbenzenesulfonate (4-SS) were polymerized from both types of initiator-modified CNCs, yielding chemically patchy and uniform CNC hybrids, via surface-initiated ATRP (SI-ATRP). Interestingly, the stereochemistry of tethered PNIPAM was affected by the precise location of ATRP initiating sites, as evidenced by 1 H NMR and circular dichroism (CD) spectroscopy. This effect may be related to the inherent right-handed chirality of CNCs. CNC/PMETAC hybrids were labeled with gold nanoparticles (AuNPs) in order to visualize the precise location of polymer tethers via cryo-electron microscopy. In some instances, the AuNPs were indeed concentrated at the end groups of the patchy CNC hybrids.The site-specific surface modification of colloidal substrates, yielding "patchy" (nano)particles, is receiving rapidly expanding interest, as a result of the new complex structural hierarchies that are becoming accessible to chemists and materials scientists through colloidal self-assembly. 1 Such patchy particles include Janus colloids, 2 genetically engineered bacteriophages, 3,4 cylindrical block copolymer micelles, 5 and polymer-tethered nanorods. 6 Particle shape anisotropy provides additional building block parameters, which can broaden the complexity of their assemblies. 7 The lyotropic liquid crystal formation capability of rod-shaped colloidal building blocks is an excellent example of such a self-assembly process. 8 In special cases, these liquid crystal (LC) phases exhibit longrange chirality, displaying so-called cholesteric or chiral nematic arrangements, which are not only fundamentally intriguing for condensed matter investigations, 9 but also useful as chiral building blocks for the creation of advanced functional materials. 10 Relatively few anisotropic colloids that exhibit such chiral phases are known; they include filamentous viruses, 11 collagen, 12 chitin, 13 and cellulose nanocrystals (CNCs). 14 CNCs are a unique class of colloidal liquid crystals in that their cholesteric LC phases are preserved upon evaporation-induced self-assembly (EISA), which together with ...

No abstract

Nanoparticles (NPs) possess unique properties useful for designing specific functionalities for biomedical applications. Ap rerequisite of as afe-by-design and effective use in any biomedical application is to study NP-cell interactions to gain abetter understanding of cellular consequences upon exposure. Cellular uptake of NPs results mainly in the localization of NPs in the complex environment of lysosomes, ac ompartment which can be mimicked by artificial lysosomal fluid. In this work we showed the applicability of lysosomal fluid as a platform for af ast assessment of gold, iron oxide and silica NP stability over 24 hi nar elevant biological fluid, by using multiple analytical methods.