Ultra-small gold nanoclusters (AuNCs) have unique size-dependent optical, electrical and chemical properties. They have emerged as a new nanomaterial with broad applications in optoelectronics, catalysis, biosensing, and bioimaging. Several strategies have been exploited to prepare AuNCs of different "magic number" sizes, using different templates e.g. dendrimers, polyethyleneimines, peptides, and more recently, proteins. Notwithstanding, almost all bio-template-protected AuNCs reported so far exhibit fairly low fluorescence quantum yields (QYs), typically <5%, which is especially true for AuNCs prepared using the protein templates. In this paper, we report a facile, one-pot aqueous synthesis of highly fluorescent AuNCs using bovine pancreatic ribonuclease A (RNase-A) as the bio-template. The as-prepared AuNCs not only fluoresce strongly at the near-infrared (NIR) region (λ(em) = 682 nm), but also exhibit an elevated QY of ∼12%. Additionally, the RNase-A-encapsulated AuNC (RNase-A-AuNC) displays an exceptionally large Stokes shift of ∼210 nm as well as a single dominant fluorescence lifetime of ∼1.5 μs, about three orders of magnitude longer than biological autofluorescence. Furthermore, by coupling vitamin B(12) (VB(12)) to the RNase-A-AuNC, we develop a multifunctional nanoplatform that is suitable for simultaneous targeting and imaging of cancer at the cellular level using Caco-2 cell lines as an in vitro model. Since VB(12) has effective uptake pathways in the digestive system, this nanoplatform may have potential for targeted oral drug delivery in vivo.

Two different zwitterionic block copolymers (BCs) and a cationic BC were synthesized from the same BC precursor, which consisted of a polystyrene (PS) block and a poly[N-(3-dimethylamino-1-propyl)acrylamide] block. The zwitterionic BCs contained the dimethylammonioacetate (carboxybetaine) and dimethylammoniopropyl sulfonate (sulfobetaine) groups. Thin films cast from these polymers were investigated for surface wettability, surface charge, and protein adsorption. Surface-energy parameters calculated with advancing contact angle (y a ) and receding contact angle (y r ) of different probe liquids showed that it was y r and not y a that was representative of the polar/ionic groups in the near-surface regions of the coatings. Electrophoretic mobility was used to characterize the influence of pH on the net surface charge. In aqueous dispersions, the carboxybetaine polymer showed an ampholyte behavior with an isoelectric point of 6, whereas the sulfobetaine polymer was found to be anionic at all pH values between 2 and 10. Protein adsorption on the carboxybetaine BC was relatively independent of the net charges on the protein or the polymer, but the negatively charged sulfobetaine polymer showed a higher adsorption of positively charged protein molecules. Regardless of the net protein charge, both zwitterionic coatings adsorbed less protein compared to the PS and poly(2,3,4,5,6-pentafluorostyrene) controls. The sulfobetaine and cationic BCs adsorbed higher amounts of oppositely charged protein molecules than like-charged protein molecules. However, the adsorption of oppositely charged protein was much higher on the cationic surface than on the sulfobetaine surface. The zwitterionic BCs, particularly the carboxybetaine polymer, from this article are expected to function as stable, low-fouling surface modifiers in different biological environments.

The sections in this article are Introduction Biocompatible Coatings Protein‐Repellant Coatings PEG ylated Thin Films Non‐ PEG ylated Hydrophilic Thin Films Thin Films of Hyperbranched Polymers Multilayer Thin Films Antithrombogenic Coatings Surface Chemistry and Blood Compatibility Membrane‐Mimetic Thin Films Heparin‐Mimetic Thin Films Clot‐Lyzing Thin Films Polyelectrolyte Multilayer Thin Films Polyurethane Coatings Vapor‐Deposited Thin Films Antimicrobial Coatings Cationic Polymers Nanocomposite Polymer Thin Films Incorporating Inorganic Biocides Antibiotic‐Conjugated Polymer Thin Films Biomimetic Antibacterial Coatings Thin Films Resistant to the Adhesion of Viable Bacteria Coatings for Tissue Engineering Substrates PEG ylated Thin Films Zwitterionic Thin Films Thin Films of Hyperbranched Polymers Polyurethane Coatings Polysaccharide‐Based Thin Films Polyelectrolyte Multilayer Thin Films Temperature‐Responsive Polymer Coatings Electroactive Thin Films Other Functional Polymer Coatings Multilayer Thin Films for Cell Encapsulation Patterned Thin Films Polymer Thin Films for Drug Delivery Polymer Thin Films for Gene Delivery Conclusions

A novel imidazolium iodide ionic liquid with an u-perfluoroalkyl poly(ethylene glycol) (PEG) tail attached to the imidazolium ring has been synthesized for its potential incorporation as an electrolyte in dye-sensitized solar cells. The ionic liquid molecules, with block oligomer tails, self-assembled to form a solvent-free ionic gel, without the assistance of an external gelator or an immobilizing matrix. The solidification was evidently facilitated by the generation of ionic clusters due to electrostatic interactions, as well as microphase separation of the immiscible perfluoroalkyl and PEG segments of the cation. We report herein the synthesis and electrochemical properties of this block oligomer ionogel, along with the results of self-consistent mean field calculations probing the formation of nanostructures in the ionogel. Although properties such as high viscosity and high ionic conductivity appear incompatible, it is shown that a nano-structured fluid can support high iodide diffusion at low effective fluidity, and that the formation of an organic alloy, by simple blending of two imidazolium iodide salts, can produce significant conductivity enhancements without lowering the viscosity.

No abstract