Mild and Efficient Preparation of Block and Gradient Copolymers by Methanesulfonic Acid Catalyzed Ring-Opening Polymerization of Caprolactone and Trimethylene Carbonate

Polycaprolactone/polytrimethylene carbonate copolymers of different microstructures have been prepared in toluene solution under mild conditions by controlled ring-opening polymerization of ε-caprolactone and trimethylene carbonate with methanesulfonic acid as catalyst. Sequential addition of the monomers led to the formation of well-defined di- and tri-block copolymers, demonstrating the ability of the catalytic system to cross-propagate. Simultaneous copolymerization yielded gradient copolymers as a result of the different copolymerization reactivity ratios and absence of undesirable redistribution reactions. DSC analyses showed a noticeable impact of the copolymer microstructure on the thermal properties

5‑Methylene-1,3-dioxane-2-one: A First-Choice Comonomer for Trimethylene Carbonate

5-Methylene-1,3-dioxane-2-one (exTMC), a six-membered ring cyclic carbonate bearing an exocyclic methylene group, has been investigated as comonomer for trimethylene carbonate (TMC) with the aim to prepare functionalized polycarbonates. Using methane sulfonic acid (MSA) as an organocatalyst, exTMC and TMC copolymerize in a controlled manner to lead to copolymers of adjusted composition and high randomness (the corresponding reactivity ratios have been determined by the Beckingham–Sanoja–Lynd (BSL) method as 0.93–0.95 and 1.04–1.07 for exTMC and TMC, respectively). Subsequent thiol-ene reaction on the exomethylene group with thioglycolic acid or thioglycerol provides aliphatic polycarbonates with adjustable amounts of COOH or OH groups randomly distributed along the polymer chains

5‑Methylene-1,3-dioxane-2-one: A First-Choice Comonomer for Trimethylene Carbonate

5-Methylene-1,3-dioxane-2-one (exTMC), a six-membered ring cyclic carbonate bearing an exocyclic methylene group, has been investigated as comonomer for trimethylene carbonate (TMC) with the aim to prepare functionalized polycarbonates. Using methane sulfonic acid (MSA) as an organocatalyst, exTMC and TMC copolymerize in a controlled manner to lead to copolymers of adjusted composition and high randomness (the corresponding reactivity ratios have been determined by the Beckingham–Sanoja–Lynd (BSL) method as 0.93–0.95 and 1.04–1.07 for exTMC and TMC, respectively). Subsequent thiol-ene reaction on the exomethylene group with thioglycolic acid or thioglycerol provides aliphatic polycarbonates with adjustable amounts of COOH or OH groups randomly distributed along the polymer chains

In Vivo Deep Tissue Fluorescence and Magnetic Imaging Employing Hybrid Nanostructures

Breakthroughs in nanotechnology have made it possible to integrate different nanoparticles in one single hybrid nanostructure (HNS), constituting multifunctional nanosized sensors, carriers, and probes with great potential in the life sciences. In addition, such nanostructures could also offer therapeutic capabilities to achieve a wider variety of multifunctionalities. In this work, the encapsulation of both magnetic and infrared emitting nanoparticles into a polymeric matrix leads to a magnetic-fluorescent HNS with multimodal magnetic-fluorescent imaging abilities. The magnetic-fluorescent HNS are capable of simultaneous magnetic resonance imaging and deep tissue infrared fluorescence imaging, overcoming the tissue penetration limits of classical visible-light based optical imaging as reported here in living mice. Additionally, their applicability for magnetic heating in potential hyperthermia treatments is assessed

Lifetime-Encoded Infrared-Emitting Nanoparticles for <i>in Vivo</i> Multiplexed Imaging

Advanced diagnostic procedures are required to satisfy the continuously increasing demands of modern biomedicine while also addressing the need for cost reduction in public health systems. The development of infrared luminescence-based techniques for <i>in vivo</i> imaging as reliable alternatives to traditional imaging enables applications with simpler and more cost-effective apparatus. To further improve the information provided by <i>in vivo</i> luminescence images, the design and fabrication of enhanced infrared-luminescent contrast agents is required. In this work, we demonstrate how simple dopant engineering can lead to infrared-emitting rare-earth-doped nanoparticles with tunable (0.1–1.5 ms) and medium-independent luminescence lifetimes. The combination of these tunable nanostructures with time-gated infrared imaging and time domain analysis is employed to obtain multiplexed <i>in vivo</i> images that are used for complex biodistribution studies