3D-printing of the polymer/insect-repellent system poly (l-lactic acid)/ethyl butylacetylaminopropionate (PLLA/IR3535)

Du, F., et al. Int. J. Pharmaceutics, 2022, DOI:https://doi.org/10.1016/j.ijpharm.2022.122023   

The polymer/solvent system poly (l-lactic acid)/ethyl butylacetylaminopropionate (PLLA/IR3535) is regarded as an insect-repellent-delivery system, serving, e.g., for fighting mosquito-borne tropical diseases. In this work, samples of the polymer/repellent system PLLA/IR3535 were prepared by 3D-printing. The experiments showed that it is possible to print 3D-parts containing up to 25 m% repellent, with an only minor loss of repellent during the printing process. The study successfully proved the applicability of the technology of extrusion-based 3D-printing for the preparation of polymer parts with a specific shape/design containing mosquito-repellent at a concentration which raises the expectation to be used as a repellent delivery-device.

3D-printing of Triamcinolone Acetonide in Triblock Copolymers of Styrene-Isobutylene-Styrene as a Slow Release System

Hilgeroth, P., et al. Polymers, 2022, DOI:https://doi.org/10.3390/polym14183742

Additive manufacturing has a wide range of applications and has opened up new methods of drug formulation, in turn achieving attention in medicine. We prepare and use styrene–isobutylene–styrene triblock copolymers (SIBS; Mn = 10 kDa–25 kDa, PDI 1,3–1,6) as a drug carrier for triamcinolone acetonide (TA), further processed by fused deposition modeling to create a solid drug release system displaying improved bioavailability and applicability. Continuous drug release and morphological investigations were conducted to probe the influence of the 3D printing process on the drug release, enabling 3D printing as a formulation method for a slow-release system of Triamcinolone.

Tuning the internal compartmentation of single-c­hain nanoparticles as fluorescent contra­st agents

Thümmler, J. F., et al. Macromol. Rapid. Commun., 2022, DOI:https://doi.org/10.1002/marc.202200618

Controlling the internal structures of single-chain nanoparticles (SCNPs) is an important factor for their targeted chemical design and synthesis, especially in view of nanosized compartments presenting different local environments as a main feature to control functionality. We here design SCNPs (sized 6 – 12 nm) bearing near-infrared fluorescent dyes embedded in hydrophobic compartments for use as contrast agents in pump–probe photoacoustic (PA) imaging. SCNPs with the dye molecules accumulate at the core and show a nonlinear PA response as a function of pulse energy—a property that can be exploited as a contrast mechanism in molecular PA tomography.

Hydrogen-bonded supramolecular polymer-micelles with pH/photothermal-responsive carmofur release and combined chemo-photothermal therapy

Wu, Y., et al. Polym. Chem., 2022, DOI:https://pubs.rsc.org/en/content/articlelanding/2022/py/d1py01634b

Integrating biomedical applications (e.g., drug delivery) into supramolecular chemistry is a promising strategy. This work targets the construction of hydrogen-bonded (H-bonded) supramolecular polymeric micelles loaded with chemotherapy drugs (carmofur) and photothermal agents (IR780) for combined chemo-photothermal therapies (CT/PTT).

3D printing of solvent-free supramolecular polymers

Rupp, H., et al. Frontiers in Chemistry, 2021, DOI:https://doi.org/10.3389/fchem.2021.771974

Additive manufacturing has significantly changed polymer science and technology by engineering complex material shapes and compositions. With the advent of dynamic properties in polymeric materials as a fundamental principle to achieve, e.g., self-healing properties, the use of supramolecular chemistry as a tool for molecular ordering has become important. We here review recent progress in the 3D printing of supramolecular polymers, with a focus on fused deposition modelling (FDM) to overcome some of its limitations still being present up to date and open perspectives for their application.

Nanoscale structure and dynamics of thermoresponsive single-chain nanoparticles investigated by EPR spectroscopy

Roos, A. H., et al. Soft Matter, 2021, DOI:https://doi.org/10.1039/D1SM00582K

We characterize temperature-dependent macroscopic and nanoscopic phase transitions and nanoscopic pre-transitions of water-soluble single chain nanoparticles (SCNPs). We analyze the temperature-dependent phase transitions of spin-labeled SCNPs by rigorous spectral simulations of a series of multicomponent EPR-spectra that derive from the nanoinhomogeneities (1) that are due to the single-chain compartmentation in SCNPs and (2) the transformation upon temperature change due to the LCST behavior. These transitions of the SCNPs and their respective polymer precursors can be monitored and understood on the nanoscale by following EPR-spectroscopic parameters like hyperfine couplings that depend on the surrounding solvent molecules or Heisenberg spin exchange.

Hydrogen-bonding mediated self-assembly of amphiphilic ABA triblock copolymers into well defined giant vesicles

Wang, H., et. al. J. Polymer Chemistry, 2021, 12, 6300-6306, https://doi.org/10.1039/D1PY01061A

Giant vesicles represent an extremely useful system to mimick biomembranes. By designing a hydrogen-bonding (H-bonding) amphiphilic ABA triblock copolymer and introducing 2,6-diaminopyridine (DAP) moieties as pendant groups within the middle hydrophobic block, we demonstrate a straightforward and effective self-assembly strategy to form giant vesicles (~3 μm in diameter) via a combination of H-bonding and amphiphilic interactions. This study provides a new opportunity for the design of supramolecular polymers, serving as polymeric vesicle scaffolds in material design and may act as red-blood-cell-like container in delivery and microreactor applications. Published with a permission of the Polymer Chemistry 2021.

Fluorescent and water dispersible single-chain nanoparticles: core-shell structured compartmentation

Hoffmann, J.F., et al. Angewandte Chemie, International Edition, 2021, accepted, https://doi.org/10.1002/anie.202015179

The internal structure of single-chain nanoparticles (SCNPs) has been investigated, forming nanosized domains preformed during the crosslinking process. We present proof for the presence of nano-compartments within SCNPs via a combination of electron paramagnetic resonance (EPR) and fluorescence spectroscopy. A novel strategy to encapsulate labels within such water dispersible SCNPs is presented.

Multicomponent stress-sensing materials fabricated by 3D-printing-methodologies

Rupp, H., et. al. Macromolecular Rapid Communications, 2021https://doi.org/10.1002/marc.202000450

The preparation and characterization of mechanoresponsive, 3D-printed composites is reported using a dual-printing setup for both, liquid dispensing and fused-deposition-modeling. The here reported stress‐sensing materials are based on high- and low molecular weight mechanophores, including  poly(e-caprolactone)-, polyurethane-, and alkyl(C11)-based latent copper(I)bis(N‐heterocyclic carbenes), which can be activated by compression to trigger a fluorogenic, copper(I)-catalyzed azide/alkyne “click”-reaction (CuAAC) of  an azide-functionalized fluorescent dye inside a bulk polymeric material. The low-molecular weight mechanophores bearing the alkyl-C11 chains displayed the best printability, yielding a useful mechanochemical response after the 3D-printing process. © 2020 The Authors. Published by Wiley‐VCH GmbH

Tuning the Self-Healing Response of Poly(dimethylsiloxane)-Based Elastomers

Döhler, D., et. al. ACS Applied Polymer Materials, 2020, 4127, https://dx.doi.org/10.1021/acsapm.0c00755

We present a comprehensive investigation of mechanical properties of supramolecular polymer networks with rationally developed multistrength hydrogen-bonding interactions. Self-healing poly(dimethylsiloxane) (PDMS)-based elastomers with varying elasticity, fracture toughness, and the ability to dissipate strain energy through the reversible breakage and re-formation of the supramolecular interactions were obtained. By changing the ratio between isophorone diisocyanate (IU), 4,4′-methylenebis(cyclohexyl isocyanate) (MCU), and 4,4′-methylenebis(phenyl isocyanate) (MPU) and by varying the molecular weight of the PDMS precursor, we obtained a library of poly(urea)s to study the interplay of mechanical performance and self-healability. Selected poly(urea)s could be processed via 3D printing by the conventional extrusion method, obtaining dimensionally stable and freestanding objects. Copyright © 2020, American Chemical Society