Tattooing Plastics with Reversible and Irreversible Encryption.

Self-healing materials are explored for restoring mechanical, electrical, and chemical properties. Inspired by the process of tattooing on human skin, a method for engraving non-permanent or permanent messages on plastics is developed. A self-healing polymer containing dynamic disulfide bonds is employed as substrate for encryption of written messages. The polymer is engraved with a dye solution which is subsequently covered by the polymer matrix upon activation with temperature increase. The dye is then located at the subsurface of the substrate so that the information cannot be removed easily by wear or extraction with solvents. Therefore, self-healing polymers can be applied as sustainable substrates for reversibly and irreversibly engraving information.

Encapsulation of emulsion droplets and nanoparticles in nanofibers as sustainable approach for their transport and storage.

HYPOTHESIS: Emulsions are metastable and can be destabilized by coalescence and Ostwald ripening, which lead to phase separation. Immobilizing emulsion droplets in a solid material shall improve their stability during storage. EXPERIMENTS: Miniemulsions and dispersions of nanocapsules are electrospun to immobilize colloids in polymer nanofibers. The nanofibers are dissolved after various period of time to re-disperse nanodroplets and nanocapsules. FINDINGS: The size of nanodroplets and nanocapsules are close to the size of the original colloids before electrospinning, meaning that the emulsion droplets are efficiently stored overtime in nanofibers. Entrapping droplets in nanofibers by electrospinning allows a reduction of weight and volume of the emulsion of up to 82%. This method is therefore beneficial for improving shelf-life of emulsions, decreasing storage volume, and decreasing energy consumption for transportation of emulsions.

Core-shell particles for drug-delivery, bioimaging, sensing, and tissue engineering.

Nanoparticles have been widely used for many applications such as catalysis, biomedicine, or self-healing. Core-shell nanoparticles are very promising for biomedical applications due to several features such as possibility of sequence-controlled release of drugs and protection of sensitive payloads from surrounding environment. Core-shell structures incorporating payloads such as drugs, peptides, or hormones have been investigated in pre-clinical studies. The present review describes state of the art techniques for designing core-shell particles for biomedical applications. We also present recent advances in the field of drug, protein/peptide, and gene delivery using different types of core-shell nanoparticles. The function of core-shell particles as contrast agents and labels for bioimaging in magnetic resonance imaging (MRI), positron emission tomography (PET), computed tomography imaging (CT), ultrasound, and optical imaging is highlighted as well as their applications as biosensors.

Synergy between polymer crystallinity and nanoparticles size for payloads release.

Drug delivery from polymer nanocarriers is usually achieved by designing polymers so that they release drugs by cleavage of labile bonds, or by preparing nanoparticles that swell or collapse in response to external stimuli. Herein, we unravel the importance of polymer crystallinity in release profiles of drugs encapsulated in polymer nanoparticles. Polycaprolactone, as a model biocompatible and biodegradable semi-crystalline polymer, was processed into nanoparticles by the miniemulsion-solvent evaporation technique. The crystallinity of the nanoparticles was controlled by the polymer concentration, size of nanoparticles, and the composition of mixtures with amorphous polymers such as poly(vinyl formal) and polystyrene. Crystallinity decreased significantly with decreasing nanoparticle diameter. Release profiles of drugs were found to be dependent on an interplay of nanoparticle size and crystallinity. Therefore, crystallinity can be used for tuning the release profiles of nanoparticles.

Emulsion Techniques for the Production of Pharmacological Nanoparticles.

Nanoparticles have the advantages over micron-sized particles to typically provide higher intracellular uptake and drug bioavailability. Emulsion techniques are commonly used methods for producing nanoparticles aiming at high encapsulation efficiency, high stability, and low toxicity. Here, the recent developments of nanoparticles prepared from emulsions, the synthesis of nanoparticles, their physicochemical properties, and their biomedical applications are discussed. Selection of techniques, such as emulsion polymerization, miniemulsion polymerization, microemulsion polymerization, and emulsion-solvent evaporation processes, strongly influences morphologies, size distributions, and particle properties. Details in the synthetic strategies governing the performance of nanoparticles in bioimaging, biosensing, and drug delivery are presented. Benefits and limitations of molecular imaging techniques are also discussed.

Hemiaminal ether linkages provide a selective release of payloads from polymer conjugates.

We introduce here hemiaminal ether linkages, synthesized by coupling a vinyl ether and a 1,2,3-triazole, as responsive groups in polymers to allow the selective release of a functional molecule. The release kinetics of benzotriazole from polymer nanoparticles shows a fast release at low pH values and a prolonged or even no release under mildly acidic conditions and at neutral pH.

Saccharides, oligosaccharides, and polysaccharides nanoparticles for biomedical applications.

Modern requirements for designing efficient nanocarriers against diseases such as cancer are very complex. A suitable nanocarrier should indeed remain colloidally stable in the body, be biodegradable, target specific tumor cells, and release efficiently drugs. These challenging tasks can be overcome by using the chemistry of saccharides and polysaccharides. We discuss here recent applications of carbohydrates-based materials for providing biodegradability, enhancing contrast in bioimaging, a stealth effect for controlling the composition of protein corona, and targeting ability.