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Stimuli-degradable polymers are regarded as interesting materials for various applications like patterning or drug delivery. In particular, light as a trigger received a lot of attention due to the possibility of adjusting wavelength, light intensity and irradiation time, which leads to a precise and controlled application. In this study, we report the synthesis of two novel light-degradable polyurethanes which are based on 6-nitropiperonal and differ in the implementation of the light-cleavable unit. Degradation of these backbone- or side-chain-cleavable polymers was analyzed by UV/Vis spectroscopy and SEC. While both polymers showed rapid decomposition in solution, differences in the degradation rates were observed dependent on the incorporation site of the light-cleavable unit. Furthermore, nanoparticles were fabricated and characterized by photon correlation spectroscopy as well as scanning electron microscopy proving the processability of the polymers for potential application as, e.g., a controlled release system.

Biocompatible polymeric materials that can degrade in response to external irradiation with high spatial and temporal control show enormous potential in the field of biomedical applications. Herein, two six-membered cyclic carbonate monomers with a light-cleavable bromocoumarin functional pendent moiety attached via a carbamate linkage were prepared from 2-amino-1,3-propanediol (serinol) and 2-(aminomethyl)-2-methylpropane-1,3-diol, respectively. A series of light-degradable polycarbonates were synthesized by organo-catalyzed ring opening polymerization (ROP) of both monomers, and meanwhile their polymerization kinetics were investigated. Upon light-induced deprotection, both types of polycarbonates degraded rapidly into low molecular-weight compounds. The results of size exclusion chromatography (SEC), nuclear magnetic resonance (NMR) spectroscopy and ultraviolet/visible (UV/VIS) spectroscopy confirmed the polymer structures and the light-induced degradation behavior. The photo-cleavage rates of bromocoumarin pendent groups and the degradation rates of the polymers were strongly dependent on polymer structures and used solvents.

Stimuli-responsive self-immolative aliphatic polycarbonates (APCs) and polyesters (APEs) have attractive advantages for biomedical and pharmaceutical applications. In the present work, polycondensation of

Although nanoparticles (NPs) bear a great potential in tumour therapy, just a few nanosized drug delivery systems are commercially available. Besides their advantages like passive drug targeting and stable embedment of lipophilic active pharmaceutical ingredients, targeted drug release is a major challenge for a safe therapy. While drug release of commonly used materials depends on physiological factors, nanoparticles prepared by using stimuli responsive polymers offer a promising approach. External irradiation of light-sensitive nanoparticles enables local drug release, resulting in selective accumulation and consequently more effective treatment with less side effects. In this study light-responsive nanoparticles based on a new innovative light-responsive polyester (Nip-SLrPE) combined with poly(DL-lactide-co-glycolide) (PLGA) were prepared and examined for their physicochemical characteristics and light-triggered properties. As model drug the photosensitizer 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorine (mTHPC) was incorporated and light-depending drug release was investigated. Furthermore, cytotoxic potential of selected formulations for PDT and intracellular accumulation of mTHPC were evaluated. In conclusion, nanoparticles based on the new light-sensitive Nip-SLrPE showed auspicious light-responsive properties, resulting in promising results for a smart drug delivery system.

Atom transfer radical polymerization (ATRP) of methacrylic acid (MAA) is challenging. Herein is reported a study of conditions for facile surface-initiated ATRP by activator regenerated electron transfer (SI-ARGET-ATRP) growth of poly-methacrylic acid (PMAA) chains from a plasma polymer surface bearing surface-immobilized α-bromoisobutyryl bromide, with no deoxygenation required. Factors that affect PMAA polymer growth off the surface under ARGET-ATRP conditions are systematically investigated, such as monomer/catalyst ratio, solvent, and, most importantly, addition of salts and change of pH. While the concentrations of the copper catalyst and acid affect grafting, the most pronounced effect arises from the concentration of chloride ions. Adding 0.1 m NaCl and acidifying the reaction solution to pH 3 offers the best trade-off between reaction rate and reproducibility; yielding ≈60 nm thick PMAA graft polymers in 1 h under ambient conditions. Using this easily scalable recipe and surface analysis, the grafted polymers are verified to be pure PMAA and the graft coatings to be homogenous across a substrate of 100 mm diameter. Refereed/Peer-reviewed