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One challenge in the development of new drug formulations is overcoming their low solubility in relevant aqueous media. Reducing the particle size of drug powders to a few hundred nanometers is a well‐known method that leads to an increase in solubility due to an elevated total surface area. However, state‐of‐the‐art comminution techniques like cryo‐milling suffer from degradation and contamination of the drugs, particularly when sub‐micrometer diameters are aspired that require long processing times. In this work, picosecond‐pulsed laser fragmentation in liquids (LFL) of dispersed drug particles in a liquid‐jet passage reactor is used as a wear‐free comminution technique using the hydrophobic oral model drugs naproxen, prednisolone, ketoconazole, and megestrol acetate. Particle size and morphology of the drug particles are characterized using scanning electron microscopy (SEM) and changes in particle size distributions upon irradiation are quantified using an analytical centrifuge. The findings highlight the superior fragmentation efficiency of the liquid‐jet passage reactor setup, with a 100 times higher fraction of submicrometer particles (SMP) of the drugs compared to the batch control, which enhances solubility and goes along with minimal chemical degradation (<1%), determined by attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR), high‐performance liquid chromatography (HPLC), and X‐ray diffraction (XRD). Moreover, the underlying predominantly photo‐mechanically induced laser fragmentation mechanisms of organic microparticles (MP) are discussed. [ABSTRACT FROM AUTHOR]

Stent therapy can reduce both morbidity and mortality of chronic coronary stenosis and acute myocardial infarction. However, delayed re‐endothelialization, endothelial dysfunction, and chronic inflammation are still unsolved problems. Alginate hydrogels can be used as a coating for stent surfaces; however, complete and fast endothelialization cannot be achieved. In this study, alginate hydrogels are modified by fibrin blending, iron nanoparticle (Fe‐NP) embedding, and serum protein coating (SPC) while surface properties and endothelialization capacity are monitored. Only a triple, synergetic modification of the alginate coating by simultaneous I) fibrin blending, II) Fe‐NP addition complemented by III) SPC is found to significantly improve endothelial cell viability (live–dead‐staining) and proliferation (WST‐8 assay). These conditions yield formation of closed endothelial cell monolayers and an up to threefold increase (p < 0.01) in viability, while, interestingly, no effect is found when the modifications (I)–(III) are conducted individually. This synergetic effect is attributed to an accumulation of agglomerated Fe‐NP and serum proteins along fibrin fibers, observed via laser scanning microscopy tracking nanoparticle scattering and tetramethylrhodamine (TRITC)‐albumin fluorescence. These synergetic effects can pave the way toward a novel strategy for the modification of various hydrogel‐based biomaterials and biomaterial coatings. [ABSTRACT FROM AUTHOR]

This work highlights the laser-based aqueous synthesis and processing of nanocomposites, composed of zinc or iron nanoparticles embedded in a N-Vinylcaprolactam microgel matrix, with potential applicability as ion releasing fiber pads for wound healing. An in situ laser process for microgel synthesis is developed and optimized for high embedded nanoparticle yields, evaluating influences of laser repetition rate and monomer concentration. The impact of the nanoparticles on polymerization was increased by embedded zinc oxide nanoparticles, and reduced in the presence of iron oxide. Furthermore, TEM images verified that the nanoparticles were homogeneously embedded into the polymer matrix. The nanoparticle-loaded microgels were thermally stable up to 429 °C, which ensures that the composites maintain their integrity after heat sterilization and during rapid prototyping by thermal polymer processing. The general suitability of the hydrogels as active biomaterial for wound healing was assessed in toxicity, cell proliferation and migration assays using human dermal fibroblasts and keratinocytes, where cytocompatibility was verified, while the proliferation was affected by the gel alone as well as the embedded nanoparticles. The hydrogels were processed to suit their use as a biomaterial for wound coverages via electrospinning resulting in a centimeter scale fully cytocompatible fiber pad with the nanoparticle-filled microgel capsules supported on the fiber's surface. [ABSTRACT FROM AUTHOR]