Branched poly(methoxy‐PEG acrylate) and thermally responsive poly(methoxy‐PEG acrylate)‐block‐poly(N‐isopropylacrylamide) are synthesized by RAFT polymerization. After reduction, these polymers are fluorescently labeled by reacting the free thiol groups with N‐(5‐fluoresceinyl)maleimide. As shown by DLS, the labeled copolymer poly(methoxy‐PEG acrylate)‐block‐poly(N‐isopropylacrylamide) forms nanoparticles at body temperature (37 °C) due to the presence of the thermosensitive poly(N‐isopropylacrylamide). These materials were used as bioprobes for imaging HUVECs in vitro and chick embryo CAM in vivo. Both labeled polymer and nanoparticles are biocompatible and can be used as efficient fluorescent bioprobes.
The preparation of reactive polyurethanes, the photopolymerization, and copolymerization of acrylates in emulsion as well as solution and the precipitation and reactive precipitation to prepare BaSO4 and silver nanoparticles, respectively, employing a spinning disk reactor (SDR) are summarized. The advantages of an SDR (excellent mass and heat transfer, minimal energy, and material usage, easy scale up as well as flexibility) are discussed. Where experiments are described comparing the SDR with traditional batch processes, known, optimized industrial batch processes are chosen. In all cases, the SDR could be shown to yield equivalent product quality while having procedural advantages.
The influence of surface roughness and charge on the cellular uptake of nanoparticles in HeLa cells is investigated with fluorescent, oppositely charged, rough, and smooth nanoparticles. Flow cytometry, cLSM, and TEM reveal that rough nanoparticles are internalized by the cells more slowly and by an unidentified uptake route as no predominant endocytosis route is blocked by a variety of inhibitory drugs, while the uptake of smooth nanoparticles is strongly dependent on dynamin, F‐actin, and lipid‐raft. Negatively charged nanoparticles are taken up to a higher extent than positively charged ones, independent of the surface roughness.
In this report, we developed a simple and green process of simultaneous formation of doxorubicin–BSA–dextran nanoparticles in aqueous solution and high‐effective encapsulation of doxorubicin. In the presence of BSA–dextran conjugates, which were produced by Maillard reaction, a binding of doxorubicin with BSA can suppress the self‐aggregation of unprotonated doxorubicin. After a heat treatment, the gelation of BSA results in a formation of the nanoparticles and the doxorubicin was fixed inside the nanoparticles. The dextran shell makes the nanoparticles dispersible in solution. The nanoparticles have a spherical morphology and a hydrodynamic radius of about 90 nm. Importantly, the nanoparticles can significantly prolong the life of murine ascites hepatoma H22 tumor‐bearing mice.
Esterification of xylan with ibuprofen via activiation of the carboxylic acid with N,N′‐carbonyldiimidazole (CDI) yields products of high drug loadings. Subsequent sulfation of xylan ibuprofen esters using the gentle agent SO3/DMF was successfully carried out in order to modify hydrophobicity of the xylan esters. The structure of the novel xylan esters was evaluated by means of NMR spectroscopy. The resulting xylan derivatives self assemble into spherical nanoparticles with mean diameters ranging from 162 to 472 nm. Preliminary stability measurements indicate that hydrolytic stability decreases with increase in degree of substitution of sulfate groups. Thus, a new concept toward improved drug delivery from polysaccharide‐based nanoparticles can be established here.
An ultra‐bright fluorescence probe comprising conjugated polymer nanoparticles is developed for biological imaging. Highly blue fluorescent polyfluorene nanoparticles (PF‐NPs) stabilized by sodium dodecylsulfate with an average diameter of 100 nm are prepared by a miniemulsion technique. A folate‐conjugated cationic triblock copolymer is employed to coat negatively charged PF‐NPs via electrostatic interaction for specific cell imaging of folate receptor over‐expressing cancer cells. The coated PF‐NPs show a similar size and morphology to the pristine PF‐NPs, while the fluorescence intensity is enhanced. Such surface‐functionalized PF‐NPs are demonstrated to be suitable probes for efficient cell imaging of folate receptor over‐expressing KB cells by CLSM and flow cytometry.
Novel ‘nano in nano’ composites consisting of biodegradable polymer nanoparticles incorporated into polymer nanofibers may efficiently modulate drug delivery. This is shown here using a combination of model compound‐loaded biodegradable nanoparticles encapsulated in electrospun fibers. The dye coumarin 6 is used as model compound for a drug in order to simulate drug release from loaded poly(lactide‐co‐glycolide) nanoparticles. Dye release from the nanoparticles occurs immediately in aqueous solution. Dye‐loaded nanoparticles which are encapsulated by electrospun polymer nanofibers display a significantly retarded release.
