Combination of chemotherapy and radiotherapy is used to enhance local drug delivery while reducing off‐target tissue effects. Anticancer drug doxorubicin (DOX) is loaded into l‐cysteine modified G4.5 dendrimer (GC/DOX) and released at different pH values in the presence and absence of γ‐radiation. Presence of γ‐radiation significantly improves DOX release from the GC/DOX under acidic pH conditions, suggesting that GC dendrimer is a radiation‐sensitive drug delivery system. GC/DOX is further evaluated by determining cytotoxicity in uterine cervical carcinoma HeLa cells. GC/DOX shows high affinity for cancer cells and effective drug release following an external stimulus (radiation exposure), whereas an in vivo zebrafish study confirms that l‐cysteine acts as a radiosensitizer. GC/DOX treatment combined with radiotherapy synergistically and successfully inhibits cancer cell growth.
In this study, we have used an agarose stamp to conduct direct printing of silver nanoparticles, nanowires and nanoplates on both planar and structured substrates. Nanoparticle solution could be first coated on an agarose stamp, and then transferred to a planar substrate. Micro-patterns comprising metal nanoparticles could be printed on planar substrates without the formation of residual layers. Thus a three-dimensional metal microstructure could be easily fabricated. The patterning of electrodes by printing Ag nanowires directly on TiO(2) was also demonstrated to fabricate resistive random access memory (RRAM) devices by all-solution-processing methods. By using a flat agarose stamp, the patterns printed on the microstructured substrates were quite different from those on the nanostructured substrates. On the microstructured substrates, direct printing could print silver nanoparticles onto the protrusion surface, and could print silver layers as thick as several microns, useful for high conductivity electrodes. On the substrates with nanostructures such as photonic crystals or nano-gratings, direct printing could transfer nanoparticles into the grooves or cavities only due to the contact of the agarose stamp with the groove or concavity surface. A new approach to fabricate metal wire grid polarizers was further demonstrated. A nanoporous agarose stamp has a good potential for printing using nanoparticle suspension.
Various surface treatment methods were investigated to improve the adhesion of abrasionresistant polymethylsilsesquioxane (PMSQ) coatings on the optical resins. The adhesion of PMSQ films was improved on polymethylmethacrylate (PMMA), polycarbonate (PC), and PC/acrylonitrile butadiene styrene (ABS) by pretreating their surface with O 2 plasma or chromic acid followed by surface grafting with trimethyl ethoxysilane (TMES). After the O 2 plasma and the subsequent TMES treatments, the adhesion of PMSQ coating on PMMA substrate was significantly enhanced by the reduction of the percentage of peeling area from $100% to <1% in cross cut tests. After the chromic acid and the subsequent TMES treatments of PC and PC/ABS substrates, the adhesion of PMSQ coatings was also significantly enhanced by reducing the percentages of peeling areas from nearly 100% to 50% and <1%, respectively, for PC and PC/ABS. The PMSQ coating might increase the hardness of the polymer by two to three levels.
Here, dual-sensitive fluorescent branched alginate-polyethyleneimine copolymer (bAPSC) nanogels were synthesized from thiolated alginate and stearoyl-derivatized branched polyethyleneimine. The formation of bAPSC conjugates was confirmed through proton nuclear magnetic resonance and Fourier transform infrared spectroscopy, whereas dynamic light scattering was used to measure the particle size and ζ potential of the nanogels. The fluorescent properties of the nanogels were confirmed through fluorescent spectroscopy and microscopy. In addition to the excitation-dependent fluorescence behavior, the fluorescence emission intensity of bAPSC was altered by both pH and γ-irradiation. This intensity was higher at a lower pH than at a higher pH, and it slightly decreased after γ-irradiation. The drug loading and encapsulation efficiency of bAPSC were 25.9% and 11.2%, respectively. An in vitro drug release study revealed that the synthesized nanogels release their doxorubicin (Dox) contents in a time-dependent manner, and the drug release was higher after 96 h of incubation. Approximately 43.74% and 88.36% of Dox was released after 96 h of incubation at pH 5.5 in the absence and presence of glutathione (GSH), respectively. However, relatively lower drug release, approximately 21.6% and 16%, was observed in the presence and absence of GSH at pH 7.4, respectively. Fluorescence microscopy confirmed that Dox-loaded bAPSC nanogels were internalized by HeLa cells, and drug distribution was easily tracked using fluorescent materials without additional probing agents. Moreover, cellular cytotoxicity and hemolysis results revealed less cytotoxicity and hemocompatibility of the synthesized nanogels, confirming that they are the most favorable alternative drug carriers for drug delivery systems.
We have developed a residual-layer-free patterning method by selectively filling the concavity of a mould with liquid solution. The method has potential for large-area roll-to-roll fabrication of micro-devices on the flexible substrates. By choosing an appropriate solution or liquid, such as polymethylmethacrylate (PMMA) solution or epoxy precursor, with suitable dynamic contact angle on the SAM-treated mould, the liquid can be coated on the concavity of the mould only. By using this method, residual-layer-free epoxy pattern could be achieved without the need of an extra step. Without forming a residual layer, the technology could simplify the fabrication of three-dimensional structures with low distortion and smooth edges. Conductive PPy/PMMA patterns can also be fabricated by selective deposition of PMMA/FeCl3 and then exposing to pyrrole/chlorobenzene vapours to induce chemical oxidative polymerization of PPy. The electrical resistivity of PPy/PMMA obtained was 0.17 Ω cm.
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