Research on nanomedicines has rapidly progressed in the past few years. However, due to the limited size of nuclear pores (9-12 nm), the nuclear membrane remains a difficult barrier to many nucleus-targeting agents. Here, we report the development of a general platform to effectively deliver chemical compounds such as drug molecules or nanomaterials into cell nuclei. This platform consists of a polyamine-containing polyhedral oligomeric silsesquioxane (POSS) unit, a hydrophilic polyethylene glycol (PEG) chain, and the photosensitizer rose bengal (RB), which can self-assemble into nanoparticles (denoted as PPR NPs). Confocal fluorescence imaging showed that PPR NPs mainly located in lysosomes after cellular internalization. After mild light irradiation, however, PPR NPs effectively disrupted lysosomal structures by singlet oxygen (O) oxidation and substantially accumulated on nuclear membranes, which enabled further disruption of the membrane integrity and promoted their final nuclear entry. Next, we selected two chemotherapeutic agents (10-hydroxycamptothecine and docetaxel) and a fluorescent dye (DiD) as payloads of PPR NPs and successfully demonstrated that this nanocarrier could efficiently deliver them into cell nuclei in a light-controlled manner. In addition to molecular compounds, we have also demonstrated that PPR NPs could facilitate the nuclear entry of nanomaterials, including Prussian blue NPs as well as gold nanorods. Compared to traditional strategies for nuclear delivery, this highly controllable nanoplatform avoids complicated modification of nucleus-targeting ligands and is generally applicable to both molecular compounds and nanomaterials.
Adhesion is important in many industrial applications including those in the microelectronics industry. Flip-chip assemblies commonly utilize epoxy underfills to promote reliability and the buried interfacial structure of underfills is crucial to device lifetime. Poor adhesion at this interface can cause premature device failure. One method to increase adhesion strength is to plasma treat the substrate attached to underfills, however, the mechanism of this increase in adhesion strength has not been thoroughly investigated at the molecular level in situ, because it is difficult to probe a buried interface where the adhesion occurs. In this work, sum frequency generation (SFG) vibrational spectroscopy was utilized to investigate the buried polymer/epoxy resin interface at the molecular level. Plasma treatment was performed on the polymer surfaces and the effects were examined. The buried interfaces between the polymer surface before and after plasma treatment and epoxy were then investigated to understand if the effects of the treatment can be observed using SFG. It was found that the molecular structure of the buried interface of the pristine polymer surface in contact with epoxy is drastically different from the buried interface of the plasma treated surface with epoxy. The buried interface containing the plasma treated polymer surface was found to be considerably more disordered and had much higher adhesion strength. This research elucidates the plasma treatment effects on structures and properties of buried polymer/epoxy interfaces, providing in-depth understanding on the mechanism of adhesion strength increase facilitated by plasma treatment.
Buried interfacial structures containing epoxy underfills are incredibly important in the microelectronics industry and their structures determine the interfacial adhesion properties and ultimately their lifetime.
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