Herein, voltage-responsive controlled release film was constructed by grafting ferrocene on the mesoporous inverse opal photonic crystal (mIOPC). The film achieved free-blockage controlled release and realized the monitoring of cargo release without external indicator. Free-blockage was attributed to the voltage switchable nanovalves which undergo hydrophobic-to-hydrophilic transition when applying voltage. Monitoring of cargo release was attributed to the optical property of mIOPC, the bandgap of mIOPC had a red shift when the solution invaded in. The film was hydrophobic enough to stop solution intrusion. Once the voltage was applied, the film became hydrophilic, leading to invasion of the solution. As a result, the cargos were released and the bandgap of mIOPC was red-shifted. Therefore, in this paper both a free-blockage controlled release film and a release sensing system was prepared. The study provides new insights into highly effective controlled release and release sensing without indicator.Keywords: controlled release; free-blockage; hydrophobicity switching; nano valve; release sensing;

AbstractThe formation and metastatic colonization of circulating tumor cells (CTCs) are responsible for the vast majority of cancer-related deaths. Over the last decade, drug-delivery systems (DDSs) have rapidly developed with the emergence of nanotechnology; however, most reported tumor-targeting DDSs are able to deliver drugs only to solid tumor cells and not CTCs. Herein, a novel DDS comprising a composite nanofiber film was constructed to inhibit the viability of CTCs. In this system, gold nanoparticles (Au NPs) were functionalized with doxorubicin (DOX) through an acid-responsive cleavable linker to obtain Au-DOX NPs. Then, the Au-DOX NPs were mixed in a solution of an acid-responsive polymer {i.e., poly[2-(dimethylamino)ethyl methacrylate]} to synthesize the nanofiber film through electrospinning technology. After that, the nanofiber film was modified with a specific antibody (i.e., anti-EpCAM) to enrich the concentration of CTCs on the film. Finally, the Au-DOX NPs were released from the nanofiber film, and they consequently inhibited the viability of CTCs by delivering DOX to the enriched CTCs. This composite nanofiber film was able to decrease the viability of CTCs significantly in the suspended and fluid states, and it is expected to limit the migration and proliferation of tumor cells.

Nano valves have been used in functional porous materials to control molecular transport by changing their properties in response to external stimuli. But most of them are limited by the blocking units and cannot show their state by themselves. Herein, pH switchable nano valves were constructed using mesoporous inverse opal photonic crystal, which realized free-blockage nano valves and achieved the monitoring of the state of the valve by the naked eye without an external indicator. The nano valves were modified by phenylamine groups, which has a convertible hydrophobic/hydrophilic property between deprotonation and protonation. The valves were hydrophobic enough to prevent solution passing through at pH 7.0, and meanwhile a green color was presented. With the decrease of the pH value of the solution, the valves became open and presented a yellow to red color because of the protonation of phenylamine groups followed by the invasion of solution. Thus, in this study not only a free-blockage valve but also nano sensing valve was constructed. We believe that our studies provide new insights into photonic crystal sensors and nano sensing valve.

Controlled release system based on mesoporous silica (MS) nanomaterials has drawn great attention over the past decades due to its potential biomedical applications. Herein, a light-responsive release system based on MS nanoparticles was achieved by adjusting the wetting of the MS surface. At the starting stage, the surface of MS modified with optimal ratio of spiropyran to fluorinated silane (MS-FSP) was protected from being wetted by water, successfully inhibiting the release of model cargo molecules, fluorescein disodium (FD). Upon irradiation with 365 nm UV light, the conformational conversion of spiropyran from a “closed” state to an “open” state caused the surface to be wetted, leading to the release of FD from the pores. The further in vitro studies demonstrated the system loaded with anticancer drug camptothecin (CPT) could be effectively controlled to release the drug by UV light stimuli to enhance cytotoxicity for EA.hy926 cells and HeLa cells. This wettability-determined smart release platform could be triggered by remote stimuli, which might hold promise in the applications of drug delivery and cancer therapy.Keywords: controlled release; light-responsive; mesoporous silica; spiropyran; wetting

A simple method for the preparation of a highly stable and reliable surface-enhanced Raman scattering (SERS) substrate was proposed. The SERS enhancement was demonstrated with good controllability and reproducibility through the controlled formation/deformation of SERS “hotspots” using a reversible DNA nanoswitch. Highly effective DNA detection was achieved using a well-designed sandwich structure.