Construction of redox-active multilayer film for electrochemically controlled release.

An electrochemically controlled drug release from a redox-active multilayer film is reported. The multilayer film is fabricated by alternate assembly of the electrochemical redox-active micelles and DNA. The buildup of multilayer films is monitored by spectroscopic ellipsometry, UV-vis spectroscopy, and fluorescence spectroscopy. A ferrocene-modified poly (ethyleneimine) (PEI-Fc) is used to form a hydrophobic ferrocene core and hydrophilic PEI shell micelle, showing the electrochemical redox-active properties. Hydrophobic pyrene (Py) molecules are then incorporated into the micelles. The PEI-Fc@Py micelles are assembled into the (PEI-Fc@Py/DNA) multilayer film by layer-by-layer assembly. Thanks to ferrocene groups with the properties of the hydrophilic-to-hydrophobic switch based on the electrical potential trigger, pyrene molecules can be control released from the multilayer film. The electrochemically controlled release of pyrene is investigated and confirmed by electrochemical quartz crystal microbalance and electrochemistry workstation. The (PEI-Fc@drug/DNA) multilayer film may have potential applications in the field of biomedical and nanoscale devices.

Electrochemically controlled stiffness of multilayers for manipulation of cell adhesion.

Stimuli-responsive thin films attract considerable attention in different fields. Herein, an electrochemical redox multilayers with tunable stiffness is constructed through the layer-by-layer self-assembly method. The redox ferrocene modified poly(ethylenimine) play an essential role to induce multilayers' swelling/shrinking under an electrochemical stimulus, resulting reversible change of elastic modulus of the multilayers. The adhesion of fibroblast cells can be thus controlled from well spreading to round shape. Such soft multilayers with electrochemically controlled stiffness could have potentials for cell-based applications.