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Graphene oxide (GO) is a promising two-dimensional (2D) nanomaterial that could improve the performance of membranes due to its unique mechanical stability and chemical tunability. Moreover, GO nanosheets may act as 2D polyelectrolytes in solution because the abundant surface functional groups confer them high dispersity. Unlike conventional polyelectrolyte systems, the assembly behavior of this 2D polyelectrolyte and its resulting characteristics in multilayered membranes have not been thoroughly investigated. Herein, we employed a layer-by-layer (LbL) assembly technique to assemble GO multilayered membranes with highly controlled thickness, roughness, and charge density depending on the assembly pH conditions. Compared to conventional GO membranes prepared by vacuum filtration, the LbL assembled GO multilayered membranes presented different internal structure, wettability, and ion-permeability. The unique properties of the 2D polyelectrolytes obtained in this study may broaden their potential in the field of materials science and membrane applications.

The superhydrophobic surface has been used in ultradry surface applications, such as the maritime industry, windshields, non-sticky surfaces, anti-icing surfaces, self-cleaning surfaces, and so forth. However, one of the main hurdles for the production of superhydrophobic surfaces is high-cost fabrication methods. Here, we report a handy process of self-synthesis fabrication of superhydrophobic surfaces with daily supplies. Driven by the physics of biscuit dunking, we introduce a method to self-synthesize superhydrophobic surfaces from daily supplies by coating a substrate with a liquid (liquids of paraffin from candles or polydimethylsiloxane) and subsequently sprinkling powders (food-desiccant silica, alumina, sugar, salt, or flour). A mechanistic study revealed that the capillary force, governed by surface energy difference, liquid viscosity, and powder pore size, draws the liquid solution into the porous channels within the powders. The entire surface of powders, in turn, is covered with the low-surface-energy liquid to maintain the porosity, creating a 3D porous nanostructure, resulting in a water contact angle over 160°. This work provides a scientific understanding that technological developments are closely related to the science that can be seen in our daily lives. Also, we believe that further intensive studies extended from this work could enable to home-fabricate a superhydrophobic surface, such as a bathtub and sink in bathrooms and a cooking area and sink in kitchens.

A ferrocenyl intercalator was investigated to develop an electrochemical DNA biosensor employing a peptide nucleic acid (PNA) sequence as capture probe. After hybridization with single strand DNA sequence, a naphthalene diimide intercalator bearing ferrocene moieties (FND) was introduced to bind with the PNA-DNA duplex and the electrochemical signal of the ferrocene molecules was used to monitor the DNA recognition.Electrochemical impedance spectroscopy was used to characterize the different modification steps. Differential pulse voltammetry was employed to evaluate the electrochemical signal of the FND intercalator related to its interaction with the complementary PNA-DNA hybrid. The ferrocene oxidation peaks were utilised for the target DNA quantification.The developed biosensor demonstrated a good linear dependence of FND oxidation peak on DNA concentration in the range 1 fM to 100 nM of target DNA, with a low detection limit of 11.68 fM. Selectivity tests were also investigated with a non-complementary DNA sequence, indicating that the FND intercalator exhibits a selective response to the target PNA-DNA duplex.