Metal aluminum (Al) is being widely used in industry and can be easily corroded in severe conditions. Recently, dopamine has been demonstrated to be an effective adhesive molecular that can be attached to virtually all material surfaces to form stable polydopamine coating (PDAc), exhibiting promising prospects in many fields. In this work, to improve the anti-corrosion performance of Al sheet, a novel polydopamine-based 3-layer organic coating has been constructed by a multi-step self-assembly technique for the first time. In brief, a self-assembled monolayer of (3-mercaptopropyl)trimethoxysilane (coded as MPTS-SAM) was firstly prepared for enhancing the adhesion between the PDAc and the Al substrate. Subsequently, a PDAc was assembled onto the Al substrate by a simple immersion into the dopamine hydrochloride solution at a pH of 8.5. At last, a layer of tetradecanoyl chloride was grafted onto the PDAc surface through amidation, which could apparently slow down the water diffusion to the interface of PDAc and Al for its prominent hydrophobicity. Corrosion resistance of the synthesized coating in NaCl solution was evaluated by potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) measurement, respectively. As results show, PDAc on bare Al can protect the substrate from corrosion to a certain extent. Significantly, after being mediated by MPTS-SAM underlayer and covered by tetradecanoyl chloride outer layer, the anti-corrosion capability of the coating has been improved markedly.

Mesoporous bioactive glass (MBG) of CaO–SiO2–P2O5 was synthesized using nonionic block copolymer (EO20PO70EO20, P123) and acetic anhydride as the template and catalyst, respectively. It was inferred that acetic anhydride could accelerate the hydrolysis of tetraethyl orthosilicate and the obtained by-product of acetic acid was harmless to the environment. The TEM analysis indicated that the synthesized MBG had two-dimensional (2D) hexagonal mesostructures, and the measured BET surface area, pore volume and pore diameter were 499 m2/g, 0.70 cm3/g and 6.1 nm, respectively. Moreover, the synthesized MBG showed an excellent bioactivity in vitro as assessed by immersion studies in simulated body fluid (SBF). In a word, this work presents a simple and environment friendly route for synthesizing MBG by use of acetic anhydride as the catalyst and would find potential applications in tissue engineering and other fields.

Titanium oxide (TiO2) films were successfully deposited onto the polymer substrates of polytetrafluoroethylene (PTFE), polyethylene (PE), and polyethylene terephthalate (PET), which were pre-modified with polydopamine coating (polydopamine and its coating are coded as PDA and PDAc, respectively), by a simple liquid phase deposition (LPD) process. The morphology and chemical state of the obtained TiO2 films were characterized by field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Subsequently, the biocompatibility of the samples was investigated by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay and acridine orange staining of MC-3T3 osteoblast cells, and the results demonstrated that the fabricated TiO2 films could markedly improve the in vitro cytocompatibility. So, the presented route is anticipated to be a promising surface modification methodology to improve the practical outcome of the implanted materials for its versatility and validity.

In this work, three novel types of peptide nucleic acid (PNA) monomers labeled by ferrocenyl–azobenzene units (Fc–Azo–PNAs, 1a, 1b, and 1c) have been synthesized and they all exhibited good reversible photoswitch and redox properties. In the different solvents of ethanol (EtOH) and acetonitrile (ACN), photoisomerization rate constants (K) of three PNA monomers under UV light irradiation have also been analyzed and compared, discovering that the values of K are closely correlative to their molecular structures. The electrochemical properties of the synthesized PNA monomers are also investigated and the typical redox properties are displayed, demonstrating that they can be regarded as the anchor to be grafted at the end of PNA oligomers for detecting themselves. Finally, according to the analyses of UV–Vis absorption spectrum and differential pulse voltammetry (DPV), the synthesized PNA monomers afford the best detection limit down to 10−8 M in EtOH. The results also illuminate that PNA monomers with new photo–redox dual stimulus–response characteristics can be realized to detect themselves by the metal complex unit together with azo moiety; moreover, the hybridization with DNA also can be tuned by the isomerization of azo moiety.Excellent reversible photoswitch and redox activities of three novel types of peptide nucleic acid monomers labeled by ferrocenyl–azobenzene units (Fc–Azo–PNAs) are investigated. These results demonstrate that these new photo–redox peptide nucleic acid monomers (PNAs) have great potential in detecting the PNAs and tuning the hybridization with DNA.

A novel 3-layer organic film was fabricated on silicon wafer with a polydopamine coating (coded as PDAc) as the interlayer by a multistep self-assembly process. The formation and structure of the films were analyzed by means of ellipsometric thickness measurement, water contact angle measurement, and attenuated total reflection-Fourier transform infrared spectrometry (ATR-FTIR). Meanwhile, an atomic force microscope (AFM) characterization was performed to evaluate the adhesive and microtribological behaviors of the 3-layer film, and a ball-on-plate tribometer was used to test macrotribological performance. As results show, the as-prepared 3-layer film possessed the excellent tribological properties characterized by lower friction and higher antiwear ability, which was ascribed to the special chemical structure of the film, i.e., the strong adhesion of the film to the silicon wafer, the chemical bonding between the adjacent layers, the cross-linked structure of the PDAc interlayer, and the hydrophobicity, high flexibility, and high elasticity of the stearoyl chloride (STC) outer layer. Hopefully, the present work provides a feasible route to construct a multilayer film with excellent structural stability and tribological behavior. The titled multilayer film might find potential applications in boundary lubrication and many other areas.