Polydopamine-based chemistry has been employed for various surface modifications attributed to the advantages of universality, versatility, and simplicity. Co-deposition of polydopamine (PDA) with polyethyleneimine (PEI) has then been proposed to realize one-step fabrication of functional coatings with improved morphology uniformity, surface hydrophilicity, and chemical stability. Herein, we report the co-deposition kinetics related to the solution composition with different dopamine/PEI ratios, PEI molecular weights, dopamine/PEI concentrations, and the substrate surface with varying chemistry and wettability. The addition of PEI to dopamine solution suppresses the precipitation of PDA aggregates, resulting in an expanded time window of steady co-deposition compared with that of PDA deposition. Low-molecular-weight PEI at low concentration accelerates the co-deposition process, while high-molecular-weight PEI and high concentration of either PEI or dopamine/PEI are detrimental to the co-deposition efficiency. Meanwhile, the surface morphology and chemical composition of the co-deposition coatings can be regulated by the solution conditions during co-deposition. Moreover, obvious deviations in the co-deposition rate and the amount of substrates bearing various functional groups, such as alkyl, phenyl, hydroxyl, and carboxyl, are revealed, which are quite different from PDA deposition. The initial adsorption rates further reflect the change in interactions between the aggregates and these substrates caused by PEI, which follows the sequence of carboxyl > hydroxyl > alkyl > phenyl. These results provide deep insights into the PDA/PEI co-deposition process on various substrates.

Oil/water separation, especially for those surfactant-stabilized oil-in-water (O/W) emulsions, is required to protect our ecological environment from destruction. Janus membranes with a function of deemulsification appear as a kind of efficient materials for the separation of O/W emulsions because of a precise adjustment of the surface nature for the hydrophilic and hydrophobic layers. However, existing strategies of membrane preparation suffer from complicated multisteps, leading to uncontrolled thickness of the hydrophilic deemulsification layer. Herein, we present a facile and tunable method to prepare a series of Janus membranes consisting of negatively or positively charged carbon nanotubes (CNTs) and hydrophobic microfiltration membranes by vacuum filtration. The thickness of the hydrophilic CNT coating is thus well-controlled by engineering the amount of CNTs deposited on the substrate membrane. The prepared Janus membranes are effective for the separation of both heavy oil and light oil from O/W emulsions through deemulsification owing to the charge-screening effect. It is very interesting that those membranes displaying a combination of water contact angle and underwater oil contact angle both above 90° have a unique oil delivery behavior and thus high separation performance of oil from O/W emulsions. Such Janus membranes can retrieve 89% of oil in 40 min from the 1,2-dichloroethane/water emulsions with the droplet size of 19 μm. This easy-to-prepare and easy-to-tune strategy provides feasibilities for practical applications of Janus membranes to the deemulsification and separation of O/W emulsions.

Targeted therapy is highly challenging and urgently needed for patients diagnosed with triple negative breast cancer (TNBC). Here, a synergistic treatment platform with plasmonic–magnetic hybrid nanoparticle (lipids, doxorubicin (DOX), gold nanorods, iron oxide nanocluster (LDGI))–loaded mesenchymal stem cells (MSCs) for photoacoustic imaging, targeted photothermal therapy, and chemotherapy for TNBC is developed. LDGI can be efficiently taken up into the stem cells with good biocompatibility to maintain the cellular functions. In addition, CXCR4 on the MSCs is upregulated by iron oxide nanoparticles in the LDGI. Importantly, the drug release and photothermal therapy can be simultaneously achieved upon light irradiation. The released drug can enter the cell nucleus and promote cell apoptosis. Interestingly, light irradiation can control the secretion of cellular microvehicles carrying LDGI for targeted treatment. A remarkable in vitro anticancer effect is observed in MDA‐MB‐231 with near‐infrared laser irradiation. In vivo studies show that the MSCs‐LDGI has the enhanced migration and penetration abilities in the tumor area via both intratumoral and intravenous injection approaches compared with LDGI. Subsequently, MSCs‐LDGI shows the best antitumor efficacy via chemo‐photothermal therapy compared to other treatment groups in the TNBC model of nude mice. Thus, MSCs‐LDGI multifunctional system represents greatly synergistic potential for cancer treatment.

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Micropatterning techniques independent of high-cost facilities are highly appreciated in bioanalysis and optoelectronics. Here we report a novel nonlithographic method based on self-assembled honeycomb films with through pores for micropatterning of zinc oxide nanowires (ZnO NWs). The ordered films were prepared via the breath figure method and used as templates for the solution growth of ZnO NWs. The resultant ZnO NW micropatterns were characterized by scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction, high-resolution transmission electron microscopy, and photoluminescence spectrometry. Room-temperature photoluminescence spectra indicate that the micropatterned ZnO NWs show greatly enhanced near-band-edge emission and have potential as high-efficiency blue or near-UV light emitters. This facile and versatile approach is further demonstrated by templating biomimetic hydroxyapatite and silver nanoparticles on polydopamine-coated substrates. This work provides an alternative route to fabricating micropatterned functional surfaces at low cost and high efficiency.

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