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Nanoparticles can improve the stability of CO 2 foam and increase oil recovery during CO 2 flooding in reservoirs. The synergistic effect of hydrophilic SiO 2 nanoparticles and hexadecyltrimethylammonium bromide (CTAB) on CO 2 foam stability was examined in this study. Experimental results show that the synergistic effect requires a CTAB/SiO 2 concentration ratio of 0.02−0.07, with 0.033 representing the best concentration ratio. With the increase in the concentration ratio, the synergistic stabilization effect of CTAB/SiO 2 dispersion first increases and then decreases. In the monolayer adsorption stage (concentration ratio from 0.02 to 0.033), when the hydrophobicity of SiO 2 nanoparticles increases with the concentration ratio, the nanoparticles tend to adsorb on the gas−liquid interface and the stability of CO 2 foam increases. In the double-layer adsorption stage (concentration from 0.033 to 0.07), when the hydrophobicity of SiO 2 nanoparticles decreases with an increase in the concentration ratio, the nanoparticles tend to exist in the bulk phase and the stability of CO 2 foam decreases. The CTAB/ SiO 2 dispersion stabilizes CO 2 foam via three mechanisms: decreasing the coarsening of CO 2 bubbles, improving interfacial properties, and reducing liquid discharge. CTAB/SiO 2 foam can greatly improve oil recovery efficiency compared to water flooding. Experimental results provide theoretical support for improving CO 2 foam flooding under reservoir conditions.

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Soft robots, compared to traditional rigid-bodied robots, are constructed with physically flexible/elastic bodies and electronics to mimic nature and enable novel applications in industry, healthcare, aviation, military, etc. Recently, building...

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Implantable medical devices have been widely applied in diagnostics, therapeutics, organ restoration, and other biomedical areas, but often suffer from dysfunction and infections due to irreversible biofouling. Inspired by the self‐defensive “vine‐thorn” structure of climbing thorny plants, a zwitterion‐conjugated protein is engineered via grafting sulfobetaine methacrylate (SBMA) segments on native bovine serum albumin (BSA) protein molecules for surface coating and antifouling applications in complex biological fluids. Unlike traditional synthetic polymers of which the coating operation requires arduous surface pretreatments, the engineered protein BSA@PSBMA (PolySBMA conjugated BSA) can achieve facile and surface‐independent coating on various substrates through a simple dipping/spraying method. Interfacial molecular force measurements and adsorption tests demonstrate that the substrate‐foulant attraction is significantly suppressed due to strong interfacial hydration and steric repulsion of the bionic structure of BSA@PSBMA, enabling coating surfaces to exhibit superior resistance to biofouling for a broad spectrum of species including proteins, metabolites, cells, and biofluids under various biological conditions. This work provides an innovative paradigm of using native proteins to generate engineered proteins with extraordinary antifouling capability and desired surface properties for bioengineering applications.

Gas bubbles widely exist in nature and numerous industrial processes. The physicochemical characteristics of bubbles such as large specific surface area, low density, and hydrophobicity make them an ideal platform for developing colloidal and interfacial technologies. Over the past few decades, much effort has been devoted to investigating the properties and behaviors of bubbles and their applications. A series of bubble-based technologies (BBTs) have been developed, which have attracted increasing attention and shown great importance in a wide range of engineering, material, and biological fields. These BBTs, such as bubble flotation and the bubble-liposome system, provide feasible and promising solutions to mineral separation, material assembling, medical diagnosis, and drug delivery. In this work, we have systematically reviewed the physicochemical characteristics of bubbles and how to modulate their behaviors in complex fluid systems, as well as the underlying fundamental interaction mechanisms of bubbles in related BBTs. Advanced nanomechanical techniques such as atomic force microscopy, which are used to quantify the interaction mechanisms in bubble-containing systems, have been introduced. The effects of various influential factors on the bubble behaviors are discussed, which provide potential approaches to improve the controllability and performance of BBTs. The recent advances in the applications of selected BBTs in engineering, biomedical, and material areas are presented. Some remaining challenging issues and perspectives for future studies have also been discussed. This review improves the fundamental understanding of characteristics and surface interaction mechanisms of bubbles, with useful implications for developing advanced BBTs.