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Correlative imaging methods can provide greater information for investigations of cellular ultra-structure, with separate analysis methods complementing each other's strengths and covering for deficiencies. Here we present a method for correlative applications of super resolution and atomic force microscopies, optimising the sample preparation for correlative imaging of the cellular cytoskeleton in COS-7 cells. This optimisation determined the order of permeabilisation and fixation, the concentration of Triton X-100 surfactant used and time required for sufficient removal of the cellular membrane while maintaining the microtubule network. Correlative SMLM/AFM imaging revealed the different information that can be obtained through each microscopy. The widths of microtubules and microtubule clusters were determined from both AFM height measurements and Gaussian fitting of SMLM intensity cross sections, these were then compared to determine the orientation of microtubules within larger microtubule bundles. The ordering of microtubules at intersections was determined from the AFM height profiles as each microtubule crosses the other. The combination of both microtubule diameter measurements enabled greater information on their structure to be found than either measurement could individually., (© 2022 IOP Publishing Ltd.)

From atomic force microscopy (AFM) experiments, we report a new phenomenon in which the dissolution rate of fused silica is enhanced by more than 5 orders of magnitude by simply pressing a second, dissimilar surface against it and oscillating the contact pressure at low kHz frequencies in deionized water. The silica dissolution rate enhancement was found to exhibit a strong dependence on the pressure oscillation frequency consistent with a resonance effect. This harmonic enhancement of the silica dissolution rate was only observed at asymmetric material interfaces (e.g., diamond on silica) with no evidence of dissolution rate enhancement observed at symmetric material interfaces (i.e., silica on silica) within the experimental time scales. The apparent requirement for interface dissimilarity, the results of analogous experiments performed in anhydrous dodecane, and the observation that the silica "dissolution pits" continue to grow in size under contact stresses well below the silica yield stress refute a mechanical deformation or chemo-mechanical origin to the observed phenomenon. Instead, the silica dissolution rate enhancement exhibits characteristics consistent with a previously described 'electrochemical pressure solution' mechanism, albeit, with greatly amplified kinetics. Using a framework of electrochemical pressure solution, an electrochemical model of mineral dissolution, and a recently proposed "surface resonance" theory, we present an electro-chemo-mechanical mechanism that explains how oscillating the contact pressure between dissimilar surfaces in water can amplify surface dissolution rates by many orders of magnitude. This reaction rate enhancement mechanism has implications not only for dissolution but also for potentially other reactions occurring at the solid-liquid interface, e.g. catalysis.

Biomedical device-related infection (BDI) is of great concern in modern clinical and medical applications. Various approaches to combat BDI are based on two major principles: the prevention of biofoulants adhering on medical devices and the ability to eradicate biofouling once formed. To minimize the risk of BDI, an antifouling coating with bactericidal ability is highly desirable. In this work, we report on the use of polynorepinephrine (PNE) as a promising strategy to prevent BDI due to its excellent antifouling and photothermal bacterial killing capabilities. PNE coatings show superior protein resistance against a model biofoulant (bovine serum albumin (BSA)) when compared with poly(ethylene glycol) (PEG) and polydopamine (PDA) coatings. The antifouling mechanism between BSA protein molecules and coating films is investigated using atomic force microscopy (AFM). We also demonstrate that PNE-modified surfaces show remarkable bacterial killing ability against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria after being irradiated with an 850 nm near-infrared (NIR) laser. These results indicate that PNE coatings present a highly promising candidate for biomedical antifouling applications.

Fluorinated hydrocarbon (FHC) contamination has attracted global attention recently because of persistence within the environment and ecosystems of many types of FHC. The surfactant perfluorooctanoic acid (PFOA) is particularly commonly found in contaminated sites, and thus, urgent action is needed for its removal from the environment. In this study, water dispersible hybrid capsules were successfully prepared from an oil-in-water emulsion stabilized by graphene oxide and including a silicate precursor to grow a strong, mesoporous capsule shell surrounding the droplets. These capsules were decorated with amine groups to present a positively charged outer corona that attracts negative PFOA molecules. The aminated capsules were effectively applied as a novel technology to adsorb and sequester PFOA contamination in water. It was confirmed that PFOA removal by the capsules was pH and PFOA concentration dependent, with adsorption efficiencies of >60 mg g -1 under ideal conditions. PFOA removal kinetics followed using high-performance liquid chromatography and liquid chromatography-mass spectrometry showed that capture of PFOA by the capsules reached a maximum of >99.9% in 2-3 days.

Encapsulation is a powerful method for the targeted delivery of concentrated reagents and capture of valuable materials in dilute systems. To this end, many encapsulation schemes for specific scenarios have been devised that incorporate chemospecificity or stimulus response in terms of uptake or release. However, an encapsulation platform that enables highly tailorable surface chemistry for targeting, stimulus response, and core chemistry for capture and release of reagents remains elusive. Here, we present such a system comprising composite core-shell capsule particles of hydrophilic polymers coated with thin silica layers synthesized via straightforward one-pot syntheses. Silica is found to encapsulate a range of polymer hydrogels through a mechanism independent of the specific core chemistry. The hybrid materials possess significantly enhanced rigidity while allowing surface modification through simple yet versatile silane coupling reactions without a reduction in the functionality of the core. They are shown to have applications as diverse as recyclable catalysis and controlled delivery vehicles for agrochemicals. The successful synthesis and utilization of this catalog of materials indicate the broader capability of simple composite structures in an array of high-value applications.