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Liquid metal‐based printing techniques are emerging as an exemplary platform for harvesting non‐layered 2D materials with a thickness down to a few nanometres, leading to an ultra‐large surface‐area‐to‐volume ratio that is ideal for sensing applications. In this work, the synthesis of 2D tin dioxide (SnO2) by exfoliating the surface oxide of molten tin is reported which highlights the enhanced sensing capability of the obtained materials to ammonia (NH3) gas is reported. It is demonstrated that amperometric gas sensors based on liquid metal‐derived 2D SnO2 nanosheets can achieve excellent NH3 sensing performance at low temperature (150 °C) with and without UV light assistance. Detection over a wide range of NH3 concentrations (5–500 ppm) is observed, revealing a limit of detection at the parts per billion (ppb) level. The 2D SnO2 nanosheets also feature excellent cross‐interference performance toward different organic and inorganic gas species, showcasing a high selectivity. Further, ab initio DFT calculations reveal the NH3 adsorption mechanism is dominated by chemisorption with a charge transfer into 2D SnO2 nanosheets. In addition, a proof of concept for prototype flexible ammonia sensors is demonstrated by depositing 2D SnO2 on a polyimide substrate, signifying the high potential of employing liquid metal printed SnO2 for realizing wearable gas sensors. [ABSTRACT FROM AUTHOR]

The colonisation of biomaterial surfaces by pathogenic bacteria is a significant issue of concern, particularly in light of the rapid rise of antibiotic resistance. Current strategies are proving ineffective as multi-drug resistant pathogenic bacteria emerge. Recently, it was discovered that surfaces with nanoscale features are capable of physically rupturing bacteria and hence displaying mechano-bactericidal activity. In this study, we investigated the interactions between methicillin- and gentamicin-susceptible and -resistant Staphylococcus aureus strains and nanostructured titanium surfaces, fabricated using a hydrothermal etching process. The nanostructured titanium surfaces proved to be equally effective and highly bactericidal against both the susceptible and resistant S. aureus strains, with killing efficiencies of 80.7% ± 12.0 and 86.8% ± 11.6, respectively. The mechano-bactericidal activity of these nanostructured titanium surfaces offers an innovative solution to establish medical device surfaces with antimicrobial activity in the context of increasing antibiotic resistance. [ABSTRACT FROM AUTHOR]

A new pyrene-phosphonate colorimetric receptor 1 has been designed and synthesized in a one-step process via amide bond formation between pyrene butyric acid chloride and phosphonate-appended aniline. The pyrene-phosphonate receptor 1 showed aggregation-induced enhanced emission (AIEE) properties in water/acetonitrile (ACN) solutions. Dynamic light scattering (DLS) characterization revealed that the aggregates of receptor 1 at 80% water fraction have an average size of ≈142 nm. Field emission scanning electron microscopy (FE-SEM) analysis confirmed the formation of spherical aggregates upon solvent evaporation. The sensing properties of receptor 1 were investigated by UV-vis, fluorescence emission spectroscopy, and other optical methods. Among the tested metal ions, receptor 1 is capable of recognizing the Fe3+ ion selectively. The changes in spectral measurements were explained on the basis of complex formation. The composition of receptor 1 and Fe3+ ions was determined by using Job's plot and found to be 1:1. The receptor 1--Fe3+ complex showed a reversible UV-vis response in the presence of EDTA. [ABSTRACT FROM AUTHOR]

Microscale devices are increasingly being developed for diagnostic analysis although conventional lysis as an initial step presents limitations due to its scale or complexity. Here, we detail the physical response of erythrocytes to the surface nanoarchitecture of black Si (bSi) and foreshadow their potential in microanalysis. The physical interaction brought about by the spatial convergence of the two topologies: (a) the nanopillar array present on the bSi and (b) the erythrocyte cytoskeleton present on the red blood cells (RBCs), provides spontaneous stress-induced cell deformation, rupture and passive lysis within an elapsed time of ~3 min from immobilisation to rupture and without external chemical or mechanical intervention. The mechano-responsive bSi surface provides highly active yet autogenous RBC lysis and a prospect as a front-end platform technology in evolving micro-fluidic platforms for cellular analyses. [ABSTRACT FROM AUTHOR]

Chain dynamics, probed by dielectric spectroscopy, provide a route to further understanding of the molecular interactions induced by hydration, degree of crosslinking, and microstructural changes occurring on swelling of biopolymers such as chitosan, which is becoming a focus for biomedical engineering and therapeutic delivery. The basis of the β-wet relaxation peak is established as segmental chain relaxation between chitosan water bridges and related to its hysteresis induced by microstructural changes during wetting and dewetting cycles. Linear expansion probes the hysteresis arising from bridging water interactions during the hydration-dehydration paths which is also shown in the resultant ionic conductivity. β-wet relaxation and ionic conductivity exhibit identical hysteresis behavior with both degrees of chemical crosslinking and water contents. X-ray diffraction shows that the degree of crosslinking and hydration also influences the degree of disorder of the polymer chains changing both the crystalline phase fraction and lattice dimensions. These molecular interactions provide power law behavior between β-wet relaxation dynamics and ionic mobility over five orders of magnitude for all degrees of chemical crosslinking and water bridging which is independent of the significant hysteresis in these properties indicative of scaling behavior within the noncrystalline gel phase. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 [ABSTRACT FROM AUTHOR]

Naphthalenediimide-tetraphenylethylene conjugates with an alanine spacer (coded as: NDI-(Ala-TPE) 2 ) were synthesized to study the influence of the chirality of the amino acid spacer on its self-assemblies. Here we particularly show that NDI-Ala-TPE bearing l-alanine gives left-handed (M-type) helical superstructure, while d-alanine produces right-handed (P-type) helical ribbons in THF:H 2 O at 40:60 % v/v ratio. However, particular aggregates were observed at 20:80 % v/v ratio. Circular dichroism was used to characterise the induction of chirality and the handedness of the helical superstructures, and the microstructure of the self-assembled materials was visualised using scanning electron microscopy while DLS analysis confirmed the formation of particular aggregates in solution., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This comprehensive review surveys developments over the past decade in the field of naphthalene diimides (NDIs). It explores their application toward: supramolecular chemistry; sensors; host-guest complexes for molecular switching devices, such as catenanes and rotaxanes; ion-channels by ligand gating; gelators for sensing aromatic systems; catalysis through anion-π interactions; and NDI intercalations with DNA for medicinal applications. We have also explored new designs, synthesis, and progress in the field of core-substituted naphthalene diimides (cNDIs), and their implications in areas such as artificial photosynthesis and solar cell technology. Also presented are some interesting synthetic routes and procedures that can be used toward further development of NDI-bearing compounds for future applications. Finally, we conclude with our views on NDI chemistry for future research endeavors, and we outline what we believe are the key obstacles that need to be overcome for NDIs to see real world applications.

Bacterial meningitis is an infection of the thin membranes covering the brain and spinal cord by a number of microorganisms including Neisseria meningitidis, which can lead to permanent neurological damage in the event of late diagnosis. Given the quick onset and severity of the disease, there is a clear need for a rapid, sensitive and specific diagnostic technique. Here, we describe the development and evaluation of an acoustic wave sensor, the quartz crystal microbalance (QCM), as a rapid immunosensor employing antibodies against the cell surface outer membrane protein 85 (OMP85) of N. meningitidis as an immobilized selective layer. These antibodies were directionally orientated as receptors by thin film deposition of structured polyvinylidene fluoride and Protein A. The sensitivity of this QCM immunosensor was further increased by conjugation of the OMP85 antigen to 50 nm gold nanoparticles providing reproducible detection of the target down to 300 ng/mL. Subsequent treatment of the QCM surface with an acidic glycine solution regenerated the immunosensor allowing each crystal to be used several times., (Copyright © 2011 Elsevier B.V. All rights reserved.)