Influence of surface coatings on the adhesion of Shewanella oneidensis MR-1 to hematite

Diverse Applications of Two-Dimensional Correlation Spectroscopy (2D-COS)

This second of the two-part series of a comprehensive survey review provides the diverse applications of two-dimensional correlation spectroscopy (2D-COS) covering different probes, perturbations, and systems in the last two years. Infrared spectroscopy has maintained its top popularity in 2D-COS over the past two years. Fluorescence spectroscopy is the second most frequently used analytical method, which has been heavily applied to the analysis of heavy metal binding, environmental, and solution systems. Various other analytical methods including laser-induced breakdown spectroscopy, dynamic mechanical analysis, differential scanning calorimetry, capillary electrophoresis, seismologic, and so on, have also been reported. In the last two years, concentration, composition, and pH are the main effects of perturbation used in the 2D-COS fields, as well as temperature. Environmental science is especially heavily studied using 2D-COS. This comprehensive survey review shows that 2D-COS undergoes continuous evolution and growth, marked by novel developments and successful applications across diverse scientific fields.

Ionic Strength-Dependent Attachment of Pseudomonas aeruginosa PAO1 on Graphene Oxide Surfaces

Graphene oxide (GO) is a widely used antimicrobial and antibiofouling material in surface modification. Although the antibacterial mechanisms of GO have been thoroughly elucidated, the dynamics of bacterial attachment on GO surfaces under environmentally relevant conditions remain largely unknown. In this study, quartz crystal microbalance with dissipation monitoring (QCM-D) was used to examine the dynamic attachment processes of a model organism Pseudomonas aeruginosa PAO1 onto GO surface under different ionic strengths (1-600 mM NaCl). Our results show the highest bacterial attachment at moderate ionic strengths (200-400 mM). The quantitative model of QCM-D reveals that the enhanced bacterial attachment is attributed to the higher contact area between bacterial cells and GO surface. The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and atomic force microscopy (AFM) analysis were employed to reveal the mechanisms of the bacteria-GO interactions under different ionic strengths. The strong electrostatic and steric repulsion at low ionic strengths (1-100 mM) was found to hinder the bacteria-GO interaction, while the limited polymer bridging caused by the collapse of biopolymer layers reduced cell attachment at a high ionic strength (600 mM). These findings advance our understanding of the ionic strength-dependent bacteria-GO interaction and provide implications to further improve the antibiofouling performance of GO-modified surfaces.

Biofriendly Waste Shell Powders/Polylactic Acid Composites for Antibacterial Engineering Applications

With the rapid progress of agriculture and aquaculture, waste shells are harming the environment because of large production, and highly valued recycling is now holding more attention. However, there are still no good ways for simultaneously solving the poor mechanical and antibacterial performance during the recycling process. In this work, antibacterial shell-grafting-Ag powders/polylactic acid (shell-g-Ag/PLA) biocompatible composites, with comparable mechanical properties to industrial polymer counterparts, were prepared via the in situ reduction of Ag ions on surfaces of polydopamine-modified shell powders. The introduction of Ag particles increases the compatibility on the interface and endows the composites with antibacterial performance by inheriting the prominent characteristic from Ag. Without scarifying the mechanical properties by improving the crystallinity and interface, the loaded Ag particles in the composites endowed the composites with valorized antibacterial performance, evidenced by a bacterial inhibition width from 0 to ∼3.29 mm. The biofriendly composites, together with comparable mechanical properties to industrial PLA products, can serve as a sustainable material to be applied in the field of disposable packaging.