Preparation and characterization of melamine-formaldehyde/Ag composite microspheres with surface-enhanced Raman scattering and antibacterial activities.

A facile and environmentally friendly approach was proposed to decorate Ag nanoparticles on melamine-formaldehyde (MF) colloidal particles (MF/Ag composite microspheres). In this approach, monodisperse MF colloidal particles were prepared via a two-step organic sol-gel process and served as the active templates for the decoration of Ag nanoparticles. Then, the [Ag(NH3)2]+ ions as the Ag precursors can be adsorbed onto the surfaces of the MF colloidal particles and were in situ reduced into metallic Ag nanoparticles, forming MF/Ag composite microspheres. During this synthesis, neither presurface activation nor extra reductants were necessary. These MF/Ag composite microspheres can be used as the surface-enhanced Raman scattering (SERS) active substrates for the trace detection of organic compounds, e.g., 4-aminobenzenethiol (4-ABT) and penicillin G sodium. Furthermore, these MF/Ag composite microspheres also showed excellent antibacterial activities against both Escherichia coli (E. coli, gram-negative bacteria) and Staphylococcus aureus (S. aureus, gram-positive bacteria).

Bioinspired one-step construction of hierarchical superhydrophobic surfaces for oil/water separation.

It is imperative to develop efficient and environmentally friendly oil-spill cleanup materials to solve the problems raised by frequent oil spillages and industrial discharge of organic solvents. Here, we present a bioinspired one-step construction of hierarchical superhydrophobic surfaces on various commercial porous materials by immersing the materials into an alkaline aqueous mixture consisting of dopamine (DA) and dodecyltrimethoxysilane (DTMS). The self-polymerization of DA constructs the bumpy surfaces, while the DTMS coatings enhance the hydrophobicity of the surfaces. The combined use of both results in the hierarchical superhydrophobic surfaces. This surface modification of porous materials allows them as the potential candidates for collecting a wide variety of oils/organic solvents from water in a highly efficient, recyclable, and durable way. This approach proposes a general, yet green path for constructing superhydrophobic surfaces, which can be further adapted to prepare economic oil/organic solvents absorbents applied in the fields of oil/water separation, wastewater remediation, and organics recovery.