Reversible Association of Nitro Compounds with p-Nitrothiophenol Modified on Ag Nanoparticles/Graphene Oxide Nanocomposites through Plasmon Mediated Photochemical Reaction

A dual enhanced anti-bacterial strategy based on high chlorin e6-loaded polyethyleneimine functionalized graphene

Bacterial infection has always been a long-term problem of human history and has nowadays became a severe threat to human health with the appearance of drug-resistant bacteria due to the abuse of antibiotics. In this study, a high chlorin e6 (Ce6) photosensitizer-loaded polyethyleneimine-functionalized graphene (PEI-G) nanocomposite (PEI-G@Ce6) was prepared. The loading capacity of Ce6 on PEI-G@Ce6 was approximately up to 32.91 wt%, which was higher than that of other nanomaterials. The as-prepared PEI-G@Ce6 not only improves the photostability of free photosensitizer Ce6 molecules but also maintains the ability of singlet oxygen generation. Based on the dual enhancement of the physical antibacterial effects of PEI-G and the photodynamic therapy (PDT) antibacterial effects of loaded photosensitizer Ce6, PEI-G@Ce6 exhibited enhanced antibacterial efficiency towards Staphylococcus aureus. Therefore, the present strategy provided an effective platform to improve antibacterial efficiency for the better treatment of wound infections.

Dual enhanced anti-bacterial strategy based on a high chlorin e6-loaded polyethyleneimine functionalized graphene nanomaterial.

Visible-light driven photodegradation on Ag nanoparticle-embedded fullerene (C60) heterostructural microcubes

Three-dimensional Ag(I)-fullerene hybrid microcrystal is fabricated by AgNO₃ assisted liquid-liquid interfacial precipitation, containing the abundant sp²-π-electron system. With a mild chemical reduction, it produces the massive Ag nanocluster/fullerene junctions, on which fullerene doubles role as the excellent electron acceptor and photon scavenger, enabling the Plasmon-driven catalytic reaction. Ag nanocluster employed alone could not perform this photocatalytic reaction, neither of fullerene (C₆₀) crystal. It implicates that Ag-fullerene interface is a key to drive catalytic process. Relative to conventional TiO₂ nanostructures, fullerene expands light absorption to most solar wavelength and possesses a tightened bandgap which intrinsically expedites the charge transfer and charge separation from coinage metals. Demonstrated by photodegradation of organic molecules, this Ag(I)-fullerene (C₆₀) composite, consisted of a plethora of electron donor-acceptor dyads renders an additional member to photocatalyst family, potentially implemented for photo-electron conversion, water remedy and beyond.

Photoelectrochemical response of Ag-graphene heterostructures: insight into the localized surface plasmon enhanced photocurrent generation process

We present Ag-graphene heterostructures by combining few layer graphene (FLG) with plasmonic silver nanoparticle (AgNP) arrays to boost the photoelectrochemical (PEC) efficiency of graphene-based nanostructures. AgNP arrays with controlled coverage and size distribution were fabricated on the graphene surface by means of gas phase cluster beam deposition. The photocurrent generation process in the FLG-based nanostructures was analyzed with a PEC amperometric measurement. A significant photocurrent enhancement was observed in the AgNPs-FLG heterostructures compared with bare FLG. It was found that the PEC performance was strongly related to the wavelength and power of the incident light, as well as the density and size of the AgNPs. The enhancement of the PEC response was attributed to the effect of the surface plasmon local fields of the AgNPs, which induce efficient generation and quick separation of the electron-hole pairs in FLG.

Distance-regulating surface plasmon catalyzed coupling reaction of p-nitrophenyl disulfide

In this study, we attempted to regulate the intermolecular distance of PNTP molecules on the surface of silver foil by breaking the S-S bond of NPDS. Though changing the laser wavelength and power, SERS conditions, the Raman spectra of NPDS and PNTP with different concentrations were compared. We found that, under SERS conditions, NPDS converted more efficiently than PNTP to DMAB at low-concentration with low-power and low-energy irradiation. The results indicate that the distance between molecules plays a significant role in the reaction of PNTP to form DMAB.

Combination of a graphene SERS substrate and magnetic solid phase micro-extraction used for the rapid detection of trace illegal additives

Surface enhanced Raman scattering (SERS) is an ultra-sensitive spectroscopy technique, which can provide rich structural information for a great number of molecules, while solid phase micro-extraction (SPME) is an efficient method for sample pretreatment in analytical chemistry, particularly in a micro-system.

Plasmon-driven surface catalytic reaction of 4-ethynylaniline in a liquid environment

There is much evidence that surface plasmon photocatalytic reactions can occur on organic molecules on metal surfaces. In this paper, we focus on the photocatalytic reaction of 4-ethynylaniline (PEAN) on silver nanoparticles (Ag NPs) in a liquid environment by surface-enhanced Raman spectroscopy (SERS). Our experiments used SERS to characterize p,p′-diynylazobenzene produced from PEAN via a selective catalytic coupling reaction on Ag NPs. This discovery not only achieved the expected results but also broadens the known plasmon-driven surface catalytic reaction system. In our work, we also regulated the photocatalytic coupling reaction conditions of PEAN on Ag NPs by laser power-dependent and time-dependent SERS spectra.

The mechanism of Ag NP induced dimerization of PEAN was investigated by using SERS spectra. A very interesting phenomenon was discovered, that is where the relative Raman intensities of b₂ modes increased either with increasing incident laser power or exposure time.

Synergistic Bacteria Killing through Photodynamic and Physical Actions of Graphene Oxide/Ag/Collagen Coating

Researchers have widely agreed that the broad spectrum antibacterial activity of silver nanoparticles (AgNPs) can be predominantly ascribed to the action of Ag⁺. This study marks the first report detailing the rapid and highly efficient synergistic bacteria killing of AgNPs, which is achieved by inspiring AgNPs' strong photocatalytic capability to rapidly produce radical oxygen species using 660 nm visible light together with the innate antimicrobial ability of Ag⁺. These AgNPs were uniformly distributed into well-defined graphene oxide (GO) nanosheets through an in situ reduction of Ag⁺ and subsequently wrapped with a thin layer of type I collagen. In vivo subcutaneous tests demonstrated that 20 min irradiation of 660 nm visible light could achieve a high antibacterial efficacy of 96.3% and 99.4% on the implant surface against Escherichia coli and Staphylococcus aureus, respectively. In addition, the collagen could reduce the coatings' possible cytotoxicity. The results of this work can provide a highly effective and universal GO-based bioplatform for combination with inorganic antimicrobial NPs (i.e., AgNPs) with excellent photocatalytic properties, which can be utilized for facile and rapid in situ disinfection, as well as long-term prevention of bacterial infection through the synergistic bacteria killing of both 660-nm light-inspired photodynamic action and their innate physical antimicrobial ability.