A simple preparation of Ag@graphene nanocomposites for surface-enhanced Raman spectroscopy of fluorescent anticancer drug

Efficient interfacial self-assembled MXene/Ag NPs film nanocarriers for SERS-traceable drug delivery

Combining the unique advantages of two-dimensional transition metal carbon/nitrogen compounds (MXene) and the excellent surface-enhanced Raman scattering (SERS) performance of noble metal materials, MXene/Ag NPs films were proposed as nanocarriers for SERS-traceable drug delivery. The films were prepared by two-step self-assembly on positively charged silicon wafers using virtue of the high evaporation of ethyl acetate, the Marangoni effect, and an oil/water/oil three-phase system. With 4-mercaptobenzoic acid (4-MBA) as the probe molecule, the SERS detection limit was 10-8 M and had shown a good linear relationship in the range of 10-8-10-3 M. Simultaneously, the film had good uniformity, repeatability, and stability. When Ti3C2Tx/Ag NPs films were used as nanocarriers, the anticancer drug doxorubicin (DOX) was loaded onto the surface through 4-MBA, and the tracking and monitoring were realized by SERS. The addition of glutathione (GSH) triggered the thiol exchange reaction, resulting in the shedding of 4-MBA from the surface of the film, which indirectly achieved the efficient release of DOX. Furthermore, the loading of DOX and the drug release effect triggered by GSH maintained a certain stability in serum, which provided a potential possibility for the subsequent loading and release of drugs by films with three-dimensional structures as scaffolds in biological therapy. Self-assembled MXene/Ag NPs film nanocarriers for SERS-traceable drug delivery and GSH-triggered high-efficiency drug release.

Detection of food spoilage and adulteration by novel nanomaterial-based sensors

Food industry is always looking for more innovative and accurate ways to monitor the food safety and quality control of final products. Current detection techniques of analytes are costly and time-consuming, and occasionally require professional experts and specialized tools. The usage of nanomaterials in sensory systems has eliminated not only these drawbacks but also has advantages such as higher sensitivity and selectivity. This article first presents a general overview of the current studies conducted on the detection of spoilage and adulteration in foods from 2015 to 2020. Then, the sensory properties of nanomaterials including metal and magnetic nanoparticles, carbon nanostructures (nanotubes, graphene and its derivatives, and nanofibers), nanowires, and electrospun nanofibers are presented. The latest investigations and advancements in the application of nanomaterial-based sensors in detecting spoilage (food spoilage pathogens, toxins, pH changes, and gases) and adulterants (food additives, glucose, melamine, and urea) have also been discussed in the following sections. To conclude, these sensors can be applied in the smart packaging of food products to meet the demand of consumers in the new era.

A green and facile synthesis for rGO/Ag nanocomposites using one-step chemical co-reduction route at ambient temperature and combined first principles theoretical analyze

Recently, graphene decorated with various inorganic nanoparticles, such as Pt, Au, Ag, TiO₂ and Fe₃O₄, among which Ag nanocomposites are good candidates for electronics, optics, electrochemistry and catalysis. However, preparation techniques for Ag nanoparticles/carbon matrix hybrids require tedious multi-step processes often involving toxic reducing agents/high temperatures which is not viable for scalable production. Here, a facile, one step and eco-friendly chemical co-reduction route was utilized to synthesis of a new nanocomposites by Ag nanoparticle anchored on reduced graphene oxide (rGO) at ambient temperature and combined first principles theoretical analyze their interfacial adsorption behavior, is reported. In this way, graphene oxide (GO) and Ag⁺ simultaneously reduced by thiourea dioxide (TD) without using any additional reduced reactants. Results indicated that GO was successfully reduced to rGO and well-dispersed Ag nanoparticles with sizes of 6-7 nm, anchored on the surface of rGO sheets. Reduction mechanism was attributed to the synergistic effect of its hydrolysis products in aqueous media. The experiment and theoretical calculation results obtained demonstrate this method to be applicable to the synthesis of other metals on rGO sheets in order to improve wettability and interfacial bonding between rGO and metal and may possibly find various forthcoming medicinal, industrial and technological applications.

Fe3O4@Resorcinol-Formaldehyde Resin/Cu2O Composite Microstructures: Solution-Phase Construction, Magnetic Performance, and Applications in Antibacterial and Catalytic Fields

Multifunctional Fe₃O₄@resorcinol-formaldehyde resin/Cu₂O composite microstructures (denoted as Fe₃O₄@RF/Cu₂O microstructures) were successfully constructed via a simple wet chemical route that has not been reported so far in the literature. The as-obtained Fe₃O₄@RF/Cu₂O microstructures were characterized using field-emission scanning electron microscopy, (high-resolution) transmission electron microscopy, selected-area electron diffraction, X-ray diffraction, and X-ray energy dispersive spectroscopy. The investigations showed that the as-obtained microstructures presented not only excellent antibacterial activity to Staphylococcus aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria) but also highly efficient catalytic ability for the reduction of 4-nitrophenol (4-NP) in a solution with excess NaBH₄. Owing to the presence of Fe₃O₄, the antibacterial reagent and the catalyst could be readily collected from the mixed systems under the assistance of an external magnetic field. It was found that the as-obtained microstructures displayed good cycling stability in antibacterial and catalytic applications. Fe₃O₄@RF/Cu₂O microstructures still retained more than 87% of the antibacterial efficiency after 5 cycles and 89% of the catalytic efficiency after 10 cycles.