Green synthesis of silver nanoparticles using aqueous extract of Citrus sinensis peels and evaluation of their antibacterial efficacy

The resistance of microorganisms towards antibiotics remains a big challenge in medicine. Silver nanoparticles (AgNPs) received attention recently for their characteristic nanosized features and their ability to display antimicrobial activities. This work reports the synthesis of AgNPs using the Citrus sinensis peels extract in their aqueous, mild, and less hazardous conditions. The effect of concentration variation (1%, 2%, and 3%) of the plant extracts on the size and shape of the AgNPs was investigated. The antimicrobial activities were tested against gram-positive Staphylococcus aureus and gram-negative Klebsiella pneumoniae. Absorption spectra confirmed the synthesis by the surface Plasmon resonance peaks in the range 400–450 nm for all the AgNPs. FTIR spectra confirmed that Citrus sinensis peels extract acted as both reducing and surface passivating agent for the synthesized AgNPs. TEM revealed spherical AgNPs with average size of 12 nm for 3% concentration as compared to the agglomeration at 1% and 2%. All the AgNPs synthesized using Citrus sinensis peels extracts (1%, 2%, and 3%) exhibited antimicrobial activity against both gram-positive and negative bacteria. These results indicated a simple, fast, and inexpensive synthesis of silver nanoparticles using the Citrus sinensis peels extract that has promising antibacterial activity.

Effects of nitrogen-doping on the photophysical properties of carbon dots

Nitrogen-doping of carbon dots enhances their photoluminescent properties but not all amines passivate the surface equally. Indeed, the chemical makeup of the passivating agent is critical in tailoring the physico-chemical and optical properties of carbon dots.

Photoluminescence mechanism and applications of Zn-doped carbon dots

Zinc ions, acting as a surface passivating agent, prevented the aggregation of graphene π–π stacking and increased the quantum yield of Zn-carbon dots.

One-step hydrothermal fabrication and optical properties of ZnO nanoplate

The surface morphology of ZnO evolving from nanorod to nanoplate is controlled through the increase of Al[Formula: see text] concentration in aqueous solution. In the process of fabricating ZnO nanoplate, Al[Formula: see text] acts as surface passivating agent and the growth rate along the [0001] orientation is suppressed. The blueshift of free excitons occurs with the increasing of Al[Formula: see text] concentration.