Light emitting diode irradiation induced shape conversion of DNA-capped silver nanoparticles and their antioxidant and antibacterial activities

Progress of Metal Nanomaterial Controllable Preparation by Photoreduction

Metal nanoparticles (NPs) are widely used in biomedicine, catalysis, environment, electronics, and other fields, which is closely related to its structural form. For this purpose, researchers have been looking for a simple, green, and controllable way to mass produce metal nanomaterials with desired characteristics (shape, size, stability, etc.). Due to the surface plasmon resonance (SPR) effect of metal nanoparticles, photoreduction method can control the morphology of metal nanoparticles well, which is also simple, large-scalable, and energy-saving. This review provides an overview of the photoreduction method for the synthesis of metal nanoparticles and discusses the factors such as the light source, pH value, reagents, and temperature on the morphology of the nanoparticles. Finally, the challenges and development trends in the controlled preparation of nanomaterials are proposed.

Light-Emitting-Diode-Assisted, Fungal-Pigment-Mediated Biosynthesis of Silver Nanoparticles and Their Antibacterial Activity

Nanoparticle synthesis, such as green synthesis of silver nanoparticles (AgNPs) using biogenic extracts, is affected by light, which changes the characteristics of particles. However, the effect of light-emitting diodes (LEDs) on AgNP biosynthesis using fungal pigment has not been examined. In this study, LEDs of different wavelengths were used in conjunction with Talaromyces purpurogenus extracellular pigment for AgNP biosynthesis. AgNPs were synthesized by mixing 10 mL of fungal pigment with AgNO₃, followed by 24 h exposure to LEDs of different wavelengths, such as blue, green, orange, red, and infrared. All treatments increased the yield of AgNPs. The solutions exposed to blue, green, and infrared LEDs exhibited a significant increase in AgNP synthesis. All AgNPs were then synthesized to determine the optimum precursor (AgNO₃) concentration and reaction rate. The results indicated 5 mM AgNO₃ as the optimum precursor concentration; furthermore, AgNPs-blue LED had the highest reaction rate. Dynamic light scattering analysis, zeta potential measurement, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to characterize the AgNPs. All LED-synthesized AgNPs exhibited an antimicrobial potential against Escherichia coli and Staphylococcus aureus. The combination of LED-synthesized AgNPs and the antibiotic streptomycin demonstrated a synergistic antimicrobial activity against both bacterial species.

Sequence Does Not Matter: The Biomedical Applications of DNA-Based Coatings and Cores

Biomedical applications of DNA are diverse but are usually associated with specific recognition of target nucleotide sequences or proteins and with gene delivery for therapeutic or biotechnological purposes. However, other aspects of DNA functionalities, like its nontoxicity, biodegradability, polyelectrolyte nature, stability, thermo-responsivity and charge transfer ability that are rather independent of its sequence, have recently become highly appreciated in material science and biomedicine. Whereas the latest achievements in structural DNA nanotechnology associated with DNA sequence recognition and Watson–Crick base pairing between complementary nucleotides are regularly reviewed, the recent uses of DNA as a raw material in biomedicine have not been summarized. This review paper describes the main biomedical applications of DNA that do not involve any synthesis or extraction of oligo- or polynucleotides with specified sequences. These sequence-independent applications currently include some types of drug delivery systems, biocompatible coatings, fire retardant and antimicrobial coatings and biosensors. The reinforcement of DNA properties by DNA complexation with nanoparticles is also described as a field of further research.

Combination of AgNPs and Domiphen is Antimicrobial Against Biofilms of Common Pathogens

Purpose

The aim was to evaluate the antimicrobial potential of AgNPs synthesized with Artemisia argyi leaf extract and investigate the antimicrobial synergistic effects of AgNPs combined with domiphen and provide an efficient and broad-spectrum combination drug strategy.

Methods

AgNPs synthesized with Artemisia argyi leaf extract were studied using UV–vis spectroscopy, FTIR spectroscopy and particle size analysis. Then, Artemisia argyi leaf extract-synthesized AgNPs and domiphen were tested against Acinetobacter baumannii (ATCC 19606), Staphylococcus aureus (ATCC 6538), Escherichia coli (8099) and Candida albicans (ATCC 10231), respectively. Then, we explore synergistic antimicrobial effect and synergistic anti-biofilm effect through combined drug susceptibility test and combined drug minimum biofilm eradication concentration (MBEC₅₀) test.

Results

Characteristic absorption bands of AgNPs were found near 430 nm in the UV–vis spectrum. Particle size analysis results revealed that the average particle size of Artemisia argyi leaf extract-synthesized AgNPs was 77.6 nm. Artemisia argyi leaf extract-synthesized AgNPs showed high antimicrobial activity against the above four strains. Minimum inhibitory concentration (MIC) of Artemisia argyi leaf extract-synthesized AgNPs against strains was 1 μg/mL for Acinetobacter baumannii, 2 μg/mL for Staphylococcus aureus, Escherichia coli and Candida albicans. MBEC₅₀ of Artemisia argyi leaf extract-synthesized AgNPs against strains was 2 μg/mL for Acinetobacter baumannii, 4 μg/mL for Staphylococcus aureus, 1/2 μg/mL for Escherichia coli and 2 μg/mL for Candida albicans. The combination of Artemisia argyi leaf extract-synthesized AgNPs and domiphen has synergistic antimicrobial effect and synergistic anti-biofilm effect. Fractional inhibitory concentration (FIC) was ≤0.5.

Conclusion

Artemisia argyi leaf extract-synthesized AgNPs had antimicrobial activity against the above four strains. The combination of Artemisia argyi leaf extract-synthesized AgNPs and domiphen has synergistic antimicrobial effects to reduce the dosage of each antimicrobial drugs. Artemisia argyi leaf extract-synthesized AgNPs and domiphen have synergistic anti-biofilm effects.