Fabrication of Surface-Enhanced Raman Spectroscopy Substrates Using Silver Nanoparticles Produced by Laser Ablation in Liquids

This research describes the use surface-enhanced Raman spectroscopy (SERS) substrates based on colloidal silver nanoparticles (AgNPs) produced by laser ablation of silver granules in pure water that are inexpensive, easy to make, and chemically stable. Here, the effects of the laser power, pulse repetition frequency, and ablation duration on the Surface Plasmon Resonance peak of AgNPs solutions, which was centered at 404 nm, were used to determine the optimal parameters. The substrates were characterized using Raman spectroscopy, and it was discovered that they were chemically stable within the first eight days of storage at room temperature since the spectroscopic profiles remained constant. The main bands were centered at 196, 640, 824, 1060, and 1538 cm-1, and they were attributed to the vibrations of O=Ag2/Ag-N, C-S-C, C-H, C-CO, C-N, and C=O, respectively. Additionally, these substrates had no impact on the Raman spectrum profiles of samples of rat blood when mixed with them. In comparison to thick blood smears on a clean piece of aluminum foil, the Raman spectral profiles of blood samples mixed with colloidal AgNPs were 14.95 times more enhanced. The Raman peaks noted were attributed to C-C stretching of lipids (932 cm-1), C-N stretching (1064 cm-1), C-C stretching (1190 cm-1), CH2 wagging (1338 and 1410 cm-1), carbonyl stretch for proteins (1650 cm-1), and C-H band of proteins (2122 cm-1). The results on the utilization of inexpensive, simple-to-prepare Raman substrates have the possibility of making surface-enhanced Raman spectroscopy available to laboratories with scarce resources in developing nations

Development and characterization of sodium alginate based active edible films incorporated with essential oils of some medicinal plants

PubMed ID: 31843601The aim of this study was to develop sodium alginate based active films incorporated with essential oils (EO) of R. officinalis L, A. herba alba Asso, O. basilicum L and M. pulegium L. the films were characterized in terms of bioactive properties including thickness, moisture content, water vapor and oxygen permeability, release test, mechanical, molecular, biodegradability and thermal properties. The results showed that the active films had a strong antibacterial effect against the six pathogenic bacteria with the inhibition zone between18.5 and 38.67 mm. furthermore, the antioxidant capacity of the films ranged from 4.57% to 23.09%. According to results of release test, physical, molecular, mechanical, biodegradability, thermal and barrier properties, the EOs were uniformly dispersed in the polymer matrix and improved slightly thermal (Tm) and barrier properties, while decreased tensile strength and it was obtained that this film is biodegradable in the soil. In conclusion, it could be said that sodium alginate based edible films incorporated with EO have a potential to be used food packaging applications. © 2019 Elsevier B.V