Researchers used Cannabis sativa (industrial hemp) extracts to produce gold and silver nanoparticles through a rapid, economical “green synthesis” process. Hemp contains biologically active compounds including cannabinoids, terpenes, flavonoids, and phenolic compounds, some of which may help form and stabilize nanoparticles.
The hemp-derived silver nanoparticles showed antibacterial and anti-biofilm activity against Pseudomonas aeruginosa and Escherichia coli, including inhibition of biofilm formation at concentrations below those needed to completely stop bacterial growth.
The authors concluded that C. sativa extracts can be effectively used for green nanoparticle synthesis and that some of these nanoparticles may have value against biofilm formation. They also emphasized that “the therapeutic value of this plant is not negligible.”
“Cannabis sativa (hemp) is a source of various biologically active compounds, for instance, cannabinoids, terpenes and phenolic compounds, which exhibit antibacterial, antifungal, anti-inflammatory and anticancer properties. With the purpose of expanding the auxiliary application of C. sativa in the field of bio-nanotechnology, we explored the plant for green and efficient synthesis of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs).
The nanoparticles were synthesized by utilizing an aqueous extract of C. sativa stem separated into two different fractions (cortex and core [xylem part]) without any additional reducing, stabilizing and capping agents. In the synthesis of AuNPs using the cortex enriched in bast fibers, fiber-AuNPs (F-AuNPs) were achieved. When using the core part of the stem, which is enriched with phenolic compounds such as alkaloids and cannabinoids, core-AuNPs (C-AuNPs) and core-AgNPs (C-AgNPs) were formed. Synthesized nanoparticles were character-ized by UV–visible analysis, transmission electron microscopy, atomic force microscopy, dynamic light scattering, Fourier transform infrared, and matrix-assisted laser desorption/ionization time-of-flight. In addition, the stable nature of nanoparticles has been shown by thermogravimetric analysis and inductively coupled plasma mass spectrometry (ICP-MS). Finally, the AgNPs were explored for the inhibition of Pseudomonas aeruginosa and Escherichia coli biofilms.
Conclusion
The synthesized nanoparticles were crystalline with an average diameter between 12 and 18 nm for F-AuNPs and C-AuNPs and in the range of 20–40 nm for C-AgNPs. ICP-MS analysis revealed concentrations of synthesized nanoparticles as 0.7, 4.5 and 3.6 mg/mL for F-AuNPs, C-AuNPs and C-AgNPs, respectively. Fourier transform infrared spectroscopy revealed the presence of flavonoids, cannabinoids, terpenes and phenols on the nanoparticle surface, which could be responsible for reducing the salts to nanoparticles and further stabilizing them. In addition, the stable nature of synthesized nanoparticles has been shown by thermogravimetric analysis and ICP-MS. Finally, the AgNPs were explored for the inhibition of P. aeruginosa and E. coli biofilms. The nanoparticles exhibited minimum inhibitory concentration values of 6.25 and 5 µg/mL and minimum bactericidal concentration values of 12.5 and 25 µg/mL against P. aeruginosa and E. coli, respectively.”
“This study demonstrated the applicability of C. sativa extracts for rapid and economical green synthesis of nanoparticles, some of which can be effectively used against biofilm formations.
The developed methodology allowed to produce several types of nanoparticles: F-AuNPs, at 1:1 ratio of plant extract:water, 100°C, 4 mM gold salt in 3 min; C-AuNPs, at 1:1 ratio of plant extract:water, 90°C, 2 mM salt in 2.5 min; C-AgNPs, with complete extract, 90°C, 5 mM silver salt in 8 min. C-AgNPs were applied for effective inhibition and disruption of P. aeruginosa and E. coli biofilms. The question generating nanoparticles that would possess the desired morphology with well-defined size and shape is still open, and further study is required to develop a technology in which nanoparticles of specific size and shape can be obtained by the use of medicinal and industrially important C. sativa plants.”
