title: Biomimetic synthesis of antimicrobial silver nanoparticles using in vitro-propagated plantlets of a medicinally important endangered species: Phlomis bracteosa.
abstract: In vitro-derived cultures of plants offer a great potential for rapid biosynthesis of chemical-free antimicrobial silver nanoparticles (AgNPs) by enhancing their phytochemical reducing potential. Here, we developed an efficient protocol for in vitro micropropagation of a high-value endangered medicinal plant species, Phlomis bracteosa, in order to explore its biogenic potential in biomimetic synthesis of antimicrobial AgNPs. Murashige and Skoog medium supplemented with 2.0 mg/L thidiazuron was found to be more efficient in inducing optimum in vitro shoot regeneration (78%±4.09%), and 2.0 mg/L indole-3-butyric acid was used for maximum root induction (86%±4.457%). Antimicrobial AgNPs were successfully synthesized by using aqueous extract (rich in total phenolics and flavonoids content) of in vitro derived plantlets of P. bracteosa. Ultraviolet-visible spectroscopy of synthesized AgNPs showed characteristic surface plasmon band in the range of 420-429 nm. The crystallinity, size, and shape of the AgNPs were characterized by X-ray diffraction and scanning electron microscopy. Face-centered cubic AgNPs of almost uniform spherical size (22.41 nm) were synthesized within a short time (1 hour) at room temperature. Fourier-transform infrared spectroscopy revealed that the polyphenols were mainly responsible for reduction and capping of synthesized AgNPs. Energy dispersive X-ray analysis further endorsed the presence of elemental silver in synthesized AgNPs. These biosynthesized AgNPs displayed significantly higher bactericidal activity against multiple drug-resistant human pathogens. The present work highlighted the potent role of in vitro-derived plantlets of P. bracteosa for feasible biosynthesis of antimicrobial AgNPs, which can be used as nanomedicines in many biomedical applications.
authors.affiliation: Department of Biotechnology, Quaid-i-Azam University, Islamabad, Pakistan.
authors.forename: Sumaira
authors.initials: S
authors.lastname: Anjum
authors.affiliation: Department of Biotechnology, Quaid-i-Azam University, Islamabad, Pakistan.
authors.forename: Bilal Haider
authors.initials: BH
authors.lastname: Abbasi
mesh_terms: D000064:Acclimatization / Q000187:drug effects; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D032701:Biomimetics / Q000379:methods*; D056727:Endangered Species; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D031345:Phlomis / Q000187:drug effects / Q000254:growth & development*; D010936:Plant Extracts / Q000737:chemistry; D018517:Plant Roots / Q000187:drug effects; D018520:Plant Shoots / Q000187:drug effects; D010946:Plants, Medicinal / Q000187:drug effects / Q000254:growth & development*; D012038:Regeneration / Q000187:drug effects; D012834:Silver / Q000494:pharmacology*; D013052:Spectrometry, X-Ray Emission; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D000890:Anti-Infective Agents; D007211:Indoles; D010936:Plant Extracts; C014612:indolebutyric acid; D012834:Silver
keywords: Phlomis bracteosa; antimicrobial; in vitro micropropagation; multidrug resistant bacteria; silver nanoparticles