title: Rapid efficient synthesis and characterization of silver, gold, and bimetallic nanoparticles from the medicinal plant Plumbago zeylanica and their application in biofilm control.
abstract: BACKGROUND
  Nanoparticles (NPs) have gained significance in medical fields due to their high surface-area-to-volume ratio. In this study, we synthesized NPs from a medicinally important plant - Plumbago zeylanica.
  
  
  METHODS
  Aqueous root extract of P. zeylanica (PZRE) was analyzed for the presence of flavonoids, sugars, and organic acids using high-performance thin-layer chromatography (HPTLC), gas chromatography-time of flight-mass spectrometry (GC-TOF-MS), and biochemical methods. The silver NPs (AgNPs), gold NPs (AuNPs), and bimetallic NPs (AgAuNPs) were synthesized from root extract and characterized using ultraviolet-visible spectra, X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The effects of these NPs on Acinetobacter baumannii, Staphylococcus aureus, and Escherichia coli biofilms were studied using quantitative biofilm inhibition and disruption assays, as well as using fluorescence, scanning electron microscopy, and atomic force microscopy.
  
  
  RESULTS
  PZRE showed the presence of phenolics, such as plumbagin, and flavonoids, in addition to citric acid, sucrose, glucose, fructose, and starch, using HPTLC, GC-TOF-MS, and quantitative analysis. Bioreduction of silver nitrate (AgNO₃) and chloroauric acid (HAuCl₄) were confirmed at absorbances of 440 nm (AgNPs), 570 nm (AuNPs), and 540 nm (AgAuNPs), respectively. The maximum rate of synthesis at 50°C was achieved with 5 mM AgNO₃ within 4.5 hours for AgNPs; and with 0.7 mM HAuCl4 within 5 hours for AuNPs. The synthesis of AgAuNPs, which completed within 90 minutes with 0.7 mM AgNO₃ and HAuCl₄, was found to be the fastest. Fourier-transform infrared spectroscopy confirmed bioreduction, while EDS and XRD patterns confirmed purity and the crystalline nature of the NPs, respectively. TEM micrographs and DLS showed about 60 nm monodispersed Ag nanospheres, 20-30 nm Au nanospheres adhering to form Au nanotriangles, and about 90 nm hexagonal blunt-ended AgAuNPs. These NPs also showed antimicrobial and antibiofilm activity against E. coli, A. baumannii, S. aureus, and a mixed culture of A. baumannii and S. aureus. AgNPs inhibited biofilm in the range of 96%-99% and AgAuNPs from 93% to 98% in single-culture biofilms. AuNPs also showed biofilm inhibition, with the highest of 98% in S. aureus. AgNPs also showed good biofilm disruption, with the highest of 88% in A. baumannii.
  
  
  CONCLUSIONS
  This is the first report on rapid and efficient synthesis of AgNPs, AuNPs and AgAuNPs from P. zeylanica and their effect on quantitative inhibition and disruption of bacterial biofilms.
authors.affiliation: Institute of Bioinformatics and Biotechnology, University of Pune, India.
authors.forename: Gayatri R
authors.initials: GR
authors.lastname: Salunke
authors.affiliation: Institute of Bioinformatics and Biotechnology, University of Pune, India.
authors.forename: Sougata
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: National Chemical Laboratory, Pune, India.
authors.forename: R J
authors.initials: RJ
authors.lastname: Santosh Kumar
authors.affiliation: Institute of Bioinformatics and Biotechnology, University of Pune, India.
authors.forename: Samiksha
authors.initials: S
authors.lastname: Khade
authors.affiliation: Department of Biotechnology, Indian Institute of Technology, Roorkee, India.
authors.forename: Priya
authors.initials: P
authors.lastname: Vashisth
authors.affiliation: National Centre for Cell Science, Pune University Complex, Pune, India.
authors.forename: Trupti
authors.initials: T
authors.lastname: Kale
authors.affiliation: Department of Microbiology, University of Pune, Pune, India.
authors.forename: Snehal
authors.initials: S
authors.lastname: Chopade
authors.affiliation: Department of Biotechnology, Indian Institute of Technology, Roorkee, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Pruthi
authors.affiliation: National Centre for Cell Science, Pune University Complex, Pune, India.
authors.forename: Gopal
authors.initials: G
authors.lastname: Kundu
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, India.
authors.forename: Jayesh R
authors.initials: JR
authors.lastname: Bellare
authors.affiliation: Institute of Bioinformatics and Biotechnology, University of Pune, India ; Department of Microbiology, University of Pune, Pune, India.
authors.forename: Balu A
authors.initials: BA
authors.lastname: Chopade
mesh_terms: D000497:Alloys / Q000008:administration & dosage / Q000138:chemical synthesis; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000138:chemical synthesis*; D017209:Apoptosis / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development*; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry* / Q000648:ultrastructure; D010936:Plant Extracts / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D029606:Plumbaginaceae / Q000737:chemistry*
chemical_list: D000497:Alloys; D000900:Anti-Bacterial Agents; D010936:Plant Extracts
keywords: AgAuNPs; AgNPs; AuNPs; GC-TOF-MS; P. zeylanica; biofilm inhibition and disruption