Biofabrication of streptomycin-conjugated calcium phosphate nanoparticles using red ginseng extract and investigation of their antibacterial potential
Authors: Gitishree Das
Kwang-Hyun Baek
Jayanta Kumar Patra
Journal: PLoS ONE (2019)
Discipline: Multidisciplinary
Keywords: Nanoparticles; Antibiotics; Calcium phosphate; Streptomycin; Antibacterial activity
Affiliations: Research Institute of Biotechnology & Medical Converged Science, Dongguk University-Seoul, Goyangsi, Republic of Korea., Department of Biotechnology, Yeungnam University, Gyeongsan, Republic of Korea.

Abstract:  Conjugation of nanoparticles (NPs) with antibiotics for treating multidrug resistant pathogens has been enormously studied now a days. In the current investigation, calcium phosphate (CaP) NPs were produced by co-precipitation using red ginseng extract as the reducing agent and were conjugated to the antibiotic streptomycin to form streptomycin-conjugated NPs (CPG-S NPs). The CPG-S NPs antibacterial activity was evaluated in this study against eight plant and five foodborne pathogenic bacteria. The synthesized CPG-S NPs were characterized by UV-VIS spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, and thermogravimetric and differential thermogravimetric analysis. CPG-S NPs exhibited promising antibacterial activity against all eight plant pathogenic bacteria and three of the five foodborne pathogenic bacteria tested; the diameter of inhibition zones ranged between 9.74-16.95 mm and 9.82-15.84 mm, respectively. CPG-S NPs displayed 50-100 μg/mL of minimum inhibitory concentration and 100 μg/mL of minimum bactericidal concentration against the plant and foodborne pathogenic bacterial strains, respectively. Furthermore, the SEM image of bacteria treated with CPG-S NPs displayed cells with a ruptured cell wall and fewer cells compared to the SEM image of untreated control bacteria displaying uniform and intact cells. SEM confirmed that CPG-S NPs degraded the bacterial cell wall and membrane resulting in lysed bacterial cells. In conclusion, the results suggest that CPG-S NPs could be effectively utilized in formulating drugs to treat bacterial plant or dental diseases and in manufacturing dental products such as toothpaste, mouthwashes, and artificial teeth. 

Retracted: Yes

PubPeer comments:
 2020 retraction. https: journals.plos.org plosone article?id=10.1371 journal.pone.0228300 After this article [1] was published, it came to light that there was a potential competing interest between the handling Academic Editor and one or more authors, who appear as co-authors on recent publications. We had the article re-assessed by a different member of PLOS ONEu2019s Editorial Board who advised that there are a number of concerns and that overall the article does not meet PLOS ONEu2019s publication criteria. The following concerns were raised in the post-publication editorial assessment: The nanoparticles (NPs) were not sufficiently characterized to meet community standards. They should have been characterized by a variety of methods to demonstrate zeta potential, population distribution, and polydispersity index. Furthermore, the reported electron microscopy data show irregular morphology and agglomeration, and NP size details are not provided. The data reported in the article do not adequately support claims about streptomycin conjugation to NPs or verify how much streptomycin was linked to the NPs. The study relied on u201czone of inhibitionu201d (diffusion-based) assays to examine antibacterial activity. Per community standards, antibacterial activity and minimum inhibitory concentration (MIC) results need to be determined in liquid culture experiments; data from u201czone of inhibitionu201d assays do not adequately support the reported results and conclusions. The articleu2019s figures do not include control data for CPG NPs (calcium phosphate nanoparticles synthesized using red ginseng extract) as a comparator for CPG-S, or streptomycin-linked CPG NPs, for example, in reporting Fourier-transform infrared spectroscopy, X-ray powder diffraction, thermogravimetric and differential thermogravimetric analysis spectra and zone of inhibition results. Conclusions about the mode of action were based on scanning electron microcopy image data, this methodology does not provide mechanistic insight and thus conclusions about the mode of action were not adequately supported. The statistical analyses and results were not adequately reported, and it is unclear from the article which groups were compared in the analyses. The authors clarified that they used ANOVA and Duncanu2019s test to compare antibacterial activity between pathogens and samples. The relevance of the study to dental care was called into question in light of the high MICs reported, lack of data to demonstrate activity of NPs against oral pathogens, and known side effects and bacterial resistance associated with streptomycin. The authors offered to perform additional experiments to address some of the items outlined. However, the extent of the issues is such that concerns about study design and experimental rigor would remain which call into question the validity and reproducibility of the results and conclusions reported in the article. In light of the above concerns, the PLOS ONE Editors retract this article. The authors did not agree with the retraction. Reference 1.Das G, Baek K-H, Patra JK (2019) Biofabrication of streptomycin-conjugated calcium phosphate nanoparticles using red ginseng extract and investigation of their antibacterial potential. PLoS ONE 14(6): e0217318. ,