Gold nanoparticles made with a leaf extract from the paradise tree, Simarouba glauca, have shown a measurable effect against cervical cancer cells in a laboratory assay, according to a study published in the journal Bioscience Nanotechnology. When the nanoparticles were coated with polyethylene glycol, a common polymer used to stabilise nanomedicines, they reduced the relative viability of HeLa cervical cancer cells in a concentration-dependent manner, reaching 49.96 percent at the highest tested concentration of 30 micrograms per millilitre after 24 hours of treatment. The work, led by Divya Sahu and colleagues, combined plant chemistry, materials characterisation, antimicrobial testing and computational modelling in a single investigation.
The researchers began with an ethanolic extract of dried S. glauca leaves collected in Raipur, Chhattisgarh, India. Qualitative screening detected tannins, phenols, flavonoids, glycosides, proteins, amino acids, carbohydrates, saponins, coumarins, quinones, cardiac glycosides and starch in the extract, while anthocyanins, anthraquinones, lignin, triterpenoids, phytosterols and phlobatannins were absent. Quantitative assays put the total phenolic content at 28 ± 0.62 milligrams of gallic acid equivalents per gram of extract, and the DPPH radical scavenging activity at 82.68 percent. These phenolic constituents are thought to contribute to the biological activity of the plant and may also help drive the reduction of gold ions during nanoparticle synthesis.
To make the nanoparticles, the team dissolved chloroauric acid trihydrate in water to give a 0.25 millimolar gold precursor solution, heated it to 70 degrees Celsius under stirring, and gradually added the leaf extract. The reaction mixture turned from pale yellow to ruby red within 30 minutes, a colour change that signals the reduction of Au3+ ions to metallic Au0 and the formation of colloidal gold nanoparticles. The resulting suspension was split into two portions: one kept untreated as pristine AuNPs, and the other mixed with a 5 percent aqueous solution of PEG-1000 and stirred at 70 degrees Celsius for two hours to produce PEG-functionalized AuNPs. Both preparations were then centrifuged, washed twice in deionised water and dried.
Characterisation confirmed that both formulations contained crystalline, face-centred cubic gold. Ultraviolet-visible spectroscopy showed weak, broad surface plasmon resonance features around 530 nanometres for the pristine particles and a sharper, more intense peak centred near 540 nanometres for the PEG-coated version, a red shift the authors attribute to changes in the local dielectric environment, particle dimensions and interparticle interactions. X-ray diffraction indexed the reflections to the (111), (200), (220) and (311) planes of face-centred cubic gold, matching the standard reference pattern ICDD/PDF 04-0784. Applying the Debye-Scherrer equation to the (111) peak gave apparent crystallite sizes of 10.30 nanometres for the pristine particles and 11.13 nanometres for the PEG-functionalized ones.
Electron microscopy added detail on particle shape and size. Transmission electron microscopy revealed rounded, quasi-spherical and faceted particles in both preparations, along with some triangular particles and regions of overlap. The mean measured particle dimension was 23.81 ± 8.28 nanometres for pristine AuNPs, based on 35 particles, and 27.07 ± 5.23 nanometres for PEG-functionalized AuNPs, based on 37 particles, with the PEG-coated population showing a narrower relative size spread. High-resolution imaging resolved lattice fringes within the particles, and selected-area electron diffraction produced concentric rings with discrete bright spots, consistent with crystalline particles of varying orientation. Energy-dispersive X-ray analysis found gold to be the dominant element by weight in both samples, at 94.7 percent for pristine and 94.5 percent for PEG-functionalized AuNPs, with smaller amounts of carbon, oxygen, sodium and chlorine.
Dynamic light scattering revealed a striking difference in how the two formulations behaved in dispersion. Pristine AuNPs had a Z-average hydrodynamic diameter of 987.3 nanometres and a polydispersity index of 0.7094, indicating substantial particle association and pronounced size heterogeneity. After PEG treatment, the Z-average dropped to 102.1 nanometres and the polydispersity index fell to 0.5629, suggesting reduced particle association and a shift towards smaller hydrodynamic populations, although the remaining larger population and relatively high index show the dispersion was still heterogeneous. Zeta potentials were similar for both, at −15.05 and −15.76 millivolts respectively, indicating that the improvement in dispersion likely stems from steric repulsion by hydrated PEG chains rather than a large increase in electrostatic repulsion.
On the biological side, both formulations inhibited the bacterium Micrococcus luteus. In an agar well diffusion test, pristine AuNPs produced a small inhibition zone of approximately 1 millimetre, while the PEG-functionalized particles produced a larger zone of nearly 2.5 millimetres. A broth turbidity assay tracking optical density at 600 nanometres over 24 and 48 hours showed that PEG-functionalized AuNPs acted faster and more strongly initially, achieving apparent growth inhibition of 44.76 percent at the 1 millilitre dose after 24 hours, compared with 7.94 percent for pristine AuNPs at the same dose. By 48 hours, however, the pristine particles had caught up considerably, reaching 48.28 percent inhibition at 1 millilitre, while the PEG-functionalized version peaked at 56.55 percent. Higher doses consistently outperformed lower ones across both time points.
The cytotoxicity results came from an MTT assay on HeLa cells, a cervical cancer cell line, treated with PEG-functionalized AuNPs at concentrations from 1 to 30 micrograms per millilitre for 24 hours. Viability relative to the untreated control stayed essentially unchanged at 1 microgram per millilitre, at 100.09 percent, then declined modestly at 5 and 10 micrograms per millilitre, to 89.04 and 86.88 percent respectively. The largest drop occurred between 10 and 20 micrograms per millilitre, where mean viability fell from 86.88 to 57.76 percent, a reduction of 29.12 percentage points, before reaching 49.96 percent at 30 micrograms per millilitre. The authors note that MTT reduction reflects both viable cell number and cellular metabolic activity, so the observed decrease may involve changes in cell abundance, metabolic activity, or both.
In a separate computational strand, gas chromatography-mass spectrometry of the leaf extract produced 72 integrated chromatographic features, dominated by two features at 5.47 and 5.55 minutes that together accounted for 93.87 percent of the integrated area, with diethyl phthalate as the leading tentative library candidate for both. The authors caution that phthalate-related signals may also reflect laboratory or analytical background, as such compounds are known potential contaminants in GC-MS analysis. Two candidate structures, ethane, 1,1-diethoxy- and a 3,8,12-tri-O-acetoxy-7-desoxyingol-7-one derivative, were then run through the SwissADME web server for predicted physicochemical and pharmacokinetic properties, and through SwissTargetPrediction for potential protein targets. Ethane, 1,1-diethoxy- was predicted to have high gastrointestinal absorption and blood-brain barrier permeation, while the larger ingol derivative was predicted to be less soluble and non-permeant.
Molecular docking of ethane, 1,1-diethoxy- against the human Nischarin PX domain, a protein associated with tumour-suppressive functions in breast-cancer models, produced a lowest calculated binding-energy estimate of −3.64 kilocalories per mole, corresponding to a score-derived inhibition constant of 2.15 millimolar, a modest predicted interaction. The authors stress that these computational findings describe predicted molecular properties and potential protein interactions of tentative library candidates, not confirmed biological activity of the extract. Taken together, the study characterises plant-mediated gold nanoparticle preparations and their formulation-dependent physicochemical and biological responses, while leaving open the question of whether such effects translate beyond the laboratory.
Subject of Research: Green synthesis of pristine and PEG-functionalized gold nanoparticles using Simarouba glauca leaf extract, with physicochemical characterisation, antimicrobial testing and HeLa-cell cytotoxicity assessment
Article Title: Simarouba glauca-mediated synthesis of pristine and PEG-functionalized gold nanoparticles: physicochemical characterisation, computational analysis, antimicrobial and anticancer activities
Article References: Sahu, D., Singh, S., Jain, B., Singh, A. K., Sanwaria, S., Soni, H., Gupta, N., & Upadhye, V. J. (2026). Simarouba glauca-mediated synthesis of pristine and PEG-functionalized gold nanoparticles: physicochemical characterisation, computational analysis, antimicrobial and anticancer activities. Bioscience Nanotechnology, 2(1), Article 30. https://doi.org/10.1186/s44331-026-00038-2
Image Credits: AI Generated
DOI: 10.1186/s44331-026-00038-2
Keywords: gold nanoparticles, Simarouba glauca, green synthesis, PEG functionalization, HeLa cells, MTT assay, Micrococcus luteus, molecular docking, SwissADME, phytochemicals, cervical cancer, nanomedicine
News Source: Nathaniel Bowman. (November 5, 2026). Plant-made gold nanoparticles, PEG-coated, curb cervical cancer cell growth in lab test. Scienmag.
