Biological effects of carbon nanotubes generated in forest wildfire ecosystems rich in resinous trees on native plants

Abstract

Carbon nanotubes (CNTs) have a broad range of applications and are generally considered human-engineered nanomaterials. However, carbon nanostructures have been found in ice cores and oil wells, suggesting that nature may provide appropriate conditions for CNT synthesis. During forest wildfires, materials such as turpentine and conifer tissues containing iron under high temperatures may create chemical conditions favorable for CNT generation, similar to those in synthetic methods. Here, we show evidence of naturally occurring multiwalled carbon nanotubes (MWCNTs) produced from Pinus oocarpa and Pinus pseudostrobus, following a forest wildfire. The MWCNTs showed an average of 10 walls, with internal diameters of ∼2.5 nm and outer diameters of ∼14.5 nm. To verify whether MWCNT generation during forest wildfires has a biological effect on some characteristic plant species of these ecosystems, germination and development of seedlings were conducted. Results show that the utilization of comparable synthetic MWCNTs increased seed germination rates and the development of Lupinus elegans and Eysenhardtia polystachya, two plants species found in the burned forest ecosystem. The finding provides evidence that supports the generation and possible ecological functions of MWCNTs in nature.

A Novel Mechanism Underlying Multi-walled Carbon Nanotube-Triggered Tomato Lateral Root Formation: the Involvement of Nitric Oxide

“…4), a well-known NO-releasing compound [30,31]. Similar inducing responses were discovered in resinous trees [41], lettuce [42], and Arabidopsis [43] when challenged with MWCNTs (OD 6-13 nm, about 9.5 nm, and 30-40 nm, respectively). For example, the application with either pristine MWCNT (p-MWCNT) or carboxylfunctionalized MWCNT (c-MWCNT) (average diameter 9.5 nm) could promote the development of LR in lettuce seedlings [42].…”

“…Until now, different responses in LR formation, promotion or inhibition, were respectively reported in various plant species when supplemented with nanomaterials, including MWCNTs [40][41][42][43], gold nanoparticles (Au NP, [44]), zinc oxide nanoparticles (ZnO NP [45,46];), titanium dioxide nanoparticles (TiO 2 NP [46];), and graphene oxide (GO [47][48][49];) (Table 1), and no study has yet provided definitive proof of a role of NO in above responses. In this study, the detection of endogenous NO by Greiss reagent method, laser scanning confocal microscopy (LSCM), and electron paramagnetic resonance (EPR) analyses revealed that the NO level was increased in MWCNT-treated tomato seedlings.…”

Ligninolytic activity of the Penicillium chrysogenum and Pleurotus ostreatus fungi involved in the biotransformation of synthetic multi-walled carbon nanotubes modify its toxicity

“…The samples (0.5 mg of dry sample) analyzed by Raman spectroscopy were dispersed in 50 μL water, aliquots of 10 μL were placed on slides, five drops for each sample, allowed to dry at room temperature to be analyzed in Raman spectrometer (Lab Ram HR Evolution; Horiba, Kyoto, Japan) with a spectral resolution of 5 cm −1 using a 20-mW He-Ne laser at 632.8 nm visual excitation, and the spectral range was scanned from 110 cm −1 to 3,690 cm −1 with an integration time of 5 s ( Lara-Romero et al, 2017 ).…”

“…High-resolution transmission electron microscopy (HR-TEM) was performed by using a Philips CM-200 analytical TEM operating at 200 kV. Specimens for HR-TEM analysis were prepared by dispersing the samples in acetone via sonication for 2 min and air-drying a drop of the suspension on a perforated carbon-coated Cu° grid at room temperature ( Lara-Romero et al, 2017 ).…”

Peer Review #1 of "Ligninolytic activity of the Penicillium chrysogenum and Pleurotus ostreatus fungi involved in the biotransformation of synthetic multi-walled carbon nanotubes modify its toxicity (v0.1)"

“…Subsequently, the ashes obtained were pulverized and suspended in distilled water or used directly for further qualitative and quantitative analyses. The samples (0.5 mg of dry sample) analyzed by Raman spectroscopy were dispersed in 50 μL water, aliquots of 10 μL were placed on slides, five drops for each sample, allowed to dry at room temperature to be analyzed in Raman spectrometer (Lab Ram HR Evolution, Horiba) with a spectral resolution of 5 cm -1 using a 20-mW He-Ne laser at 632.8 nm visual excitation, and the spectral range was scanned from 110 cm -1 to 3690 cm -1 with an integration time of 5 s (Lara-Romero et al 2017). Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy of samples obtained under the aforementioned conditions were analyzed, and the spectra were recorded via a Nicolet iS10 spectrophotometer (Thermo Scientific) by the attenuated total reflection (ATR) technique.…”