Corrigendum to "Toxicity of Graphene Shells, Graphene Oxide, and Graphene Oxide Paper Evaluated with Escherichia coli Biotests".

The paper titled “Toxicity of Graphene Shells, Graphene Oxide, and Graphene Oxide Paper Evaluated with Escherichia coli Biotests” [1] contains textual errors we wish to correct. The corrections are as follows.

In Section “2.1. Graphene-Family Nanomaterials” the sentence “Aqueous suspensions of GS and GO (from 10−3 to 2 × 10−5 mg/L) …” has numerical errors. The correct sentence is as follows: “… (from 1000 to 20 mg/L)….”

In Section “2.6. Efflux of Intracellular DNA Content” the sentence “The plasmid-containing E. coli K12 TG1 lac::lux strain was cultured in mid-exponential growth phase with ampicillin and then separated from its cultivation medium and incubated with aqueous GO suspensions at concentrations of 1.25 × 10−4, 5 × 10−4, and 2 × 10−3 mg/L for 60 min,…” has numerical errors. The correct sentence is as follows: “… at concentrations of 125, 500, and 2000 mg/L….”

In Section “2.7. Zeta Potential Measurement” the sentence “A bacterial suspension (3.7 × 108 CFU/mL) was mixed with serially diluted GO aqueous suspensions to a final concentration from 3.1 × 10−5 to 5 × 10−4 mg/L” has numerical errors. The correct sentence is as follows: “… to a final concentration from 31.25 to 500 mg/L.”

In Section “3.1.1. GFN Toxicity Assessment Using a Bacterial Bioluminescence Inhibition Assay” the sentence “In the current system containing 3.7 × 108 CFU/mL cells, GO toxicity was characterized by EC50 values of 1.13 ± 0.05 × 10−4, 1.04 ± 0.03 × 10−4, and 7.92 ± 0.24 × 10−5 mg/L …” has numerical errors. The correct sentence is as follows: “… by EC50 values of 113.1 ± 4.52, 104.2 ± 3.12, and 79.2 ± 2.37 mg/L….”

The sentence “At the 60th min of measurement these values varied from 1.13 ± 0.05 × 10−4 to 2.55 ± 0.10 × 10−5 mg/L …” has numerical errors. The correct sentence is as follows: “… values varied from 113.1 ± 4.52 to 25.5 ± 1.01 mg/L….”

In Figure 4 legend designations have numerical errors: “1: 10−3 mg/L; 2: 5 × 10−4 mg/L; 3: 2.5 × 10−4 mg/L; 4: 1.25 × 10−4 mg/L; 5: 6.25 × 10−5 mg/L; 6: 3.13 × 10−5 mg/L; 7: 1.56 × 10−5 mg/L; 8: 7.81 × 10−6 mg/L; 9: 3.91 × 10−6 mg/L; C: control; wp: white paper, bp: black paper, GO-P: graphene oxide paper.”

The correct designations are as follows: “1: 1000 mg/L; 2: 500 mg/L; 3: 250 mg/L; 4: 125 mg/L; 5: 62.5 mg/L; 6: 31.25 mg/L; 7: 15.62 mg/L; 8: 7.81 mg/L; 9: 3.91 mg/L; C: control; wp: white paper; bp: black paper; GO-P: graphene oxide paper.”

The x-axis values of GO in Figure 5 should be corrected to the following: from 0 to 250 mg/L.

In Table 2 the values of EC50 (mg/L content) should be replaced by those shown in the corrected table.

In Section “3.1.2. GFN Bioactivity in a Fluorescent Cell Assay” the sentence “In contrast, bacterial cells treated with GO suspensions became red-fluorescent after 60 min in a dose-dependent manner, from 48.8 ± 1.9% (at 1.25 × 10−4 mg/L GO) to 93.0 ± 2.8% (at 5 × 10−4 mg/L GO) …” has numerical errors. The correct sentence is as follows: “… from 48.8 ± 1.9% (at 125 mg/L GO) to 93.0 ± 2.8% (at 500 mg/L GO)….”

In Figure 6 legend, the E. coli K12 TG1 cells were treated with graphene shells suspensions at 1000 mg/L instead of 10−3 mg/L and treated with graphene oxide suspension at 125 mg/L instead of 1.25 × 10−4 mg/L.

In Section “3.2.1. GO Validation as a Potential Oxidative Stress Inducer in Lux-Biotests” the sentence “The 1.2–1.5-fold light intensity growth only has been recorded at subtoxic GO concentrations (1.95 × 10−6–10−3 mg/L)” has numerical errors. The correct sentence is as follows: “… at subtoxic GO concentrations (1.95–1000 mg/L).”

The sentence “In turn, GO concentrations of 2 × 10−3 mg/L or more were toxic …” should be corrected to the following: “In turn, GO concentrations of 2000 mg/L or more were toxic….”

In Section “3.2.2 Intracellular DNA Efflux Measurement in GO-Treated Escherichia coli Cells” the sentence “In turn, DNA levels in supernatants of cells exposed to GO at concentrations of 1.25 × 10−4–2 × 10−3 mg/L …” should be corrected to the following: “… 125–2000 mg/L….”

In Section “3.2.3. Effect of GO Treatment on Zeta Potential Properties of Escherichia coli Cells” the sentence “Finally, the GO concentration required for complete zeta potential neutralization was 2.50 × 10−4 mg/L, whereas concentrations in the range of 3.13 × 10−5–1.25 × 10−4 mg/L …” has numerical errors. The correct values are “… 250 mg/L …” and “… 31.25–125 mg/L …,” respectively.

The x-axis values of GO in Figure 7 should be corrected to the following: from 0 to 500 mg/L.

These corrections do not influence the results, discussion, or conclusion of this work.

Table 1

Dose-dependent and time-dependent GO aqueous suspensions toxicity in bacterial bioluminescence inhibition assay characterized by EC50 value (mg/L content) at varying bacterial cell number in the sample.

E. coli K12 TG1 lac::lux,CFU per 1 mL	Time measurement
	60 min	120 min	180 min
3.70 × 108	113.1 ± 4.52	104.2 ± 3.12	79.2 ± 2.37
1.85 × 108	88.1 ± 2.64	82.0 ± 3.27	56.7 ± 1.69
9.25 × 107	55.7 ± 2.22	50.4 ± 2.26	38.8 ± 1.16
4.62 × 107	25.5 ± 1.01	24.9 ± 0.99	22.8 ± 0.89