There was an error in the original publication [1] regarding the biosurfactant used in this study, which we called ‘Sodium-Surfactin’ (SS). It is more accurately a crude mixture of lipopeptides (LP) derived from bacterial fermentation. This correction is made to avoid potential conflicts of interest in future publications using ‘Surfactin’, a commercial biosurfactant specifically developed for use in cosmetic applications. This is different from the biosurfactant used in this study in the optimization, purification, and characterization processes.
When the specification of the hybrid system is required, ‘Surfactin’ and ‘SS’ are substituted with ‘LipoPeptide’ and ‘LP’, respectively.
Title Change
The word ‘Surfactin’ in the title is now substituted with ‘Based’.
Text Correction
In addition to systematic substitution carried out across the text, the authors added the following paragraph to the Introduction, placing it after the third paragraph:
Lipopeptides are a class of biosurfactants that have been widely studied and utilized for various biomedical and environmental applications due to their diverse properties, including antimicrobial, antiadhesive, antitumor, and bioremediation activities [6–12]. Lipopeptides possess surfactant properties due to their amphiphilic nature, having both hydrophilic (peptide) and hydrophobic (lipid) components. This allows them to interact with cell membranes, disrupting their structures and functions. As a result, lipopeptides can exhibit potent antimicrobial effects against a wide range of pathogens, including bacteria, fungi, and even some viruses [13,14].
The authors rephrased the fourth paragraph of the Introduction with the following text:
Lipopeptides also exhibits good stabilizing properties used in the sol–gel synthesis of metal nanoparticles [15–19]. Thus, we decided to exploit the coupling between TiO2 NPs and a mixture of lipopeptides (LP), to investigate the physicochemical identity of the hybrid phase and the possible synergetic, antagonist, or independent effects in terms of functionality [20,21].
Errors in Figure/Table Legends and Figures/Tables
The legends and/or texts of Scheme 1, Figures 1, 2, 3, 4, 5, 6, S1, S2, S3, S4, S5, S6 and S8 and Tables 1, 2, 3, 4, 5, 6, S1, S2, and S3 have been corrected. All uses of the abbreviation ‘SS’ (‘Sodium-Surfactin’) have been substituted with ‘LP’ (crude lipopeptide mixture). The corrected Figures and Tables appear below.
Scheme 1.
Multifunctional platform designed for the removal of water/soil pollutants.
Figure 1.
Zeta potential as a function of pH curves for TiO2@LP_S samples obtained via sol–gel synthesis.
Figure 2.
XRD diffractograms of TiO2@LP_S_SFD samples (◊, LP; □, anatase; ●, brookite; ○, sodium chloride).
Figure 3.
TEM images of (a) TiO2@LP_S_1:0.1 and (b) TiO2@LP_S_1:1 samples.
Figure 4.
XRD diffractograms of TiO2/LP_E_SFD samples (◊, LP; □, anatase; ●, brookite; ○, sodium chloride).
Figure 5.
(a) FTIR spectra of TiO2@TX (black), LP (light blue), TiO2@LP_1:1_S (light gray), and TiO2/LP_1:1_E (dark green) samples and (b) specific surface area data (m2/g).
Figure 6.
NO depletion trend as a function of UV light time of irradiation.
Table 1.
Data from colloidal characterization of TiO2@LP_S samples obtained via sol–gel synthesis.
| Sample | dDLS (nm) | Zeta-potELS (mV) | pHiep |
|---|---|---|---|
| LP | nd * | −38 ± 6 | 1.7 |
| TiO2@TX | 64 ± 2 | +39 ± 7 | 6.2 |
| TiO2@LP_1:0.1_S | 77 ± 4 | +33 ± 6 | 6.1 |
| TiO2@LP_1:0.5_S | 215 ± 15 | +28 ± 5 | 6.0 |
| TiO2@LP_1:1_S | 720 ± 143 | +24 ± 4 | 6.0 |
| TiO2@LP_1:2_S | 870 ± 84 | −7 ± 2 | 1.7 |
| TiO2@LP_1:6_S | 1000 ± 25 | −40 ± 8 | 2.1 |
| TiO2@LP_1:8_S | 1020 ± 178 | −43 ± 5 | 1.7 |
nd *, not determined.
Table 2.
Data from colloidal characterization of TiO2/LP_E samples obtained via heterocoagulation.
| Sample | dDLS (nm) | Zeta-potELS (mV) | pHiep |
|---|---|---|---|
| LP | nd * | −38 ± 6 | 1.7 |
| TiO2@TX | 64 ± 2 | +39 ± 7 | 6.2 |
| TiO2/LP_1:1_E | 1100 ± 200 | −16 ± 4 | 3.4 |
| TiO2/LP_1:6_E | 216 ± 5 | −31 ± 58 | 1.7 |
| TiO2/LP_1:8_E | 243 ± 2 | −41 ± 5 | 1.5 |
nd *, not determined.
Table 3.
Conversion (%) and kinetic constant (min−1) data obtained via photocatalytic tests of TiO2@LP_S samples synthesized via the sol–gel method.
| Sample | Conversion (%) | k (min−1) |
|---|---|---|
| TiO2@TX (ref.) | 99 | 9.5 × 10−2 |
| TiO2@LP_1:0.1_S | 99 | 8.5 × 10−2 |
| TiO2@LP_1:0.5_S | 90 | 4.0 × 10−2 |
| TiO2@LP_1:1_S | 87 | 2.3 × 10−2 |
| TiO2@LP_1:2_S | 47 | 0.6 × 10−2 |
| TiO2@LP_1:6_S | 16 | 0.5 × 10−2 |
| TiO2@LP_1:8_S | 12 | 0.1 × 10−2 |
Table 4.
Conversion (%) and kinetic constant (min−1) obtained via photocatalytic tests of TiO2/LP_E samples prepared via heterocoagulation.
| Sample | Conversion (%) | k (min−1) |
|---|---|---|
| TiO2@TX (ref.) | 99 | 9.5 × 10−2 |
| TiO2/LP_1:1_E | 18 | 0.5 × 10−2 |
| TiO2/LP_1:6_E | 5 | 0.6 × 10−3 |
| TiO2/LP_1:8_E | 5 | 0.6 × 10−3 |
Table 5.
Results of Cu2+ sorption (mgCu2+/gsample) tests performed on representative samples.
| Sample | Cu2+ Sorption (mg Cu2+/gsample) | |
|---|---|---|
| 1 h | 24 h | |
| LP | 2.53 | 2.53 |
| TiO2@TX (ref.) | 1.36 | 1.39 |
| TiO2@LP_1:0.1_S | 1.16 | 1.28 |
| TiO2@LP_1:1_S | 1.28 | 1.23 |
| TiO2@LP_1:8_S | 2.53 | 2.53 |
| TiO2/LP_1:1_E | 1.18 | 1.35 |
| TiO2/LP_1:8_E | 2.53 | 2.53 |
Table 6.
Results of antibacterial tests performed on representative samples.
| Sample | Add-on (%) | Bacterial Reduction (%) |
|---|---|---|
| LP | 1.7 | 40 |
| TiO2@TX (ref.) | 3.1 | 72 |
| TiO2@LP_1:0.1_S | 3.9 | 89 |
| TiO2@LP_1:1_S | 3.9 | 85 |
| TiO2@LP_1:8_S | 5.3 | 77 |
Figure S1.
Particle size distribution of TiO2@LP samples obtained via the sol–gel synthesis method.
Figure S2.
SAED patterns of the (a) TiO2@LP_S_1:0.1 and (b) TiO2@LP_S_1:1 samples.
Figure S3.
(a) Particle size distribution and (b) Zeta potential as a function of pH curves of TiO2/LP_E samples obtained via the heterocoagulation process.
Figure S4.
(a) Trends of A/A0 and (b) conversion (%) over time for TiO2@LP_S samples obtained via the sol–gel synthesis method.
Figure S5.
(a) Trends of A/A0 and (b) conversion (%) over time for TiO2/LP_E samples obtained via the heterocoagulation process.
Figure S6.
Scheme of (a) sol–gel processes using Triton X (TX) and mixture of lipopeptides (LP) as a surfactant and (b) the heterocoagulation process.
Figure S8.
Diffuse reflectance over different wavelengths of TiO2@LP_S samples.
Table S1.
Sample codes and TiO2:LP weight ratios of nanosols obtained via the sol–gel synthesis process and relative powders obtained via the SFD process.
| Sample Code | TiO2:LP Weight Ratio | |
|---|---|---|
| Nanosol | Powder | |
| TiO2@LP_1:0.1_S | TiO2@LP_1:0.1_S_SFD | 10.0 |
| TiO2@LP_1:0.5_S | TiO2@LP_1:0.5_S_SFD | 2.0 |
| TiO2@LP_1:1_S | TiO2@LP_1:1_S_SFD | 1.0 |
| TiO2@LP_1:2_S | TiO2@LP_1:2_S_SFD | 0.5 |
| TiO2@LP_1:6_S | TiO2@LP_1:6_S_SFD | 0.17 |
| TiO2@LP_1:8_S | TiO2@LP_1:8_S_SFD | 0.13 |
| TiO2@TX_S | TiO2@TX_S_SFD | 16.7 * |
* TiO2:Triton X weight ratio.
Table S2.
Sample codes and TiO2:LP weight ratios of nanosols obtained via the heterocoagulation process and relative powders obtained via the SFD process.
| Sample Code | TiO2:LP Weight Ratio | |
|---|---|---|
| Nanosol Sample | Powder Sample | |
| TiO2/LP_1:1_E | TiO2/LP_1:1_E_SFD | 1.0 |
| TiO2/LP_1:6_E | TiO2/LP_1:6_E_SFD | 0.17 |
| TiO2/LP_1:8_E | TiO2/LP_1:8_E_SFD | 0.13 |
The TiO2 used to produce the heterocoagulated samples is TiO2@TX_S of Table S1 (containing around 6 wt.% of Triton X).
Table S3.
Adsorption properties derived by UV-Vis analysis.
| Powder Sample Code | Absorption Range (nm) | Band Gap Energy (eV) |
|---|---|---|
| TiO2@TX_SFD | 350–450 | 3.14 |
| TiO2 P25 * | 350–420 | 3.19 |
| TiO2@LP_1:0.1_S_SFD | 350–420 | 3.17 |
| TiO2@LP_1:0.5_S_SFD | 350–420 | 3.18 |
| TiO2@LP_1:1_S_SFD | 350–420 | 3.18 |
| TiO2@LP_1:2_S_SFD | 300–380 | 3.33 |
| TiO2@LP_1:6_S_SFD | 300–360 | 3.41 |
| TiO2@LP_1:8_S_SFD | 300–360 | 3.41 |
* TiO2 P25 (commercial powder sample from Degussa-Evonik).
Revised References
Previous references focused exclusively on Surfactin. Due to the proposed correction (substitution of Surfactin with a mixture of lipopeptides), it was necessary to revise references specifically addressing lipopeptides to strengthen the rationale behind this study.
References 7 and 10 from the original publication [1] have now been removed. Also, the following citations have now been inserted as references 6, 10, 12, 15, and 16 into the Introduction. With this correction, the order of some references has been adjusted accordingly.
-
6.
Meena, K.R.; Kanwar, S.S. Lipopeptides as Antifungal and Antibacterial Agents: Applications in Food Safety and Therapeutics. BioMed Res. Int. 2015, 2015, 473050. https://doi.org/10.1155/2015/473050.
-
10.
Inès, M.; Dhouha, G. Lipopeptide Surfactants: Production, Recovery and Pore Forming Capacity. Peptides 2015, 71, 100–112. https://doi.org/10.1016/j.peptides.2015.07.006.
-
12.
Kourmentza, C.; Freitas, F.; Alves, V.; Reis, M.A.M. Microbial conversion of waste and surplus materials into high-value added products: the case of biosurfactants. In Microbial Applications; Kalia, V., Kumar, P., Eds.; Springer: Cham, Switzerland, 2017; Volume 1, pp. 29–77. https://doi.org/10.1007/978-3-319-52666-9_2.
-
15.
Sharma, R.K.; Dey, G.; Banerjee, P.; Maity, J.P.; Lu, C.M.; Siddique, J.A.; Wang, S.C.; Chatterjee, N.; Das, K.; Chen, C.Y. New Aspects of Lipopeptide-Incorporated Nanoparticle Synthesis and Recent Advancements in Biomedical and Environmental Sciences: A Review. J. Mater. Chem. B 2023, 11, 10–32. https://doi.org/10.1039/D2TB01564A.
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16.
Christopher, F.C.; Ponnusamy, S.K.; Ganesan, J.J.; Ramamurthy, R. Investigating the Prospects of Bacterial Biosurfactants for Metal Nanoparticle Synthesis—A Comprehensive Review. IET Nanobiotechnol. 2019, 13, 243. https://doi.org/10.1049/iet-nbt.2018.5184.
Missing Conflict of Interest
In the original publication [1], the Conflicts of Interest statement of authors Giovanni Baldi and Valentina Dami were not included. The updated Conflict of Interest has been added as follows:
Giovanni Baldi and Valentina Dami was employed by the company Ce.Ri.Col, Colorobbia Consulting S.R.L. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Author’s Information
This article has been republished with a minor update to the correspondence contact information.
The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.
Footnotes
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Reference
- 1.Ortelli S., Vespignani M., Zanoni I., Blosi M., Vineis C., Piancastelli A., Baldi G., Dami V., Albonetti S., Costa A.L. Design of TiO2-Based Hybrid Systems with Multifunctional Properties. Molecules. 2023;28:1863. doi: 10.3390/molecules28041863. [DOI] [PMC free article] [PubMed] [Google Scholar]