Correction: Takakura et al. In Vitro and In Vivo Cell Uptake of a Cell-Penetrating Peptide Conjugated with Fluorescent Dyes Having Different Chemical Properties. Cancers 2021, 13, 2245

There was an error in the description in the original publication, and it contained information that should not have been disclosed [1].

Reference [9] does not contain information on the peptide. The inventors of the peptide have not disclosed the peptide sequence in any scientific papers yet. We obtained the information only through private communication and published it without their agreement.

Therefore, all the concrete information about the peptide, including its sequence, should have been removed from the original publication. The structure of the peptide has been concealed and the name replaced by Peptide A. The research work is scientifically valid and unchanged. No corrections regarding the testing of the peptide were made.

Thus, we raised the correction as below:

• Replace all peptide designation with “peptide A” in the main text. The relevant information for it also needs to be updated.
• Delete “using mRNA display technology for BxPC3 cells, human pancreatic ductal adenocarcinoma [9].” in the last paragraph of the Introduction.
• Section 2.2 should be corrected as below:

Cy5-peptide A. Peptide A (0.74 mg) and Cy5 succinimidyl ester (SE) (0.20 mg, 0.32 μmol) were dissolved in 0.1 mL of DMSO, and 0.1 mL of 1 mM Na₂HPO₄aq was added to the solution. The reaction mixture was stirred for 1 h at 50 °C. Then, 0.2 mL of TFA was added to the reaction mixture. The mixture was further stirred for 30 min at 50 °C. The product was purified by semi-preparative reverse-phase HPLC (eluent A: H₂O/1% TFA, eluent B: 99% CH₃CN/0.1% TFA, A:B = 70:30 to 0:100 in 20 min) to produce a blue solid (0.41 mg). The HPLC chart of Cy5-peptide A is shown in Figure S1.

sulfoCy5-peptide A. sulfoCy5-peptide A was synthesized from peptide A and sulfoCy5-SE by the same method as that used to obtain Cy5-peptide A. The product was purified by semi-preparative reverse-phase HPLC (A:B = 80:20 to 20:80 in 25 min) to produce a blue solid. The HPLC chart of sulfoCy5-peptide A is shown in Figure S1.

Cy3-peptide A. Cy3-peptide A was synthesized from peptide A and Cy3-SE by the same method as that used to obtain Cy5-peptide A. The product was purified by semi-preparative reverse-phase HPLC (A:B = 70:30 to 0:100 in 20 min) to produce a red solid. The HPLC chart of Cy3-peptide A is shown in Figure S1.

sulfoCy3-peptide A. sulfoCy3-peptide A was synthesized from peptide A and sulfoCy3-SE by the same method as that used to obtain Cy5-peptide A. The product was purified by semi-preparative reverse-phase HPLC (A:B = 80:20 to 20:80 in 25 min) to produce a red solid. The HPLC chart of sulfoCy3-peptide A is shown in Figure S1.

4.

Figure 1 should be corrected as below:

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Figure 2 should be updated as below:

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Figure 3 should be updated as:

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Figure 4 should be updated as:

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Figure 5 should be updated as:

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Figure 6 is updated as:

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Figure 7 is updated as:

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Figure 8 should be updated as:

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Change the supplementary information

Figure S1 should be:

Figure S1. HPLC charts of dye-SE and dye-peptide A conjugates.

Figure S1. HPLC charts of dye-SE and dye-peptide A conjugates.

Figure S2 should be removed. Since some references have been deleted, the citation of them should be removed from the main text accordingly.

The authors apologize for any inconvenience caused and state that the scientific conclusions are unaffected. The original publication has also been updated.