PONE-D-24-08899Development and Application of Decontamination Methods for the Re-Use of Laboratory Grade Plastic Pipette TipsPLOS ONE

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PLOS ONE

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Reviewers' comments:

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Reviewer #1: Partly

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: N/A

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: No

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: General Comment.

The comparison between traditional methods of cleaning, like detergents, and more recent ones, like UV or CAP, is a subject of outmost interest and value in public health. For instance, CAP have been extensively researched in the last 20 years for different applications, but its actual implementation has evolved more slowly, precisely due to the requirement of more studies about its performance.

The paper has strong points like the organized structure of the manuscript, the thorough description of the protocol and elements used in the biological experiments, as well as the presentation of the results (graphs and tables).

My main concern with the manuscript is that I do not think the authors did a good job in comparing the performance of the three methods. There are parameters that are not consistent, like the number of samples, or seem to be chosen arbitrarily. In addition, there is the perception of lack of knowledge in the explanation of the results that were obtained. Although this is not a physics paper, the authors should have a minimum basic knowledge of the methods they are comparing.

Finally, the paper would benefit from a review by a native speaker who could improve the text and make it more natural and fluid.

Specific comments.

Line 45 and 48: “the highest turnover ratio (95.9 %) ... the second highest turnover ratio (98.4 %)”. There is an incoherence in that statement.

Line 48: 14400 PPM * minutes, remove the ‘s’.

Lines 50 to 52: “Relatively, lower turnover ratio and log reduction of CAP could be attributed to development/optimization of treatment conditions, including increases in exposure time and relative to tip positioning.” It is very difficult to make sense of this sentence, please rewrite.

Line 73: instead of using “[8]; Alconox® is a widely used laboratory cleaner” I would suggest using “[8], which is a widely used laboratory cleaner.” to make the reading more fluid.

Lines 75 and 76: The authors wrote “ozone is a reactive allotrope of oxygen with a lone unpaired electron (free radical) that dimerize with valence electrons on other molecules.” That statement is not correct, please check.

Lines 84 and 85: The authors describe CAP as “a thermal non-equilibrium state between heavy positive ions and electrons achieved [10, 11] through rapid atmospheric pressure discharge.” The statement is not entirely accurate. The presence of negative ions in plasma is very important for Electronegative gases like oxygen and therefore, air. In the method presented in the manuscript, plasma is ignited first using helium gas. However, the decontamination effect is achieved through reactive species of oxygen and nitrogen formed through ionization of the surrounding air.

In addition, they should explain briefly and in a very simple (basic) form how the CAP machine works, or its principle of operation (DBD). In lines 243 and 244 they mention the voltage and frequency used, but without said explanation, that information is entirely useless for the reader.

Line 87: “CAP maintains temperatures of 25- 45°C…”. Please, add references.

Lines 94 to 96: The paragraph should be rewritten, because it is not easy to understand.

Lines 245 to 247: The authors mentioned that the pipette tips were placed 2 to 5 cm under the plasma jet for 1 minute. How and why such distance and exposure time were selected.

Line 368 (table 4): Why are there inconsistencies in the number of samples used (73 vs 63)? The turnover ratio is better for O3 14400 ppm than for detergent, but the authors claim otherwise.

I do not think the authors are making a fair comparison or assessment of the cleaning methods proposed, since they seem to have chosen arbitrary exposure distance and time for CAP. They soaked the tip racks for 30 minutes in the detergent solution and used the same time exposure for O3 14400 ppm; however, for CAP they exposed the pipettes for 1 minute, without further explanation to justify that decision. Furthermore, as mentioned before, CAP decontamination is mostly achieved through the action of ROS/RNS (O3 being among them). UV radiation may have some effect if the object is placed near enough to the plasma luminescence. It would have been very useful if the authors could have roughly measured the concentration of at least some of the ROS/RNS, although I understand that this is only possible if they have access to some specialized equipment. However, the authors at least should have done a preliminary study to establish a minimum exposure time, after which the variations in log reduction are not considerable.

Reviewer #2: The experiment and data presented is good to be accepted as it is. The experiment and statistical analysis were done. A clear disinfection protocol was also outlined. Only the figures need to be in high quality for publication. Others are okay.

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Reviewer #1: No

Reviewer #2: Yes: Mohd Ridha Muhamad

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Development and Application of Decontamination Methods for the Re-Use of Laboratory Grade Plastic Pipette Tips

PONE-D-24-08899R1

Dear Dr. Lee,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Abdul Rauf Shakoori

Academic Editor

PLOS ONE

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