Controlling Nanoparticle Formulation: A Low-Budget Prototype for the Automation of a Microfluidic Platform

Round 1

Reviewer 1 Report

In this manuscript, the authors presented an automated microfluidic mixing platform to program polyplexes with different formulations. The integration of automation control system and microfluidic chips should be of interest to the communities. I suggest accepting this manuscript after they address the following concerns.

 

1. In the DMC setup, how do you prevent backflow from the syringe pump? Do you have any surface treatment to change the hydrophobicity of glass and PDMS to get rid of air bubbles? 
2. For Figure 5C and D, what’s the corresponding flow rates?
3. Section 3.5 needs better organized. The author started with Figure 4 to demonstrate the influences of formulation parameters from 2 component pipetting and then compared DMC and 3 component pipetting. Is there any data to study the influence of volume ratio in the 3 component pipetting as shown in Figure 4? Please have more discussions on the characterization process of the microfluidics generating 2/3 components polyplexes.
4. What’s the repeatability of the formulations from chip and chip? 

 

Some minor issues:

1. Line 251, 252, 259, 260, please correct “Error! Reference source not found”
2. Line 289, typo: “und”

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The discussion in this article extends from the author's another article published in 2019. However, the configuration and assembly of the microfluidic device are described more detail in this article. There are several issues need to be clarified:

1. The author prepares polyplexes with different ratios of oligo and siRNA, even from 1:11 to 11:1, can the author explain the difference in function
2. The author proposes two different devices in the article: single-meander channel and double-meander channel。 However, only the polyplexes produced by double-meander channel application are discussed. How about the performance of single-meander channel ?
3. Because different preparation methods would affect the stability of the polyplexes. The author needs to present and

   The discussion in this article extends from the author's another article published in 2019. However, the configuration and assembly of the microfluidic device are described more detail in this article. There are several issues need to be clarified:

   1. The author prepares polyplexes with different ratios of oligo and siRNA, even from 1:11 to 11:1, can the author explain the difference in function
   2. The author proposes two different devices in the article: single-meander channel and double-meander channel。However, only the polyplexes produced by double-meander channel application are discussed. How about the performance of single-meander channel ?
   3. Because different preparation methods would affect the stability of the polyplexes. The author needs to present the results of the stability test of these polyplexes from different method.
   4. The microfluidic chips were made from polydimethylsiloxane (PDMS). However, different solvent will swell PDMS with different degree. The authors should compare the consistency of product after multiple trials.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

In this manuscript titled "Controlling nanoparticle formulation: a low-budget 2 prototype for the automation of a microfluidic 3 platform" the authors in a very eloquent manner describe the feature of the working prototype and demonstrate its power with polyplexes formulated from siRNA and two different oligomers that are fed to the chip at two different stages during the assembly of the nanoparticles. 

The authors have presented and described in a descriptive manner how to control a nanoparticle formulation. The only caveat that is observed is the authors have not provided details on how the system is standardized. What is the quality controls the authors used to confirm the sensitivity of the formulation?

The authors will have to show some data on the efficacy of the nanoparticle formualtion between the manual and automated systems in a biological system. 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have satisfactorily addressed the comments on the original manuscript, especially addressing my concerns about the backflow. However, I think the author accidentally submitted the revised manuscript with track of changes. After clearing the format, I recommend the manuscript for publication as it stands.

Author Response

Dear Editors, dear Reviewer,

thank you very much for revising the second version of our manuscript and your recommendation for publication!

Please accept our apologies for submitting the previous version with track changes enabled. We have removed all track changes and uploaded a clean version of our manuscript.

Yours sincerely,

Dominik Loy