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Synthesis and Application of Superabsorbent Polymer Microspheres for Rapid Concentration and Quantification of Microbial Pathogens in Ambient Water

Wu, Xunyi and Huang, Xiao and Zhu, Yanzhe and Li, Jing and Hoffmann, Michael R. (2020) Synthesis and Application of Superabsorbent Polymer Microspheres for Rapid Concentration and Quantification of Microbial Pathogens in Ambient Water. Separation and Purification Technology, 239 . Art. No. 116540. ISSN 1383-5866. PMCID PMC7045201.

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Even though numerous methods have been developed for the detection and quantification of waterborne pathogens, the application of these methods is often hindered by the very low pathogen concentrations in natural waters. Therefore, rapid and efficient sample concentration methods are urgently needed. Here we present a novel method to pre-concentrate microbial pathogens in water using a portable 3D-printed system with super-absorbent polymer (SAP) microspheres, which can effectively reduce the actual volume of water in a collected sample. The SAP microspheres absorb water while excluding bacteria and viruses by size exclusion and charge repulsion. To improve the water absorption capacity of SAP in varying ionic strength waters (0-100 mM), we optimized the formulation of SAP to 180 g∙L⁻¹ Acrylamide, 75 g∙L⁻¹ Itaconic Acid and 4.0 g∙L⁻¹ Bis-Acrylamide for the highest ionic strength water as a function of the extent of cross-linking and the concentration of counter ions. Fluorescence microscopy and double-layer agar plating respectively showed that the 3D-printed system with optimally-designed SAP microspheres could rapidly achieve a 10-fold increase in the concentration of Escherichia coli (E. coli) and bacteriophage MS2 within 20 minutes with concentration efficiencies of 87% and 96%, respectively. Fold changes between concentrated and original samples from qPCR and RT-qPCR results were found to be respectively 11.34-22.27 for E. coli with original concentrations from 10⁴ to 10⁶ cell·mL⁻¹, and 8.20-13.81 for MS2 with original concentrations from 10⁴-10⁶ PFU·mL⁻¹. Furthermore, SAP microspheres can be reused for 20 times without performance loss, significantly decreasing the cost of our concentration system.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Huang, Xiao0000-0002-3737-6939
Zhu, Yanzhe0000-0002-2260-1830
Li, Jing0000-0003-0639-9422
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 2020 Published by Elsevier B.V. Received 26 September 2019, Revised 11 December 2019, Accepted 9 January 2020, Available online 11 January 2020. The authors acknowledge the financial support provided by the Bill and Melinda Gates Foundation (grant no. OPP1111252). The authors thank Dr. Katharina Urmann, Dr. Xingyu Lin and Dr. Xing Xie for their helpful advices and discussions. CRediT authorship contribution statement: Xunyi Wu: Conceptualization, Methodology, Investigation, Formal analysis, Writing - original draft. Xiao Huang: Conceptualization, Methodology, Writing - review & editing. Yanzhe Zhu: Writing - review & editing. Jing Li: Methodology, Writing - review & editing. Michael R. Hoffmann: Conceptualization. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Funding AgencyGrant Number
Bill and Melinda Gates FoundationOPP1111252
Subject Keywords:Super-absorbent polymer (SAP); Concentration method; Waterborne pathogen; 3D printing; Point-of-sample collection
PubMed Central ID:PMC7045201
Record Number:CaltechAUTHORS:20200113-095556475
Persistent URL:
Official Citation:Xunyi Wu, Xiao Huang, Yanzhe Zhu, Jing Li, Michael R. Hoffmann, Synthesis and application of superabsorbent polymer microspheres for rapid concentration and quantification of microbial pathogens in ambient water, Separation and Purification Technology, Volume 239, 2020, 116540, ISSN 1383-5866, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100671
Deposited By: Tony Diaz
Deposited On:13 Jan 2020 18:14
Last Modified:18 May 2020 23:43

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