A Caltech Library Service

“Nanofiltration” Enabled by Super-Absorbent Polymer Beads for Concentrating Microorganisms in Water Samples

Xie, Xing and Bahnemann, Janina and Wang, Siwen and Yang, Yang and Hoffmann, Michael R. (2016) “Nanofiltration” Enabled by Super-Absorbent Polymer Beads for Concentrating Microorganisms in Water Samples. Scientific Reports, 6 . Art. No. 20516. ISSN 2045-2322. PMCID PMC4753426.

[img] PDF - Published Version
Creative Commons Attribution.

[img] PDF - Supplemental Material
Creative Commons Attribution.


Use this Persistent URL to link to this item:


Detection and quantification of pathogens in water is critical for the protection of human health and for drinking water safety and security. When the pathogen concentrations are low, large sample volumes (several liters) are needed to achieve reliable quantitative results. However, most microbial identification methods utilize relatively small sample volumes. As a consequence, a concentration step is often required to detect pathogens in natural waters. Herein, we introduce a novel water sample concentration method based on superabsorbent polymer (SAP) beads. When SAP beads swell with water, small molecules can be sorbed within the beads, but larger particles are excluded and, thus, concentrated in the residual non-sorbed water. To illustrate this approach, millimeter-sized poly(acrylamide-co-itaconic acid) (P(AM-co-IA)) beads are synthesized and successfully applied to concentrate water samples containing two model microorganisms: Escherichia coli and bacteriophage MS2. Experimental results indicate that the size of the water channel within water swollen P(AM-co-IA) hydrogel beads is on the order of several nanometers. The millimeter size coupled with a negative surface charge of the beads are shown to be critical in order to achieve high levels of concentration. This new concentration procedure is very fast, effective, scalable, and low-cost with no need for complex instrumentation.

Item Type:Article
Related URLs:
URLURL TypeDescription Information CentralArticle
Xie, Xing0000-0002-2253-0964
Bahnemann, Janina0000-0002-7008-1673
Wang, Siwen0000-0002-8553-425X
Yang, Yang0000-0003-3767-8029
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 2016 Nature Publishing Group. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit received: 07 October 2015; accepted: 05 January 2016; Published: 15 February 2016. The authors would like to acknowledge the financial support of the Bill and Melinda Gates Foundation (BMGF OPP1111246). We also would like to thank Dr. Sunny Jiang and Dr. Mamadou Diallo for helpful discussions. Author Contributions: M.R.H. was the project PI. X.X. and M.R.H. conceived and designed the study. X.X. synthesized the polymer beads and performed most of the experiments. J.B., S.W. and Y.Y. contributed to various aspects of the experiments. All authors contributed to the scientific planning, analysis and interpretation of data, and to the writing of manuscript. The authors declare no competing financial interests.
Funding AgencyGrant Number
Bill and Melinda Gates FoundationOPP1111246
PubMed Central ID:PMC4753426
Record Number:CaltechAUTHORS:20160222-094329335
Persistent URL:
Official Citation:Xie, X. et al. "Nanofiltration" Enabled by Super-Absorbent Polymer Beads for Concentrating Microorganisms in Water Samples. Sci. Rep. 6, 20516; doi: 10.1038/srep20516 (2016).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64626
Deposited By: Tony Diaz
Deposited On:22 Feb 2016 17:54
Last Modified:03 Mar 2020 13:01

Repository Staff Only: item control page