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Diep E, Schiffman JD. Living Antimicrobial Wound Dressings: Using Probiotic-Loaded, Alginate Nanofibers for Protection against Methicillin-Resistant Staphylococcus aureus. ACS Appl Bio Mater 2024; 7:787-790. [PMID: 38324992 DOI: 10.1021/acsabm.3c01240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Living probiotic bacteria can be used as an alternative treatment to fight antibiotic-resistant, pathogenic bacteria. Electrospinning probiotics into nanofibers allows the probiotics to be conveniently applied like a wound dressing to protect open wounds while providing antimicrobial activity. In this letter, we encapsulated Lactococcus lactis into biocompatible, alginate-based nanofiber scaffolds. After cross-linking the scaffold to increase the chemical stability of the fibers, the encapsulated L. lactis cells maintained their ability to inhibit the growth of Staphylococcus aureus. This living wound dressing was especially effective at inhibiting the growth of clinically relevant methicillin-resistant S. aureus.
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Affiliation(s)
- Emily Diep
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
| | - Jessica D Schiffman
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
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Hancock SN, Yuntawattana N, Diep E, Maity A, Tran A, Schiffman JD, Michaudel Q. Ring-opening metathesis polymerization of N-methylpyridinium-fused norbornenes to access antibacterial main-chain cationic polymers. Proc Natl Acad Sci U S A 2023; 120:e2311396120. [PMID: 38079554 PMCID: PMC10742381 DOI: 10.1073/pnas.2311396120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 10/31/2023] [Indexed: 12/18/2023] Open
Abstract
Cationic polymers have been identified as a promising type of antibacterial molecules, whose bioactivity can be tuned through structural modulation. Recent studies suggest that the placement of the cationic groups close to the core of the polymeric architecture rather than on appended side chains might improve both their bioactivity and selectivity for bacterial cells over mammalian cells. However, antibacterial main-chain cationic polymers are typically synthesized via polycondensations, which do not afford precise and uniform molecular design. Therefore, accessing main-chain cationic polymers with high degrees of molecular tunability hinges upon the development of controlled polymerizations tolerating cationic motifs (or cation progenitors) near the propagating species. Herein, we report the synthesis and ring-opening metathesis polymerization (ROMP) of N-methylpyridinium-fused norbornene monomers. The identification of reaction conditions leading to a well-controlled ROMP enabled structural diversification of the main-chain cationic polymers and a study of their bioactivity. This family of polyelectrolytes was found to be active against both Gram-negative (Escherichia coli) and Gram-positive (Methicillin-resistant Staphylococcus aureus) bacteria with minimal inhibitory concentrations as low as 25 µg/mL. Additionally, the molar mass of the polymers was found to impact their hemolytic activity with cationic polymers of smaller degrees of polymerization showing increased selectivity for bacteria over human red blood cells.
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Affiliation(s)
- Sarah N. Hancock
- Department of Chemistry, Texas A&M University, College Station, TX77843
| | | | - Emily Diep
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA01003
| | - Arunava Maity
- Department of Chemistry, Texas A&M University, College Station, TX77843
| | - An Tran
- Department of Chemistry, Texas A&M University, College Station, TX77843
| | - Jessica D. Schiffman
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA01003
| | - Quentin Michaudel
- Department of Chemistry, Texas A&M University, College Station, TX77843
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX77843
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Diep E, Schiffman JD. Ethanol-free Cross-Linking of Alginate Nanofibers Enables Controlled Release into a Simulated Gastrointestinal Tract Model. Biomacromolecules 2023. [PMID: 37183416 DOI: 10.1021/acs.biomac.3c00274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The use of alginate nanofibers in certain biomedical applications, including targeted delivery to the gut, is limited because an ethanol-free, biocompatible cross-linking method has not been demonstrated. Here, we developed water-stable, alginate-based nanofibers by systematically exploring post-electrospinning cross-linking approaches that used calcium ions dissolved in (1) a glycerol/water cosolvent system and (2) acidic, neutral, or basic aqueous solutions. Scanning electron microscopy proved that the fibers cross-linked in a glycerol cosolvent or pH-optimized solutions had maintained the same morphology as the ethanol-based literature control. Notably, cross-linked fibers were generally smaller in diameter than the as-spun fibers due to both chemical interactions and mass loss during cross-linking, which was supported by mass measurements, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. During stability tests wherein the cross-linked fibers were exposed to three aqueous solutions, the cross-linked fibers were stable in water and acid buffer yet swelled in phosphate buffer saline, making them useful scaffolds for pH-controlled release applications. Proof-of-concept release experiments were conducted using a simulated gastrointestinal tract model. As desired, the cargo remained encapsulated within the cross-linked nanofibers when exposed to an acidic solution that modeled the stomach. Upon exposure to a solution that mimicked the intestines, the cargo was released. We suggest that these cross-linked, alginate-based nanofiber mats hold the potential to be broadly used in biomedical and environmental applications.
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Affiliation(s)
- Emily Diep
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
| | - Jessica D Schiffman
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
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Diep E, Schiffman JD. Electrospinning Living Bacteria: A Review of Applications from Agriculture to Health Care. ACS Appl Bio Mater 2023; 6:951-964. [PMID: 36791266 DOI: 10.1021/acsabm.2c01055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Living bacteria are used in biotechnologies that lead to improvements in health care, agriculture, and energy. Encapsulating bacteria into flexible and modular electrospun polymer fabrics that maintain their viability will further enable their use. This review will first provide a brief overview of electrospinning before examining the impact of electrospinning parameters, such as precursor composition, applied voltage, and environment on the viability of encapsulated bacteria. Currently, the use of nanofiber scaffolds to deliver live probiotics into the gut is the most researched application space; however, several additional applications, including skin probiotics (wound bandages) and menstruation products have also been explored and will be discussed. The use of bacteria-loaded nanofibers as seed coatings that promote plant growth, for the remediation of contaminated wastewaters, and in energy-generating microbial fuel cells are also covered in this review. In summary, electrospinning is an effective method for encapsulating living microorganisms into dry polymer nanofibers. While these living composite scaffolds hold potential for use across many applications, before their use in commercial products can be realized, numerous challenges and further investigations remain.
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Affiliation(s)
- Emily Diep
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
| | - Jessica D Schiffman
- Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
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Diep E, Schiffman JD. Correction: Encapsulating bacteria in alginate-based electrospun nanofibers. Biomater Sci 2022; 10:1596. [PMID: 35199114 DOI: 10.1039/d2bm90016e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Correction for 'Encapsulating bacteria in alginate-based electrospun nanofibers' by Emily Diep et al., Biomater. Sci., 2021, 9, 4364-4373, DOI: 10.1039/D0BM02205E.
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Affiliation(s)
- Emily Diep
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, Massachusetts 01003-9303, USA.
| | - Jessica D Schiffman
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, Massachusetts 01003-9303, USA.
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Abstract
Encapsulation technologies are imperative for the safe delivery of live bacteria into the gut where they regulate bodily functions and human health. In this study, we develop alginate-based nanofibers that could potentially serve as a biocompatible, edible probiotic delivery system. By systematically exploring the ratio of three components, the biopolymer alginate (SA), the carrier polymer poly(ethylene oxide) (PEO), and the FDA approved surfactant polysorbate 80 (PS80), the surface tension and conductivity of the precursor solutions were optimized to electrospin bead-free fibers with an average diameter of 167 ± 23 nm. Next, the optimized precursor solution (2.8/1.2/3 wt% of SA/PEO/PS80) was loaded with Escherichia coli (E. coli, 108 CFU mL-1), which served as our model bacterium. We determined that the bacteria in the precursor solution remained viable after passing through a typical electric field (∼1 kV cm-1) employed during electrospinning. This is because the microbes are pulled into a sink-like flow, which encapsulates them into the polymer nanofibers. Upon electrospinning the E. coli-loaded solutions, beads that were much smaller than the size of an E. coli were initially observed. To compensate for the addition of bacteria, the SA/PEO/PS80 weight ratio was reoptimized to be 2.5/1.5/3. Smooth fibers with bulges around the live microbes were formed, as confirmed using fluorescence and scanning electron microscopy. By dissolving and plating the nanofibers, we found that 2.74 × 105 CFU g-1 of live E. coli cells were contained within the alginate-based fibers. This work demonstrates the use of electrospinning to encapsulate live bacteria in alginate-based nanofibers for the potential delivery of probiotics to the gut.
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Affiliation(s)
- Emily Diep
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, Massachusetts 01003-9303, USA.
| | - Jessica D Schiffman
- Department of Chemical Engineering, University of Massachusetts, Amherst, Amherst, Massachusetts 01003-9303, USA.
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Chen H, Diep E, Langrish TAG, Glasser BJ. Continuous fluidized bed drying: Residence time distribution characterization and effluent moisture content prediction. AIChE J 2020. [DOI: 10.1002/aic.16902] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Hao Chen
- Department of Chemical and Biochemical Engineering Rutgers University Piscataway New Jersey
| | - Emily Diep
- Department of Chemical and Biochemical Engineering Rutgers University Piscataway New Jersey
| | - Timothy A. G. Langrish
- School of Chemical and Biomolecular Engineering The University of Sydney Sydney New South Wales Australia
| | - Benjamin J. Glasser
- Department of Chemical and Biochemical Engineering Rutgers University Piscataway New Jersey
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Habibi M, Diep E. A linear, time-invariant model for cancerous and normal breast tissue. Annu Int Conf IEEE Eng Med Biol Soc 2013; 2012:4899-902. [PMID: 23367026 DOI: 10.1109/embc.2012.6347092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Electrical properties of biological cells and human tissue have been used to characterize cancerous vs. normal tissue. Commonly, measured dielectric spectra (permittivity and conductivity) are fitted into an empirical function and the best-fit parameters of the function are considered as a tool to differentiate various types of tissue; however, these parameters do not provide any explanation for the underlying molecular structure. In this work, we modeled the frequency dependence of impedance data collected from human breast tissue using a high-order, linear, time-invariant filter. The results show that the parameters of the filter not only can be used to classify tissue types, they may provide meaningful information about the properties and structure of tissues.
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Affiliation(s)
- M Habibi
- Minnesota State University, Mankato, Iron Range Engineering Program, Mankato 55792, USA.
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