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International Journal of Bioprinting 3DP hydrogels to combat antibiotic-resistant bacteria

Figure 5. In vitro cumulative release and concentration of Rif (a, c) and Van (b, d) from LMW, MMW, and HMW PLGA NPs in PBS at 37°C.

Figure 6. Development of resistance of S. aureus RN4220 against Rif (a) and Van (b) over 25 passages (n = 2).
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RN4220 Van for subsequent experiments to maintain Van-NPs hydrogels with a ZOI for 5 days (Figure 7c).
its resistance. Hence, the high local release of Van was still able to kill
Van-resistant bacteria. The clinical S. aureus strain AMC
3.7. Antibacterial activity of GelMA-PLGA NPs 201 had a ZOI with the GelMA-Rif-NPs, GelMA-Van-NPs,
hydrogels over time or GelMA-Rif-Van-NPs hydrogels for 3, 6, and 3 days,
GelMA-Rif-NPs, GelMA-Van-NPs, and GelMA-Rif- respectively. As expected, GelMA-C-NPs hydrogels did
Van-NPs hydrogels were transferred to fresh agar not form any ZOI for any S. aureus strain (not shown). In
plates inoculated with different test strains on a daily summary, the GelMA-Rif-NPs hydrogels formed ZOI for
basis, and they created a zone of inhibition (ZOI) that S. aureus RN4220, S. aureus RN4220 Van , and S. aureus
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prevented bacterial growth for S. aureus RN4220 for 10, AMC201, but not for S. aureus RN4220 Rif . The GelMA-
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9, and 10 days, respectively, with diameters of the zones Van-NPs hydrogels formed ZOI for the four S. aureus
decreasing over time as expected with the release of the strains, with S. aureus RN4220 Van being less susceptible
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antibiotics (Figure 7a). The GelMA-Van-NPs or GelMA- and S. aureus RN4220 Rif more susceptible than the other
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Rif-Van-NPs showed a ZOI for S. aureus RN4220 Rif for strains. The GelMA-Rif-Van-NPs hydrogels formed ZOI
7 and 5 days, respectively (Figure 7b). S. aureus RN4220 for all S. aureus strains, showing that this double antibiotic-
Rif showed to be more sensitive for the GelMA-Van-NPs releasing hydrogel targets both resistant strains.
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than the other S. aureus strains as it showed a larger ZOI.
As expected, no ZOI formed around the GelM-Rif-NPs for 3.8. Antimicrobial and anti-adhesive activity of the
S. aureus RN4220 Rif , meaning that the release of Rif did 3D-printed GelMA hydrogels loaded with Rif-NPs
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not inhibit the bacterial growth. S. aureus RN4220 Van and Van-NPs
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showed to be slightly more sensitive to GelMA-Rif-NPs In vitro antimicrobial and antiadhesive activity of the
with a ZOI for 10 days and less susceptible to the GelMA- GelMA-Rif-NPs, GelMA-Van-NPs, or GelMA-Rif-Van-NPs
Volume 9 Issue 3 (2023) 72 https://doi.org/10.18063/ijb.683