Biologically Benign Multi-functional Mesoporous Silica Encapsulated Gold/Silver Nanorods for Anti-bacterial Applications by On-demand Release of Silver Ions

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Although silver (Ag)-based nanoparticles (NPs) are frequently used for bactericidal purposes, they have critical issues including excessive release of Ag+, severe oxidation, and cytotoxicity. In this study, we designed a multifunctional, on-demand antibacterial agent by successively encapsulating bimetallic gold/silver nanorods (Ag/AgNRs) with mesoporous silica (mSiO2) shells. Au/AuNRs were synthesized by coating Ag on AuNRs in a controlled manner, so that they exhibited a localized surface plasmon resonance peak in the near-infrared (NIR) region. When Au/AgNR@mSiO2 NPs were irradiated with an NIR laser under optimal conditions (0.4 W/cm2), they generated a small amount of heat (40–45 oC), which successively triggered the release of Ag+ and induced bacterial cell death. Here, mSiO2 shells play critical roles because they not only protect Ag from oxidation but also prevent the burst release of Ag+ and improve biocompatibility of the antibacterial agent against normal cells. We found that this multifunctional bacterial agent effectively kills gram-negative Escherichia coli and gram-positive Staphylococcus aureus without significantly increasing the temperature of the medium. Au/AgNR@mSiO2 NPs were also biologically benign with high biocompatibility against mammalian cells.

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This research was supported by the National Research Foundation (NRF) of Korea for a Bio-inspired Innovation Technology Development Project (NRF-2018M3C1B7021997) funded by the Ministry of Science and ICT and Basic Science Research Program funded by the Ministry of Education (NRF-2019R1A6A1A03033215). This work was also supported by Basic Science Research Capacity Enhancement Project through Korea Basic Science Institute (National Research Facilities and Equipment Center) grant funded by the Ministry of Education (2019R1A6C1010031).

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Correspondence to Jung Heon Lee.

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Conflict of Interests The authors declare no competing financial interests.

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Yoon, S., Chung, Y., Lee, J.W. et al. Biologically Benign Multi-functional Mesoporous Silica Encapsulated Gold/Silver Nanorods for Anti-bacterial Applications by On-demand Release of Silver Ions. BioChip J 13, 362–369 (2019).

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  • Gold/Silver nanorod
  • Mesoporous silica
  • Antibacterial agent
  • Drug delivery
  • Near-infrared (NIR)
  • Controlled silver release
  • Biocompatibility