Amino-Functionalized Nitrogen-Doped Graphene Quantum Dots for Efficient Enhancement of Two-Photon-Excitation Photodynamic Therapy: Functionalized Nitrogen as a Bactericidal and Contrast Agent

Int J Nanomedicine. 2020 Sep 22:15:6961-6973. doi: 10.2147/IJN.S242892. eCollection 2020.

Abstract

Background: Although graphene quantum dots (GQDs) have received considerable research attention for their applications in various fields, the use of GQDs, such as nitrogen-doped GQDs (N-GQDs) and amino-functionalized N-GQDs (amino-N-GQDs), as photosensitizers to facilitate photodynamic therapy (PDT) has received limited research intention. To address this research gap, this study prepared novel amino-N-GQDs and investigated their properties.

Methods: The amino-N-GQDs subjected to two-photon excitation (TPE) exhibited remarkable bactericidal capability in PDT. The bonding compositions of nitrogen and the amino-functionalized group played a critical role in their antimicrobial effects.

Results: Compared with amino-group-free N-GQDs and amino-N-free GQDs, the amino-N-GQDs generated a higher amount of reactive oxygen species, demonstrating their superior efficacy for two-photon PDT. Additionally, the intrinsic luminescence properties and high photostability of the amino-N-GQDs demonstrate their suitability as an effective two-photon contrast agent for tracking bacteria during two-photon biomedical imaging.

Conclusion: The amino-N-GQD and their remarkable properties may provide an efficient alternative approach for observing and easily eliminating malignant microbes in the future.

Keywords: amino-functionalized and nitrogen atom-doped graphene quantum dots; nitrogen atom-doped graphene quantum dots; two-photon biomedical imaging; two-photon contrast agent; two-photon photodynamic therapy.

MeSH terms

  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology*
  • Bacillus subtilis / drug effects
  • Contrast Media / chemistry*
  • Graphite / chemistry
  • Luminescence
  • Nitrogen / chemistry
  • Nitrogen / pharmacology*
  • Photochemotherapy / methods*
  • Photons
  • Photosensitizing Agents / chemistry
  • Photosensitizing Agents / pharmacology
  • Quantum Dots / chemistry*

Substances

  • Anti-Bacterial Agents
  • Contrast Media
  • Photosensitizing Agents
  • Graphite
  • Nitrogen

Grants and funding

This work was supported by Research Start-Up Fund of Nanjing University of Information Science & Technology, China (2018r047), An Nan Hospital, China Medical University, Taiwan (ANHRF108-19), Ministry of Science and Technology, Taiwan (MOST 108-2314-B-006-053-, 109-2622-E-006-013-CC3, 109-2636-E-006-018-) and the Center of Applied Nanomedicine and Medical Device Innovation Center (MDIC) at National Cheng Kung University from the Featured Areas Research Center Program within the framework of the Higher Education Sprout Project, Ministry of Education, Taiwan. And thanks to the technical services provided by the i-MANI center of National Core Facility for Biopharmaceuticals, Instrument Development Center, Ministry of Science and Technology, Taiwan