Fluorescent Carbon Dot–Curcumin Nanocomposites for Remarkable Antibacterial Activity with Synergistic Photodynamic and Photothermal Abilities

Abstract

Photosensitizer (PS)-mediated photodynamic therapy (PDT) has attracted more and more attention as an alternative to traditional antibiotic therapy. Nevertheless, the limitations of traditional photosensitizers seriously hinder their practical application, as a result, the methods to improve the antibacterial properties of traditional photosensitizers have become a hot topic in the field of photomedicine. Herein, a compound nano-PS system has been constructed with synergistic photodynamic and photothermal (PTT) antibacterial effects, triggered by a dual-wavelength illumination. Fluorescent carbon dots (CDs) were synthesized and employed as carriers for the delivery of curcumin (Cur) to obtain CDs/Cur. Upon combined near-infrared and 405 nm visible dual-wavelength irradiation, CDs/Cur could simultaneously generate ROS and a moderate temperature increase, triggering synergistic antibacterial effects against both Gram-positive and Gram-negative bacteria. The results of scanning electron microscopy and fluorescence confocal imaging showed that the combined effect of CDs/Cur with PDT and PTT caused more serious damage to the cell membrane. In addition, CDs/Cur exhibited low cytotoxicity and negligible hemolytic activity, showing great biocompatibility. Therefore, the construction of CDs/Cur by employing CDs as photosensitizer delivery carriers provides a strategy for the improvement of the antibacterial effect of the photosensitizer and the design of next-generation antibacterial agents in photomedicine.

Carbon Dots as Drug Delivery Vehicles for Antimicrobial Applications: A Minireview

“…This research develops a GQD nanovehicle as a suitable alternative to antibiotics for enhanced treatment of bacterial infections in deeply situated organs or blood. In another study of Yan et al., the authors developed a CD–PS nanocomposite for synergistic PDT and photothermal therapy (PTT) against bacteria [24b] . The fluorescent nitrogen‐ and sulphur‐doped CDs were first prepared by one‐step hydrothermal treatment of thiourea and citric acid, and were then combined with curcumin (Cur) under stirring.…”

Orange-red to NIR emissive carbon dots for antimicrobial, bioimaging and bacteria diagnosis

“…As a result, fluorescent CQDs with green fluorescence have recently been synthesized by our group and employed as carriers for the delivery of Cur to obtain composites using a two-step method, which could simultaneously generate ROS and a moderate temperature rise, triggering synergistic antibacterial effects against both Gram-positive and Gram-negative bacteria. 50 In this study, we prepared Cur-NRCQDs with orange-red to NIR fluorescence from citric acid (CA), neutral red (NR) and Cur, using a onestep hydrothermal synthesis method to simplify the preparation procedures. Compared with Cur-CDs with green fluorescence emission, the red fluorescence of Cur-NRCQDs made them more suitable for the detection of bacteria and cells, as the blue, green or yellow CQDs are harmful to biological systems or living cells due to their short wavelength excitation.…”

Preparation and photodynamic antibacterial/anticancer effects of ultralong-lifetime room-temperature phosphorescent N-doped carbon dots

“…As novel photoluminescent nanomaterials, carbon dots (CDs) feature simple preparation, low cost, low toxicity and high biocompatibility, and are extensively applied in photoelectric devices, 15,16 sensors, 17,18 catalysis, 19,20 bacterial therapy, 21,22 and forgery prevention. 23,24 Specically, N-doped carbon dot (CND) RTP nanomaterials have higher T 1 quantum yield, and more easily convert the ground state triplet O 2 to 1 O 2 , and CNDs have the characteristics of low cost and high biocompatibility.…”