Manganese‐doped green tea‐derived carbon quantum dots as a targeted dual imaging and photodynamic therapy platform

Abstract

In this work, manganese‐doped carbon quantum dots (Mn‐CQDs) have been synthesized through a one‐pot hydrothermal method by using waste green tea. The Mn2+ dopants were introduced to impart magnetic resonance capability. Upon optimization of the experimental conditions, magnetofluorescent Mn‐CQDs exhibit an excitation‐dependent blue emission. The abundant functional groups on Mn‐CQDs not only promote water solubility but also allow straightforward functionalization with amine groups. The amine‐terminated Mn‐CQDs were then subsequently conjugated to folic acid (FA) and chlorin e6 (Ce6) to obtain the Mn‐CQDs@FA/Ce6 magnetofluorescent photodynamic therapy (PDT) agent. in vitro studies using three different cells indicated specific targeting of Mn‐CQDs@FA/Ce6 to the overexpressing folate receptor human epithelial carcinoma cell line (HeLa) cancer cells. Furthermore, Mn‐CQDs@FA/Ce6 enhanced magnetic resonance imaging (MRI) signal with an r2/r1 ratio of 5.77. Favorably, by using the Mn‐CQDs@FA delivery system, active Ce6 can reach the cellular interior while its red fluorescence (FL) and reactive oxygen species generation can be retained, as has been verified by confocal microscopy. in vitro cell viability studies verified the biocompatibility of Mn‐CQDs@FA/Ce6 nanohybrid with no significant toxicity up to 500 ppm while PDT treatment with 5 min irradiation (671 nm, 1 W cm−2) was effective in killing >90% of cells. The light‐triggered Mn‐CQDs@FA/Ce6 multifunctional hybrid can serve as a dual‐modal FL/MRI probe and as an efficient PDT agent to detect and eradicate cancer cells remotely.

Multifunctional MnCuInSe/ZnS quantum dots for bioimaging and photodynamic therapy

“…Additionally, HR-TEM examination in Figure 1(c) revealed highly crystalline structure of MnCuInSe showing a distance of 0.31 nm between adjacent lattice fringes associated to the (100) plane. 23 EDS results in Figure 1(d) indicate the presence of Cu, In, Se, and Mn. The presence of low Mn concentration confirms the successful co-doping of Mn species.…”

“…19,20 This method has brought forward facile synthesis of these biocompatible QDs at a shorter time and a lower cost, also allowing for straightforward doping as a way to enhance the optical and electrochemical properties of the QDs. 21–23 A variety of transition metal dopants have already been investigated to enhance the quality and functions of QDs in biological labeling applications, light-emitting devices, optoelectronics, and solar energy harvesting. 24–26 Doping transition metal ions into QDs would create electronic states in the mid-gap region of the QDs and thus change the charge separation and recombination process.…”

Recent advances of biomass carbon dots on syntheses, characterization, luminescence mechanism, and sensing applications

“…Using potato starch [ 21 ] as carbon source, CQDs with abundant oxygen groups were synthesized by ultrasonic method, the particle size and QY were 3–5 nm and 10%, respectively. At the same time, green tea, [ 22 ] ocimum tenuiflorum, [ 23 ] and cyanobacteria, [ 24 ] etc. were also used as carbon source to synthesize carbon dots.…”

“…Among them, the QY of CQDs prepared with pennisetum glaucum was the highest (up to 33%), and that of CQDs from wheat was the lowest (reach to 16%), indicating that the carbon source is a crucial factor affecting the QY under the same treatment conditions. At present, many biomass carbon dots can emit different single color fluorescence, blue fluorescence of carbon dots can be seen by the naked eye, which were prepared from waste tea leaves and peanut shells, [ 127 ] silk fibroin, [ 41 ] crab shell, [ 12 ] anthracite coal, [ 55 ] green fluorescence of that from petroleum asphalt, [ 65,128 ] yellow fluorescence of that from coal, [ 17 ] red fluorescence of that from green tea, [ 22 ] orange fluorescence of that from durian, [ 129 ] and so on.…”

Green Approaches to Carbon Nanostructure-Based Biomaterials

“…Graphene quantum dots (GQDs), which consist of nano-sized graphene monolayers that exhibit quantum confinement, can be produced in a variety of methods, of which the most popular are pyrolysis [69,70] and hydrothermal [57][58][59][60][61]63,64] routes. Other methods that could be carried out at lower temperatures have attracted attention, especially using microwaves [67,68,106], but also ultrasound-assisted approaches [72].…”