Orange-Emissive Carbon Dots with High Photostability for Mitochondrial Dynamics Tracking in Living Cells

Abstract

Mitochondria play significant roles in maintaining a stable internal environment for cell metabolism. Hence, real-time monitoring of the dynamics of mitochondria is essential for further understanding mitochondria-related diseases. Fluorescent probes provide powerful tools for visualizing dynamic processes. However, most mitochondria-targeted probes are derived from organic molecules with poor photostability, making long-term dynamic monitoring challenging. Herein, we design a novel mitochondria-targeted probe based on carbon dots with high performance for long-term tracking. Considering that the targeting ability of CDs is related to surface functional groups, which are generally determined by the reaction precursors, we successfully constructed mitochondria-targeted O-CDs with emission at 565 nm through solvothermal treatment of m-diethylaminophenol. The O-CDs are bright with a high quantum yield of 12.61%, high mitochondria-targeting ability, and good stability. The O-CDs possess a high quantum yield (12.61%), specific mitochondria-targeting ability, and outstanding optical stability. Owing to the abundant hydroxyl and ammonium cations on the surface, O-CDs showed obvious accumulation in mitochondria with a high colocalization coefficient of up to 0.90 and remained steady even after fixation. Besides, O-CDs showed outstanding compatibility and photostability under various interruptions or long-time irradiation. Therefore, O-CDs are preferable for the long-term tracking of dynamic mitochondrial behavior in live cells. We first observed the mitochondrial fission and fusion behaviors in HeLa cells, and then, the size, morphology, and distribution of mitochondria in physiological or pathological conditions were clearly recorded. More importantly, we observed different dynamics interactions between mitochondria and lipid droplets during the apoptosis and mitophagy processes. This study provides a potential tool for exploring interactions between mitochondria and other organelles, further promoting the research on mitochondria-related diseases.

Multi-Color-Emissive Magneto-Luminescent Nanoarchitectures for Targeted Identification of Heterogeneous Exosomes Associated with Lung Cancer Metastasis

“…From SEM reported in Figure B and DLS data reported in Table S4, we found out the size of AREG (+), TNC (+), and PDL-1 (+) exosomes varies in the range of 160 ± 40 nm and zeta potential in the range of −30.0 ± 4.8 mV. We have also used the human TNC enzyme-linked immunoassay (ELISA) Kit, AREG ELISA Kit, and PDL-1 ELISA Kit for quantitation of the amount of captured TNC (+)-, AREG (+)-, and PDL-1 (+)-positive exosomes. − As reported in Figure C, ELISA data show that the separated exosomes are only TNC (+) exosomes when HCC827 lung cancer cells are used. As reported in Figures S12 and S13 in the Supporting Information, ELISA data show that the separated exosomes are only AREG (+) exosomes when lung cancer A549 cells are used and separated exosomes are only PDL (+) exosomes when lung cancer H460 cells are used.…”

“…After that, we kept the mixture for half an hour and the multi-color-emissive magnetic nanoarchitecture-attached AREG (+), TNC (+), and PDL-1 (+) exosomes were separated using a bar magnet. Next, we used a human TNC ELISA Kit, an AREG ELISA Kit, and a PDL-1 ELISA Kit for quantitation of the amount of captured TNC (+)-, AREG (+)-, and PDL-1 (+)-positive exosomes from whole blood samples. − We have also performed single photon fluorescence imaging for finding the selectivity.…”

“…Due to the differences in the expressed surface receptors, NSCLC exosomes are highly heterogeneous, which is a huge obstacle for the use of exosomes as “liquid biopsy” biomarkers in clinical settings. − To address the above problem, in the current paper, we have reported the design of a specific antibody-conjugated multi-color (orange, yellow and green)-emissive carbon dot (CD)-attached cobalt spinel ferrite (CoFe 2 O 4 )-based magneto-luminescent nanoarchitecture for targeted capture and identification of TNC (+), AREG (+), and PDL-1­(+) exosomes selectively and simultaneously from whole blood samples. CDs designed from abundant carbon-based materials are proving to be better bio-imaging materials due to the photostability, biocompatibility, and ease to produce bulk amounts. − …”

“…For the identification of AREG-, TNC-, and PDL-1-expressing exosomes, we have designed biocompatible phenylenediamine precursor-based CDs which emit green, yellow, and orange color photoluminescence when they are excited by a single wavelength. ,,,− For this purpose, we have used nitrogen (N), sulfur (S), and oxygen (O) dopant-based CDs, which allow emission spectral shift from a green to an orange wavelength. ,,,− Since a blood or urine sample contains different types of exosomes, other vesicles, and different biologically important molecules such as DNA/RNA, selective capturing of targeted exosomes is the minimum requirement to separate cancer-derived exosomes from biological fluids before we can identify those exosomes’ wavelength. − As a result, to capture and identify the targeted TNC (+) exosome from an infected whole blood sample, an anti-TNC antibody-attached yellow color-emissive carbon dot (YECD)-conjugated CoFe 2 O 4 magnetic nanoparticle (MNP)-based magnetic-yellow luminescent nanoarchitecture has been developed, which has the capability to capture the targeted TNC (+) exosome from the infected whole blood sample. Similarly, a green color-emissive carbon dot (GECD)- and anti-AREG antibody-attached magnetic-green luminescent nanoarchitecture has been developed, which has the capability to capture the targeted AREG (+) exosome from the cell culture as well as from the infected whole blood sample.…”

“Three-in-one” platform based on Fe-CDs nanozyme for dual-mode/dual-target detection and NIR-assisted bacterial killing

“…20–22 However, most carbon-based nanozymes, such as carbon nanotubes (CNTs) and graphene oxide (GO), are toxic to healthy cells and likely to lead to apoptosis. Carbon dots (CDs), which are famous for their good biocompatibility, 23–25 have become “hotspots” in the area of nanozymes because of their ultrasmall size, prominent optical characteristics and considerable catalytic performance. In particular, their high surface area endows them with more active sites and functional groups for further surface modifications.…”