It is well known that the calcium ion is essential for maintaining life activities in living organisms, and it is of great significance to detect the intracellular calcium concentration. For the detection of calcium ions, we developed a new type of fluorescent carbon dots (CDs), whose surface was modified by ethylenebis­(oxyethylenenitrilo)­tetraacetic acid (EGTA) through a secondary hydrothermal method. This is a simple and convenient chemical preparation method because all reactions are carried out in the same autoclave, and the final product is directly the EGTA-modified CDs. The CDs exhibit bright blue fluorescence, and as the calcium concentration increases, the fluorescence intensity drops sharply. The fluorescence quenching correlates with the concentration of calcium ions and has a good linearity in the range of 15–300 μM with a detection limit of 0.38 μM. The experimental results confirmed that the detection of calcium ions by CDs is a static fluorescence quenching process. Also, cytotoxicity test and cellular imaging experiments have shown that the CDs are nontoxic and biocompatible.

It is well-known that the ratio of reduced L-glutathione (GSH) to oxidized L-glutathione (GSSG) is a vital biomarker for monitoring overall cellular health, thus detecting the intracellular concentration of glutathione is of great significance. Recently, an increasing number of reports have published various methods for GSH detection, but studies on the detection of GSSG are still rare. Here, we report a kind of new yellow fluorescent carbon dots (CDs) for the detection of GSSG through a fluorescence "off-on" process. Because the surface is rich in amino groups, the CDs show a positive potential. When the concentration of GSSG was continuously increased, the CDs' fluorescence dropped sharply, while the fluorescence gradually recovered after the addition of sodium sulfide. The phenomenon of fluorescence quenching is linear with the concentration of the quencher (GSSG)(0−200 μM), and 0.18 μM is calculated as the detection limit. More interestingly, as a fluorescent probe, the CDs can be further used for fluorescence imaging in living cells and zebrafish.

Although sulfate- and sulfonate-based electrolytes have been widely used in the study on aqueous zinc-ion batteries (AZIBs), the discrepancies in the Faradaic reaction kinetics of cations interfacial chemistry including Mn2+...

Immunomagnetic beads are important tools for the isolation and detection of circulating tumor cells (CTCs).

Schematic diagram for the detection of ferric ions and hematin by Fe,N-CDs.

We described biodegrade mesoporous silica nanoparticles coating cancer cell membrane for berberine therapy of liver cancer.

Hydrogel has been widely used in modern biotherapeutics due to its excellent biocompatibility, degradability, and high drug loading capacity. Among them, the construction of a phototherapy system including photosensitizer and hydrogel has aroused great interest in tumor therapy. Unfortunately, complex modifications are necessary to integrate different photosensitizers into the hydrogel. In this work, an injectable hydrogel was proposed by the Schiff base reaction between HA-CHO and carbon dots (CDs), which can realize PTT and PTT simultaneously. Notably, the CDs with rich −NH 2 can be used not only as a photosensitizer but also as an efficient crosslinking agent for the Schiff base reaction to form a hydrogel network. The CD@ Hydrogel with outstanding biosafety showed a high antitumor effect after 660 nm laser irradiation in in vitro and in vivo experiments. In summary, the CD@ Hydrogel can not only realize PTT and PDT synergistic treatment under one light source but also act as a cross-linking agent to react with HA-CHO to form hydrogel, which is simple and efficient, providing a new strategy for cancer phototherapy.

Calcium ion (Ca) plays a critical and indispensable role in many physiological and biochemical processes in the human body. In this report, we demonstrate a novel electrochemical method for the determination of the Ca level aided by three functional DNA probes and gold nanoparticles (AuNPs). It affords high selectivity in sensing Ca over other metal cations, which is due to the adoption of the DNAzyme at the electrode interface with exceptionally high binding ability. This method also integrates recycling formation of DNAzyme and AuNPs-mediated amplification; thus, high sensitivity is promised. Therefore, this work provides a favorable way to probe Ca for biomedical applications.