Capsicum-Derived Biomass Quantum Dots Coupled with Alizarin Red S as an Inner-Filter-Mediated Illuminant Nanosystem for Imaging of Intracellular Calcium Ions.

Calcium ion (Ca2+) plays crucial roles in the signal transduction pathways associated with various physiological and pathological events. Monitoring intracellular Ca2+ is of great significance for cell biology research. Here, we report the use of biomass quantum dots (BQDs) as a fluorescent reporter for imaging of intracellular Ca2+, based on the inner-filter-mediated luminescence which was assisted by a Ca2+ chelator alizarin red S (ARS). BQDs were prepared by hydrothermal heating of capsicum. The absorption of ARS overlaps with the excitation of the BQDs, the fluorescence of BQDs being quenched through the inner-filter effect. But the absorption of Ca-ARS complex red shifts and shows a poor inner-filter effect. Thus, Ca2+ can be detected by the inner-filter-mediated luminescence using the BQDs-ARS nanohybrid system. Using the proposed nanosystem, the imaging of intracellular Ca2+ and real-time monitoring of the Ca2+ level change under histamine stimulation were also achieved. Thus, this nanosystem holds potential applications in other Ca2+-related signal transduction study.

Photo-metallo-immunotherapy: Fabricating Chromium-Based Nanocomposites to Enhance CAR-T Cell Infiltration and Cytotoxicity against Solid Tumors.

The infiltration and cytotoxicity of chimeric antigen receptor (CAR)-T cells are crucial for effective elimination of solid tumors. While metallo-immunotherapy is a promising strategy that can activate the antitumor immunity, its role in promoting CAR-T cell therapy remains elusive. The first single-element nanomaterial based on chromium nanoparticles (Cr NPs) for cancer photo-metallo-immunotherapy has been reported previously. Herein, an extended study using biodegradable polydopamine as a versatile carrier for these nanoparticles, enabling synergistic CAR-T cell therapy, is reported. The results show that these nanocomposites with or without further encapsulation of the anticancer drug alpelisib can promote the CAR-T cell migration and antitumor effect. Upon irradiation with near-infrared light, they caused mild hyperthermia that can "warm" the "cold" tumor microenvironment (TME). The administration of B7-H3 CAR-T cells to NOD severe combined immunodeficiency gamma mice bearing a human hepatoma or PIK3CA-mutated breast tumor can significantly inhibit the tumor growth after the induction of tumor hyperthermia by the nanocomposites and promote the secretion of serum cytokines, including IL-2, IFN-γ, and TNF-α. The trivalent Cr3+ ions, which are the major degradation product of these nanocomposites, can increase the CXCL13 and CCL3 chemokine expressions to generate tertiary lymphoid structures (TLSs) in the tumor tissues, facilitating the CAR-T cell infiltration.

Self-assembled nanomaterials for synergistic antitumour therapy.

Self-assembly is a bottom-up strategy that can be used to construct a wide range of nanostructures. This review discusses the applications of self-assembled nanomaterials in the field of antitumour therapy. A variety of materials have been developed, such as nanomaterials self-assembled from polymers, biomacromolecules, proteins, peptides, inorganic materials, nucleic acids, and organic molecules, among others, and their applications include phototherapy, chemotherapy, gene therapy, imaging, immunotherapy and other fields. These therapeutic methods can combine with each other as synergistic therapy. Here, we review the progress of self-assembled anticancer nanomaterials applied to target tumours, decrease drug resistance, cross the blood-brain barrier to treat metastases, and perform other tasks. Additional challenges to be overcome in this field are also discussed.

Dual functionalized natural biomass carbon dots from lychee exocarp for cancer cell targetable near-infrared fluorescence imaging and photodynamic therapy.

Photodynamic therapy (PDT) is a non-invasive phototherapy that has gained significant attention for cancer therapy. However, image-guided PDT still remains a considerable challenge. Herein, we developed a targeted, near-infrared (NIR) fluorescence imaging nanoprobe for cancer cells by preparing natural biomass carbon dots (NBCDs) from lychee exocarp, and loading transferrin and a photosensitizer on the NBCD surfaces for image-guided PDT of cancer cells and mouse tumors. Because the surfaces of cancer cells exhibit more transferrin receptors, the proposed NIR fluorescent nanoprobe can better penetrate cancer cells for cancer cell targetable fluorescence imaging. Thus, the dual-function nanoprobe made from natural biomass can be used as a specific agent for NIR fluorescence imaging and PDT. More importantly, the functional nanoprobe prepared from natural biomass emits NIR fluorescence, shows very low biological toxicity, and can minimize side effects on normal cells. After directly injecting the nanoprobes into tumor tissues, the photosensitizers on the surface of the NBCDs can produce singlet oxygen (1O2) through photodynamic reactions when irradiated with 650 nm light to kill cancer cells, thus inhibiting tumor growth in PDT-treated mice. Therefore, the functional fluorescent nanoprobe made from natural biomass has been employed as a PDT agent, and holds great promise in image-guided tumor PDT.

Fluorescent carbon dots with tunable emission by dopamine for sensing of intracellular pH, elementary arithmetic operations and a living cell imaging based INHIBIT logic gate.

Fluorescent carbon dots (C-dots) have drawn great attention in recent years, and many researchers have focused on developing preparation routes and broadening the applications of C-dots. In this work, novel luminescent C-dots with tunable emission were prepared by the pyrolysis of citric acid (CA) and dopamine (DA). By adjusting the molar ratio of CA and DA in the precursor from 2 : 1 to 2 : 3, the maximum fluorescence emission of the obtained C-dots is at 510 nm in acid solution, while it shifts to 450 nm under neutral conditions, and the fluorescence is quenched in a basic solution. By controlling the unique fluorescence emission at different pH values, a three-state switch is achieved. Half-addition and half-subtraction were performed at 525 nm and 450 nm emissions as outputs. And a living cell imaging based INHIBIT logic gate operation was achieved by imaging the channel ratio of the cells.

One-pot green synthesis of oxygen-rich nitrogen-doped graphene quantum dots and their potential application in pH-sensitive photoluminescence and detection of mercury(II) ions.

Nitrogen doping has been a powerful method to modulate the properties of carbon materials for various applications, and N-doped graphene quantum dots (GQDs) have gained remarkable interest because of their unique chemical, electronic, and optical properties. Herein, we introduce a facile one-pot solid-phase synthesis strategy for N-doped GQDs using citric acid (CA) as the carbon source and 3,4-dihydroxy-L-phenylalanine (L-DOPA) as the N source. The as-prepared N-GQDs with oxygen-rich functional groups are uniform with an average diameter of 12.5 nm. Because of the introduction of nitrogen atoms, N-GQDs exhibit excitation-wavelength-independent fluorescence with the maximum emission at 445 nm, and a high quantum yield of 18% is achieved at an excitation wavelength of 346 nm. Furthermore, a highly efficient fluorosensor based on the as-prepared N-GQDs was developed for the detection of Hg(2+) because of the effective quenching effect of metal ions via nonradiative electron transfer. This fluorosensor exhibits high sensitivity toward Hg(2+) with a detection limit of 8.6 nM. The selectivity experiments reveal that the fluorescent sensor is specific for Hg(2+). Most importantly, the practical use of the sensor based on N-GQDs for Hg(2+) detection was successfully demonstrated in river-water samples.