Helpful elements: A facile bottom-up method using citric acid and L-cysteine as a precursor has been developed to prepare graphene quantum dots (GQDs) co-doped with nitrogen and sulfur. A new type and high density of surface state of GQDs arises, leading to high yields (more than 70 %) and excitation-independent emission. FLQY = fluorescence quantum yield.

No abstract

No abstract

Quantum dots (QDs) are nanoparticles with size-dependent optical and electronic properties that have been proposed for various applications, such as energy-efficient displays and lighting, photovoltaic devices, and biological markers. [1][2][3][4][5][6] Compared with other fluorescent (FL) materials (conventional dyes, polymers, or propeins), QDs offer many promising advantages, such as bright fluorescence, high photostability, and resistance to metabolic degradation in bioapplications. [7][8][9] However, most high-performance QDs are limited by toxicity from their metal elements, such as cadmium. [10,11] Extensive efforts have thus been made on the development of non-or low-toxic FL nanomaterials as alternatives to the semiconductor-based QDs. Carbon-based dots (CDs), including carbon nanoparticles of less than 10 nm in size, [12] which are known as carbon quantum dots (CQDs) and graphene nanosheets of less than 100 nm in size, [13] which are known as graphene quantum dots (GQDs), are particularly encouraging owing to their outstanding optical properties, low toxicity, good biocompatibility, and robust chemical inertness. [6,12] Various methods have been demonstrated in preparation of FL CDs, such as electrochemical oxidation processes, [14,15] chemical oxidation methods, [6,12,[16][17][18] hydrothermal cutting strategies, [19,20] and carbonizing organics routes. [21][22][23][24] Nevertheless, most of the developed methods are unsatisfactory owing to expensive equipment required, low yields, or complicated procedures. In particular, most obtained CDs have a relatively low FL quantum yield (FLQY, usually less than 50 %) in comparison to the conventional semiconductor QDs. Most recently, doped CDs were proposed for highly FL dots. [25][26][27] For example, ZnS-doped CDs with the passivation of oligomeric poly(ethylenelycol) diamine (PEG1500N) molecules show a 78 % FLQY after a gel column fractionation. [26] However, the preparation of highly FL ZnS-doped CDs is complicated. Moreover, the poor chemical inertness of the ZnS would be a severe limitation to broad applications of the CDs. Thus, there is a great need to develop a facile, low-cost, and high-yield method for the preparation of CDs with strong FL emission. Herein, citric acid (CA) and l-cysteine were used to produce nitrogen and sulfur co-doped CDs (N,S-CDs) through a one-step hydrothermal treatment. The CA serves as the carbon source, while the l-cysteine provides nitrogen and sulfur. Compared with other reported CDs, the as-prepared N,S-CDs exhibit very high FLQY (73 %) and excitationindependent emission, resulting from the synergy effect of the doped nitrogen and sulfur atoms.The obtained N,S-CD solution exhibits a long-term homogeneous phase without any noticeable precipitation at room temperature. The transmission electron microscopy (TEM) image (Figure 1 a,g) shows that the size of the asprepared N,S-CDs is distributed in the range from 5 to 9 nm, with an average size of 7 nm. High-resolution TEM (HRTEM) images (Figure 1 b) reveal the high crystallin...

No abstract

Nanotechnology has been extensively explored for drug delivery. Here, we introduce the concept of a nanodrug based on synergy of photothermally-activated physical and biological effects in nanoparticle-drug conjugates. To prove this concept, we utilized tumor necrosis factor-alpha coated gold nanospheres (Au-TNF) heated by laser pulses. To enhance photothermal efficiency in near-infrared window of tissue transparency we explored slightly ellipsoidal nanoparticles, its clustering, and laser-induced nonlinear dynamic phenomena leading to amplification and spectral sharpening of photothermal and photoacoustic resonances red-shifted relatively to linear plasmonic resonances. Using a murine carcinoma model, we demonstrated higher therapy efficacy of Au-TNF conjugates compared to laser and Au-TNF alone or laser with TNF-free gold nanospheres. The photothermal activation of low toxicity Au-TNF conjugates, which are in phase II trials in humans, with a laser approved for medical applications opens new avenues in the development of clinically relevant nanodrugs with synergistic antitumor theranostic action.

No abstract

Mifepristone (RU486) is a born-for-woman molecule discovered three decades ago. Unlike those antihypertensive and antipsychotic pharmaceutical blockbusters, this abortifacient offers relatively low profit potential. Current understanding of mechanism of action of mifepristone and its on-going clinical trials are changing our views on the drug beyond its abortifacient scope. Here we briefly review its metabolism and pharmacokinetic properties including its unique enterohepatic circulation, its mechanisms of actions involving antiprogesterone and antiglucocorticoid, growth inhibition of various cancer cell lines, suppression of invasive and metastatic cancer potential, downregulation of Cdk2, Bcl-2, and NF-kappa B, interference of heterotypic cell adhesion to basement membrane, and cell migration. We comprehensively analyze recent results from preclinical and clinical studies using mifepristone as an anticancer drug for breast, meningioma, and gliomas tumors in the central nervous system, prostate cancer, ovarian and endometrial cancer, and gastric adenocarcinoma. Although mifepristone has more benefits for global public health than we originally thought, its effect as a postmetastatic chemotherapeutic agent is limited. Nonetheless, owing to its unique safe, metabolism and other pharmacological properties, metapristone (the primary metabolite of mifepristone) may have potential for cancer metastatic chemoprevention.