The in vivo translocation of nanoemulsions (NEs) was tracked by imaging tools with an emphasis on the size effect. To guarantee the accurate identification of NEs in vivo, water-quenching environment-responsive near-infrared fluorescent probes were used to label NEs. Imaging evidence confirmed prominent digestion in the gastrointestinal tract and oral absorption of integral NEs that survive digestion by enteric epithelia in a size-dependent way. In general, reducing particle size leads to slowed in vitro lipolysis and in vivo digestion, a prolonged lifetime in the small intestine, increased enteric epithelial uptake, and enhanced transportation to various organs. Histological examination revealed a pervasive distribution of smaller NEs (80 nm) into enterocytes and basolateral tissues, whereas bigger ones (550, 1000 nm) primarily adhered to villi surfaces. Following epithelial uptake, NEs are transported through the lymphatics with a fraction of approximately 3–6%, suggesting a considerable contribution of the lymphatic pathway to overall absorption. The majority of absorbed NEs were found 1 h post administration in the livers and lungs. A similar size dependency of cellular uptake and transmonolayer transport was confirmed in Caco-2 cell lines as well. In conclusion, the size-dependent translocation of integral NEs was confirmed with an absolute bioavailability of at least 6%, envisioning potential applications in oral delivery of labile entities.Keywords: drug delivery; environment-responsive; in vivo fate; nanoemulsions; nanoparticles; oral; particle size;

•A one-pot synthesis of unsymmetrical disulfide with TCCA as oxidant was developed.•The reaction was finished within 5 min and wide group tolerance was allowed.•Ar-Ar and Ar-alkyl disulfides were synthesized in good to excellent yields.•Challenging aliphatic-aliphatic disulfides could also be obtained in good yields.We report herein a one-pot synthesis of unsymmetrical disulfides with trichloroisocyanuric acid (TCCA) as an oxidant. Under facile conditions, aromatic-aromatic disulfides and aromatic-aliphatic disulfides were synthesized in good to excellent yields even without base. For the construction of the challenging aliphatic-aliphatic disulfides, good yields of the desired products were also obtained with slightly modified conditions. Additionally, the reactions demonstrated a wide range of substrate scope, very short reaction time (<5 min), and convenient procedures.

•Novel phthalazine compounds were developed as Hh signaling pathway inhibitors.•23b showed inhibition with an IC50 value of 0.17 nM in Gli-luciferase assay.•23a and 23b effectively inhibited medulloblastoma cells proliferation in vitro.•In vivo allograft studies of 23b also indicated encouraging results.We report herein the design and synthesis of a series of optimized phthalazine compounds as novel hedgehog signaling pathway inhibitors. The 4-methylamino-piperidine moiety of Taladegib was replaced by different four, five or six-membered azacycle or azaspirocycle building blocks. The in vitro Gli-luciferase assay results demonstrate that the scaffold hopping in this region afforded significant influences on Hh pathway inhibition. Pyrrolidin-3-amine moiety was found to be the best linker between pharmacophores phthalazine and fluorine substituted benzoyl group. Meanwhile the optimization of 1-methyl-1H-pyrazol by different aromatic rings was also investigated and the SAR was described. Many new derivatives were found to show potent Hh signaling inhibitory activity with nanomolar IC50 values. Among these compounds, compound 23b showed the highest inhibitory potency with an IC50 value of 0.17 nM, which was 35-fold more potent than the lead compound Taladegib and 23-fold more potent than the marketed drug Vismodegib. The selected compounds 23a and 23b also possess potent antitumor activities against medulloblastoma cells proliferation in vitro. In vivo efficacy of 23b in a ptch+/−p53−/− mouse medulloblastoma allograft model also indicated encouraging results.Download high-res image (166KB)Download full-size image

Whether and to what extent solid lipid nanoparticles (SLNs) can be absorbed integrally via oral delivery should be clarified because it is the basis for elucidation of absorption mechanisms. To address this topic, the in vivo fate of SLNs as well as their interaction with biomembranes is investigated using water-quenching fluorescent probes that can signal structural variations of lipid-based nanocarriers. Live imaging indicates prolonged retention of SLNs in the stomach, whereas in the intestine, SLNs can be digested quickly. No translocation of intact SLNs to other organs or tissues can be observed. The in situ perfusion study shows bioadhesion of both SLNs and simulated mixed micelles (SMMs) to intestinal mucus, but no evidence of penetration of integral nanocarriers. Both SLNs and SMMs exhibit significant cellular uptake, but fail to penetrate cell monolayers. Confocal laser scanning microscopy reveals that nanocarriers mainly concentrate on the surface of the monolayers, and no evidence of penetration of intact vehicles can be obtained. The mucous layer acts as a barrier to the penetration of both SLNs and SMMs. Both bile salt-decoration and SMM formulation help to strengthen the interaction with biomembranes. It is concluded that evidence does not support absorption of intact SLNs via oral delivery.

A novel turn-on fluorescent 8-amino BODIPY-based probe carrying a thiourea unit as the mercury ion recognition unit has been developed. Due to the cascade reaction processes, consecutive color changes reflecting the electronic absorption and emission responses were observed upon addition of increased concentrations of mercury(II) ions. The likely sensing mechanism was proposed as mercury ion-promoted cyclization and subsequent hydrolysis. The probe displayed a selective response to mercury ions over other metal ions. Additionally, experiments with living Human Hepatoma SMMC-7721 cells to visualize intracellular mercury ions in biological systems were carried out with the probe.

One of the biggest challenges in bioimaging of nanoparticles is how to identify integral particles from bulk signals of probes. Signals of free probes are always mistakenly counted into total signals of particles. In this study, in vivo fate of intravenous polymeric micelles (PMs, mPEG2.5k–PDLLA2.5k) was explored using a highly sensitive near-infrared environment-responsive fluorescent probe. This probe is able to emit fluorescence when embedded in nanocarriers but quench spontaneously and absolutely upon release into water, based on the aggregation-caused quenching effect, which means that the interference generated by free probes can be completely diminished. Analysis of blood-borne fluorescence reveals rapid clearance of PMs from blood following a tricompartmental pharmacokinetic model. Live imaging shows pervasive distribution of PMs throughout the body, and a tendency of accumulation to extremities with fluorescence density 3–5 times higher than the trunk. Ex vivo examination reveals that most PMs are found in vital organs following an order of lung > liver > spleen > heart > kidney in concentration, but an order of liver > lung > spleen > heart ≈ kidney in total amount. The distribution to other organs and tissues is even lower, and to brain, negligible. It is concluded that the biodistribution of PMs to vital organs and extremities warns of potential toxicity and can be translated to explain the toxicity of its commercial counterpart with similar chain lengths.Keywords: biodistribution; bioimaging; environment-responsive; fluorescent probes; long-circulating; PEG−PLA; polymeric micelles; stealth;

•A novel turn-on red fluorescent BODIPY-based probe for the detection of GSH was developed.•The probe carries a para-dinitrophenoxy benzyl pyridinium moiety at the meso position of a BODIPY dye as self-immolative linker.•The probe displayed sensitivity and selectivity for GSH.•The probe have been used to detect mitochondrial GSH in living cells.A novel turn-on red fluorescent BODIPY-based probe (Probe 1) for the detection of glutathione was developed. Such a probe carries a para-dinitrophenoxy benzyl pyridinium moiety at the meso position of a BODIPY dye as self-immolative linker. Probe 1 responds selectively to glutathione with the detection limit of 109 nM over other amino acids, common metal ions, reactive oxygen species, reactive nitrogen species, and reactive sulfur species. A novel electrostatic interaction to modulate the SNAr attack of glutathione was believed to play significant role for the observed selective response to glutathione. The cleavage of dinitrophenyl ether by glutathione leads to the production of para-hydroxybenzyl moiety which is able to self-immolate through an intramolecular 1,4-elimination reaction to release the fluorescent BODIPY dye. The low toxic probe has been successfully used to detect mitochondrial glutathione in living cells.A novel turn-on red fluorescent BODIPY-based probe (Probe 1) for the detection of GSH wes developed. Such a probe carrys a para-dinitrophenoxy benzyl pyridinium moiety at meso position as self-immolative linker. A novel electrostatic interaction to modulate the SNAr attack of GSH was believed to play significant role for the observed selective response to GSH. Such a probe is low toxic and has been successfully used to detect mitochondrial GSH in living cells.

We report herein the design and synthesis of a series of novel benzylphthalazine derivatives as hedgehog signaling pathway inhibitors. Gli-luciferase assay demonstrated that changing piperazine ring of Anta XV to different four, five or six-membered heterocyclic building blocks afforded significant influences on Hh pathway inhibition. In particular, compound 10e with piperidin-4-amine moiety was found to possess 12-fold higher Hh inhibitory activities comparing to the lead compound in vitro. In vivo efficacy of 10e in a ptch+/−p53−/− mouse medulloblastoma allograft model also indicated encouraging results.A series of novel benzylphthalazine derivatives were prepared and their in vitro hedgehog signaling pathway inhibitory activities as well as in vivo antitumor potency were reported.

The co-existence and similar properties of amino acids make the detection of individual amino acids challenging. Herein we discovered that probe 1 may act as a smart example to classify and differentiate basic amino acids (Arg/Lys/His), thiol-containing amino acids (Cys/HCy), and GSH through different sensing mechanisms in selected environments.

A new selective fluorescent and colorimetric chemosensor for the detection of GSH was developed. The discrimination of GSH from Cys and Hcy is achieved through two emission channel detection. The detection limit of probe 1 for GSH reached 10 nM (3 ppb). The excellent sensitivity and selectivity of probe 1 allow the selective detection of GSH over Cys and Hcy, which can be visualized colorimetrically and/or fluorescently. The sensitive detection of GSH allowed for convenient measurement of the GSH content in human plasma. The presence of GSH in cells was demonstrated through cell imaging.

A highly selective and sensitive turn-on red fluorescent 1-amino BODIPY-based probe (where BODIPY denotes indole-based boron-dipyrromethene) with high off-to-on contrast ratio has been developed. The probe displayed selective response to thiophenols over aliphatic thiols. Probe 1 is promising for the quantitative detection of thiophenol with a linear response from 6 × 10–6 M to 1 × 10–4 M, and the detection limit for thiophenol (PhSH) reaches 4 × 10–6 M measured in acetonitrile/PBS buffer. The detection limit could be improved to 37 nM (detection limit to 4 ppb) in water when 1% Tween 20 was used to assist the dissolvation of probe 1 in water. Probe 1 is also a useful fluorescent probe for detecting thiophenols in living cells in red emission, which may greatly improve the detectable sensitivity.

A series of compounds with quinazoline scaffold were designed, synthesized and evaluated as novel potent 5-HT2A receptor ligands. N-(4-Chlorophenyl)-2-(piperazin-1-yl)quinazolin-4-amine (5o) has a Ki value of 14.04 ± 0.21 nM, with a selectivity more than 10,000 fold over 5-HT1A receptors (D1 and D2-like receptors). The functional assay showed that this compound is an antagonist to 5-HT2A receptor with an IC50 value of 1.66 μM.

Novel bis[3H]-naphtho[2,1-b]pyrans 1a–1g and bis[2H]-naphtho[1,2-b]pyrans 2a–2g were prepared efficiently. Such thiophene-linked bispyrans display distinct color change under continuous UV irradiation with up to 110 nm of bathochromic shift between the finally generated colored forms and initially generated forms. They also show high colorability, as well as good fatigue-resistance.

Environment-responsive near-infrared (NIR) aza-BODIPY dyes capable of fluorescence quenching in water were explored to visualize the in vivo fate of model lipid-based nanocarriers, solid lipid nanoparticles (SLNs). The water-quenching effect of the dyes was confirmed to be sensitive and remained stable for at least 24 h. In vitro lipolysis measured by fluorescence quenching completed within 20 min, which was in correlation with alkaline compensation results. In vivo live imaging indicated predominant digestion of SLNs within 2 h and complete digestion within 4 h, which correlated well to in vitro data. Rekindling of quenched dyes by mixed micelles was observed in vitro, but not in vivo. In sharp contrast, SLNs encapsulating another NIR dye DiR showed persistent fluorescence both in vitro and in vivo despite significant lipolysis. It was envisaged that water-quenching fluorescence dyes can be used as probes to monitor the in vivo fate of lipid-based nanocarriers.From the Clinical EditorLipid-based drug delivery systems can provide an excellent nanocarrier platform for the delivery of poorly water-soluble drugs. Nonetheless, the mechanism of oral absorption and subsequent kinetics is poorly understood. In this article, the authors studied the novel use of near-infrared (NIR) aza-BODIPY dyes to visualize the fate of these lipid-based nanocarriers. The positive finding means that this approach may be useful for in-vivo monitoring of lipid-based nanocarriers.Near-infrared fluorescent dyes (P2) encapsulated in solid lipid nanoparticles (SLN) quenched spontaneously upon contact with water after being released from SLNs. This class of water-quenching dyes could accurately report the in vivo fate of lipid-based nanocarriers through live imaging, whereas the conventional non-water-quenching dyes (DiR) provided false signals.

Chronic myeloid leukemia (CML) is characterized by abnormal Bcr and Abl genes and enhanced tyrosine kinase activity. Anti-CML therapy has been much improved along with the applications of tyrosine kinase inhibitors (TKIs) which selectively target Bcr-Abl and have a cytotoxic effect on CML. Recently, four-membered heterocycles as “compact modules” have attracted much interest in drug discovery. Grafting these small four-membered heterocycles onto a molecular scaffold could probably provide compounds that retain notable activity and populate chemical space otherwise not previously accessed. Accordingly, a novel TKI, Thiotanib, has been designed and synthesized. It selectively targets Bcr-Abl, inducing growth inhibition, cell cycle arrest, and apoptosis of CML cells. Meanwhile, the compound Thiotanib could also induce autophagy in CML cells. Interestingly, inhibition of autophagy promotes Thiotanib-induced apoptosis with no further activation of caspase 3, while inhibition of caspases did not affect the cell survival of CML cells. Moreover, the compound Thiotanib could inhibit phosphorylation of Akt and mTOR, increase beclin-1 and Vps34, and block the formation of the Bcl-2 and Beclin-1 complex. This indicates the probable pathway of autophagy initiation. Our results highlight a new approach for TKI reforming and further provide an indication of the efficacy enhancement of TKIs in combination with autophagy inhibitors.

A domino synthesis of 5,12-dihydroindolo[2,1-b]quinazoline derivatives via copper-catalyzed Ullmann-type intermolecular C–C and intramolecular C–N couplings is reported. Good yields of various 5,12-dihydroindolo[2,1-b]quinazoline derivatives were obtained. Reaction scopes, limitations, and the reaction mechanism are discussed.

A new selective fluorescent and colorimetric chemosensor for the detection of GSH was developed. The discrimination of GSH from Cys and Hcy is achieved through two emission channel detection. The detection limit of probe 1 for GSH reached 10 nM (3 ppb). The excellent sensitivity and selectivity of probe 1 allow the selective detection of GSH over Cys and Hcy, which can be visualized colorimetrically and/or fluorescently. The sensitive detection of GSH allowed for convenient measurement of the GSH content in human plasma. The presence of GSH in cells was demonstrated through cell imaging.

The co-existence and similar properties of amino acids make the detection of individual amino acids challenging. Herein we discovered that probe 1 may act as a smart example to classify and differentiate basic amino acids (Arg/Lys/His), thiol-containing amino acids (Cys/HCy), and GSH through different sensing mechanisms in selected environments.