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Objectives Tonkinensine B, a novel compound with cytisine–pterocarpan skeleton isolated from the root of Sophora tonkinensis Gagnep, was reported to have a significant antitumor effect. The effect and intrinsic mechanism of tonkinensine B on tumour need to be further investigated. Methods With the help of cell cytotoxicity, the effect of tonkinensine B on MDA-MB-231 cells was investigated. By observing mitochondrial function changes, the intrinsic mechanism was further studied. The levels of key apoptosis-associated proteins Bcl-2, Bax, caspase-9, caspase-3 and AKT in MDA-MB-231 cells were analysed to determine whether tonkinensine B caused apoptosis via the mitochondrial pathway. Key findings After treated with tonkinensine B, MDA-MB-231 cells multiplication was repressed, and the decreased mitochondrial membrane potential, loss of ATP synthesis and elevated ROS generation were detected. Furthermore, the proportions of Bax/Bcl-2, cleaved caspase-3 and caspase-9 proteins production were up-regulated, indicating that tonkinensine B acted on intrinsic mitochondrial-mediated apoptosis pathway. In addition, tonkinensine B also reduced phosphorylation levels of AKT, and thus the activation of apoptosis might likewise be correlated with the inhibition of the PI3K/AKT pathway. Conclusions Tonkinensine B may be a hopeful candidate for human triple-negative breast cancer, and further structural optimization is expected to improve its anti-tumour activity.

A series of novel artemisinin-piperazine-phosphoramide mustard (PPM) hybrids were designed and synthesized by incorporating phosphoramide mustard (PM) into dihydroartemisinin (DHA) via an efficient, catalyst-free two-step sequential substitution. Artemisinin-PPM hybrids showed better cytotoxic potency against HepG2 cells than both the parent DHA and the reference, vincristine (VCR). Structure-activity relationship (SAR) studies showed that the cytotoxicity was significantly enhanced by the introduction of a thiazole moiety. Hybrid 7 h, the most potent compound with the highest selectivity index IC

A series of novel rhein-piperazine-dithiocarbamate hybrids 3 were efficiently synthesized from rhein through a catalyst-free and one-pot, three-step sequence involving chlorination and N-acylation followed by dithiocarbamate formation. Hybrids 3 were evaluated for their in vitro cytotoxic potency by MTT assay against several human cancer and non-cancer cells. Five of the hybrids were more cytotoxic to human lung cancer cell line A549 than the parent rhein and the reference, cytarabine (CAR). Structure-activity relationship (SAR) analysis indicated that cytotoxicity was significantly enhanced when ester groups were incorporated into the hybrids (3h-j). In particular, hybrid 3h (IC

Because of their excellent capacity to significantly improve the bioavailability and solubility of chemotherapy drugs, block copolymer micelles are widely utilized for chemotherapy drug delivery. In order to further improve the anti-tumor ability and reduce unwanted side effects of drugs, tumor-targeting peptides were used to functionalize the surface of polymer micelles so that the micelles can target tumor tissues. Herein, we synthesized a kind of PEG-PLA that is maleimide-terminated and then conjugated with a specific peptide F3 which revealed specific capacity binding to nucleolin that is overexpressed on the surface of many tumor cells. Then, F3 conjugated, paclitaxel loaded nanoparticles (F3-NP-PTX) were prepared as stable micelles that displayed an enhanced accumulation via a peptide-mediated cellular association in human breast cancer cells (MCF-7). Furthermore, F3-NP-PTX showed a prominent anti-tumor efficacy compared with non-targeting nanoparticles (NP-PTX) both in vitro and in vivo, and showed great potential as an efficacious targeting drug delivery system for breast cancer treatment.

Background Chrysomycin A (CA) has been reported as numerous excellent biological activities, such as antineoplastic and antibacterial. Though, poor solubility of CA limited its application in medical field. Due to good amphiphilicity and potential anticancer effect of disodium glycyrrhizin (Na2GA) as an excipient, an amorphous solid dispersion (Na2GA/CA-BM) consisting of CA and Na2GA was prepared in the present study by mechanochemical technology (roll mill ML-007, zirconium balls, 30 rpm, 2.5 h) to improve the solubility and oral bioavailability of CA. Then, Na2GA/CA-BM was self-assembled to micelles in water. The interaction of CA and Na2GA in solid state were investigated by X-ray diffraction studies, polarized light microscopy, and scanning electron microscope. Meanwhile, the properties of the sample solution were analyzed by dynamic light scattering and transmission electron. Furthermore, the oral bioavailability and antitumor ability of Na2GA/CA-BM in vivo were tested, providing a theoretical basis for future application of CA on cancer therapy. Results CA encapsulated by Na2GA was self-assembled to nano-micelles in water. The average diameter of nano-micelle was 131.6 nm, and zeta potential was − 11.7 mV. Three physicochemical detections showed that CA was transformed from crystal into amorphous form after treated with ball milling and the solubility increased by 50 times. Na2GA/CA-BM showed a significant increase of the bioavailability about two time that of free CA. Compared with free CA, the in-vivo antitumor studies also exhibited that Na2GA/CA-BM had an excellent inhibition of tumor growth. Conclusions Na2GA/CA-BM nanoparticles (131.6 nm, − 11.7 mV) prepared by simple and low-cost mechanochemical technology can improve oral bioavailability and antitumor efficacy of CA in vivo, suggesting a potential formulation for efficient anticancer treatment. Graphic abstract

Purpose The purpose of this study was to overcome the clinical defects of 7-ethyl-10-hydroxycamptothecin (SN-38) and explore its characteristics and antitumor effects. Materials and methods An amorphous solid dispersion of SN-38 with disodium glycyrrhizin (Na2GA) was prepared by mechanical ball milling (Na2GA/SN-38-BM). Moreover, an untreated mixture of Na2GA and SN-38 (Na2GA/SN-38-UM), a pure drug SN-38, was prepared for comparison with Na2GA/SN-38-BM. The samples were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), dynamic light scattering, and transmission electron microscopy. Then, further in vitro and in vivo studies were performed including cell uptake, cytotoxicity, antitumor efficacy, tissue distribution, and histopathological evaluation (H&E staining). Results SN-38 loaded in Na2GA was self-formed as nano-micelles in water. The particle size of nano-micelle was 69.41 nm and ζ-potential was -42.01 mV. XRD and SEM analyses showed that the ball milling transformed SN-38 crystals into amorphous form and that solubility increased by 189 times. Compared with SN-38 and Na2GA/SN-38-UM, Na2GA/SN-38-BM has a stronger cytotoxicity to tumor cells and exhibited a significant inhibition of tumor growth. Then, pharmacokinetic studies showed that the bioavailability of Na2GA/SN-38-BM was about four times that of SN-38 suspension. Conclusion Na2GA/SN-38-BM (69 nm, -42 mV) nanoparticles which had excellent phar-macokinetic and distribution properties can dramatically enhance the anticancer efficacy of SN-38 in vitro and in vivo, suggesting a promising formulation for efficient anticancer therapy.

The clinical benefit of PD-1/PD-L1 blockade immunotherapy is substantially restricted by insufficient infiltration of T lymphocytes into tumors and compromised therapeutic effects due to immune-related adverse events following systemic administration. Some chemotherapeutic agents have been reported to trigger tumor-associated T cell responses, providing a promising strategy to achieve potent immune activation in a synergistic manner with PD-1 blockade immunotherapy. In light of this, a localized chemoimmunotherapy system was developed using an anti-cancer drug-based supramolecular polymer (SP) hydrogel to “re-edit” the host's immune system to combat cancer. This in situ forming injectable aPD1/TT6 SP hydrogel serves as a drug-delivery depot for sustained release of bioactive camptothecin (CPT) and aPD1 into the tumor microenvironment, priming the tumor for robust infiltration of tumor-associated T cells and subsequently prompting a response to the immune checkpoint blockade. Our in vivo results demonstrate that this chemoimmunotherapy hydrogel provokes a long-term and systemic anticancer T cell immune response, which elicits tumor regression while also inhibiting tumor recurrence and potential metastasis.

A prodrug hydrogelator serves as an effective immune booster for checkpoint blocker–based cancer immunotherapy., Immune checkpoint blockers (ICBs) have shown great promise at harnessing immune system to combat cancer. However, only a fraction of patients can directly benefit from the anti–programmed cell death protein 1 (aPD1) therapy, and the treatment often leads to immune-related adverse effects. In this context, we developed a prodrug hydrogelator for local delivery of ICBs to boost the host’s immune system against tumor. We found that this carrier-free therapeutic system can serve as a reservoir for extended tumoral release of camptothecin and aPD1 antibody, resulting in an immune-stimulating tumor microenvironment for boosted PD-1 blockade immune response. Our in vivo results revealed that this combination chemoimmunotherapy elicits robust and durable systemic anticancer immunity, inducing tumor regression and inhibiting tumor recurrence and metastasis. This work sheds important light into the use of small-molecule prodrugs as both chemotherapeutic and carrier to awaken and enhance antitumor immune system for improved ICBs therapy.

On account of their excellent capacity to significantly improve the bioavailability and solubility of chemotherapy drugs, amphiphilic block copolymer-based micelles have been widely utilized for chemotherapy drug delivery. In order to further improve the antitumor ability and to also reduce undesired side effects of drugs, cell-penetrating peptides have been used to functionalize the surface of polymer micelles endowed with the ability to target tumor tissues. Herein, we first synthesized functional polyethylene glycol-polylactic acid (PEG-PLA) tethered with maleimide at the PEG section of the block polymer, which was further conjugated with a specific peptide, the transactivating transcriptional activator (TAT), with an approved capacity of aiding translocation across the plasma membrane. Then, TAT-conjugated, paclitaxel-loaded nanoparticles were self-assembled into stable nanoparticles with a favorable size of 20 nm, and displayed a significantly increased cytotoxicity, due to their enhanced accumulation via peptide-mediated cellular association in human breast cancer cells (MCF-7) in vitro. But when further used in vivo, TAT-NP-PTX showed an acceleration of the drug&rsquo, s plasma clearance rate compared with NP-PTX, and therefore weakened its antitumor activities in the mice model, because of its positive charge, its elimination by the endoplasmic reticulum system more quickly, and its targeting effect on normal cells leading towards being more toxic. So further modification of TAT-NP-PTX to shield TAT peptide&rsquo, s positive charges may be a hot topic to overcome the present dilemma.

Ferritin naturally exists in most organisms and can specifically recognize the transferrin 1 receptor (TfR1), which is generally highly expressed on various types of tumor cells. The pH dependent reversible assembling and disassembling property of ferritin renders it as a suitable candidate for encapsulating a variety of anticancer drugs and imaging probes. Ferritins external surface is chemically and genetically modifiable which can serve as attachment site for tumor specific targeting peptides or moieties. Moreover, the biological origin of these protein cages makes it a biocompatible nanocarrier that stabilizes and protects the enclosed particles from the external environment without provoking any toxic or immunogenic responses. Recent studies, further establish ferritin as a multifunctional nanocarrier for targeted cancer chemotherapy and phototherapy. In this review, we introduce the favorable characteristics of ferritin drug carriers, the specific targeted surface modification and a multifunctional nanocarriers combined chemotherapy with phototherapy for tumor treatment. Taken together, ferritin is a potential ideal base of engineered nanoparticles for tumor therapy and still needs to explore more on its way.

Pyrano[2,3-c]pyrazole derivatives have been reported as exerting various biological activities. One compound with potential anti-tumor activity was screened out by MTT assay from series of dihydropyrazopyrazole derivatives we had synthesized before using a one-pot, four-component reaction, and was named as 6-amino-4-(2-hydroxyphenyl)-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (hereinafter abbreviated as AMDPC). The IC50 of AMDPC against Bcap-37 breast cancer cells was 46.52 &mu, g/mL. Then the hydrophobic AMDPC was encapsulated in PEG-PLGA block copolymers, and then self-assembled as polymeric micelle (mPEG-PLGA/AMDPC) to improve both physiochemical and release profiles. The effect of mPEG-PLGA/AMDPC on BCAP-37 cancer cells showed similar anti-tumor effects as AMDPC. Furthermore, the anti-tumor mechanism of mPEG-PLGA/AMDPC was investigated, which can probably be attributed to stimulating the expression of P21 gene and therefore protein production on BCAP-37 cells, and then blocked the cell cycle through the P53-independent pathway both in S phase and G2 phase. Thus, mPEG-PLGA/AMDPC is a promising therapeutic agent for cancer treatment, and further in vivo studies will be developed.

Despite its central role in tumor progression and treatment resistance, poor vascularization that necessitates penetration of therapeutics through tumor extracellular matrix (ECM) constitutes a significant challenge to managing tumor hypoxia via conventional systemic treatment regimens. In addition, methods to target hypoxic tumor cells are lacking. Here, we discovered that human ferritin nanocages (FTn) possess an intrinsic ability to preferentially engage with hypoxic tumor tissues, in addition to normoxic tumor areas. We also developed a simple method of endowing FTn with spatially controlled "mosaic" surface poly(ethylene glycol) (PEG) coatings that facilitate deep penetration of FTn through ECM to reach hypoxic tumor tissues while retaining its inherent hypoxia-tropic property. Hypoxia-inhibiting agents systemically delivered via this surface-PEGylated FTn were readily accumulated in hypoxic tumor tissues, thereby providing significantly enhanced therapeutic benefits compared to the identical agents delivered in solution as a stand-alone therapy or an adjuvant to restore efficacy of conventional systemic chemotherapy.

Cytisine-pterocarpan derived compounds were biomimetically synthesized with (-)-cytisine and (-)-maackiain via a N,N-4-dimethyl-4-aminopyridine (DMAP)-mediated synthetic strategy in a mild manner. In the present study, tonkinensine B (4) was elaborated in good and high yields with the optimized reaction conditions. The in vitro cytotoxicity of compound 4 was evaluated against breast cancer cell lines and showed that 4 had a better cytotoxicity against MDA-MB-231 cells (IC50 = 19.2 μM). Depending on the research on cytotoxicities of 4 against RAW 264.7 and BV2 cells, it was suggested that 4 produced low cytotoxic effects on the central nervous system. Further study indicated that 4 demonstrated cytotoxic activity against MDA-MB-231 cells and the cytotoxic activity was induced by apoptosis. The results implied that the apoptosis might be induced by mitochondrion-mediated apoptosis via regulating the ratio of Bax/Bcl-2 and promoting the release of cytochrome c from the mitochondrion to the cytoplasm in MDA-MB-231 cells.

In research of anti-triple negative breast cancer (TNBC) agents, a series of cytisine-flavonoid conjugates (A-1 ~ G-1) were designed and synthesized in high yields with (−)-cytisine and flavonoids via N,N-4-dimethyl-4-aminopyridine (DMAP)-catalyzed synthetic strategy. In addition, the in vitro cytotoxicity of the conjugates was tested, and the results showed that some compounds had better cytotoxicity against human breast cancer cells (MDA-MB-231) than the positive control drug Paclitaxel. The studies of structure-activity relationship showed that the conjugates formed by cytisine featuring 5-chloro and flavonoids had better anti-proliferative effect on MDA-MB-231 cells.

Polymer micelles are one of the most investigated nanocarriers for drug delivery; many have entered clinical trials and some are in clinic use, but their delivery systems have not yet shown the expected high therapeutic efficacy in clinics. Further understanding their in vivo behaviors, particularly how quickly and by what mechanism polymer micelles are cleared ( i. e., via micelles or unimers) once injected, is key to solving this dilemma. Herein, we hope to answer these questions for the clinically relevant polyethylene glycol- block-poly(e-caprolactone) (PEG-PCL) and PEG- block-poly(d,l-lactide) (PEG-PDLLA) micelles. A small fraction of the hydrophobic chain ends was conjugated with a pair of fluorescence resonance energy transfer (FRET) dyes, Cy5 and Cy5.5, and used to fabricate FRET micelles whose FRET efficiency was correlated to the percentage of polymer chains in the micelles, the micelle degree. In vitro, serum proteins induced PEG-PCL micelle dissociation to some extent; mouse serum or blood surprisingly did not induce micelle dissociation but once with shear applied by a microfluidic channel caused most PEG-PCL micelles dissociated. After intravenous administration in mice, the PEG-PCL or PEG-PDLLA micelles were quickly sequestered into the liver as unimers, and the micelle degree in the blood quickly decreased to about 20%. The FRET-imaging experiments showed that in blood vessels the micelles quickly dissociated into unimers, which were found associated with albumin in blood and in liver. Thus, it is concluded that, upon intravenous injection, the shear and the bloodborne proteins (particularly albumin) induced the most (∼80%) PEG-PCL and PEG-PDLLA micelles to quickly dissociate into unimers, which were sequestered by Kupffer cells, while intact micelles were difficult to clear. These micelles were able to penetrate tumors and were very stable with cell membranes, but dissociated gradually inside cells. These findings on in vivo micelle fate and the clearance mechanism are directional for the rational design of polymer micelles for improved therapeutics; particularly, improving micelle stability in blood is the prerequisite for surface functionalizations such as introducing targeting ligands.

We developed a tumor-targeted contrast agent based on linear polylysine (PLL) by conjugating a small molecular imaging agent, fluorescent molecule and targeting agent amino phenylboronic acid onto the amino groups of polylysine, which can specifically target monosaccharide sialic acid residues overexpressing on the surface of tumor cell membranes. Further, 3,4,5,6-Tetrahydrophthalic anhydride (DCA) was attached to the free amino groups of the polylysine to change to a negative charge at physiology pH to lower the cytotoxicity, but it soon regenerated to a positive charge again once reaching the acidic intratumoral environment and therefore increased cell uptake. Laser confocal microscopy images showed that most of the polymeric contrast agents were bound to the cancer cell membrane. Moreover, the tumor targeting contrast agent showed the same magnetic resonance imaging (MRI) contrasting performance in vitro as the small molecule contrast agent used in clinic, which made it a promising tumor-targeting polymeric contrast agent for cancer diagnosis.

A prodrug forms nanocapsules responsive to tumor GSH/ROS heterogeneity releasing the parent drug SN38 via thiolysis in the presence of GSH (glutathione) or via enhanced hydrolysis due to ROS (reactive oxygen species)-oxidation of the linker, giving rise to high in vitro cytotoxicity and in vivo anticancer therapeutic activity. The nanocapsules are a suitable size for tumor targeting by means of the EPR effect and have a fixed SN38 loading content of 35 wt%, ideal for translational nanomedicine.

Doxorubicin (DOX) is a widely used chemotherapeutic drug to treat a range of cancers. However, its unfavorable effects, particularly the cardiotoxicity and the induction of multidrug resistance (MDR), significantly limit its clinical applications. Herein, a novel doxorubicin prodrug, PEG2K -DOX, is synthesized by conjugating a deprotonated doxorubicin molecule with the polyethylene glycol (PEG, MW: 2K) chain via pH-responsive hydrazone bond, and its potential as a better alternative than doxorubicin is evaluated. The data show that the amphiphilic PEG2K -DOX can self-assemble into stable nanoparticles with a high and fixed doxorubicin loading content (≈20 wt%), a favorable size of 91.5 nm with a narrow polydispersity (PDI = 0.14), good stability, and pH-dependent release behavior due to the acid-cleavable linkage between PEG and doxorubicin. Although doxorubicin hardly accumulates in MDR cells, PEG2K -DOX nanoparticles significantly increase the cellular uptake and cell-killing activity of doxorubicin in two MDR cancer cell lines MCF-7/ADR and KBv200, with the IC50 values dropped to 1.130% and 42.467% of doxorubicin, respectively. More impressively, PEG2K -DOX nanoparticles exhibit significantly improved plasma pharmacokinetics, increased in vivo therapeutic efficacy against MDR xenograft tumors, and better in vivo safety compared with doxorubicin. PEG2K -DOX nanoparticles hold the promise to become a better alternative than doxorubicin for cancer treatment, especially for MDR tumors.

A "cluster-bomb"-like lipid-dendrimer nanoassembly synergizes the functions of its components and thereby efficiently accomplishes the drug delivery cascade for high efficacy in treating cancer. The nanoassembly successfully circulates in the blood and accumulates in the tumor. Once in the tumor, it releases small dendrimers that act like "bomblets", enabling tumor penetration, cell internalization, and drug release.

In vivo monitoring of the biodistribution and activation of prodrugs is urgently required. Near infrared (NIR) fluorescence-active fluorophores with excellent photostability are preferable for tracking drug release in vivo. Herein, we describe a NIR prodrug DCM-S-CPT and its polyethylene glycol-polylactic acid (PEG-PLA) loaded nanoparticles as a potent cancer therapy. We have conjugated a dicyanomethylene-4H-pyran derivative as the NIR fluorophore with camptothecin (CPT) as the anticancer drug using a disulfide linker. In vitro experiments verify that the high intracellular glutathione (GSH) concentrations in tumor cells cause cleavage of the disulfide linker, resulting in concomitantly the active drug CPT release and significant NIR fluorescence turn-on with large Stokes shift (200 nm). The NIR fluorescence of DCM-S-CPT at 665 nm with fast response to GSH can act as a direct off-on signal reporter for the GSH-activatable prodrug. Particularly, DCM-S-CPT possesses much better photostability than ICG, which is highly desirable for in situ fluorescence-tracking of cancer chemotherapy. DCM-S-CPT has been successfully utilized for in vivo and in situ tracking of drug release and cancer therapeutic efficacy in living animals by NIR fluorescence. DCM-S-CPT exhibits excellent tumor-activatable performance when intravenously injected into tumor-bearing nude mice, as well as specific cancer therapy with few side effects. DCM-S-CPT loaded in PEG-PLA nanoparticles shows even higher antitumor activity than free CPT, and is also retained longer in the plasma. The tumor-targeting ability and the specific drug release in tumors make DCM-S-CPT as a promising prodrug, providing significant advances toward deeper understanding and exploration of theranostic drug-delivery systems.

CaIPF19998, a functionally unknown gene in Candida albicans, was identified by its homology to Saccharomyces cerevisiae AIF1 gene, which is involved in cell apoptosis. In this study, ipf19998 null mutant was generated with the URA-blaster method and the construction of overexpression of CaIPF19998 was measured by quantitative RT-PCR. Minimal inhibitory concentrations determination showed that the ipf19998 overexpressed strains was more resistant to the antifungals tested than the wildtype (strain CAI4). The 2,3-bis (2-methoxy-4-nitro-5-sulfo-phenyl)-2Htetrazolium-5-carboxanilide reduction assay showed that CaIPF19998 could enhance the capacity of C. albicans biofilms formation. On Candida biofilms mode, intracellular levels of reactive oxygen species were significantly decreased and real-time RT-PCR showed that some important redox-related genes, including ALD5, CIT1, PIL1, AHP1, TRX1 and TSA1, were up-regulated in the CaIPF19998 overexpressed strains. These results demonstrate that CaIPF19998 played an important role in C. albicans biofilms formation and intracellular redox homeostasis, therefore led to a close relationship between CaIPF19998 and drug susceptibility in C. albicans.

Platinum(IV) prodrug diaminedichlorodihydroxyplatinum (ACHP) conjugated with a histone deacetylase (HDAC) inhibitor valproic acid (VA), VAAP, exhibited strong synergistic cytotoxicity, about 50-100 times more cytotoxic than ACHP or its simple mixture with VA, against various human carcinoma cell lines. VAAP could be quickly absorbed in the cell membrane and diffused into the cytosol. VAAP loaded in polyethylene glycol-polycaprolactone micelles (PEG-PCL) was taken up via endocytosis. The cytosolic VAAP was intracellular reduced to Pt(II) and released VA eliciting a HDAC inhibitory effect and subsequently induced cell cycle arrest at the S phase in 24 h and cell apoptosis in a time-dependent manner. The in vivo antitumor experiment on A549-xenograft tumor model showed that VAAP dispersed in Tween 80 or loaded in PEG-PCL nanoparticles had long blood circulation times and thereby high accumulation in tumors and exerted a significant in vivo inhibitory effect on tumor growth with low systemic toxicity. Therefore, this novel conjugate is very promising for cancer chemotherapy.

Trehalose is a non-reducing disaccharide and can be accumulated in response to heat or oxidative stresses in Candida albicans. Here we showed that a C. albicans tps1Δ mutant, which is deficient in trehalose synthesis, exhibited increased apoptosis rate upon H(2)O(2) treatment together with an increase of intracellular Ca(2+) level and caspase activity. When the intracellular Ca(2+) level was stimulated by adding CaCl(2) or A23187, both the apoptosis rate and caspase activity were increased. In contrast, the presence of two calcium chelators, EGTA and BAPTA, could attenuate these effects. Moreover, we investigated the role of Ca(2+) pathway in C. albicans apoptosis and found that both calcineurin and the calcineurin-dependent transcription factor, Crz1p, mutants showed decreased apoptosis and caspase activity upon H(2)O(2) treatment compared to the wild-type cells. Expression of CaMCA1, the only gene found encoding a C. albicans metacaspase, in calcineurin-deleted or Crz1p-deleted cells restored the cell sensitivity to H(2)O(2). Our results suggest that Ca(2+) and its downstream calcineurin/Crz1p/CaMCA1 pathway are involved in H(2)O(2)-induced C. albicans apoptosis. Inhibition of this pathway might be the mechanism for the protective role of trehalose in C. albicans.

Optical near-infrared (NIR) nanomaterials provide a unique opportunity for applications in bioimaging and medical diagnosis. A kind of hydrophilic NIR fluorescent core–shell structured silica nanoparticle containing NIR cyanine chromophore, named as CyN-12@NHs, for in vivo bioimaging is developed through a facile one-pot strategy. The hydrophobic CyN-12 molecules can be successfully encapsulated into the core via the self-assembly of the amphiphilic block copolymer PS-b-PAA and subsequent shell cross-linking of silane. The as-prepared CyN-12@NHs exhibits typically spherical core–shell structure, which has a uniform size of 35 nm with a narrow size distribution, and excellent dispersity in aqueous solution. Moreover, NIR absorption (690 nm) and bright fluorescence (800 nm) of CyN-12@NHs with a large Stokes shift (110 nm) in aqueous system make it an amenable high quality bioimaging contrast agent. The core–shell nanostructure significantly enhances the chemical and photo-stability of CyN-12 via the encapsulation, which possesses a 50-times longer half-life period than free CyN-12, along with a better resistance to reactive oxygen species (ROS). Furthermore, in living cell imaging, CyN-12@NHs shows nearly no cytotoxicity and is able to outline the HepG2 cells. The in vivo imaging on a tumor-bearing mouse model indicates that CyN-12@NHs selectively accumulates in the liver after intravenous injection, and has a long retention in tumor after intra-tumor injection without decrease in fluorescence activity. Overall, the excellent photo-properties of CyN-12@NHs could meet the intricate requirements for tumor imaging, such as high sensitivity, sufficient tissue penetration, and high spatial resolution. The strategy of the silica–cyanine hybrid nanoparticles paves a desirable and efficient route to fabricate highly hydrophilic NIR fluorescent contrast agents for tumor imaging and therapy, especially with a breakthrough in photo-stability, bright fluorescence as well as large Stokes shift.

Amides with β-carboxylic acid groups are stable and negatively charged at physiological pH, but hydrolyze back to the corresponding amines and anhydrides once in an acidic environment. We thereby developed charge-reversal nanocarriers for drug delivery. In these systems, the anhydrides served only as groups to amidize the amines in cationic polymers and had no therapeutic use after being cleaved from the carrier in the cells. Herein, we utilized the characteristic anhydride structure of norcantharidin (NCTD) and the pH-dependent hydrolysis of its β-carboxylic amides and developed novel acid-labile conjugates for the targeted delivery of NCTD. In this study, NCTD was used as both an anticancer drug and an acid-labile anhydride to react with cationic polymers including PEI and PLL to form β-carboxylic amides. The obtained conjugates (PEI–NCTD and PLL–NCTD) had not only significantly improved NCTD solubility and high drug loading contents (as high as 72.3% and 56.8%, respectively, for PEI–NCTD and PLL–NCTD), but also favorable acid-labile capabilities. These conjugates were stable and negatively charged at neutral pH, but once in acidic environments (e.g. endo/lysosomes), they hydrolyzed and regenerated not only NCTD as an antitumor drug, but also the PEI or PLL, which could assist the endo/lysosomal escape and release of the drugs. Further, functionalizing the acid-labile conjugates with targeting moiety folic acid (FA) increased the cellular uptake of the conjugates into folate receptor-overexpressing tumor cells and thereby the in vitro cytotoxicity. These targeted acid-labile conjugates may help to reduce the side effects of NCTD and improve its clinical applications.