Fast dissolving drug delivery membrane based on the ultra-thin shell of electrospun core-shell nanofibers.

Structural nanocomposites that provide fast dissolving drug release profiles are highly in demand in pharmaceutics. In this study, a poorly water-soluble drug such as quercetin or tamoxifen citrate (TC) was selected as a model active pharmaceutical ingredient. Core-shell nanofibers with ultra-thin shells were designed and prepared using modified coaxial electrospinning. Polyvinylpyrrolidone (PVP) K90 or Polycaprolactone (PCL) was selected as core. The drugs and PVP K10 were selected as shell. All types of solutions can be used as the shell fluids in modified coaxial process regardless of their electrospinnability, which means the increasing functional ingredients and unspinnable matrix can be processed. Evaluations via SEM and TEM demonstrated that the core-shell nanofibers had linear morphology with a shell thickness smaller than 100 nm. XRD and FTIR results showed that the model drug was distributed in the polymeric matrix amorphously and that PVP K10 had good compatibility with quercetin or TC. In vitro dissolution tests suggested that the core-shell nanofibers with ultra-thin shells released the loaded cargoes in the dissolution media within 1 min. The present investigation paved a new way for implementing the modified coaxial processes, which can be utilized to fabricate structural nanocomposites with ultra-thin shells for enhancing the fast dissolution of poorly water-soluble drugs.

Hypoxia induces universal but differential drug resistance and impairs anticancer mechanisms of 5-fluorouracil in hepatoma cells.

Hepatocellular carcinoma (HCC) is one of the most refractory cancers. The mechanisms by which hypoxia further aggravates therapeutic responses of advanced HCC to anticancer drugs remain to be clarified. Here, we report that hypoxia (1% O2) caused 2.55-489.7-fold resistance to 6 anticancer drugs (sorafenib, 5-fluorouracil [5-FU], gemcitabine, cisplatin, adriamycin and 6-thioguanine) in 3 HCC cell lines (BEL-7402, HepG2 and SMMC-7721). Among the 6 drugs, sorafenib, the sole one approved for HCC therapy, inhibited proliferation with little influence from hypoxia and displayed the smallest variation among the 3 HCC cell lines tested. By contrast, the inhibition of proliferation by 5-FU, which has been extensively tested in clinical trials but has not been approved for HCC therapy, was severely affected by hypoxia and showed a large variation among these cell lines. In 5-FU-treated HCC cells, hypoxia reduced the levels of basal thymidylate synthase (TS) and functional TS, leading to decreased dTMP synthesis and DNA replication. Hypoxia also affected the accumulation of FdUTP and its misincorporation into DNA. Consequently, both single-strand breaks and double-strand breaks in DNA were reduced, although hypoxia also inhibited DNA repair. In 5-FU-treated HCC cells, hypoxia further abated S-phase arrest, alleviated the loss of mitochondrial membrane potential, diminished the activation of caspases, and finally resulted in reduced induction of apoptosis. Thus, hypoxia induces universal but differential drug resistance. The extensive impacts of hypoxia on the anticancer mechanisms of 5-FU contributes to its hypoxia-induced resistance in HCC cells. We propose that hypoxia-induced drug resistance and interference of hypoxia with anticancer mechanisms could be used as candidate biomarkers in selecting and/or developing anticancer drugs for improving HCC therapy.

Microporous Polymers from a Carbazole-Based Triptycene Monomer: Synthesis and Their Applications for Gas Uptake.

Two kinds of novel organic microporous polymers TCPs (TCP-A and TCP-B) were prepared by two cost-effective synthetic strategies from the monomer of tricarbazolyltriptycene (TCT). Their structure and properties were characterized by FT-IR, solid (13) C NMR, powder XRD, SEM, TEM, and gas absorption measurements. TCP-B displayed a high surface area (1469 m(2) g(-1) ) and excellent H2 storage (1.70 wt % at 1 bar/77 K) and CO2 uptake abilities (16.1 wt % at 1 bar/273 K), which makes it a promising material for potential application in gas storage.

A Porous Tricyclooxacalixarene Cage Based on Tetraphenylethylene.

A quadrangular prismatic tricyclooxacalixarene cage 1 based on tetraphenylethylene (TPE) was efficiently synthesized by a one-pot S(N)Ar condensation reaction. As a result of the porous internal structure in the solid state, cage 1 exhibited a good CO2 uptake capacity of 12.5 wt% and a high selectivity for CO2 over N2 adsorption of 80 (273 K, 1 bar) with a BET surface area of 432 m(2) g(-1). Formation of cage 1 led to the fluorescence of TPE being switched on in solution. The system was employed as a single-molecule platform to study the mechanism of aggregation-induced emission (AIE) by examining the restriction of intramolecular rotation (RIR).

A mechanism for nano-titanium dioxide-induced cytotoxicity in HaCaT cells under UVA irradiation.

Nano-TiO2 has been reported to be an efficient photocatalyst, which is able to produce reactive oxygen species (ROS) under UVA irradiation. In this study, we investigated the effects of nano-TiO2 on the cytotoxicity, induction of apoptosis, and the putative pathways of its actions in HaCaT cells. We show that nano-TiO2 is a potent inducer of apoptosis and that it transduces the apoptotic signal via ROS generation, thereby inducing mitochondrial permeability transition (MPT) and activating Caspase-3 from HaCaT cells. ROS production, mitochondrial alteration, and subsequent apoptotic cell death in nano-TiO2-treated cells were blocked by the MPT pore-blocker cyclosporin A. Taken together, our data indicate that nano-TiO2 induces the ROS-mediated MPT and resultant Caspase-3 activation.

Temperature-sensitive fluorescent organic nanoparticles with aggregation-induced emission for long-term cellular tracing.

Temperature-sensitive organic nanoparticles with AIE effect were assembled in water from tetraphenylethene-based poly(N-isopropylacrylamide) (TPE-PNIPAM), which was synthesized by ATRP using TPE derivative as initiator. The size and fluorescence of TPE-PNIPAM nanoparticles can be tuned by varying the temperature. These nanoparticles can be internalized readily by HeLa cells and can be used as long-term tracer in live cells to be retained for as long as seven passages.

Tetraphenylethylene-based expanded oxacalixarene: synthesis, structure, and its supramolecular grid assemblies directed by guests in the solid state.

A novel TPE-based expanded oxacalixarene with typical aggregation-induced emission properties was synthesized by the SNAr reaction of dihydroxytetraphenylethylene with 2,6-dichloropyrazine. The conformation of the oxacalixarene is adjusted by the encapsulated guests (benzene or THF), which results in different supramolecular grid structures in the solid state.

Pharmaceutical nanotechnology for oral delivery of anticancer drugs.

Oral chemotherapy is an important topic in the 21st century medicine, which may radically change the current regimen of chemotherapy and greatly improve the quality of life of the patients. Unfortunately, most anticancer drugs, especially those of high therapeutic efficacy such as paclitaxel and docetaxel, are not orally bioavailable due to the gastrointestinal (GI) drug barrier. The molecular basis of the GI barrier has been found mainly due to the multidrug efflux proteins, i.e. P-type glycoproteins (P-gp), which are rich in the epithelial cell membranes in the GI tract. Medical solution for oral chemotherapy is to apply P-gp inhibitors such as cyclosporine A, which, however, suppress the body's immune system either, thus causing medical complication. Pharmaceutical nanotechnology, which is to apply and further develop nanotechnology to solve the problems in drug delivery, may provide a better solution and thus change the way we make drug and the way we take drug. This review is focused on the problems encountered in oral chemotherapy and the pharmaceutical nanotechnology solutions such as prodrugs, nanoemulsions, dendrimers, micelles, liposomes, solid lipid nanoparticles and nanoparticles of biodegradable polymers. Proof-of-concept in vitro and in vivo results for oral delivery of anticancer drugs by the various nanocarriers, which can be found so far from the literature, are provided.

Supramolecular gel-assisted formation of fullerene nanorods.

Gel it like it is: Fullerene nanorods (see figure) with a length of several micrometers, can be easily synthesized by a supramolecular gel-assisted self-assembly method (SGAS). The results presented here may be useful for the design and construction of new organic nanomaterials by SGAS.

Triptycene-Based Microporous Polymers: Synthesis and Their Gas Storage Properties.

A novel kind of star triptycene-based microporous polymer (STPs) was synthesized efficiently from trihalotriptycenes by nickel(0)-catalyzed Ullmann cross-coupling reactions. STPs display a BET surface area of 1305 m2 g-1 and 1990 m2 g-1, and reversibly adsorb 1.60 and 1.93 wt % H2 at 1.0 bar/77 K, 16.15 and 18.20 wt % CO2 at 1.0 bar/273 K for STP-I and STP-II, respectively.

[Methodological study on magnetic affinity immunoassay for detecting chloramphenicol].

AIM: To establish a sensitive immunoassay for detection chloramphenicol using magnetic beads as solid phase. METHODS: This assay employs the competitive inhibition, the FITC conjugated with anti-chloramphenicol monoclonal antibodies and the alkaline phosphatase conjugated with chloramphenicol respectively. Magnetic beads were coupled with sheep anti-FITC antibodies as solid phase. And phenolphthalein monophosphate was used as substrate to set up MEIA for detection chloramphenicol. RESULTS: MEIA for detection chloramphenicol was Established, the reaction time is 40 minutes, the sensitivity is 0.03 microg/L, the liner range is 0.1-8.1 microg/L, the intra and inter coefficient variation (CV) was 3.9%-5.3% and 4.8%-8.1% respectively and the recovery is 97%-101.5%. Comparing with national standard method of liquid chromatography-mass spectrometry, the Correlation coefficient of test results is 0.9817 (r=0.9817). CONCLUSION: The chloramphenicol MEIA method is sensitive, accurate, and fast, it provides a new method of immunoassay for the monitoring of chloramphenicol residues in food.

Preparation of uniform-sized multiple emulsions and micro/nano particulates for drug delivery by membrane emulsification.

Much attention has in recent years been paid to fine applications of drug delivery systems, such as multiple emulsions, micro/nano solid lipid and polymer particles (spheres or capsules). Precise control of particle size and size distribution is especially important in such fine applications. Membrane emulsification can be used to prepare uniform-sized multiple emulsions and micro/nano particulates for drug delivery. It is a promising technique because of the better control of size and size distribution, the mildness of the process, the low energy consumption, easy operation and simple equipment, and amendable for large scale production. This review describes the state of the art of membrane emulsification in the preparation of monodisperse multiple emulsions and micro/nano particulates for drug delivery in recent years. The principles, influence of process parameters, advantages and disadvantages, and applications in preparing different types of drug delivery systems are reviewed. It can be concluded that the membrane emulsification technique in preparing emulsion/particulate products for drug delivery will further expand in the near future in conjunction with more basic investigations on this technique.

A novel fast disintegrating tablet fabricated by three-dimensional printing.

BACKGROUND: Based on computer-aided models, three-dimensional printing (3DP) technology can exercise local control over the material composition, microstructure, and surface texture during it layer-by-layer manufacturing process to endow the products with special properties. It can be a useful tool in the development of novel solid dosage forms. METHOD: In this study, a novel fast disintegrating tablet (FDT) with loose powders in it was designed and fabricated using 3DP process. The inner powder regions were formed automatically by depositing the binder solutions onto selected regions during the layer-printing processes. RESULTS: Environmental scanning electron microscope images clearly showed that the printed regions were bound together. The particle size was reduced or individual particles could no longer be distinguished. In contrast, the unprinted regions were uncompacted with cracks and fissures among the loose powders. The tablets had a hardness value of 54.5 N/cm(2) and 0.92% mass loss during the friability tests. The disintegration time of the tablets was 21.8 seconds and the wetting time was 51.7 seconds. The in vitro dissolution tests showed that 97.7% acetaminophen was released in the initial 2 min. CONCLUSION: 3DP process is able to offer novel methods for preparing FDTs.

Novel oral fast-disintegrating drug delivery devices with predefined inner structure fabricated by Three-Dimensional Printing.

OBJECTIVES: Novel fast-disintegrating drug delivery devices with special inner structure characteristics were designed and fabricated using Three-Dimensional Printing. METHODS: Based on computer-aided design models, fast-disintegrating drug delivery devices containing loose powders were prepared automatically using the Three-Dimensional Printing system. The inner powder regions were prepared by depositing the binder solutions onto selected regions during the layer-printing process. RESULTS: The devices showed acceptable pharmacotechnical properties and fine hardness (63.4 N/cm(2)) due to the synergistic action of several binding mechanisms, but unsatisfactory friability, with 3.55% total mass loss during the friability tests. Scanning electron microscope images clearly showed that the printed regions were well bound, and that the drug particle size was reduced or individual particles could no longer be distinguished. In contrast, the unprinted regions were uncompacted, with cracks and fissures among the loose mixed powder. All the drug delivery devices disintegrated and wetted rapidly in in-vitro tests. The average disintegration and wetting times were 23.4 s and 67.6 s, respectively. Dissolution tests showed that 98.5% of the drug was released within 2 min. CONCLUSIONS: Three-Dimensional Printing offers strategies for the development of novel oral fast-disintegrating drug delivery devices.

Novel drug delivery devices for providing linear release profiles fabricated by 3DP.

Novel doughnut-shaped multi-layered drug delivery devices (DDDs) were developed with local variations of the drug and release-retardant material for providing linear release profiles. Based on computer-aided design models, different DDDs containing acetaminophen as a model drug, hydroxypropyl methylcellulose as matrix and ethyl cellulose (EC) as a release-retardant material were prepared automatically using a three-dimensional printing (3DP) system. In vitro dissolution assays demonstrated that all the 3DP DDDs had with different diameters, heights, concentrations of EC and central hole diameters were able to give linear release profiles. Morphological and erosion studies showed that acetaminophen was released through a simultaneous surface erosion process involving the outer peripheries and inner apertures. The barrier layers on both bases of DDDs had good adhesion strength with the drug-contained regions and offered consistent release retardation for the whole duration of the dissolution process. The release time periods of the DDDs were dependent on the annular thicknesses or the passes of binder solution containing a release-retardant material. The dosage of the DDD can be adjusted independently by changing the heights of the DDDs. Thus, 3DP is capable of offering novel strategies for developing DDDs with complex design features for desired drug release profiles.

Inactivation of GABA transaminase by 3-chloro-1-(4-hydroxyphenyl)propan-1-one.

Previously it was found that 4-hydroxybenzaldehyde is a competitive inhibitor of GABA transaminase. Here 3-chloro-1-(4-hydroxyphenyl)propan-1-one (9), a 4-hydroxybenzaldehyde analogue, was found to inactivate potently the enzyme in a time-dependent manner. alpha-Ketoglutarate prevented the enzyme from inactivation, suggesting that the inactivation occurs in its active site. Several experiments indicated that the inactivation is irreversible. This study provides a novel strategy for the design of more effective inhibitors.

[Establishment of the magnetic separation enzyme immunofluorescence method for detecting insulin].

AIM: To establish a convenient and sensitive magnetic separation enzyme immunofluorescence (MEIF) method for detecting human insulin. METHODS: Two monoclonal antibodies (mAbs) were conjugated with FITC and alkaline phosphatase (AP) respectively, which were incorporated magnetic solid phase separation. Magnetic beads were coupled with sheep anti-FITC antibody as solid phase and 4-Methylumbelliferyl-phosphoric acid (4-MUP) was used as substrate to set up MElF for detecting insulin. RESULTS: The sensitivity of this assay was 2.0 microIu/mL, the linear range was from 0 microIu/mL to 188.52 microIu/mL, and the intra-assay variation and inter-assay variation were 4.3%-5.2% and 2.6%-9.5%, respectively. The recovery rate of dilution was 92.6%-117% and the recovery rate of accession was 106%-121%.The result of the assay correlated well with that of magnetic enzyme chemiluminescence immunoassay system. CONCLUSION: The MEIF for detecting insulin is low at cost, sensitive, specific and stable, which can be widely used in clinical immune detection.

Three-dimensional printing in pharmaceutics: promises and problems.

Three-dimensional printing (3DP) is a rapid prototyping (RP) technology. Prototyping involves constructing specific layers that uses powder processing and liquid binding materials. Reports in the literature have highlighted the many advantages of the 3DP system over other processes in enhancing pharmaceutical applications, these include new methods in design, development, manufacture, and commercialization of various types of solid dosage forms. For example, 3DP technology is flexible in that it can be used in applications linked to linear drug delivery systems (DDS), colon-targeted DDS, oral fast disintegrating DDS, floating DDS, time controlled, and pulse release DDS as well as dosage form with multiphase release properties and implantable DDS. In addition 3DP can also provide solutions for resolving difficulties relating to the delivery of poorly water-soluble drugs, peptides and proteins, preparation of DDS for high toxic and potent drugs and controlled-release of multidrugs in a single dosage forms. Due to its flexible and highly reproducible manufacturing process, 3DP has some advantages over conventional compressing and other RP technologies in fabricating solid DDS. This enables 3DP to be further developed for use in pharmaceutics applications. However, there are some problems that limit the further applications of the system, such as the selections of suitable excipients and the pharmacotechnical properties of 3DP products. Further developments are therefore needed to overcome these issues where 3DP systems can be successfully combined with conventional pharmaceutics. Here we present an overview and the potential 3DP in the development of new drug delivery systems.