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  • 1
    In: PLoS ONE, 2015, Vol.10(7)
    Description: Over the last few decades the establishment of nanoparticles as suitable drug carriers with the transport of drugs across biological barriers such as the gastrointestinal barrier moved into the focus of many research groups. Besides drug transport such carrier systems are well suited for the protection of drugs against enzymatic and chemical degradation. The preparation of biocompatible and biodegradable nanoparticles based on poly(lactic-co-glycolic acid) (PLGA) is intensively described in literature, while especially nanoparticles with cationic properties show a promising increased cellular uptake. This is due to the electrostatic interaction between the cationic surface and the negatively charged lipid membrane of the cells. Even though several studies achieved the successful preparation of nanoparticles stabilized with the cationic surfactants such as didodecyldimethylammonium bromide (DMAB), in most cases insufficient attention was paid to a precise analytical characterization of the nanoparticle system. The aim of the present work was to overcome this deficit by presenting a new perspective in the formulation and characterization of DMAB-stabilized PLGA nanoparticles. Therefore these nanoparticles were carefully examined with regard to particle diameter, zeta potential, the effect of variation in stabilizer concentration, residual DMAB content, and electrolyte stability. Without any steric stabilization, the DMAB-modified nanoparticles were sensitive to typical electrolyte concentrations of biological environments due to compression of the electrical double layer in conjunction with a decrease in zeta potential. To handle this problem, the present study proposed two modifications to enable electrolyte stability. Both polyvinyl alcohol (PVA) and polyethylene glycol (PEG) modified DMAB-PLGA-nanoparticles were stable during electrolyte addition. Furthermore, in contrast to unmodified DMAB-PLGA-nanoparticles and free DMAB, such modifications led to a lower cytotoxic activity against Caco-2 cells. In conclusion this study offers a closer and critical point of view on preparation, in vitro and analytical evaluation of DMAB-stabilized PLGA nanoparticles for the physiological use.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 2
    Language: English
    In: International Journal of Pharmaceutics, 30 January 2017, Vol.517(1-2), pp.338-347
    Description: The physico-chemical characterisation of nanoparticles is often lacking the determination of the glass transition temperature, a well-known parameter for the pure polymer carrier. In the present study the influence of water on the glass transition temperature of poly (DL-lactic-co-glycolic acid) nanoparticles was assessed. In addition, flurbiprofen and THPP as model drugs were incorporated in poly (DL-lactic-co-glycolic acid), poly (DL-lactic acid), and poly (L-lactic acid) nanoparticles. For flurbiprofen-loaded nanoparticles a decrease in the glass transition temperature was observed while THPP exerted no influence on this parameter. Based on this observation, the release behaviour of the drug-loaded nanoparticles was investigated at different temperatures. For all preparations an initial burst release was measured that could be attributed to the drug adsorbed to the large nanoparticle surface. At temperatures above the glass transition temperature an instant drug release of the nanoparticles was observed, while at lower temperatures less drug was released. It could be shown that the glass transition temperature of drug loaded nanoparticles in suspension more than the corresponding temperature of the pure polymer is the pivotal parameter when characterising a nanostructured drug delivery system.
    Keywords: Drug Delivery System ; Poly (DL-Lactic-Co-Glycolic Acid) ; Poly (Lactic Acid) ; Differential Scanning Calorimetry ; Release Profile ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0378-5173
    E-ISSN: 1873-3476
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  • 3
    Language: English
    In: International Journal of Pharmaceutics, 30 December 2015, Vol.496(2), pp.942-952
    Description: The study on cholangiocellular cell lines was conducted with THPP-loaded nanoparticles with different polymers as matrices. Nanoparticles were characterized and the effect of the carrier system was examined . Comparison of free substance, embedded substance and different materials revealed severe differences for cellular uptake and activity after activation by illumination. The photodynamic therapy with porphyrin derivatives is an established approach to targeted tumor therapy, but is still afflicted with disadvantages of the physicochemical characteristics of the photosensitizer. To overcome drug-related restrictions in photodynamic therapy, three 5,10,15,20-tetrakis( -hydroxyphenyl) porphyrin ( THPP)-loaded nanoparticulate formulations based on poly( -lactide- -glycolide) (PLGA), poly( , -lactide) (PLA), and Eudragit E were prepared in a consistent diameter range and compared with free THPP . Formulation behavior was investigated in two different cholangiocellular cell lines, EGI-1 and TFK-1. High cytotoxicity was shown for all photosensitizer loaded nanoparticle (NP) formulations and free THPP, with EC values ranging from 0.2 to 1.3 μM. PLA based NP were not as effective in all performed tests as other formulations. Nanoparticulate embedded THPP remained photodynamically active and resulted in caspase-3 activation even at low concentrations of 250 nM. PLGA based NP exhibited highest caspase-3 activation. For all formulations an effective intracellular accumulation of THPP was observed, whereby for THPP-Eudragit E-NP a 200-fold drug accumulation was shown. Polymer based nanoparticles were shown to be an effective and highly active transport vehicle for the photosensitizer THPP . Problems like low solubility of free drug can be circumvented by successful embedding into nanoparticulate carrier systems, maintaining therapeutic effects of the photosensitizer.
    Keywords: Drug Delivery System ; Photodynamic Therapy ; Cholangiocarcinoma ; Nanoparticle ; Cytotoxicity ; Polymer Influence ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0378-5173
    E-ISSN: 1873-3476
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  • 4
    Language: English
    In: Journal of agricultural and food chemistry, 16 January 2013, Vol.61(2), pp.462-71
    Description: The ergot alkaloids as secondary metabolites from fungi of the genus Claviceps are the focus of many investigations because of their pharmacological and toxicological properties. The main effects of ergot alkaloids are referred to an interaction with several receptor systems in the human body. It is well-known that ergot alkaloids are able to isomerize with one isomer being biologically active and one being only weakly active, whereas the activity is restricted to receptor interactions. Latest investigations have proven that ergot alkaloids also show cytotoxic effects and induce apoptosis in human primary cells. These effects seem to correlate with accumulation properties. It was the aim of our current study to determine such effects in cancer cell lines, because ergot derivatives are also used in tumor therapy. Our results confirm the apoptotic effects in two cancer cell lines (HepG2 and HT-29) in a high range, and accumulation measurements show an interesting correlation between the alkaloid concentration in the cell lysate of the receptor-inactive isomers and cytotoxicity. In addition, the strong accumulative effects were first visualized by fluorescence microscopy by taking advantage of the natural fluorescence properties of ergot alkaloids.
    Keywords: Antineoplastic Agents -- Pharmacology ; Carcinoma -- Drug Therapy ; Ergot Alkaloids -- Pharmacology
    ISSN: 00218561
    E-ISSN: 1520-5118
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  • 5
    Language: English
    In: Journal of agricultural and food chemistry, 27 July 2011, Vol.59(14), pp.7798-807
    Description: Ergot alkaloids are known toxic secondary metabolites of the fungus Claviceps purpurea occurring in various grains, especially rye products. The liver is responsible for converting the ergot alkaloids into metabolites; however, the toxic impact of these end products of metabolism is still unknown. The aim of this study was to analyze the metabolism of ergot alkaloids in colon and liver cell lines (HT-29, HepG2), as well as in human primary renal cells (RPTEC). It was shown that cells in vitro are able to metabolize ergot alkaloids, forming a variety of metabolic compounds. Significant differences between the used cell types could be identified, and a suitable model system was established using HT-29 cells, performing an intensive metabolism to hydroxylated metabolites. The formed substances were analyzed by coupling of high-performance liquid chromatography with fluorescence detection and Fourier transformation mass spectrometry (HPLC-FLD-FTMS) as a powerful tool to identify known and unknown metabolites.
    Keywords: Ergot Alkaloids -- Analysis ; Kidney -- Metabolism ; Liver -- Metabolism ; Mass Spectrometry -- Methods ; Mycotoxins -- Analysis
    ISSN: 00218561
    E-ISSN: 1520-5118
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  • 6
    Language: English
    In: Biomacromolecules, 10 December 2018, Vol.19(12), pp.4677-4690
    Description: Aliphatic poly(carbonate)s (APCs) with rapid and controlled degradation upon specific stimulation have great advantages for a variety of biomedical and pharmaceutical applications. In the present work, we reported a new poly(trimethylene carbonate) (PTMC)-based copolymer containing multiple 4,5-dimethoxy-2-nitrobenzyl photo cleavable groups as pendent chains. The six-membered light-responsive cyclic carbonate monomer (LrM) was first prepared from 2-(hydroxymethyl)-2-methylpropane-1,3-diol and 4,5-dimethoxy-2-nitrobenzyl alcohol and then copolymerized with trimethylene carbonate (TMC) by 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) catalyzed ring-opening polymerization (ROP) to afford the light-responsive polycarbonate (LrPC). The light-triggered decomposition of LrM and LrPC was studied by NMR, UV/vis spectroscopy, and size exclusion chromatography (SEC), as well as ESI-ToF mass spectrometry. Stable monodisperse nanoparticles with hydrodynamic diameter of 100 nm could be formulated from 25% LrPC and 75% poly(lactide- co-glycolide) (PLGA) and applied for the encapsulation of temoporfin. Upon irradiation with UV light these particles displayed a significant decrease of the particle countrate and increased the release rate of temoporfin in comparison to standard PLGA nanoparticles. This work demonstrated that a combination of encapsulation of photosensitizer and light degradation using light-responsive polymers is suitable to enhance photodynamic therapy (PDT).
    Keywords: Photochemotherapy ; Drug Carriers -- Chemistry ; Nanoparticles -- Chemistry ; Polyesters -- Chemistry
    ISSN: 15257797
    E-ISSN: 1526-4602
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  • 7
    Language: English
    In: PLoS ONE, 01 January 2018, Vol.13(1), p.e0189970
    Description: Symmetry is rarely found on cellular surfaces. An exception is the brush border of microvilli, which are essential for the proper function of transport epithelia. In a healthy intestine, they appear densely packed as a 2D-hexagonal lattice. For in vitro testing of intestinal transport the cell line Caco-2 has been established. As reported by electron microscopy, their microvilli arrange primarily in clusters developing secondly into a 2D-hexagonal lattice. Here, atomic force microscopy (AFM) was employed under aqueous buffer conditions on Caco-2 cells, which were cultivated on permeable filter membranes for optimum differentiation. For analysis, the exact position of each microvillus was detected by computer vision; subsequent Fourier transformation yielded the type of 2D-lattice. It was confirmed, that Caco-2 cells can build a hexagonal lattice of microvilli and form clusters. Moreover, a second type of arrangement was discovered, namely a rhombic lattice, which appeared at sub-maximal densities of microvilli with (29 ± 4) microvilli / μm2. Altogether, the findings indicate the existence of a yet undescribed pattern in cellular organization.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 8
    Language: English
    In: Toxicology, 2011, Vol.282(3), pp.112-121
    Description: Ergot alkaloids are secondary metabolites produced by fungi of the species . Toxic effects after consumption of contaminated grains are described since mediaeval times. Of the more than 40 known ergot alkaloids six are found predominantly. These are ergotamine, ergocornine, ergocryptine, ergocristine, ergosine and ergometrine, along with their corresponding isomeric forms (-inine-forms). Toxic effects are known to be induced by an interaction of the ergot alkaloids as neurotransmitters, like dopamine or serotonin. Nevertheless data concerning cytotoxic effects are missing and therefore a screening of the six main ergot alkaloids was performed in human primary cells in order to evaluate the toxic potential. As it is well known that ergot alkaloids isomerize easily the stability was tested in the cell medium. Based on these results factors were calculated to correct the used concentration values to the biologically active lysergic (-ine) form. These factors range from 1.4 for the most stable compound ergometrine to 5.0 for the most unstable ergot alkaloid ergocristine. With these factors, reflecting the instability, several controverse literature data concerning the toxicity could be explained. To evaluate the cytotoxic effects of ergot alkaloids, human cells in primary culture were used. These cells remain unchanged in contrast to cell lines and the data allow a better comparison to the situation than using immortalized cell lines. To characterize the effects on primary cells, renal proximal tubule epithelial cells (RPTEC) and normal human astrocytes (NHA) were used. The parameters necrosis (LDH-release) and apoptosis (caspase-3-activation, DNA condensation and fragmentation) were distinguished. The results show that depending on the individual structure of the peptide ergot alkaloids the toxic properties change. While ergometrine as a lysergic acid amide did not show any effect, the peptide ergot alkaloids revealed a different toxic potential. Of all tested ergot alkaloids ergocristine was the most cytotoxic compound inducing apoptosis in human kidney cells starting at a concentration of 1 μM in RPTEC. Uptake studies underline the cytotoxic properties, with an accumulation of peptide ergot alkaloids and no uptake of ergometrine. The results represent a new description of effects of ergot alkaloids regarding cytotoxicity and accumulation in human primary cells. For the first time apoptosis has been identified besides well described receptor effects. This gives a hint for a more complex mode of action of ergot alkaloids than described in literature so far.
    Keywords: Primary Cells ; Apoptosis ; Ergot Alkaloids ; Stability ; Uptake ; Accumulation ; Pharmacy, Therapeutics, & Pharmacology ; Public Health
    ISSN: 0300-483X
    E-ISSN: 1879-3185
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  • 9
    Language: English
    In: Analytica Chimica Acta, 28 September 2016, Vol.938, pp.106-113
    Description: Limited drug penetration into tumor tissue is a significant factor to the effectiveness of cancer therapy. Tumor spheroids, a 3D cell culture model system, can be used to study drug penetration for pharmaceutical development. In this study, a method for quantitative bioimaging of platinum group elements by laser ablation (LA) coupled to inductively coupled plasma mass spectrometry (ICP-MS) is presented. Different matrix-matched standards were used to develop a quantitative LA-ICP-MS method with high spatial resolution. To investigate drug penetration, tumor spheroids were incubated with platinum complexes (Pt(II)acetylacetonate, cisplatin) and the palladium tagged photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin ( THPP). Distribution and accumulation of the pharmaceuticals were determined with the developed method.
    Keywords: La-Icp-MS ; Quantification ; Tumor Spheroids ; Pt Cytostatics ; Photosensitizer ; Chemistry
    ISSN: 0003-2670
    E-ISSN: 1873-4324
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  • 10
    Language: English
    In: Materials Today: Proceedings, 2017, Vol.4, pp.S193-S199
    Description: The blood brain-barrier is a major obstacle in the treatment of several central nervous disorders. In this context polysorbate 80-coated nanoparticles, which are quite well characterised concerning their behaviour , are an often described approach to enable transport of certain drugs into the brain. In the present study we prepared polysorbate 80-coated nanoparticles based on poly(lactid acid) and quantified the amount of adsorbed polysorbate 80 spectrophotometrically. In order to receive information about the behaviour in biological systems we analysed the protein corona by SDS-PAGE and finally investigated the cellular uptake in dependence of a previous incubation with fetal bovine serum.
    Keywords: Nanoparticles ; Polysorbate 80 ; Protein Adsorption ; Endothelial Cells ; Cellular Uptake
    ISSN: 2214-7853
    E-ISSN: 2214-7853
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