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  • 1.
    Badal Tejedor, Maria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP, Technical Research Institute of Sweden, Box 5607, SE-114 86 Stockholm, Swede.
    Nordgren, N.
    Schuleit, M.
    Rutland, Mark W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. SP, Technical Research Institute of Sweden, Box 5607, SE-114 86 Stockholm, Swede.
    Millqvist-Fureby, A.
    Tablet mechanics depend on nano and micro scale adhesion, lubrication and structure2015In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 486, no 1-2, p. 315-323Article in journal (Refereed)
    Abstract [en]

    Tablets are the most convenient form for drug administration. However, despite the ease of manufacturing problems such as powder adhesion occur during the production process. This study presents surface and structural characterization of tablets formulated with commonly used excipients (microcrystalline cellulose (MCC), lactose, mannitol, magnesium (Mg) stearate) pressed under different compaction conditions. Tablet surface analyses were performed with scanning electron microscopy (SEM), profilometry and atomic force microscopy (AFM). The mechanical properties of the tablets were evaluated with a tablet hardness test. Local adhesion detected by AFM decreased when Mg stearate was present in the formulation. Moreover, the tablet strength of plastically deformable excipients such as MCC was significantly decreased after addition of Mg stearate. Combined these facts indicate that Mg stearate affects the particle-particle bonding and thus elastic recovery. The MCC excipient also displayed the highest hardness which is characteristic for a highly cohesive material. This is discussed in the view of the relatively high adhesion found between MCC and a hydrophilic probe at the nanoscale using AFM. In contrast, the tablet strength of brittle materials like lactose and mannitol is unaffected by Mg stearate. Thus fracture occurs within the excipient particles and not at particle boundaries, creating new surfaces not previously exposed to Mg stearate. Such uncoated surfaces may well promote adhesive interactions with tools during manufacture.

  • 2. Bannow, J.
    et al.
    Benjamins, J. -W
    Wohlert, Jakob
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Löbmann, K.
    Svagan, Anna J.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Solid nanofoams based on cellulose nanofibers and indomethacin—the effect of processing parameters and drug content on material structure2017In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 526, no 1-2, p. 291-299Article in journal (Refereed)
    Abstract [en]

    The unique colloidal properties of cellulose nanofibers (CNF), makes CNF a very interesting new excipient in pharmaceutical formulations, as CNF in combination with some poorly-soluble drugs can create nanofoams with closed cells. Previous nanofoams, created with the model drug indomethacin, demonstrated a prolonged release compared to films, owing to the tortuous diffusion path that the drug needs to take around the intact air-bubbles. However, the nanofoam was only obtained at a relatively low drug content of 21 wt% using fixed processing parameters. Herein, the effect of indomethacin content and processing parameters on the foaming properties was analysed. Results demonstrate that a certain amount of dissolved drug is needed to stabilize air-bubbles. At the same time, larger fractions of dissolved drug promote coarsening/collapse of the wet foam. The pendant drop/bubble profile tensiometry was used to verify the wet-foam stability at different pHs. The pH influenced the amount of solubilized drug and the processing-window was very narrow at high drug loadings. The results were compared to real foaming-experiments and solid state analysis of the final cellular solids. The parameters were assembled into a processing chart, highlighting the importance of the right combination of processing parameters (pH and time-point of pH adjustment) in order to successfully prepare cellular solid materials with up to 46 wt% drug loading.

  • 3.
    Dahlberg, Carina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Drugs and polymers in dissolving solid dispersions: NMR imaging and spectroscopy2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The number of poorly water-soluble drug substances in the pharmaceutical pipeline is increasing, and thereby also the need to design effective drug delivery systems providing high bioavailability. One favourable formulation approach is preparation of solid dispersions, where dispersing a poorly water-soluble drug in a water-soluble polymer matrix improves the dissolution behaviour and the bioavailability of the drug. However, in order to take full advantage of such formulations the impact of material properties on their performance needs to be investigated.

     

    An experimental toolbox has been designed, and applied, for analysing the processes which govern the behaviour of solid pharmaceutical formulations in general, and that of solid dispersions in particular. For the purpose of monitoring multifaceted phenomena in situ during tablet dissolution, nuclear magnetic resonance (NMR) spectroscopy and NMR imaging are superior to many other techniques, both on macroscopic and molecular levels. The versatility of NMR with its isotope and chemical selectivity allows one to follow the influence of the original tablet properties on polymer mobilisation, drug migration and water penetration selectively. Mapping these processes on relevant time scales in dissolving tablets highlighted the gel layer inhomogeneity below the originally dry tablet surface as a key factor for drug release kinetics.

     

    Furthermore, NMR relaxometry has been shown to provide novel information about the particle size of the drug and its recrystallisation behaviour within swelling solid dispersions. The NMR experiments have been complemented and supported by investigation of the crystalline state, the powder morphology and the surface composition of the dry solid dispersions. These experiments have been performed by X-ray photoelectron spectroscopy (XPS),  scanning electron microscopy (SEM), powder X-ray diffraction (pXRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and dynamic contact angle (DAT) measurements.

     

    The methods presented in this thesis provide a new avenue towards better understanding of the behaviour of solid dispersions, which in turn may result in more effective distribution of promising drug candidates despite their low water-solubility.

  • 4. Fransson, Magnus
    et al.
    Johansson, Jonas
    Sparén, Anders
    Svensson, Olof
    Quantitative Analysis Of Solid Pharmaceutical Formulations Using Transmission Raman Spectroscopy2010In: XXII INTERNATIONAL CONFERENCE ON RAMAN SPECTROSCOPY   / [ed] Champion PM, Ziegler LD, 2010, Vol. 1267, p. 160-161Conference paper (Refereed)
  • 5. Gupta, Sonali
    et al.
    Tewatia, Parul
    KTH, School of Computer Science and Communication (CSC), Computational Science and Technology (CST).
    Misri, Jyoti
    Singh, Rajni
    Molecular Modeling of Cloned Bacillus subtilis Keratinase and Its Insinuation in Psoriasis Treatment Using Docking Studies2017In: Indian Journal of Microbiology, ISSN 0046-8991, E-ISSN 0973-7715, Vol. 57, no 4, p. 485-491Article in journal (Refereed)
    Abstract [en]

    Present study demonstrated the expression of cloned Bacillus subtilis RSE163 keratinase gene and in silico binding affinities of deduced protein with psoriasis topical drugs for systemic absorption and permeation through skin. The ker gene expressed in E. coli showed significantly higher keratinase activity 450 +/- 10.43 U representing 1342 bp nucleotides encoding 447 amino acids with molecular weight of 46 kDa. The modeled structure was validated using ramachandran's plot showing 305 residues (84.3%) in most favoured region. Docking studies using extra precision (XP) method of Glide showed optimum binding affinities with the drugs Acitretin (- 39.62 kcal/mol), Clobetasol propionate (- 37.90 kcal/mol), Fluticasone (- 38.53 kcal/mol), Desonide (- 32.23 kcal/mol), Anthralin (- 38.04 kcal/mol), Calcipotreine (- 21.55 kcal/mol) and Mometasone (- 28.40 kcal/mol) in comparison to other psoriasis drugs. The results can further be correlated with in vitro enzymatic experiments using keratinase as an effective drug mediator through skin to serve the unmet need of industries.

  • 6. Hedenus, M.
    et al.
    Näsman, Per
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics.
    Liwing, J.
    Economic evaluation in Sweden of epoetin beta with intravenous iron supplementation in anaemic patients with lymphoproliferative malignancies not receiving chemotherapy2008In: Journal of Clinical Pharmacy and Therapeutics, ISSN 0269-4727, E-ISSN 1365-2710, Vol. 33, no 4, p. 365-374Article in journal (Refereed)
    Abstract [en]

     Background and objective: Functional iron deficiency is one reason for lack of response to erythropoietin treatment. Concomitant intravenous (IV) iron supplementation has the potential to improve response to erythropoietin, allowing a decrease in erythropoietin dose requirements. In a recent study of anaemic, iron-replete patients with lymphoproliferative malignancies (Leukemia, 21, 2007, 627), the haemoglobin (Hb) increase and response rate were significantly greater in patients receiving epoetin beta with concomitant IV iron compared with patients receiving epoetin beta without IV iron (P < 0 05). The present analysis aimed to investigate whether a combination of epoetin beta and IV iron is cost-effective compared with epoetin beta without IV iron.

    Methods: This analysis was performed from a Swedish societal perspective as a within-trial evaluation of overall costs (based on differences in drug costs and resource use between groups) and effect (differences in Hb increases) during 16 weeks' treatment with epoetin beta with or without concomitant IV iron.

    Results and discussion: There was an improved response to epoetin beta with IV iron therapy and an almost 2-fold greater increase in Hb levels. Overall mean cost per patient in the epoetin beta with IV iron group was is an element of 5558 and in the epoetin beta without IV iron group was is an element of 6228. Thus, treatment with epoetin beta with IV iron resulted in overall cost savings of about 11% compared with epoetin beta without iron, mainly due to reduced erythropoietin dosages.

    Conclusion: Epoetin beta with concomitant IV iron in anaemic patients with lymphoproliferative malignancies not receiving chemotherapy resulted in better outcomes at lower cost compared with epoetin beta without iron. This suggests that epoetin beta with IV iron is a dominant therapy from a Swedish perspective.

  • 7.
    Hsieh, Yves S. Y.
    et al.
    University of Sydney, Australia.
    Taleski, Deni
    Wilkinson, Brendan L.
    Wijeyewickrema, Lakshmi C.
    Adams, Ty. E.
    Pike, Robert N.
    Payne, Richard J.
    Effect of O-glycosylation and tyrosine sulfation of leech-derived peptides on binding and inhibitory activity against thrombin2012In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 48, no 10, p. 1547-9Article in journal (Refereed)
    Abstract [en]

    Synthesis of sulfated and unsulfated (glyco)peptide fragments of Hirudin P6 (a potent anticoagulant from the leech Hirudinaria manillensis) is described. The effect of O-glycosylation and tyrosine sulfation on thrombin binding and peptidolytic activity was investigated, together with the inhibition of fibrinogen cleavage.

  • 8.
    Hsieh, Yves S. Y.
    et al.
    University of Sydney, Australia.
    Wilkinson, Brendan L.
    O'Connell, Mitchell R.
    Mackay, Joel P.
    Matthews, Jacqueline M.
    Payne, Richard J
    Synthesis of the bacteriocin glycopeptide sublancin 168 and S-glycosylated variants2012In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, no 7, p. 1910-3Article in journal (Refereed)
    Abstract [en]

    The synthesis of sublancin 168, a unique S-glucosylated bacteriocin antibiotic, is described. The natural product and two S-glycosylated variants were successfully prepared via native chemical ligation followed by folding. The synthetic glycopeptides were shown to possess primarily an α-helical secondary structure by CD and NMR studies.

  • 9.
    Huaiyu, Yang
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystallization of Parabens: Thermodynamics, Nucleation and Processing2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this work, the solubility of butyl paraben in 7 pure solvents and in 5 different ethanol-water mixtures has been determined from 1 ˚C to 50 ˚C. The solubility of ethyl paraben and propyl paraben in various solvents has been determined at 10 ˚C. The molar solubility of butyl paraben in pure solvents and its thermodynamic properties, measured by Differential Scanning Calorimetry, have been used to estimate the activity of the pure solid phase, and solution activity coefficients.

    More than 5000 nucleation experiments of ethyl paraben, propyl paraben and butyl paraben in ethyl acetate, acetone, methanol, ethanol, propanol and 70%, 90% ethanol aqueous solution have been performed. The induction time of each paraben has been determined at three different supersaturation levels in various solvents. The wide variation in induction time reveals the stochastic nature of nucleation. The solid-liquid interfacial energy, free energy of nucleation, nuclei critical radius and pre-exponential factor of parabens in these solvents have been determined according to the classical nucleation theory, and different methods of evaluation are compared. The interfacial energy of parabens in these solvents tends to increase with decreasing mole fraction solubility but the correlation is not very strong. The influence of solvent on nucleation of each paraben and nucleation behavior of parabens in each solvent is discussed. There is a trend in the data that the higher the boiling point of the solvent and the higher the melting point of the solute, the more difficult is the nucleation. This observation is paralleled by the fact that a metastable polymorph has a lower interfacial energy than the stable form, and that a solid compound with a higher melting point appears to have a higher solid-melt and solid-aqueous solution interfacial energy.

    It has been found that when a paraben is added to aqueous solutions with a certain proportion of ethanol, the solution separates into two immiscible liquid phases in equilibrium. The top layer is water-rich and the bottom layer is paraben-rich. The area in the ternary phase diagram of the liquid-liquid-phase separation region increases with increasing temperature. The area of the liquid-liquid-phase separation region decreases from butyl paraben, propyl paraben to ethyl paraben at the constant temperature.

    Cooling crystallization of solutions of different proportions of butyl paraben, water and ethanol have been carried out and recorded using the Focused Beam Reflectance Method, Particle Vision and Measurement, and in-situ Infrared Spectroscopy. The FBRM and IR curves and the PVM photos track the appearance of liquid-liquid phase separation and crystallization. The results suggest that the liquid-liquid phase separation has a negative influence on the crystal size distribution. The work illustrates how Process Analytical Technology (PAT) can be used to increase the understanding of complex crystallizations.

    By cooling crystallization of butyl paraben under conditions of liquid-liquid-phase separation, crystals consisting of a porous layer in between two solid layers have been produced. The outer layers are transparent and compact while the middle layer is full of pores. The thickness of the porous layer can reach more than half of the whole crystal. These sandwich crystals contain only one polymorph as determined by Confocal Raman Microscopy and single crystal X-Ray Diffraction. However, the middle layer material melts at lower temperature than outer layer material.

  • 10. Kim, D.
    et al.
    Lee, J.
    Lee, Sunjae
    KTH, Centres, Science for Life Laboratory, SciLifeLab. Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, South Korea.
    Park, J.
    Lee, D.
    Predicting unintended effects of drugs based on off-target tissue effects2016In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 469, no 3, p. 399-404Article in journal (Refereed)
    Abstract [en]

    Unintended effects of drugs can be caused by various mechanisms. Conventional analysis of unintended effects has focused on the target proteins of drugs. However, an interaction with off-target tissues of a drug might be one of the unintended effect-related mechanisms. We propose two processes to predict a drug’s unintended effects by off-target tissue effects: 1) identification of a drug’s off-target tissue and; 2) tissue protein - symptom relation identification (tissue protein - symptom matrix). Using this method, we predicted that 1,177 (10.7%) side-effects were related to off-target tissue effects in 11,041 known side-effects. Off-target tissues and unintended effects of successful repositioning drugs were also predicted. The effectiveness of relations of the proposed tissue protein - symptom matrix were evaluated by using the literature mining method. We predicted unintended effects of drugs as well as those effect-related off-target tissues. By using our prediction, we are able to reduce drug side-effects on off-target tissues and provide a chance to identify new indications of drugs of interest.

  • 11. Liao, Shih-Fen
    et al.
    Liang, Chi-Hui
    Ho, Ming-Yi
    Hsu, Tsui-Ling
    Tsai, Tsung-I
    Hsieh, Yves S-Y
    Academia Sinica, Taiwan.
    Tsai, Chih-Ming
    Li, Shiou-Ting
    Cheng, Yang-Yu
    Tsao, Shu-Ming
    Lin, Tung-Yi
    Lin, Zong-Yan
    Yang, Wen-Bin
    Ren, Chien-Tai
    Lin, Kuo-I
    Khoo, Kay-Hooi
    Lin, Chun-Hung
    Hsu, Hsien-Yeh
    Wu, Chung-Yi
    Wong, Chi-Huey
    Immunization of fucose-containing polysaccharides from Reishi mushroom induces antibodies to tumor-associated Globo H-series epitopes.2013In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 110, no 34, p. 13809-13814Article in journal (Refereed)
    Abstract [en]

    Carbohydrate-based vaccines have shown therapeutic efficacy for infectious disease and cancer. The mushroom Ganoderma lucidum (Reishi) containing complex polysaccharides has been used as antitumor supplement, but the mechanism of immune response has rarely been studied. Here, we show that the mice immunized with a l-fucose (Fuc)-enriched Reishi polysaccharide fraction (designated as FMS) induce antibodies against murine Lewis lung carcinoma cells, with increased antibody-mediated cytotoxicity and reduced production of tumor-associated inflammatory mediators (in particular, monocyte chemoattractant protein-1). The mice showed a significant increase in the peritoneal B1 B-cell population, suggesting FMS-mediated anti-glycan IgM production. Furthermore, the glycan microarray analysis of FMS-induced antisera displayed a high specificity toward tumor-associated glycans, with the antigenic structure located in the nonreducing termini (i.e., Fucα1-2Galβ1-3GalNAc-R, where Gal, GalNAc, and R represent, respectively, D-galactose, D-N-acetyl galactosamine, and reducing end), typically found in Globo H and related tumor antigens. The composition of FMS contains mainly the backbone of 1,4-mannan and 1,6-α-galactan and through the Fucα1-2Gal, Fucα1-3/4Man, Fucα1-4Xyl, and Fucα1-2Fuc linkages (where Man and Xyl represent d-mannose and d-xylose, respectively), underlying the molecular basis of the FMS-induced IgM antibodies against tumor-specific glycans.

  • 12. Löhr, J. -M
    et al.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Fagerberg, B.
    Nanoparticles for cancer therapy2017In: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 114, no 27-29Article in journal (Refereed)
    Abstract [en]

    Nanoparticles carry a big promise in oncology, for diagnosis/imaging, therapy, or both (theragnostics). As common in medical history, there is a huge gap between the exciting experimental possibilities and data and clinical studies making use of it. Of the cell-containing nanoparticles, only one formulation using gene-directed enzyme prodrug therapy (GDEPT) with CYP2B1 and ifosfamide was used in early clinical studies. Of the cellfree nanoparticles, some drug-releasing (doxorubicin) ones are in clinical use for trans-arterial chemoembolization (TACE) in liver tumors and metastasis. Using liposomes, both paclitaxel and irinotecan have been used in pancreatic cancer as the model indication. Nanoparticle-albumin-bound paclitaxel (NAB-paclitaxel) has also been developed and is now registered as a drug for first-line therapy of pancreatic cancer, as is the liposomal irinotecan. The novel nanoparticle formulations carry a big promise for even better performance, both in diagnosis and therapy; however, few of these has entered the clinic as of today.

  • 13. Poongavanam, Vasanthanathan
    et al.
    Namasivayam, Vigneshwaran
    Vanangamudi, Murugesan
    Al Shamaileh, Hadi
    Veedu, Rakesh N.
    Kihlberg, Jan
    Natarajan Arul, Murugan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Theoretical Chemistry and Biology.
    Integrative approaches in HIV-1 non-nucleoside reverse transcriptase inhibitor design2018In: Wiley Interdisciplinary Reviews. Computational Molecular Science, ISSN 1759-0876, E-ISSN 1759-0884, Vol. 8, no 1, article id e1328Article in journal (Refereed)
    Abstract [en]

    The design of inhibitors for human immunodeficiency virus type-1 reverse transcriptase (HIV-1 RT) is one of the most successful approaches for the treatment of HIV infections. Among the HIV-1 RT inhibitors, non-nucleoside reverse transcriptase inhibitors (NNRTIs) constitute a prominent drug class, which includes nevirapine, delavirdine, efavirenz, etravirine, and rilpivirine approved for clinical use. However, the efficiency of many of these drugs has been undermined by drug-resistant variants of HIV-1 RT, and it therefore becomes inevitable to design novel drugs to cope with resistance. Here, we discuss various drug design strategies, which include traditional medicinal chemistry, computational chemistry, and chemical biology approaches. In particular, computational modeling approaches, including machine learning, empirical descriptors-based, force-field, ab initio, and hybrid quantum mechanics/molecular mechanics-based methods are discussed in detail. We foresee that these methods will have a major impact on efforts to guide the design and discovery of the next generation of NNRTIs that combat RT multidrug resistance.

  • 14. Svagan, A. J.
    et al.
    Kusic, A.
    De Gobba, C.
    Larsen, F. H.
    Sassene, P.
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience.
    Van De Weert, M.
    Mullertz, A.
    Jørgensen, B.
    Ulvskov, P.
    Rhamnogalacturonan-I based microcapsules for targeted drug release2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 12, article id e0168050Article in journal (Refereed)
    Abstract [en]

    Drug targeting to the colon via the oral administration route for local treatment of e.g. inflammatory bowel disease and colonic cancer has several advantages such as needle-free administration and low infection risk. A new source for delivery is plant-polysaccharide based delivery platforms such as Rhamnogalacturonan-I (RG-I). In the gastro-intestinal tract the RG-I is only degraded by the action of the colonic microflora. For assessment of potential drug delivery properties, RG-I based microcapsules (~1 μm in diameter) were prepared by an interfacial poly-addition reaction. The cross-linked capsules were loaded with a fluorescent dye (model drug). The capsules showed negligible and very little in vitro release when subjected to media simulating gastric and intestinal fluids, respectively. However, upon exposure to a cocktail of commercial RG-I cleaving enzymes, ~ 9 times higher release was observed, demonstrating that the capsules can be opened by enzymatic degradation. The combined results suggest a potential platform for targeted drug delivery in the terminal gastro-intestinal tract.

  • 15.
    Svagan, Anna J.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. University of Copenhagen, Denmark.
    Benjamins, Jan-Willem
    Al-Ansari, Zeinab
    Bar Shalom, Daniel
    Mullertz, Anette
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Lobmann, Korbinian
    Solid cellulose nanofiber based foams - Towards facile design of sustained drug delivery systems2016In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 244, p. 74-82Article in journal (Refereed)
    Abstract [en]

    Control of drug action through formulation is a vital and very challenging topic within pharmaceutical sciences. Cellulose nanofibers (CNF) are an excipient candidate in pharmaceutical formulations that could be used to easily optimize drug delivery rates. CNF has interesting physico-chemical properties that, when combined with surfactants, can be used to create very stable air bubbles and dry foams. Utilizing this inherent property, it is possible to modify the release kinetics of the model drug riboflavin in a facile way. Wet foams were prepared using cationic CNF and a pharmaceutically acceptable surfactant (lauric acid sodium salt). The drug was suspended in the wetstable foams followed by a drying step to obtain dry foams. Flexible cellular solid materials of different thicknesses, shapes and drug loadings (up to 50 wt%) could successfully be prepared. The drug was released from the solid foams in a diffusion-controlled, sustained manner due to the presence of intact air bubbles which imparted a tortuous diffusion path. The diffusion coefficient was assessed using Franz cells and shown to be more than one order of magnitude smaller for the cellular solids compared to the bubble-free films in the wet state. By changing the dimensions of dry foams while keeping drug load and total weight constant, the drug release kinetics could be modified, e.g. a rectangular box-shaped foam of 8 mm thickness released only 59% of the drug after 24 h whereas a thinner foam sample (0.6 mm) released 78% of its drug content within 8 h. In comparison, the drug release from films (0.009 mm, with the same total mass and an outer surface area comparable to the thinner foam) was much faster, amounting to 72% of the drug within 1 h. The entrapped air bubbles in the foam also induced positive buoyancy, which is interesting from the perspective of gastroretentive drug-delivery.

  • 16. Valetti, Sabrina
    et al.
    Wankar, Jitendra
    Ericson, Marica B.
    Feiler, Adam
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Manet, Ilse
    Mesoporous silica particles as a lipophilic drug vehicle investigated by fluorescence lifetime imaging2017In: Journal of materials chemistry. B, ISSN 2050-750X, E-ISSN 2050-7518, Vol. 5, no 17, p. 3201-3211Article in journal (Refereed)
    Abstract [en]

    Three types of new label-free fluorescent mesoporous silica micro- and nanoparticles were prepared by controlled thermal decomposition of carboamino groups linked on the surface without compromising the drug loading capacity of the silica particles. Clofazimine, a lipophilic antibiotic drug with excellent in vitro activity against mycobacterium tuberculosis, was encapsulated inside these fluorescent particles to obtain multifunctional drug carriers of interest in the field of theranostics. The morphological features together with the photophysical properties of both powders and aqueous suspensions are described. The photophysical properties seem to be independent of the mesoporosity features but correlate with the residual carboamino functionalization. The particles are endowed with emission in the visible region and have fluorescence lifetimes of up to 9.0 ns that can be easily discriminated from intrinsic biological fluorescence. Furthermore, their fluorescence lifetime offers a promising tool to follow the release of the encapsulated drug which is not possible by means of simple fluorescence intensity. We report here a novel attractive theranostic platform enabling monitoring of drug release in biological environments by means of fluorescence lifetime.

  • 17.
    Yang, Huaiyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. Limerick University.
    Nucleation of butyl paraben in different solvents2013In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 13, no 10, p. 4226-4238Article in journal (Refereed)
    Abstract [en]

    The primary nucleation induction time of butyl paraben in pure solvents: acetone, ethyl acetate, methanol, ethanol, and propanol and in 70% and 90% ethanol aqueous mixtures has been determined. At each condition, about 100 experiments have been performed in 5 mL scale to capture the statistics of the nucleation process. The induction times at each condition show a wide variation. The data has been evaluated within the framework of the classical nucleation theory using several of the current approaches. Overall, the data obtained from the different methods of evaluation are surprisingly consistent. At comparable driving forces, nucleation is clearly fastest in acetone and slowest in propanol, with methanol, ethyl acetate, and ethanol in between. Adding water to the ethanol leads to a clear reduction in the nucleation rate. The solid-solution interfacial energy of butyl paraben in the different solvents decreases in the order: 70% ethanol > 90% ethanol > propanol > ethanol > ethyl acetate > methanol > acetone, which is surprisingly well-correlated to a decreasing solvent boiling point. It is shown that the same trend can be found for other systems in the literature. With the assumption that the stronger the bonding in the bulk phases, the higher the interfacial energy becomes, this observation is paralleled by the fact that a metastable polymorph has a lower interfacial energy than the stable form and that a solid compound with a higher melting point appears to have a higher solid-melt and solid-solution interfacial energy.

  • 18.
    Yang, Huaiyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. Solid-State Research Group, Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, United Kingdom .
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. University of Limerick, Department of Chemical and Environmental Science, Materials and Surface Science Institute, Ireland .
    Sandwich crystals of butyl paraben2014In: CRYSTENGCOMM, ISSN 1466-8033, Vol. 16, no 37, p. 8863-8873Article in journal (Refereed)
    Abstract [en]

    Butyl paraben crystals having a porous layer in between two solid non-porous layers have been produced by cooling crystallization in mixtures of ethanol and water. The outer layers are transparent and fully crystalline, while the middle layer appears to be polycrystalline and is full of pores of various dimensions, down to below 0.1 mu m diameters. The thickness of the porous layer reaches about 40% of the whole crystal. The crystals contain one polymorph only and appear to be essentially fully crystalline. They are stable for more than a year when stored on the shelf at room temperature. When the crystals dissolve, the porous layer dissolves faster, leaving the outer layers for slower dissolution. The sandwich crystals are easily cleaved through the middle layer parallel to the (100) plane. This type of sandwich crystals may provide new useful properties to pharmaceutical solids, e. g. larger specific surface area, higher dissolution rates and improved compaction properties.

  • 19.
    Yang, Huaiyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. Limerick University.
    Ternary diagrams of ethyl paraben and propyl parabenManuscript (preprint) (Other academic)
  • 20.
    Yang, Huaiyu
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. Strathclyde Institute of Pharmacy and Pharmaceutical Sciences, University of Strathclyde3, United Kingdom .
    Svärd, Michael
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. Department of Chemical and Environmental Science, Materials and Surface Science Institute, University of Limerick, Ireland .
    Zeglinski, Jacek
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. Department of Chemical and Environmental Science, Materials and Surface Science Institute, University of Limerick, Ireland .
    Influence of Solvent and Solid-State Structure on Nucleation of Parabens2014In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, no 8, p. 3890-3902Article in journal (Refereed)
    Abstract [en]

    In the present work, the induction time for nucleation of ethyl paraben (EP) and propyl paraben (PP) in ethanol, ethyl acetate, and acetone has been measured at different levels of supersaturation. The induction time shows a wide variation among repeat experiments, indicative of the stochastic nature of nucleation. The solid-liquid interfacial energy and the size of the critical nucleus have been determined according to the classical nucleation theory. Combined with previous results for butyl paraben (BP), the nucleation behavior is analyzed with respect to differences in the solid phase of the three pure compounds, and with respect to differences in the solution. The results indicate that the difficulty of nucleation in ethanol and acetone increases in the order BP < PP < EP but is approximately the same in ethyl acetate. For each of the three parabens, the difficulty of nucleation increases in the order acetone < ethyl acetate < ethanol. The Gibbs energy of melting increases in the order BP < PP < EP, but the crystal structures are quite similar resulting in the basic crystal shape being very much the same. The solid-liquid interfacial energy is reasonably well correlated to the solvation energy, and even better correlated to the deformation energy, of the solute molecule within the first solvation shell as obtained by density functional theory calculations.

  • 21.
    Yin, Huijuan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cellular Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Fontana, Jacopo M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cellular Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Solandt, Johan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cellular Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab. AstraZeneca R&D, Sweden.
    Jussi, Johnny Israelsson
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cellular Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Xu, Hao
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cellular Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cellular Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Fu, Ying
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cellular Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Quantum dots modulate intracellular Ca2+ level in lung epithelial cells2017In: International Journal of Nanomedicine, ISSN 1176-9114, E-ISSN 1178-2013, Vol. 12, p. 2781-2792Article in journal (Refereed)
    Abstract [en]

    While adverse effects of nanoparticles on lung health have previously been proposed, few studies have addressed the direct effects of nanoparticle exposure on the airway epithelium. In this work, we examine the response of the pulmonary airway to nanoparticles by measuring intracellular Ca2+ concentration ([Ca2+](i)) in the Calu-3 epithelial layer stimulated by 3-mercaptopropionic-acid (3MPA) coated CdSe-CdS/ZnS core-multishell quantum dots (QDs). Simultaneous transient transepithelial electrical resistance (TEER) decrease and global [Ca2+](i) increase in Calu-3 epithelial layer, accompanied by cell displacements, contraction, and expansion, were observed under QD deposition. This suggests that a QD-induced global [Ca2+](i) increase in the Calu-3 epithelial layer caused the transient TEER decrease. The [Ca2+](i) increase was marked and rapid in the apical region, while [Ca2+](i) decreased in the basolateral region of the epithelial layer. TEER transient response and extracellular Ca2+ entry induced by QD deposition were completely inhibited in cells treated with stretched-activated (SA) inhibitor GdCl3 and store-operated calcium entry (SOCE) inhibitor BTP2 and in cells immersed in Ca2+-free medium. The voltage-gated calcium channel (VGCC) inhibitor nifedipine decreased, stabilized, and suppressed the TEER response, but did not affect the [Ca2+](i) increase, due to QD deposition. This demonstrates that the Ca2+ influx activated by QDs' mechanical stretch occurs through activation of both SA and SOCE channels. QD-induced [Ca2+](i) increase occurred in the Calu-3 epithelial layer after culturing for 15 days, while significant TEER drop only occurred after 23 days. This work provides a new perspective from which to study direct interactions between airway epithelium and nanoparticles and may help to reveal the pathologies of pulmonary disease.

1 - 21 of 21
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