Light and Electron Microscopy

  • Heike BunjesEmail author
  • Judith Kuntsche
Part of the Advances in Delivery Science and Technology book series (ADST)


Microscopic techniques have a long history in pharmaceutical formulation research and development. They are especially useful for the study of systems containing particles of different length scales (like powders, granules, or colloidal suspensions) but can also be employed for the study of compact solid forms like tablets or of semisolids. As they yield a visual impression of the object of study they provide a rather natural way to the comprehension of sample behavior. As with all analytical techniques, however, there may be limitations and pitfalls that should be known in order to employ the methods correctly. This chapter explains the basic features of the microscopic techniques traditionally employed in pharmaceutical research—optical light microscopy as well as scanning and transmission electron microscopy with their respective variations. Apart from a short overview on instrumentation, the different sample preparation techniques are explained and a selection of pharmaceutical application examples is provided to illustrate the wealth of information that can be obtained and to stimulate a more detailed exploration of the possibilities of these fascinating methods.


Optical microscopy Polarized light microscopy Transmission electron microscopy Cryoelectron microscopy Freeze-fracture Negative staining Scanning electron microscopy Energy dispersive X-ray spectrometry 


  1. Abbaspour M, Sadeghi F, Afrasiabi Garekani H (2008) Design and study of ibuprofen disintegrating sustained-release tablets comprising coated pellets. Eur J Pharm Biopharm 68:747–759PubMedCrossRefGoogle Scholar
  2. Abramowitz M, Davidson MW (2014) Immersion media. Accessed 30 Nov 2014
  3. Abramowitz M, Spring KR, Keller HE, Davidson MW (2002) Basic principles of microscope objectives. BioTechniques 33:772–781PubMedGoogle Scholar
  4. Adi H, Larson I, Stewart PJ (2007) Adhesion and redistribution of salmeterol xinafoate particles in sugar-based mixtures for inhalation. Int J Pharm 337:229–238PubMedCrossRefGoogle Scholar
  5. Ainalem M, Carnerup AM, Janiak J, Alfredsson V, Nylander T, Schillén K (2009) Condensing DNA with poly(amido amine) dendrimers of different generations: means of controlling aggregate morphology. Soft Matter 5:2310–2320CrossRefGoogle Scholar
  6. Alfredsson V (2005) Cryo-TEM studies of DNA and DNA–lipid structures. Curr Opin Colloid Interf Sci 10:269–273CrossRefGoogle Scholar
  7. Almgren M, Edwards K, Karlsson G (2000) Cryo transmission electron microscopy of liposomes and related structures. Coll Surf A 174:3–21CrossRefGoogle Scholar
  8. Amar-Yuli I, Garti N (2005) Transitions induced by solubilized fat into reverse hexagonal mesophases. Colloids Surf B 43:72–82CrossRefGoogle Scholar
  9. Attama A, Schicke B, Müller-Goymann CC (2006) Further characterization of theobromae oil–beeswax admixtures as lipid matrices for improved drug delivery systems. Eur J Pharm Biopharm 64:294–306PubMedCrossRefGoogle Scholar
  10. Barauskas J, Johnsson M, Tiberg F (2005) Self-assembled lipid superstructures: beyond vesicles and liposomes. Nano Lett 5:1615–1619PubMedCrossRefGoogle Scholar
  11. Barauskas J, Misiunas A, Gunnarsson T, Tiberg F, Johnsson M (2006) “Sponge” nanoparticle dispersions in aqueous mixtures of diglycerol monooleate, glycerol dioleate, and polysorbate 80. Langmuir 22:6328–6334PubMedCrossRefGoogle Scholar
  12. Bauer J, Spanton S, Henry R, Quick J, Dziki W, Porter W, Morris J (2001) Ritonavir: an extraordinary example of conformational polymorphism. Pharm Res 18:859–866PubMedCrossRefGoogle Scholar
  13. Benedini L, Schulz EP, Messina PV, Palma SD, Allemandi DA, Schulz PC (2011) The ascorbyl palmitate-water system: phase diagram and state of water. Colloids Surf A 375:178–185CrossRefGoogle Scholar
  14. Bhakay A, Merwade M, Bilgili E, Dave RN (2011) Novel aspects of wet milling for the production of microsuspensions and nanosuspensions of poorly water-soluble drugs. Drug Dev Ind Pharm 37:963–976PubMedCrossRefGoogle Scholar
  15. Bibi S, Kaur R, Henriksen-Lacey M, McNeil SE, Wilkhu J, Lattmann E, Christensen D, Mohammed AR, Perrie Y (2011) Microscopy imaging of liposomes: from coverslips to environmental SEM. Int J Pharm 417:138–150PubMedCrossRefGoogle Scholar
  16. Bitterlich A, Laabs C, Busmann E, Grandeury A, Juhnke M, Bunjes H, Kwade A (2014) Challenges in nanogrinding of active pharmaceutical ingredients. Chem Eng Technol 37:840–846CrossRefGoogle Scholar
  17. Brandl M, Drechsler M, Bachmann D, Bauer K (1997) Morphology of semisolid aqueous phosphatidylcholine dispersions, a freeze fracture electron microscopy study. Chem Phys Lipids 87:65–72CrossRefGoogle Scholar
  18. Bunjes H, Drechsler M, Koch MHJ, Westesen K (2001) Incorporation of the model drug ubidecarenone into solid lipid nanoparticles. Pharm Res 18:287–293PubMedCrossRefGoogle Scholar
  19. Bunjes H, Steiniger F, Richter W (2007) Visualizing the structure of triglyceride nanoparticles in different crystal modifications. Langmuir 23:4005–4011PubMedCrossRefGoogle Scholar
  20. Burrows ND, Penn RL (2013) Cryogenic transmission electron microscopy: aqueous suspensions of nanoscale objects. Microsc Microanal 19:1542–1553PubMedCrossRefGoogle Scholar
  21. Carlton RA (2011) Pharmaceutical microscopy. Springer, New YorkGoogle Scholar
  22. Cheng L, Guo S, Wu W (2009) Characterization and in vitro release of praziquantel from poly(ɛ-caprolactone) implants. Int J Pharm 377:112–119PubMedCrossRefGoogle Scholar
  23. Chow K, Tong HHY, Lum S, Chow AHI (2008) Engineering of pharmaceutical materials: an industrial perspective. J Pharm Sci 97:2855–2877PubMedCrossRefGoogle Scholar
  24. Corveleyn S, Remon JP (1997) Formulation and production of rapidly disintegrating tablets by lyophilisation using hydrochlorothiazide as a model drug. Int J Pharm 152:215–225CrossRefGoogle Scholar
  25. Couvreur P, Reddy LH, Mangenot S, Poupaert JH, Desmaële D, Lepêtre-Mouelhi S, Pili B, Bourgaux C, Amenitsch H, Ollivon M (2008) Discovery of new hexagonal supramolecular nanostructures formed by squalenoylation of an anticancer nucleoside analogue. Small 4:247–253PubMedCrossRefGoogle Scholar
  26. Crisp J, Dann S, Blatchford C (2011) Antisolvent crystallization of pharmaceutical excipients from aqueous solutions and the use of preferred orientation in phase identification by powder X-ray diffraction. Eur J Pharm Sci 42:568–577PubMedCrossRefGoogle Scholar
  27. Davidson MW, Fellers TJ (2003) Understanding conjugate planes and Köhler illumination. Accessed 30 Nov 2014
  28. Dawidczyk CM, Russell LM, Searson PC (2014) Nanomedicines for cancer therapy: state-of-the-art and limitations to pre-clinical studies that hinder future developments. Front Chem 2:article 69Google Scholar
  29. Demana PH, Davies NM, Vosgerau U, Rades T (2004) Pseudo-ternary phase diagrams of aqueous mixtures of Quil A, cholesterol and phospholipid prepared by the lipid-film hydration method. Int J Pharm 270:229–239PubMedCrossRefGoogle Scholar
  30. Devi S, Williams D (2013) Morphological and compressional mechanical properties of freeze-dried mannitol, sucrose, and trehalose cakes. J Pharm Sci 102:4246–4255PubMedCrossRefGoogle Scholar
  31. Drent P (2005) Properties and selection of objective lenses for light microscopy applications. Microsc Anal 16:5–7Google Scholar
  32. Driscoll DF (2006) Lipid injectable emulsions: Pharmacopeial and safety issues. Pharm Res 23:1959–1969PubMedCrossRefGoogle Scholar
  33. Egelhaaf SU, Schurtenberger P, Müller M (2000) New controlled environment vitrification system for cryo-transmission electron microscopy: design and application to surfactant solutions. J Microsc 200:128–139PubMedCrossRefGoogle Scholar
  34. Elliot MS, Poon WCK (2001) Conventional optical microscopy of colloidal suspensions. Adv Colloid Interf Sci 92:133–194CrossRefGoogle Scholar
  35. Finke JH, Schmolke H, Klages C, Müller-Goymann CC (2013) Controlling solid lipid nanoparticle adhesion by polyelectrolyte multilayer surface modifications. Int J Pharm 449:59–71PubMedCrossRefGoogle Scholar
  36. Flegler SL, Heckman JW, Klomparens KL (1995) Scanning and transmission electron microscopy. An introduction. Oxford University Press, New YorkGoogle Scholar
  37. Friedrich H, Frederik PM, deWith G, Sommerdijk NAJM (2010) Imaging of self-assembled structures: interpretation of TEM and cryo-TEM images. Angew Chem Int Ed 49:7850–7858CrossRefGoogle Scholar
  38. Gašperlin M, Kristl J, Šmid-Korbar J, Kerč J (1994) The structure elucidation of semisolid w/o emulsion systems containing silicone surfactant. Int J Pharm 107:51–56CrossRefGoogle Scholar
  39. Gaumet M, Gurny R, Delie F (2007) Fluorescent biodegradable PLGA particles with narrow size distributions: preparation by means of selective centrifugation. Int J Pharm 342:222–230PubMedCrossRefGoogle Scholar
  40. George M, Ghosh I (2013) Identifying the correlation between drug/stabilizer properties and critical quality attributes (CQAs) of nanosuspension formulation prepared by wet media milling technology. Eur J Pharm Sci 48:142–152PubMedCrossRefGoogle Scholar
  41. Ghalanbor Z, Körber M, Bodmeier R (2010) Improved lysozyme stability and release properties of poly(lactide-co-glycolide) implants prepared by hot-melt extrusion. Pharm Res 27:371–379PubMedCrossRefGoogle Scholar
  42. Ghanam D, Hassan I, Kleinebudde P (2010) Compression behaviour of κ-carrageenan pellets. Int J Pharm 390:117–127Google Scholar
  43. Gilchrist SE, Letchford K, Burt HM (2012) The solid-state characterization of fusidic acid. Int J Pharm 422:245–253Google Scholar
  44. Goldberg O (1980) Köhler illumination. Microscope 28:15–21Google Scholar
  45. Goldstein JI, Newbury DE, Echlin P, Joy DC, Lyman CE, Lifshin E, Sawyer L, Michael JR (2003) Scanning electron microscopy and X-ray microanalysis, 3rd edn. Springer, BostonCrossRefGoogle Scholar
  46. Gong X, Moghaddam MJ, Sagnella SM, Conn CE, Danon SJ, Waddington LJ, Drummond CJ (2011) Lyotropic liquid crystalline self-assembly material behavior and nanoparticulate dispersions of a phytanyl pro-drug analogue of cepecitabine-A chemotherapy agent. ACS Appl Mater Interfaces 3:1552–1561PubMedCrossRefGoogle Scholar
  47. Grasmeijer F, Hagedoorn P, Frijlink HW, de Boer HA, Haverkamp RG (2013) Mixing time effects on the dispersion performance of adhesive mixtures for inhalation. PLoS ONE 8, e69263PubMedPubMedCentralCrossRefGoogle Scholar
  48. Grassucci RA, Taylor DJ, Frank J (2007) Preparation of macromolecular complexes for cryo-electron microscopy. Nat Protoc 2:3239–3246PubMedPubMedCentralCrossRefGoogle Scholar
  49. Grassucci RA, Taylor D, Frank J (2008) Visualization of macromolecular complexes using cryo-electron microscopy with FEI Tecnai transmission electron microscopes. Nat Protoc 3:330–339PubMedPubMedCentralCrossRefGoogle Scholar
  50. Haaser M, Naelapää K, Gordon KC, Pepper M, Rantanen J, Strachan CJ, Taday PF, Zeitler JA, Rades T (2013) Evaluating the effect of coating equipment on tablet film quality using terahertz pulsed imaging. Eur J Pharm Biopharm 85:1095–1102PubMedCrossRefGoogle Scholar
  51. Harris JR (1997) Negative staining and cryoelectron microscopy. The thin film techniques. Microscopy handbooks, vol 35. BIOS Scientific Publishers in association with the Royal Microscopical Society, Oxford, UK, Herndon, VAGoogle Scholar
  52. Harris JR (2007) Negative staining of thinly spread biological samples. In: Kuo J (ed) Electron microscopy. Methods and protocols, 2nd edn. Humana Press, Totowa, pp 107–142CrossRefGoogle Scholar
  53. Healy AM, Amaro MI, Paluch KJ, Tajber L (2014) Dry powders for oral inhalation free of lactose carrier particles. Adv Drug Deliv Rev 75:32–52PubMedCrossRefGoogle Scholar
  54. Ho R, Naderi M, Heng JYY, Williams DR, Thielmann F, Bouza P, Keith AR, Thiele G, Burnett DJ (2012) Effect of milling on particle shape and surface energy heterogeneity of needle-shaped crystals. Pharm Res 29:2806–2816PubMedCrossRefGoogle Scholar
  55. Hope MJ, Wong KF, Cullis PR (1989) Freeze-fracture of lipids and model membrane systems. J Micros Tech 13:277–287CrossRefGoogle Scholar
  56. Hoppel M, Mahrhauser D, Stallinger C, Wagner F, Wirth M, Valenta C (2014) Natural polymer-stabilized multiple water-in-oil-in-water emulsions: a novel dermal drug delivery system for 5-fluorouracil. J Pharm Pharmcol 66:658–667CrossRefGoogle Scholar
  57. Hoppentocht M, Hagedoorn P, Frijlink H, de Boer A (2014) Technological and practical challenges of dry powder inhalers and formulations. Adv Drug Deliv Rev 75:18–31PubMedCrossRefGoogle Scholar
  58. Jeong S, Park K (2008) Development of sustained release fast-disintegrating tablets using various polymer-coated ion-exchange resin complexes. Int J Pharm 353:195–204PubMedCrossRefGoogle Scholar
  59. Jeyanthi R, Thanoo B, Metha RC, DeLuca PP (1996) Effect of solvent removal technique on the matrix characteristics of polylactide/glycolide microspheres for peptide delivery. J Control Release 38:235–244CrossRefGoogle Scholar
  60. Jores K, Mehnert W, Drechsler M, Bunjes H, Johann C, Mäder K (2004) Investigations on the structure of solid lipid nanoparticles (SLN) and oil-loaded solid lipid nanoparticles by photon correlation spectroscopy, field-flow fractionation and transmission electron microscopy. J Control Release 95:217–227PubMedCrossRefGoogle Scholar
  61. Juhnke M, Märtin D, John E (2012) Generation of wear during the production of drug nanosuspensions by wet media milling. Eur J Pharm Biopharm 81:214–222PubMedCrossRefGoogle Scholar
  62. Jurasin D, Pustak A, Habus I, Smit I, Filipovic-Vincekovic N (2011) Polymorphism and mesomorphism of oligomeric surfactants: effect of the degree of oligomerization. Langmuir 27:14118–14130PubMedCrossRefGoogle Scholar
  63. Keck C (2010) Particle size analysis of nanocrystals: improved analysis method. Int J Pharm 390:3–12PubMedCrossRefGoogle Scholar
  64. Keck C, Müller RH (2008) Size analysis of submicron particles by laser diffractometry—90 % of the published measurements are false. Int J Pharm 355:150–163PubMedCrossRefGoogle Scholar
  65. Klang V, Matsko NB, Valenta C, Hofer F (2012) Electron microscopy of nanoemulsions: an essential tool for characterisation and stability assessment. Micron 43:85–103PubMedCrossRefGoogle Scholar
  66. Klang V, Valenta C, Matsko NB (2013) Electron microscopy of pharmaceutical systems. Micron 44:45–74PubMedCrossRefGoogle Scholar
  67. Kleinebudde P (1997) The crystallite-gel-model for microcrystalline cellulose in wet granulation, extrusion, and speronization. Pharm Res 14:804–809PubMedCrossRefGoogle Scholar
  68. Koning RI, Koster AJ (2009) Cryo-electron tomography in biology and medicine. Ann Anatom 191:427–445CrossRefGoogle Scholar
  69. Krauel K, Girvan L, Hook S, Rades T (2007) Characterisation of colloidal drug delivery systems from the naked eye to Cryo-FESEM. Micron 38:796–803PubMedCrossRefGoogle Scholar
  70. Kubavat HA, Shur J, Ruecroft G, Hipkiss D, Price R (2012) Investigation into the influence of primary crystallization conditions on the mechanical properties and secondary processing behaviour of fluticasone propionate for carrier based dry powder inhaler formulations. Pharm Res 29:994–1006PubMedCrossRefGoogle Scholar
  71. Kuntsche J, Westesen K, Drechsler M, Koch MHJ, Bunjes H (2004) Supercooled smectic nanoparticles: a potential novel carrier system for poorly water soluble drugs. Pharm Res 21:1834–1843PubMedCrossRefGoogle Scholar
  72. Kuntsche J, Koch M, Drechsler M, Bunjes H (2005) Crystallization behavior of supercooled smectic cholesteryl myristate nanoparticles containing phospholipids as stabilizers. Coll Surf B 44:25–35CrossRefGoogle Scholar
  73. Kuntsche J, Bunjes H, Fahr A, Pappinen S, Rönkkö S, Suhonen M, Urtti A (2008) Interaction of lipid nanoparticles with human epidermis and an organotypic cell culture model. Int J Pharm 354:180–195PubMedCrossRefGoogle Scholar
  74. Kuntsche J, Klaus K, Steiniger F (2009a) Size determinations of colloidal fat emulsions: a comparative study. J Biomed Nanotechnol 5:384–395PubMedCrossRefGoogle Scholar
  75. Kuntsche J, Koch MHJ, Fahr A, Bunjes H (2009b) Supercooled smectic nanoparticles: influence of the matrix composition and in vitro cytotoxicity. Eur J Pharm Sci 38:238–248PubMedCrossRefGoogle Scholar
  76. Kuntsche J, Freisleben I, Steiniger F, Fahr A (2010a) Temoporfin-loaded liposomes: physicochemical characterization. Eur J Pharm Sci 40:305–315PubMedCrossRefGoogle Scholar
  77. Kuntsche J, Koch MH, Steiniger F, Bunjes H (2010b) Influence of stabilizer systems on the properties and phase behavior of supercooled smectic nanoparticles. J Coll Interf Sci 350:229–239CrossRefGoogle Scholar
  78. Kuntsche J, Horst JC, Bunjes H (2011) Cryogenic transmission electron microscopy (cryo-TEM) for studying the morphology of colloidal drug delivery systems. Int J Pharm 417:120–137PubMedCrossRefGoogle Scholar
  79. Lauf U, Fahr A, Westesen K, Ulrich AS (2004) Novel lipid nanotubes in dispersions of DMPC. ChemPhysChem 5:1246–1249PubMedCrossRefGoogle Scholar
  80. Lee WL, Seh YC, Widjaja E, Chong HC, Tan NS, Joachim Loo SC (2012) Fabrication and drug release study of double-layered microparticles of various sizes. J Pharm Sci 101:2787–2797PubMedCrossRefGoogle Scholar
  81. Li X, Hirsh DJ, Cabral-Lilly DZA, Gruner SM, Janoff AS, Perkins WR (1998) Doxorubicin physical state in solution and inside liposomes loaded via a pH gradient. Biochim Biophys Acta 1415:23–40PubMedCrossRefGoogle Scholar
  82. Lindfors L, Skantze P, Skantze U, Westergren J, Olsson U (2007) Amorphous drug nanosuspensions. 3. Particle dissolution and crystal growth. Langmuir 23:9866–9874PubMedCrossRefGoogle Scholar
  83. Littringer EM, Noisternig MF, Mescher A, Schroettner H, Walzel P, Griesser UJ, Urbanetz NA (2013) The morphology and various densities of spray dried mannitol. Powder Technol 246:193–200CrossRefGoogle Scholar
  84. Madsen HB, Arboe-Andersen HM, Rozlosnik N, Madsen F, Ifversen P, Kasimova MR, Nielsen HM (2010) Investigation of the interaction between modified ISCOMs and stratum corneum lipid model systems. Biochim Biophys Acta 1798:1779–1789PubMedCrossRefGoogle Scholar
  85. Mercuri A, Belton PS, Royall PG, Barker SA (2012) Identification and molecular interpretation of the effects of drug incorporation on the self–emulsification process using spectroscopic, micropolarimetric and microscopic measurements. Mol Pharmaceutics 9:2658–2668Google Scholar
  86. Meyer H, Richter W (2001) Freeze-fracture studies on lipids and membranes. Micron 32:615–644PubMedCrossRefGoogle Scholar
  87. Muhsin Ö, Höglund S, Gelderblom HR, Morein B (1989) Quarternary structure of the immunostimulating complex (Iscom). J Ultrastruc Mol Struc Res 102:240–248CrossRefGoogle Scholar
  88. Müller-Goymann CC (1984) Liquid crystals in emulsions, creams, and gels containing ethoxylated sterols as surfactant. Pharm Res 4:154–158CrossRefGoogle Scholar
  89. Munk T, Baldursdottir S, Hietala S, Rades T, Kapp S, Nuopponen M, Kalliomäki K, Tenhu H, Rantanen J (2012) Crystal morphology modification by the addition of tailor–made stereocontrolled poly(N-isopropyl acrylamide). Mol Pharmaceutics 9:1932–1941Google Scholar
  90. Nagy ZK, Balogh A, Vajna B, Farkas A, Patyi G, Kramarics Á, Marosi G (2012) Comparison of electrospun and extruded Soluplus®-based solid dosage forms of improved dissolution. J Pharm Sci 101:322–332Google Scholar
  91. Narayan P, Hancock BC (2003) The relationship between the particle properties, mechanical behavior, and surface roughness of some pharmaceutical excipient compacts. Mat Sci Eng A 355:24–36CrossRefGoogle Scholar
  92. Nichols G, Frampton CS (1998) Physicochemical characterization of the orthorhombic polymorph of paracetamol crystallized from solution. J Pharm Sci 87:684–693Google Scholar
  93. Nonomura Y, Nakayama K, Aoki Y, Fujimori A (2009) Phase behavior of bile acid/lipid/water systems containing model dietary lipids. J Colloid Interf Sci 339:222–229CrossRefGoogle Scholar
  94. Oheim M, Micheal DJ, Geisbauer M, Madsen D, Chow RH (2006) Principles of two-photon excitation fluorescence microscopy and other nonlinear imaging approaches. Adv Drug Del Rev 58:788–808CrossRefGoogle Scholar
  95. Oldenbourg R (1996) A new view on polarization microscopy. Nature 381:811–812PubMedCrossRefGoogle Scholar
  96. Otte A, Carvajal MT (2011) Assessment of milling-induced disorder of two pharmaceutical compounds. J Pharm Sci 100:1793–1804PubMedCrossRefGoogle Scholar
  97. Pajander J, Haugshøj KB, Bjørneboe K, Wahlberg P, Rantanen J (2013) Foreign matter identification from solid dosage forms. J Pharm Biopharm Anal 80:116–125CrossRefGoogle Scholar
  98. Paspaleeva-Kühn V, Nürnberg E (1992) Participation of macrogolstearate 400 lamellar phases in hydrophilic creams and vesicles. Pharm Res 9:1336–1340PubMedCrossRefGoogle Scholar
  99. Pingali KC, Mendez R (2014) Nanosmearing due to process shear—influence on powder and tablet properties. Adv Powder Technol 25:952–959CrossRefGoogle Scholar
  100. Piston DW (1998) Choosing objective lenses: the importance of numerical aperture and magnification in digital optical microscopy. Bio Bull 195:1–4CrossRefGoogle Scholar
  101. Pitchayajittipong C, Price R, Shur J, Kaerger JS, Edge S (2010) Characterisation and functionality of inhalation anhydrous lactose. Int J Pharm 390:134–141PubMedCrossRefGoogle Scholar
  102. Pluta M (1969) A phase-contrast device with positive and negative image contrast. J Microsc 89:205–216PubMedCrossRefGoogle Scholar
  103. Prehm M, Enders C, Anzahaee MY, Glettner B, Baumeister U, Tschierke C (2008) Distinct columnar and lamellar liquid crystalline phases formed by new bolaamphiphiles with linear and branched lateral hydrocarbon chains. Chem Eur J 14:6352–6368PubMedCrossRefGoogle Scholar
  104. Rades T, Müller-Goymann CC (1997) Electron and light microscopical investigation of defect structures in mesophases of pharmaceutical substances. Colloid Polym Sci 275:1169–1178CrossRefGoogle Scholar
  105. Raijada D, Genina N, Fors D, Wisaeus E, Peltonen J, Rantanen J, Sandler N (2013) A step toward development of printable dosage forms for poorly soluble drugs. J Pharm Sci 102:3694–3704PubMedCrossRefGoogle Scholar
  106. Rank A, Hauschild S, Förster S, Schubert R (2009) Preparation of monodisperse block copolymer vesicles via a thermotropic cylinder − vesicle transition. Langmuir 25:1337–1344PubMedCrossRefGoogle Scholar
  107. Rasenack N, Müller BW (2002) Dissolution rate enhancement by in situ micronization of poorly water-soluble drugs. Pharm Res 19:1894–1900PubMedCrossRefGoogle Scholar
  108. Rizwan S, Dong Y, Boyd B, Rades T, Hook S (2007) Characterisation of bicontinuous cubic liquid crystalline systems of phytantriol and water using cryo field emission scanning electron microscopy (cryo FESEM). Micron 38:478–485PubMedCrossRefGoogle Scholar
  109. Rosenblatt KM, Bunjes H (2009) Poly(vinyl alcohol) as emulsifier stabilizes solid triglyceride drug carrier nanoparticles in the α-modification. Mol Pharmaceutics 6:105–120Google Scholar
  110. Rowe RC, Sheskey PJ, Quinn ME (2009) Handbook of pharmaceutical excipients, 6th edn. Pharmaceutical Press, LondonGoogle Scholar
  111. Savic S, Vuleta G, Daniels R, Müller-Goymann CC (2005) Colloidal microstructure of binary systems and model creams stabilized with an alkylpolyglucoside non-ionic emulsifier. Colloid Polym Sci 283:439–451CrossRefGoogle Scholar
  112. Schmidt PC (2002) Secondary electron microscopy in pharmaceutical technology. In: Swarbrick J, Boylan JC (eds) Encyclopedia of pharmaceutical technology, vol 3, 2nd edn. Marcel Dekker, New York, pp 2401–2435Google Scholar
  113. Schütze W, Müller-Goymann CC (1992) Mutual interactions between nonionic surfactants and gelatin—investigations in cubic liquid crystalline systems and micellar systems. Colloid Polym Sci 269:85–90CrossRefGoogle Scholar
  114. Scoutaris N, Vithani K, Slipper I, Chowdhry B, Douroumis D (2014) SEM/EDX and confocal Raman microscopy as complementary tools for the characterization of pharmaceutical tablets. Int J Pharm 470:88–98PubMedCrossRefGoogle Scholar
  115. Seefeldt K, Miller J, Alvarez-Nunez F, Nodriguez-Hornedo N (2007) Crystallization pathways and kinetics of carbamazepine-nicotinamide cocrystals form the amorphous state by in situ thermomicroscopy, spectroscopy and calorimetry studies. J Pharm Sci 96:1147–1158PubMedCrossRefGoogle Scholar
  116. Severs NJ (2007) Freeze-fracture electron microscopy. Nat Protoc 2:547–576PubMedCrossRefGoogle Scholar
  117. Siekmann B, Westesen K (1995) Preparation and physicochemical characterization of aqueous dispersions of coenzyme Q10 nanoparticles. Pharm Res 12:201–208PubMedCrossRefGoogle Scholar
  118. Spring KR, Keller HE, Davidson MW (2014) Microscope objectives introduction. Accessed 30 Nov 2014
  119. Sternberg B, Sorgi FL, Huang L (1994) New structures in complex formation between DNA and cationic liposomes visualized by freeze-fracture electron microscopy. FEBS Lett 356:361–366PubMedCrossRefGoogle Scholar
  120. Tian F, Baldursdottir S, Rantanen J (2009) Effects of polymer additives on the crystallization of hydrates: a molecular-level modulation. Mol Pharmaceutics 6:202–2010Google Scholar
  121. Unruh T, Westesen K, Bösecke P, Lindner P, Koch MHJ (2002) Self-assembly of triglyceride nanocrystals in suspension. Langmuir 18:1796–1800CrossRefGoogle Scholar
  122. van Eerdenbrugh B, Froyen L, van Humbeeck J, Martens JA, Augustijns P, van den Mooter G (2008) Alternative matrix formers for nanosuspension solidification: dissolution performance and X-ray microanalysis as an evaluation tool for powder dispersion. Eur J Pharm Sci 35:344–353PubMedCrossRefGoogle Scholar
  123. Vehring R (2008) Pharmaceutical particle engineering via spray drying. Pharm Res 25:999–1022PubMedCrossRefGoogle Scholar
  124. Velluto D, Demurtas D, Hubbell JA (2008) PEG-b-PPS diblock copolymer aggregates for hydrophobic drug solubilization and release: cyclosporin A as an example. Mol Pharmaceutics 5:632–642Google Scholar
  125. Vielreicher M, Schürmann S, Detsch R, Schmidt MA, Buttereit A, Boccaccini A, Friedrich O (2013) Taking a deep look: modern microscopy technologies to optimize the design and functionality of biocompatible scaffolds for tissue engineering in regenerative medicine. J R Soc Interface 10:0263CrossRefGoogle Scholar
  126. Villalobos-Hernández J, Müller-Goymann C (2005) Novel nanoparticulate carrier system based on carnauba wax and decyl oleate for the dispersion of inorganic sunscreens in aqueous media. Eur J Pharm Biopharm 60:113–122PubMedCrossRefGoogle Scholar
  127. Weaver R (2003) Rediscovering polarized light microscopy. American Lab 35:55–61Google Scholar
  128. Westesen K, Wehler T (1992) Physicochemical characterization of a model intravenous oil-in-water emulsion. J Pharm Sci 81:777–786PubMedCrossRefGoogle Scholar
  129. White NS, Errington RJ (2005) Fluorescence techniques for drug delivery research: theory and practice. Adv Drug Del Rev 57:17–42CrossRefGoogle Scholar
  130. Williams DB, Carter CB (2009) Transmission electron microscopy. A textbook for materials science, 2nd edn. Springer, New YorkGoogle Scholar
  131. Witt C, Kissel T (2001) Morphological characterization of microspheres, films and implants prepared from poly(lactide-co-glycolide) and ABA triblock copolymers: is the erosion controlled by degradation, swelling or diffusion? Eur J Pharm Biopharm 51:171–181PubMedCrossRefGoogle Scholar
  132. Wu JX, Xia D, van den Berg F, Amigo JM, Rades T, Yang M, Rantanen J (2012) A novel image analysis methodology for online monitoring of nucleation and crystal growth during solid state phase transformations. Int J Pharm 433:60–70PubMedCrossRefGoogle Scholar

Copyright information

© Controlled Release Society 2016

Authors and Affiliations

  1. 1.Institut für Pharmazeutische TechnologieTechnische Universität BraunschweigBraunschweigGermany
  2. 2.Department of Physics, Chemistry and PharmacyUniversity of Southern DenmarkOdenseDenmark

Personalised recommendations