Microencapsulation of probiotic bacteria for gastrointestinal delivery

Orally administered live probiotic bacteria have gained popularity in recent years as potentially beneficial health supplements. However, these bacteria require additional protection if they are to survive passage through the low pH environment of the stomach after oral administration [1]. This talk will describe the use of alginates for microencapsulation of live probiotic bacteria. It will discuss the methods of microencapsulation, methods of drying alginate capsules (tray drying, freeze drying, fluidized bed drying), coating approaches (formation of single layer or multilayer coats; materials that can be used to coat alginates), as well as in vitro experimentation to demonstrate the ability of these matrices to protect live bacterial cells in gastric juice and target release to the intestine [2-4]. The efficiency of coating was evaluated using confocal microscopy with fluorescently-labeled chitosan. The mechanism of live bacteria protection from stomach acid was established using confocal microscopy with model bacteria labeled with two pH-responsive fluorescent dyes [4]. The influence of microencapsulation on the survival of probiotics in fruit juices and product storage stability will also be discussed [5-7]. References 1.Cook M.T., Tzortzis G., Charalampopoulos D., Khutoryanskiy V.V., J.Controlled Release, 162, 56-67 (2012) 2.Cook M., Tzortzis G., Charalampopoulos D., Khutoryanskiy V.V., Biomacromolecules, 12, 2834–2840 (2011) 3. Cook M.T., Tzortzis G., Khutoryanskiy V.V., Charalampopoulos D., J. Mater. Chem. B, 1, 52-60 (2013) 4. Cook M.T., Saratoon T., Tzortzis G., Edwards A.D., Charalampopoulos D., Khutoryanskiy V.V., Biomacromolecules, 14, 387–393 (2013) 5. Nualkaekul S., Lenton D., Cook M.T., Khutoryanskiy V.V., Charalampopoulos D., Carbohydrate Polymers, 90, 1281-1287 (2012) 6. Nualkaekul S., Cook M.T., Khutoryanskiy V.V., Charalampopoulos D., Food Res. Int., 53, 304-311 (2013) 7. Albadran H.A., Chatzifragkou A., Khutoryanskiy V.V., Charalampopoulos D. Food Res. Int., 74, 208-216 (2015

Preparation and publication of chemistry papers in international peer-reviewed journals

Some recommendations presented on the preparation of chemistry papers for publication in peer-reviewed journals, indexed in Scopus and Web of Science. Some advice given on the selection of a journal for publication. Impact factors and other types of classifications for different chemistry journals and publication business models by publishers briefly discussed. Some publishers specialising on publication of chemistry papers considered. Recommendations given on the preparation of each section in a manuscript, quality of illustrations as well as the documents necessary for submission of these to the journal. Some approaches used to revise the manuscript and to deal with reviewer comments also briefly discussed. This work is prepared based on the course “How to write a paper” delivered by the author at the University of Reading (United Kingdom) for a number of years for post-graduate students from physical natural sciences as well as the courses delivered in some institutions of China, Estonia, Kazakhstan and Russia. The course is based on author’s own experience in publishing over 150 papers in different peerreviewed journals, refereeing numerous manuscripts as well as his work as an editor for some journals

Beyond PEGylation: alternative surface-modification of nanoparticles with mucus-inert biomaterials

Mucus is a highly hydrated viscoelastic gel present on various moist surfaces in our body including the eyes, nasal cavity, mouth, gastrointestinal, respiratory and reproductive tracts. It serves as a very efficient barrier that prevents harmful particles, viruses and bacteria from entering the human body. However, the protective function of the mucus also hampers the diffusion of drugs and nanomedicines, which dramatically reduces their efficiency. Functionalisation of nanoparticles with low molecular weight poly(ethylene glycol) (PEGylation) is one of the strategies to enhance their penetration through mucus. Recently a number of other polymers were explored as alternatives to PEGylation. These alternatives include poly(2-alkyl-2-oxazolines), polysarcosine, poly(vinyl alcohol), other hydroxyl-containing non-ionic water-soluble polymers, zwitterionic polymers (polybetains) and mucolytic enzymes. This review discusses the studies reporting the use of these polymers or potential application to facilitate mucus permeation of nanoparticles

Mucoadhesion and mucosa-mimetic materials - a mini-review

Mucoadhesion describes an attractive interaction between dosage form and mucosal membrane. The evaluation of mucoadhesive excipients often requires the use of ex vivo mucosal tissues taken from laboratory animals. These can be difficult to source, highly heterogeneous, and require the use of animal products. Thus, from both a user-convenience and ethical point-of-view, it is desirable to produce a synthetic alternative to these tissues - a mucosa-mimetic material. In this mini-review, the use of alternative materials to test the performance of mucoadhesives is reviewed and discussed. There is a surprising prevalence of the use of mucosa-mimics in the literature, which hitherto has not been compiled and compared.Peer reviewe

Synthesis and evaluation of mucoadhesive acryloyl-quaternized PDMAEMA nanogels for ocular drug delivery

Poly((2-dimethylamino)ethyl methacrylate) (PDMAEMA) nanogels were synthesized via surfactant-free free-radical polymerization technique in aqueous conditions utilizing N,N’-methylene-bis-acrylamide (MBA) as a crosslinking agent. The PDMAEMA nanogels were subsequently quaternized with acryloyl chloride in order to yield mucoadhesive materials which incorporate two mucoadhesive concepts; electrostatic interactions and covalent bond forming acrylate groups. The native PDMAEMA nanogels were found to exhibit good mucoadhesive properties on ex vivo bovine conjunctival tissues, which was found to increase proportionally with the degree of quaternization. With a view to determine the ocular drug delivery capabilities of the materials, both quaternized and native nanogels were loaded with pilocarpine hydrochloride via an absorption method, and their in vitro release profiles were analysed. The nanogels were found to exhibit a high loading capacity (>20% of total weight) and a sustained release over 6 h

Enzyme assisted extraction of chitin from shrimp shells (Litopenaeus vannamei)

BACKGROUND: Chemical chitin extraction generates large amounts of wastes and increases partial deacetylation of the product. Therefore, the use of biological methods for chitin extraction is an interesting alternative. The effects of process conditions on enzyme assisted extraction of chitin from the shrimp shells in a systematic way were the focal points of this study. RESULTS: Demineralisation conditions of 25C, 20 min, shells-lactic acid ratio of 1:1.1 w/w; and shells-acetic acid ratio of 1:1.2 w/w, the maximum demineralisation values were 98.64 and 97.57% for lactic and acetic acids, respectively. A total protein removal efficiency of 91.10% by protease from Streptomyces griseus with enzyme-substrate ratio 55 U/g, pH 7.0 and incubation time 3 h is obtained when the particle size range is 50-25 μm, which was identified as the most critical factor. The X-ray diffraction and 13C NMR spectroscopy analysis showed that the lower percent crystallinity and higher degree of acetylation of chitin from enzyme assisted extraction may exhibit better solubility properties and less depolymerisation in comparison with chitin from the chemical extraction. CONCLUSION: The present work investigates the effects of individual factors on process yields, and it has shown that, if the particle size is properly controlled a reaction time of 3 h is more than enough for deproteination by protease. Physicochemical analysis indicated that the enzyme assisted production of chitin seems appropriate to extract chitin, possibly retaining its native structure

Polysaccharide food matrices for controlling the release, retention and perception of flavours

Polysaccharides have many roles across both the food and pharmaceutics industries. They are commonly used to enhance viscosity, stabilise emulsions and to add bulk to food products. In the pharmaceutics industry, they are also utilised for their mucoadhesive nature. Mucoadhesive polysaccharides can facilitate retention of active ingredients at mucosal sites for a prolonged time and formulations can be designed to control their release and bioavailability. This study investigates how polysaccharides, with differing physicochemical properties (e.g. functional groups and molecular weight), affect the release and perception of flavour compounds from films. Polysaccharide films were prepared using either high or low viscosity carboxymethyl cellulose, pullulan or hydroxypropyl methylcellulose. Glucose, vanillin or a combination of both was also added to the films to assess the effect of flavour release and perception over time. The films were assessed for glucose release in vitro, swelling and disintegration times, and mucoadhesive ability. Results show that flavour release and perception depend on the polysaccharide matrix properties; this includes how quickly the films dissolves, the rate of release of tastant compounds, and the mucoadhesive strength of the polysaccharide. A higher viscosity and slower disintegration time resulted in slower release of glucose in vitro and flavour perception in vivo

Enhancement in corneal permeability of riboflavin using calcium sequestering compounds

Ethylenediaminetetraacetic acid, ethylenediamine-N,N′-disuccinic acid and ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid are polyaminocarboxylic acids that are able to sequester metal ions. Calcium is implicated in maintenance of intercellular matrix, zonula occludens (tight junctions) and zonula adherens of epithelium and endothelium cells. Corneal epithelium is impervious to many aqueous formulations due to it being lipophilic, whereby transcellular drug transit is resisted, whilst tight junctions restrict access via the paracellular route. Research has shown that integrity of tight junctions breaks down through loss of Ca2+ for endothelial and epithelial cells. This study investigates different Ca2+ sequestering compounds and their effect on corneal permeability of riboflavin at physiological pH. Riboflavin is a topically administered ocular drug applied during UV-induced corneal cross-linking for the treatment of keratoconus

Hydrogels in wound management

One of the most prevalent applications of hydrogels is wound management. Thanks to their high water content and unique physical properties, hydrogels could potentially resemble biological tissues including human skin. (Peppas et al. 2000, Gupta et al. 2010, Caló & Khutoryanskiy 2014, Jones et al. 2006) There is active interest in the development of new and advanced hydrogel-based products from both an academic and industrial perspective. In fact, hydrogels exhibit many characteristics of the ‘ideal’ wound dressing. These include: the capability of maintaining a moist environment at the wound site allowing gas exchange (moisture vapour transmission), biocompatibility, fast absorption of wound exudate, protection of newly formed or delicate skin and easy and relatively painless dressing removal. (Thomas 1990, Gupta et al. 2010, Vowden & Vowden 2014, Boateng & Catanzano 2015) In this Chapter we will provide the reader with an overview of the most recent hydrogel materials designed for wound management

Chitosan/β-glycerophosphate in situ gelling mucoadhesive systems for intravesical delivery of mitomycin-C

The development of mucoadhesive in situ gelling formulations for intravesical application may improve the therapeutic outcomes of bladder cancer patients. In this work, chitosan/β-glycerophosphate (CHIGP) thermosensitive formulations have been prepared using three different chitosan grades (62, 124 and 370 kDa). Their ability to form in situ gelling systems triggered by changes in temperature upon administration to urinary bladder were evaluated using vial inversion and rheological methods. Texture analysis was used to study their mucoadhesive properties as well as syringeability through the urethral catheter. The retention of CHIGP formulations, with fluorescein sodium as the model drug, was studied on porcine urinary bladder mucosa ex vivo using the flow-through technique and fluorescent microscopy. CHIGP formulations containing mitomycin-C were prepared and drug release was studied using in vitro dialysis method. It was established that the molecular weight of chitosan influenced the thermogelling, mucoadhesive and drug release behaviour of the in situ gelling delivery systems. Formulations prepared from chitosan with greatest molecular weight (370 kDa) were found to be the most promising for intravesical application due to their superior gelling properties and in vitro retention in the bladder