Development of new polyelectrolyte complex (PEC) capsules/beads for biotechnological applications such as the immunoisolation of Langerhans islets for the treatment of diabetes and the stabilization and reuse of enzymes and bacterial cells as biocatalysts is very important [1]. Morphological characterization and study of PEC beads properties represents important challenge for electron microscopy. These very beam-sensitive bio-polymer capsules used for immobilization of cells are laboratory produced as a uniform with a controlled shape, size, membrane thickness, permeability and mechanical resistance [1]. Owing to importance to study above mentioned parameters, samples must be inspected in their fully native and functional state. It means free of freezing, chemical contamination or preparation, shape distortion and in thermodynamically stabile and fully wet state, precisely reached after very slow changing of conditions in the specimen chamber of ESEM. Violation of these conditions leads to deformation and burst of thin semipermeable membrane surrounding liquid core, containing live bacterial cells, for example E. coli. The aim of this work is to prove ability to use our non-commercial ESEM AQUASEM II for inspection and developmental support of this type of samples and demonstrate their sensitivity on two types of PEC beads prepared from alternative materials.PEC beads has been produced by air-stripping nozzle via polyelectrolyte complexation (20 min) of sodium alginate and cellulose sulphate (CS) as polyanions, poly(methylene-co-guanidine) as a polycation, CaCl 2 as a gelling agent and NaCl as an antigelling agent [1] without the use of a multiloop reactor. Two different sources of CS have been tested for preparation of PEC beads (CS from Across Organics, N.J., USA; Fig. 1) and alternative PEC beads (tailor-made CS from Senova, Weimar, Germany; Fig 2). Due to the relatively big size of samples (800m in diameter) and their beam sensitivity, a combination of our newly published method [2] and special improvement of our ionization detector of SE were used. The gentle and slow sample chamber pumping procedure [2] and our ionization detector of SEs [3] (beam current up to 40 pA) enhanced for larger field of view (850 μm) were combined. Samples were observed in small droplet (approximately 10 l) of distilled water. Both types of matrices were observed at sample to second pressure limiting aperture distance 4 mm. For thermodynamic equilibrium adjustment control, Pfeiffer pressure gauges CMR 261 and CMR 263, a custom build Peltier stage and a hydration system were used.
Cannabis sativa L. is an important multipurpose herbaceous plant known for its high content of phytochemicals but as well as, an important source of both cellulosic and woody fibers. Heavy metal accumulation in plants is often restricted to the root tissue, with only small amounts transported to the shoot [1]. An understanding of the toxicological and physiological responses of a plant to metal contamination is of particular relevance when attempting to predict the impact of a metal ion on the growth of an industrial plant like hemp. This is particularly important nowadays when the number of contaminated riparian ecosystems is increasing. Heavy metal exposure can affect plant's capability to receive nutrients and change plant's anatomy. There are various methods to determine morphological changes in root cross sections. However, there are disadvantages of these methods such as limited resolution (histology) [2], time consuming chemical treatment with possible artifacts formation (SEM) and high cost of the equipment (cryo-SEM) [3].
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