Artificial cell

T. M. S. Chang, Artificial Kidney, Artificial Eiver, and Artificial Cells, Plenum Publishing Corp., New York, 1978. 

Clark, L C, Jr, Hoffmann, R E, Davis, S L Biomater Artificial Cells Immobilimtion Biotechnol 1992, 20, 1085... 

With the development of the polymer field in medicine, great attention has been paid to particulate forms of drugs [82], The most widespread methods for the preparation of particulate drugs are microencapsulation and microgranulation, i.e., the inclusion of BAS into spherical shapes of predetermined dimensions. One form of particulate drugs is microcapsules or artificial cells as they were called by... 

Chang TMS (1972) Artificial Cells. C Thomas Publ Springfield, Illinois... 

Recently, unique vesicle-forming (spherical bUayers that offer a hydrophilic reservoir, suitable for incorporation of water-soluble molecules, as well as hydrophobic wall that protects the loaded molecules from the external solution) setf-assembUng peptide-based amphiphilic block copolymers that mimic biological membranes have attracted great interest as polymersomes or functional polymersomes due to their new and promising applications in dmg delivery and artificial cells [ 122]. However, in all the cases the block copolymers formed are chemically dispersed and are often contaminated with homopolymer. 

The research dealing with models for the first primitive cells has had one central topic for many years the minimal cell . According to Luisi et al. (2006a), this is defined as an artificial or semi-artificial cell which contains a minimal (but sufficient) number of components to keep the cell alive . The cell is considered to be living when three conditions are fulfilled ... 

In recent years, the transitions from nonliving to living matter have been the subject of three seminars, bringing together theoreticians and experimentalists in the Los Alamos National Laboratory, in the Santa Fe Institute and in Dortmund. The biogenesis problem was expanded to the question, how can simple life forms be synthesised in the laboratory Artificial cells (sometimes called protocells) could be quite different from the cell types known today, or from primeval cells they might, for example, be orders of magnitude smaller than a bacterium. The seminars posed three questions for further work ... 

How can the flow of information from theory and simulation to artificial cell experiments be improved (Rasmussen, 2004)... 

Perhaps most exciting is that we are now living in a time when enough knowledge has accumulated so that there are initial attempts to fabricate versions of living cells in the laboratory. Entire genomes have been transferred from one bacterial species to another, and it is now possible to reconstitute a system of membranes, DNA, RNA and ribosomes that can synthesize a specific protein in an artificial cell. 

Quong, D., O Neill, I. K., Poncelet, D., and Neufeld, R. J., Immobilized Cells Basics and Applications, in Gastro-Intestinal Protection of Cellular Component DNA within an Artificial Cell System for Environmental Carcinogen Biomonitoring (R. G. Wijffels, R. M. Buitelaar, H. S. Wessels, C. Bucke, and J. Tramper Eds.), p. 814. Elsevier Science, Amsterdam (1996). 

The prospect of creating an artificial cell, however, is very promising, with the potential to design an artificial cell for a particular biosynthetic task - growing insulin for example. The current suggestion is that this sort of organism will be created within the next 30 years and would have the characteristics detailed in Table 9.1. 

The use of artificial cells for biotechnology applications is simplified if the replication and reproduction characteristics are removed so that an artificial cell does one particular job. A liposome structure would continue to uptake molecules from the environment and synthesise proteins or cofactors, but the molecular inventory within the liposome is comparatively small. 

E. J. Truter, Artificial Cells Blood Substitutes Immobilization Biotechnol. 23, 579 (1995). 

Figure 27.1 Principle of silver nanoparticle enhanced fluorescence applied to artificial cell surfaces.

Artificial cell-free systems have been investigated, to test models of photosynthetic production of H2. Benemann et al. (1973) demonstrated that it was possible to produce H2 and O2 by combining chloroplasts from green plants and bacterial hydrogenase, with ferredoxin as the intermediate electron carrier ... 

Chang TM. Artificial cells for cell and organ replacements. Artif Organs 2004 28 265. 

PC. Marijuan, Enzymes, artificial cells and the nature of biological information, BioSystems, 35, 167-170 (1995). 

K. F. Gu and T. M. S. Chang, Conversion of ammonia or urea into L-leucine, L-valine and L-isoleucine using artificial cells containing an immobilized multienzyme system and dextran-NAD+, glucose dehydrogenase for co-factor recycling, A 4/0, 11(1), 24-28 (1988). 

Zhao, J., Jedlicka, S. S., Larmu, J. D., Bhunia, A. K., and Rickus, J. L. (2006). Liposome-doped nanocomposites as artificial cell-based biosensors Detection of listeriolysin O. Biotechnol. Prog. 22,32-37. 

Chang TMS. Semipermeable aqueous microcapsules (artificial cells)—with emphasis on experiments in an extracorporeal shunt system. Trans Am Soc Artif Internal Organs 1966 12 13-19. 

Pohorille, A. and Deamer, D. (2002). Artificial cells prospects for biotechnology. Trends Biotech., 20, 123-8. 

Studies on molecular recognition by artificial receptors are thus one of the most important approaches to such characterization in relation to supramolecular chemistry [4]. Functional simulation of intracellular receptors in aqueous media has been actively carried out with attention to various noncovalent host-guest interactions, such as hydrophobic, electrostatic, hydrogen-bonding, charge-transfer, and van der Waals modes [5-10]. On the other hand, molecular recognition by artificial cell-surface receptors embedded in supramolecular assemblies has been scarcely studied up to the present time, except for channel-linked receptors [11-13]. 

We have already reported that synthetic peptide lipids, having ot-amino acid residuefs) interposed between a polar head moiety and a hydrophobic doublechain segment, can be used as models for functional simulation of biomembranes [23]. On this ground, we are to clarify molecular recognition specificity by supramolecular assemblies formed in combination of the macrocyclic receptors with the peptide lipid as artificial cell-surface receptors. 

The steroid cyclophane also provides a sizable and well-desolvated hydro-phobic cavity in aqueous media in a manner as observed for the octopus cyclophane. The molecular recognition ability of the steroid cyclophane is inferior to that of the octopus cyclophane in aqueous solution due to the structural rigidity of steroid segments of the former host. When the steroid cyclophane is embedded in the bilayer membrane to form a hybrid assembly, however, the steroid cyclophane becomes superior to the octopus cyclophane with respect to functions as an artificial cell-surface receptor, performing marked guest discrimination. 

The cage-type cyclophane furnishes a hydrophobic internal cavity for inclusion of guest molecules and exercises marked chiral discrimination in aqueous media. The host embedded in the bilayer membrane is capable of performing effective molecular recognition as an artificial cell-surface receptor to an extent comparable to that demonstarated by the host alone in aqueous media. 

Meinert, H. Knoblich. A. Biomoterials, Artificial Cells, and Immobilization Biotechnology 1993, 21, 583. 

Figure 9.24 The polyoxomolybdate nanocluster [P]2(Mo204(MeCO ) 30l42 (P = (Mo)Mo502i (I I20)6 6 ) that behaves as an artificial cell, showing the pore opening in the centre (reprinted from [21] with permission of Elsevier).

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