Poly based

The question mark ( ) indicates the hypothetical positions of Pt(poly) based on the Ea value given by Frumkin,10 and of Pt(l 11) based on the Eano value proposed by Iwasite.210... 

Haynes, M., Garrett, R.A. and Gratzer, W.B. (1970) Structure of nucleic acid-poly base complexes. Biochemistry, 9, 44KM416. 

PECs are the association complexes mainly formed between oppositely charged particles (e.g., polymer-polymer, polymer-drug, polymer-surfactant, polymer-protein). These complexes are formed due to electrostatic interaction between oppositely charged polyions. This interaction avoids the use of chemical cross-linking agents that can reduce the possible toxicity and other undesirable effects of the reagents. The PECs formed between a poly acid and poly base are less affected by the pH variation of the dissolution medium. The complexation, between DNA and chitosan, has been extensively studied in the development of delivery vehicle for gene therapy and oral vaccination. 

Polyanion polyanion Polybase poly base Polycarbonat... 

TABLE 2.7. Characteristics of the Two Highest Filled and Lowest Unfilled Bands of the Two Poly(base pairs), Poly(A-T) and Poly(G-C), and of the Three Polynucleotides, Poly(adenylic acid), Polythymidine and Polycytidine (in ev)"... 

The band structures of the periodic DNA models obtained with the aid of the PPP CO method can be divided into two groups. The five homopolynucleotides (also including poly and the two poly (base pairs) [poly(A-T) and poly(G-C)]< > possess rather broad bands (the widths of the valence bands are 0.2-0.3 eV, those of the conduction bands about 0.1 eV, and the widths of the lowest filled bands are in most cases approximately 1 eV). On the other hand, for the more complicated periodic DNA models, where we have two different base pairs in the unit cell, such as poly(Glc). the bands are very narrow (the widths of the valence bands are usually 0.01-0.03 eV, those of the conduction bands about 0.01 eV, and the widths of the lowest filled bands are approximately 0.1 eV). The CNDO/2 CO calculations of periodic base stacks and of the sugar-phosphate chain of DNA< > again give rather broad bands [valence bandwidths between 0.15 and 0.50 eV for the base stacks and 0.05 eV for poly(SP), and conduction bandwidths 0.1-0.25 eV for both kinds of system], while the MINDO/2 CO results for the base stacks indicate somewhat less-broad bands (widths of valence bands 0.03-0.30 eV and of conduction bands 0.03-0.17 eV). Further details of the PPP and all-valence-electron CO calculations of different periodic DNA models can be found in original papers " as well as in a review paper. ... 

Key features of chitosan The amino and hydroxyl groups of chitosan that are chemically modifiable make it a highly versatile molecule for various applications (Table 2.1). The metabolism of chitosan by lysozyme makes it biodegradable. Chitosan exhibits a pH-sensitive behavior as a weak poly-base because of the large quantities of amino groups on its chain. At low pH conditions, the amino groups of chitosan are protonated and exhibit pH-sensitive swelling. 

Chen, J., Heitmann, J.A., Hubbe, M.A. Dependency of polyelectrolyte eomplex stoiehiometiy on the order of addition. 1. Effect of salt concentration during streaming eurrent titrations with strong poly-acid and poly-base. Colloids Surf., A 223(1-3), 215-230 (2003)... 

Results are reported of ab initio Hartree-Fock CO calculations using a minimal atomic basis set for the single stranded periodic B-DNA models of cytosine (C), thymine (T), adenine (A) and guanine (G) stacks and two polynucleotides with adenylic acid (ASP) and th)miidine (TSP) as repeating unit, respectively. Further the energy band structures of two poly(base pairs), poly(adenine-thymine), (A-T),and poly(guanine-cytosine), (G-C), representing a simple model of B-DNA double helix are discussed. 

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