Stiff Virus Particles Polymer

Probably the best examples of rod-like colloidal particles are stiff vims particles such as the plant vims tobacco mosaic virus (TMV) and the bacteriophage feline distemper (fd). In Table 6.1 we summarize the characteristics of TMV and fd, including their linear charge densities at neutral pH. 

As early as 1942, Cohen [9] observed, in a study directed at the isolation of TMV from infectious juice, that the addition of 5 mg/ml of the polysaccharide heparin to a dilute TMV suspension (2 mg/ml) in 0.1 M phosphate buffer (pH = 7.1) resulted in the production of needle-shaped paracrystals of length 5-20 pm 

6 Phase Transitions in Suspensions of Rod-Like Colloids Plus Polymers 

Leberman [10] observed that addition of 6 mg/ml of the flexible polymer polyethylene oxide (PEO), with molar mass M = 6 kDa and radius of gyration 

Rg = 3.6 nm, to a dilute 1 mg/ml TMV suspension leads to precipitation of TMV, which may be considered as a sign of the I-N transition. To compare this experimental observation with theory we present in Fig. 6.13 the theoretical phase diagram for L/D = 300/18 = 17 and q = 2Rg/D = 2 3.6/18 = 0.4, which are the relevant parameters for this mixed TMV-PEO suspension. 

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