Reactive LC molecule

Fig. 9.19. (left) A schematic of the molecular order of the reactive LC molecules in a coated thin film retarder. The order is forced to be planar by the rubbed poly-imide. (right) An image of a uniaxial planar wet-coated retarder viewed in between two crossed polarisers and its orientation with respect to the crossed polarisers. (A) Analyser, (P) polariser, and (R) retarder. 

The birefringence of the LC gel observed above the clearing temperature of the non-reactive LC is attributed to the thermally stable network that remains oriented at elevated temperatures. However, this birefringence of the gels measured above the clearing temperature is higher than what is expected from the network alone, indicating that part of the non-reactive LC molecules... 

Use of sulfo-NHS-LC-SPDP or other heterobifunctional crosslinkers to modify PAMAM dendrimers may be done along with the use of a secondary conjugation reaction to couple a detectable label or another protein to the dendrimer surface. Patri et al. (2004) used the SPDP activation method along with amine-reactive fluorescent labels (FITC or 6-carboxytetramethylrhodamine succinimidyl ester) to create an antibody conjugate, which also was detectable by fluorescent imaging. Thomas et al. (2004) used a similar procedure and the same crosslinker to thiolate dendrimers for conjugation with sulfo-SMCC-activated antibodies. In this case, the dendrimers were labeled with FITC at a level of 5 fluorescent molecules per G-5 PAMAM molecule. 

Biotinylated liposomes usually are created by modification of PE components with an amine-reactive biotin derivative, for example NHS-LC-Biotin (Chapter 11, Section 1). The NHS ester reacts with the primary amine of PE residues, forming an amide bond linkage (Figure 22.19). A better choice of biotinylation agent may be to use the NHS-PEG -biotin compounds (Chapter 18), because the hydrophilic PEG spacer provides better accessibility in the aqueous environment than a hydrophobic biotin spacer. Since the modification occurs at the hydrophilic end of the phospholipid molecule, after vesicle formation the biotin component protrudes out from the liposomal surface. In this configuration, the surface-immobilized biotins are able to bind (strept)avidin molecules present in the outer aqueous medium. 

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