Interfacial properties of a novel pyrimidine derivative and poly(ethylene glycol)-grafted phospholipid floating monolayers

4-amino-2-phenyl, 6(p-fluor-phenyl)-5-carbonitrile-pyrimidine (APCP) is a new derivative of pyrimidine with low solubility in water and anti-inflammatory properties. We compared the interfacial behaviors of spread films of poly(ethylene glycol)-grafted phospholipid (DSPE-PEG2000), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and APCP and a mixture of these molecules. The surface pressure–area (Π–A) isotherm showed that APCP and DSPE-PEG2000 molecules were stable at the air/water interface and could be evenly inserted into a DPPC floating monolayer. The introduction of APCP into the DPPC/(DSPE-PEG2000) binary monolayer generally causes an overall increase in surface potential. Analyses of distance variation between the grafted sites are associated with a change of mushroom to brush conformation and this behavior is observed for the DPPC/(DSPE-PEG2000) and DPPC/(DSPE-PEG2000)/APCP monolayers. Langmuir–Blodgett (LB) films of molecules of biological interest were transferred onto mica in order to investigate their interaction. AFM images do not show any regular shape or size and are randomly distributed.

. AFM topographic image of DPPC/(DSPE-PEG2000)/APCP ternary systems.Figure optionsDownload as PowerPoint slideResearch highlights▶ APCP molecules exhibited expanded isotherms for the entire pH range studied. ▶ DSPE-PEG2000 monolayer shows a transition from pancake to brush conformation. ▶ The introduction of APCP onto DPPC molecules prevents them from close packing. ▶ The negative charge of the phospholipid headgroup attracts the protonated APCP. ▶ AFM image shows elevated structures with irregular shape and randomly distributed.