Tetrahedron Letters,Vo1.26,No.4O,pp 4827-4830,1985 004o-4o39,'85 $3.00 + .OO Printed in Great Britain cl985 peraarnon Press Ltd. CHARGE TYPE AND TRANS-MEMBRANE TRANSPORT OF FLUORESCENT PROBES IN SURFACTANT VESICLES Robert A. Moss,* Shanti Swarup, Bogusaawa Wilk, and Thomas F. Hendrickson Department of Chemistry, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903 Summary. We describe the effects of charge type on the trans-membrane transport of anionfc and cationic fluorescent probes in cationic, anionic, and zwitterionic surfactant vesicles. To what extent does the charge type of surfactant vesicles or liposomes determine the rate of trans-membrane transport of organic ionic fluorescent probes?' This question is significant because of the central role played by surfactant assemblies in the study of membrane mimetic reactions .* Studies bearing on this problem have been carried out with bilayer-coated nylon capsules3a and with photoactivated carrier permeants in phosphatidylcholine liposomes.3b However, time-resolved kinetic studies of more complicated permeants in simpie synthetic vesicles are few. 1p3c Here we report initial results from a study of four vesicular surfactants and two probes that help shape an answer to our initial question. The surfactants and probes are illustrated in Chart I. Cationic dihexadecyldimethyl- ammonium bromide (162),ls4 anionic dicetyl phosphate (DCP, Sigma),*d and zwitterionic dipalmitoylphosphatidylcholine (DPPC, Sigma)1 were all readily available. Zwitterionic N,N-dicetyl-z--methylglycfnate (DCMG) was synthesized by quaternization of N,N-dicetyl-x- -- -- methylamine with ethyl bromoacetate (refluxing ethanol, 21 days, recryst. 2X from ether), followed by saponification (0.11 M NaOH in refluxing 97% aqueous EtOH, 48 hrs), neutral- ization (HCl), leaching with hot CHC13, and recrystallization (2X, EtOAc). We thus obtained DCMG, mp '76"C, in 58% overall yield based on the tertiary amine. Satisfactory spectral and analytical data were obtained for DCMG. The fluorescent probes were commercially available: l-anilino-8-naphthalene sulfonate (ANS, Aldrich) and ethidium bromide (EB, Sigma). All vesicle solutions were prepared by sonication5 at 55-6O"C, cooled to ambient temperature, and passed through 0.8 nM Millex PF filters before use. Sonicated vesicles of 4827