Hevesi, János

Molnár, Miklós

English

Hevesi János

Molnár Miklós

University of Szeged

T I M E S T A B I L I T Y O F D E T E R G E N T ( M I C E L L E ) S Y S T E M S C O N T A I N I N G O R G A N I C D Y E S By J. HEVESI and M. MOLNÁR Institute of Biophysics and Institute of Experimental Physics, Attila József University, Szeged ( Received January 10, 1975) Micelle systems, containing organic dyes are often used as in vitro models to study physical? processes of photosynthesis. Time stability is an important characteristic of the applicability of" this model. In this paper the dependence of optical properties of dye-detergent systems on the duration of keeping the system in dark is investigated. It can be stated on the basis of o u r measurements that the dye systems studied, kept in the dark for a longer period, especially below critical micelle concentration (c.m.c.) and at higher temperatures, fade and seem to become "ex-hausted", i.e. their absorption maxima and fluorescence intensities decrease. Introduction Micelle systems containing organic dyes are often used as in vitro models of chloroplasts, as they approximate well the structure of chloroplast be well [1—3], which play an important role in photosynthesis. The model system being exposed to various external influences during the investigation, its stability against these influences is at the same time a measure of its applicability. The temperature dependence of the stability of micelle systems has been in-vestigated earlier [4]. The present paper describes the influence on stability exerted, by holding the system in dark for a longer period. Composition of the systems. Experimental methods The composition of the model used was the same as described earlier [4]. Absorp-tion and emission properties of three dye-detergent systems, namely thionin +sodium laurylsulphate (Th + SLS); Rhodamine 6G +sodium laurylsulphate (Rh 6G + SLS); methylene blue + sodium laurysulphate (MB + SLS) were studied at three different temperatures (30 °C, 50 °C, 70 °C), holding the systems in the dark. Absorption and emission spectra were measured at the time of preparation of the solutions as well as 6, 24, 54, and 96 hours later. This choice of the times of measurement was: determined partly by the circumstance that we wished to follow the changes in the spectral characteristics after different times spent in the dark, and partly by practical, (technical) conditions of the measurements. .32 J. HEVESI AND M. MOLNÁR Darkness and constant temperature were secured by placing the systems examined in a light-tight thermostat. A recording spectrophotometer Optica Milano Type CF 4 DR was applied for absorption measurements, a recording spectrophotometer Type DFS—12 for meas-uring the emission. During the measurements the temperature was held constant by cuvette holders the temperature of which was regulated by a Hoppler thermostat Type U—10. Results and discussion 1. Absorption measurements The degree of stability of the micelle system clearly depends on the changes in the absorption properties of the system produced by holding it in the dark at constant temperature for different times. The dependence of the micelle system on these parameters is presented in Table I for the a absorption band of thionin. It can be seen that above c.m.c. the sys-Table I Values and location of k (A)m„< of the a absorption band o / T h + SLS systems t T Csls-103(M/I) (°C) (hours) 0 2 3 3,5 4 8 0 k W m a x A m „ , (cm-1) (nm) 0 . 6 1 0 6 0 0 . 0 0 . 1 2 6 6 0 1 . 0 0 . 3 2 4 6 0 3 . 0 0 . 5 9 4 6 0 3 . 5 0 . 6 7 0 6 0 2 . 0 0 . 7 0 6 6 0 3 . 5 3 0 24 A'(A)m a x max (cm-1) (nm) 0 . 5 9 2 6 0 0 . 0 0 . 1 0 4 6 0 4 . 0 0 . 2 4 0 6 0 2 . 0 0 . 4 0 7 6 0 3 . 0 0 . 6 4 8 6 0 3 . 0 0 . 7 3 1 6 0 3 . 0 9 6 * U ) m « ; '•mill il 0 . 6 1 1 6 0 0 . 5 0 . 1 0 1 6 0 0 . 0 0 . 2 1 4 6 0 3 . 0 0 . 3 2 9 6 0 3 . 0 0 . 6 1 6 6 0 3 . 5 0 . 7 0 6 6 0 3 . 5 0 A r ( A ) „ „ (cm-1) (nm) 0 . 5 6 4 5 9 8 . 0 0 . 1 5 5 6 0 2 . 5 0 . 3 4 8 6 0 1 . 0 0 . 5 8 1 6 0 1 . 5 0 . 6 4 5 6 0 1 . 0 0 . 6 9 5 6 0 1 . 0 5 0 2 4 ^•max ll 0 . 5 5 9 5 9 7 . 5 0 . 1 2 3 6 0 0 . 0 0 .281 6 0 1 . 0 0 .421 6 0 0 . 5 0 . 6 2 5 6 0 1 . 0 0 . 6 9 5 6 0 1 . 5 9 6 k (A) m a j [ Am», (cm"1) (nm) 0 . 5 3 7 5 9 7 . 0 0 . 1 2 5 5 9 9 . 0 0 . 2 6 0 6 0 0 . 5 0 . 3 6 6 6 0 1 . 0 0 . 6 1 4 6 0 1 . 0 0 . 6 9 2 6 0 1 . 0 0 ^•max (cm-1) (nm) 0 . 5 9 6 5 9 7 . 0 0 . 2 0 8 6 0 2 . 0 0 . 4 1 5 6 0 1 . 0 0 . 5 2 7 6 0 1 . 0 0 . 5 8 3 6 0 1 . 5 0 . 6 8 5 6 0 0 . 5 7 0 2 4 '•max (cm-1) (nm) 0 . 5 7 5 5 9 5 . 5 0 . 1 9 7 5 9 8 . 0 0 . 3 3 0 5 9 8 . 0 0 . 4 3 4 6 0 0 . 0 0 . 5 2 3 6 0 0 . 5 0 . 6 7 3 6 0 0 . 5 9 6 A ' ( A ) m „ ^•max (cm-1) (nm) 0 . 4 9 2 5 9 5 . 5 0 . 1 7 8 5 9 8 . 0 0 . 2 8 3 6 0 0 . 0 0 . 3 7 3 6 0 1 . 0 0 . 4 8 9 6 0 0 . 5 0 . 6 3 6 6 0 0 . 5 TIME STABILITY OF DETERGENT (MICELLE) SYSTEMS CONTAINING ORGANIC DYES 3 3 tem Th + SLS is very stable, even after a longer period (96 hours) in the dark. At low detergent concentrations, however, the maxima of the a-band significantly decrease with increasing duration of the dark period, even at lower temperatures. At 70 °C, even systems found to be stable above c.m.c. do not show such stability; at this temperature an important decrease in absorption is found even at higher detergent concentrations. It can also be seen that at low detergent concentrations, especially at 50 °C and 70 °C, the maximum of the a-band is slightly shifted towards shorter wawelengths; above c.m.c. this shift cannot be observed. Table II Values and location of A-(A)mai of the a. absorption band of R h 6 G + SLS systems I T CSLS-10»(M/1) (C°) (hours) 0 2 3 3,5 4 8 0 ^max (cm-1) (nm) 0 . 7 8 9 5 2 8 . 0 0 . 7 6 4 536 .5 0 . 8 5 0 5 3 5 . 5 0 . 8 8 0 5 3 5 . 5 0 . 8 9 5 535 .5 0 . 9 4 0 5 3 5 . 0 3 0 24 ^ (^ )max ^max (cm-1) (nm) 0 . 9 1 6 527 .5 0 . 7 3 5 535 .5 0 . 8 2 8 5 3 5 . 0 0 . 8 7 5 5 3 5 . 0 0 . 8 8 5 5 3 5 . 0 0 . 9 2 0 535 .0 9 6 k W m a * •̂ •max (cm-1) (nm) 0 . 8 4 3 5 2 6 . 0 0 . 7 3 8 5 3 4 . 0 0 . 8 3 6 5 3 5 . 0 0 . 8 6 2 5 3 5 . 0 0 . 8 8 6 5 3 5 . 0 0 . 8 9 2 5 3 5 . 0 0 k (^)max ^•mai (cm-1) (nm) 0 . 8 4 0 5 2 6 . 0 0 . 8 0 0 534 .0 0 . 8 4 5 5 3 4 . 0 0 . 8 5 1 5 3 4 . 0 0 . 8 4 9 5 3 4 . 0 0 . 8 5 0 5 3 4 . 0 5 0 24 k (^)ma* ^max (cm-1) (nm) 0 .811 5 2 6 . 5 0 . 7 7 6 5 3 5 . 0 0 . 8 3 5 5 3 4 . 5 0 . 8 5 4 5 3 4 . 0 ' 0 . 8 6 0 5 3 4 . 0 0 . 8 9 0 533 .5 9 6 m»* ^•max (cm-1) (nm) 0 . 8 5 5 526 .5 0 . 7 5 6 534 .5 0 . 8 3 0 5 3 5 . 0 0 . 8 5 0 5 3 5 . 0 0 . 8 5 6 5 3 4 . 5 0 . 8 9 7 533 .5 0 k (^)max ; '•max (cm-1) (nm) 0 . 8 1 9 527 .0 0 . 7 6 7 534 .5 0 . 7 9 4 5 3 4 . 0 0 . 8 2 2 5 3 4 . 0 0 . 8 2 6 5 3 4 . 0 0 . 8 4 4 5 3 4 . 0 7 0 24 k (^)max ^•max (cm-1) (nm) 0 . 8 0 6 526 .5 0 . 7 3 5 5 3 4 . 5 0 . 7 6 5 5 3 4 . 5 0 . 8 1 0 5 3 4 . 5 0 . 8 0 3 534 .5 0 . 8 6 0 5 3 4 . 0 9 6 k (A)max 1 '•max (cm-1) (nm) 0 . 8 1 5 526 .0 0 . 7 2 1 5 3 4 . 0 0 . 7 9 7 5 3 3 . 0 0 . 8 1 9 5 3 3 . 5 0 . 8 1 2 533 .5 0 . 8 6 7 5 3 2 . 0 Table II shows the changes in the absorption maxima of the system Rh 6G+SLS, caused by holding the system in the dark. It can be seen that the influence of the dark period on the absorption of the system is less important, the changes remain generally below 5%; at higher temperatures, the changes are somewhat more sig-nificant. Concerning the changes in absorption of MB + SLS systems due to longer periods in the dark, the same can be said as for Th+SLS systems. 3 .34 J. HEVESI AND M. MOLNÁR 2. Emission measurements The changes in emission caused by longer dark periods are presented in Table III. It can be seen that, up to 4-10~3 M/l SLS concentration, the luminescence intensity at 30 °C decreases due to the dark period, while at higher concentrations it remains constant. At 50 °C and 70 °C a significant decrease in intensity is observed even at Table III Values and location of emission maxima ( / q (A) m o i ) o / T h + SLS systems T CSLS103(M/1) (°C) (hours) 0 2 3 3.5 4 8 0 (%) (nm) 100.0 6 1 9 . 0 17.3 6 1 8 . 5 4 2 . 3 6 2 1 . 5 76 .4 6 2 1 . 0 146.4 6 2 1 . 0 179 .0 6 2 0 . 5 30 24 fq (^)max (%) ( n m ) 104.0 6 2 0 . 0 11.3 6 2 1 . 5 2 9 . 9 6 2 0 . 0 50 .5 6 2 2 . 0 137 .4 6 2 1 . 0 184 .3 6 2 0 . 5 9 6 (%) (nm) 76 .2 6 1 9 . 0 9 . 6 6 2 1 . 5 2 4 . 8 6 2 2 . 5 4 0 . 5 6 2 1 . 0 133 .3 6 2 0 . 179.8 6 2 0 . 0 0 fq (^)max ^•max (%) ( n m ) 100.0 6 2 0 . 0 3 2 . 0 6 2 1 . 5 4 2 . 6 6 2 1 . 0 7 3 . 2 6 2 0 . 5 121 .3 6 1 9 . 5 166.7 6 2 0 . 0 50 • 24 ^msx (%) (nm) 9 8 . 5 6 2 0 . 0 2 6 . 3 6 2 1 . 5 4 3 . 2 6 2 1 . 0 5 9 . 3 6 2 0 . 5 103.5 6 2 0 . 0 151.7 6 2 0 . 0 9 6 fq (^)max ^'max (%) (nm) 9 0 . 9 6 2 0 . 0 12.6 6 2 1 . 5 3 2 . 9 6 2 2 . 0 4 6 . 7 6 2 1 . 5 6 9 . 4 6 2 0 . 5 104 .7 6 2 0 . 5 0 ^max fq (^)mix (nm) (%) 100 .0 6 1 9 . 0 53 .9 6 2 2 . 0 6 2 . 6 6 2 1 . 5 71 .2 6 2 0 . 5 81 .8 6 2 0 . 0 143 .6 6 1 9 . 5 70 24 ^•max fq{,^*) max (nm) (%) 9 3 . 2 6 1 9 . 5 4 9 . 4 6 2 1 . 5 5 5 . 0 6 2 1 . 5 6 4 . 5 6 2 1 . 0 6 9 . 8 6 2 0 . 0 137 .6 6 1 9 . 5 9 6 fjWmai ^•raax (%) (nm) 95 .6 6 2 0 . 0 4 1 . 4 6 2 2 . 0 49 .1 6 2 1 . 0 57 .0 6 2 1 . 5 71 .8 6 2 0 . 5 133 .4 6 2 0 . 0 higher detergent concentrations. This shows that the systems seem to become "ex-hausted", especially at higher temperatures. Table IV shows the changes caused by the dark period in fluorescence intensity of the Rh6G+SLS systems. It can be seen that at detergent concentrations below. c.m.c. the values of /9(A)max significantly decrease at all three temperatures;, above c.m.c. a less significant increase is found. Concerning the changes in fluorescence intensity due to the dark period of system's containing MB, the same can be said as in the case of thionin. TIME STABILITY OF DETERGENT (MICELLE) SYSTEMS CONTAINING ORGANIC DYES 3 5 Table IV Values and location of emission maxima ( / q ( / l ) m „ ) of Rh 6G + SLS systems t T C S L S - 1 0 » ( M / 1 ) (°C) ( h o u r s ) 1 2 3 3,5 4 8 0 (%) (nm) 1 0 0 . 0 5 5 2 . 0 2 1 . 2 5 5 8 . 5 7 1 . 5 5 5 9 . 0 8 2 . 1 5 5 9 . 5 8 4 . 8 5 5 9 . 0 8 1 . 9 5 5 7 . 0 3 0 2 4 ' • m a x (%) (nm) 1 0 1 . 5 5 5 3 . 0 7 . 5 5 5 8 . 5 4 8 . 0 5 6 1 . 0 7 9 . 2 5 6 1 . 0 8 5 . 4 5 6 0 . 0 7 3 . 6 5 5 8 . 5 9 6 / , a ) m „ ^ m a x (%) (nm) 1 2 4 . 6 5 5 3 . 0 6 . 9 5 5 7 . 5 4 3 . 2 5 6 0 . 5 8 7 . 1 5 5 9 . 5 1 0 1 . 9 5 5 9 . 0 9 3 . 8 5 5 7 . 5 0 f q ( ^ ) m a x •^max (%) (nm) 1 0 0 . 0 5 5 2 . 5 2 9 . 3 5 6 1 . 0 5 6 . 6 5 6 0 . 5 6 6 . 5 5 6 0 . 0 7 5 . 4 5 5 9 . 0 7 4 . 3 5 5 8 . 0 5 0 2 4 / , ( À ) m „ ^ m a * (%) (nm) 1 0 4 . 8 5 5 3 . 0 2 4 . 7 5 6 0 . 0 5 3 . 8 5 6 0 . 5 7 1 . 8 5 6 0 . 0 8 0 . 0 5 5 8 . 5 6 4 . 6 5 5 7 . 0 9 6 ^ m a x (%) (nm) 1 0 4 . 4 5 5 3 . 0 1 3 . 1 5 6 0 . 5 4 4 . 4 5 5 9 . 5 5 8 . 5 5 5 9 . 5 7 1 . 0 5 5 8 . 5 7 1 . 4 5 5 8 . 0 0 f q ( ^ ' )max An,«* (%) (nm) 1 0 0 . 0 5 5 3 . 5 1 6 . 3 5 5 5 . 0 3 5 . 9 5 5 9 . 5 4 5 . 9 5 5 9 . 5 6 1 . 3 5 5 8 . 0 • 7 4 . 4 5 5 7 . 0 7 0 2 4 f q ( ^ ) m a x ^•max (%) (nm) 1 1 1 . 7 5 5 4 . 0 1 6 . 2 5 5 7 . 5 3 5 . 7 5 6 1 . 0 5 6 . 3 5 6 0 . 0 6 1 . 9 5 6 0 . 0 9 5 . 2 5 5 7 . 5 9 6 f q ( ^ ) m a x ^ m a x (%) (nm) 1 0 3 . 2 5 5 4 . 0 1 1 . 5 5 5 8 . 5 3 9 . 8 5 6 0 . 0 4 9 . 2 5 6 0 . 0 5 6 . 7 5 5 9 . 5 8 3 . 8 5 5 6 . 0 Summarizing the results, it can be stated that below c.m.c. the systems studied significantly fade by being kept in the dark. Good stability above c.m.c. is found in Rh6G + SLS systems. In Th + SLS and MB + SLS systems above c.m.c., slight decreases in absorptions intensity can be observed at higher temperatures. The systems seem to become "exhausted" by the dark period, their ability of emission decreases. Below c.m.c., i.e. before the formation of an ordered structure, the three dye-detergent systems studied are instable, while above c.m.c. they are more stable at all temperatures. References [1] Singhal, G. S„ E. Rabinowitch, J. Hevesi, V. Srinivasan: Photochem. Photobiology 11, 531 (1970). [2] Winsor, P. A.: Chem. Rev. 68, 1 (1968). [3] Hevesi, J., E. Lehoczki, E. Bálint: Zh. Prikl. Spektr. 13, 458 (1970). [4] Molnár, M., J. Hevesi: Acta Phys. Polon. Sci., (in press). 3' .36 J. HEVESI AND M. MOLNÁR ЗАВИСИМОСТЬ СТАБИЛЬНОСТИ СИСТЕМ КРАСИТЕЛЬ-ДЕТЕРГЕНТ ОТ ВРЕМЕНИ Я. Хевеши и М. Молнар В работе исследовалась зависимость оптических свойств систем краситель-детергент от длительности хранения в темноте. Экспериментальные результаты показывают, что исследованные системы при постоянных температурах после длительного времени хранения в темноте, главным образом при концентрациях ниже критической концентрации мицелло-образования (ККМ), и при порвышенных температурах выцветают, значения максимумов поглощения и интенсивности флуоресценции уменьшаются. 

Time stability of detergent (micelle) systems containing organic dyes

http://acta.bibl.u-szeged.hu/23950/1/phys_chem_021_fasc_001_002_031-036.pdf

Time stability of detergent (micelle) systems containing organic dyes

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