Preparation of Giant Vesicles Exhibiting Visible-light-induced Morphological Changes

Summary

The synthesis of ruthenium complex surfactants exhibiting photoisomerization in giant vesicles is described. The preparation and light irradiation of the giant vesicles are also described.

Abstract

We describe the preparation of giant vesicles that incorporate a photoresponsive ruthenium complex having two alkyl chains. The vesicles exhibited morphological changes when exposed to visible light. The ruthenium complex proximal-[Ru(L1)(L2)OH₂](NO₃)₂, proximal-2 (L1 is 4'-decyloxy-2,2';6',2"-terpyridine, L2 is 2-(2'-(6'-decyloxy)-pyridyl)quinoline) was prepared by a thermal reaction of Ru(L1)Cl₃ and L2, followed by removal of a chloride ligand. In an aqueous solution and vesicle dispersions, proximal-2 was reversibly photoisomerized to the distal isomer. Giant vesicles containing proximal-2 were prepared by hydration of phospholipid films containing proximal-2 in the dark at 80 °C. Giant vesicles were frequently found in the dispersions prepared from DOPC/proximal-2 rather than from DPPC/proximal-2 (DOPC is 1,2-dioleoyl-sn-glycero-3-phosphocholine, DPPC is 1,2-dipalmitoyl -sn-glycero-3-phosphocholine). The ratio of proximal-2 and DOPC in the vesicle preparation was varied from 5:100 to 20:100. The light-induced morphological changes were observed for proximal-2/DOPC in the presence of Na₂SO₄. However, they were highly suppressed in the presence of NaOH. Incubation of light-exposed vesicles at 45 °C in the dark induced reverse morphological changes. Morphological changes were observed under fluorescence microscopy using 635 nm (red) light. Rhodamine-DOPC [rhodamine-DOPC: 1,2-dioleoyl-sn-glycero-3-phos-phoethanolamine-N-(lissamine rhodamine B sulfonyl)] was used to fluorescently label the vesicles.

Introduction

Controlling the morphologies and shapes of macro- and meso-scale molecular assemblies by external stimuli has attracted considerable attention.^1,2 In particular, the control of vesicle morphologies by remote stimuli such as light has potential applications for drug delivery.³ In this context, organic photochromic molecules with hydrophobic and hydrophilic moieties have been widely incorporated into liposomes and polymer vesicles.^4,5,6,7,

Protocol

NOTE: Ru(tpy)Cl₃³⁰, L1²⁹, 2-(2'-(6'-chloro)-pyridyl)quinoline²⁹, proximal- 1²⁹ were synthesized as previously described.

1. Synthesis of 2-(2'-(6'-decyloxy)-pyridyl)quinoline (L2)

1. Add 2-(2'-(6'-chloro)-pyridyl)quinoline (16.3 mg, 63 µmol), 1-decanol (0.1 mL), dimethyl sulfoxide (1 mL), KOH (0.12 g) to a 50.......

Discussion

The ruthenium chloro complex proximal-[Ru(L1)(L2)Cl]⁺ was prepared by thermal synthesis of Ru(L1)Cl₃ and a bidentate ligand L2 in the presence of triethylamine. The proximal isomer was the major product and a distal isomer and Ru(L1)₂²⁺ was a minor impurity. The crude product was purified with size-exclusion chromatography using methanol as an eluent. Coordinating solvents, such as wat.......

Materials

Name	Company	Catalog Number	Comments
Triethylamine	Wako Pure Chemical Industries, Ltd.	202-02646
Lithium Chloride	Wako Pure Chemical Industries, Ltd.	125-01161
Chloroform	Kanto Chemical Co. Ltd.	07278-03	Used for vesicle preparation
Chloroform	Junsei Chemical Co. Ltd.	28560-0382	Used for ligand synthesis
Acetone	Junsei Chemical Co. Ltd.	11265-0382
Ethanol	Junsei Chemical Co. Ltd.	17065-0382
Ethyl Acetate	Junsei Chemical Co. Ltd.	67150-0382
Hexane	Junsei Chemical Co. Ltd.	31055-0382
Silica gel	Kanto Chemical Co. Ltd.	37558-79	100-210 μm
1-decanol	Tokyo Chemical Industry Co., Ltd.	D0031	25 mL
Potassium hydroxide	Kanto Chemical Co. Ltd.	32344-00
Sodium hydrixude	Wako Pure Chemical Industries, Ltd.	197-02125
Dimethyl sulfoxide (DMSO)	Kanto Chemical Co. Ltd.	10378-00
d-DMSO	Sigma-Aldrich	166290100
CD3OD	Kanto Chemical Co. Ltd.	25221-43
d-Acetone	Kanto Chemical Co. Ltd.	01054-43
D2O	Cambridge Isotope Laboratories, Inc.	DLM-4-100
Ruthenium chloride n-Hydrate	Wako Pure Chemical Industries, Ltd.	183-00823
2,2':6',2"-Terpyridine	Sigma-Aldrich	234672-5G
0.1 mol/L Silver nitrate solution	Wako Pure Chemical Industries, Ltd.	192-00855
Sodium sulfate	Kanto Chemical Co. Ltd.	37280-00
1,2 Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)	Wako Pure Chemical Industries, Ltd.	160-12781	100 mg, stored at -20°C
1,2 Dioleoyl-sn-glycero-3-phosphocholine (DOPC)	Sigma-Aldrich	P6354-100mg	100 mg, stored at -20°C
1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(carboxyfluorescein) (ammonium salt)	Avanti Polar Lipids, Inc.	Avanti 810332p	5 mg, stored at -20°C
1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(lissamine rhodamine B sulfonyl) (ammonium salt)	Avanti Polar Lipids, Inc.	Avanti 810150c	1 mg, stored at -20°C
Dextran gel	GE healthcare Japan	17009010	Sephadex LH-20
Amber glass vial	Maruemu	0407-06
Septum	Sigma-Aldrich	Z564648-100EA
Heater	Advantech	DRM 320 DB
Silicon film	AS ONE	6-9085-03	Thickness: 0.2 mm
Slide glass	Matsunami	S003130	76×26 mm, thickness: 0.8-1.0 mm
Cover glass	Matsunami	C218181	18×18 mm, thickness: 0.12-0.17 mm
Transfer pipette	Brand GMBH	704774
Round-bottom flask	Vidtech	1500-05
Sonicator	AS ONE	1-4591-32
Optical power meter	OPHIR	ORION/PD P/N 1Z01803
Oil bath	Riko	MH-3D
Magnetic stirrer	Riko	MSR-10
Diatomite	Wako Pure Chemical Industries, Ltd.	537-02305	Celite 545
Evaporator	Yamato	RE-52
Glass funnel	Kiriyama	SB-21	10 mL, 21 mmφ
Bell jar	Kiriyama	VKB-200
Filter paper	Kiriyama	No.4	21 mmφ
Optical microscope	KEYENCE	VHX-5000
Confocal fluorescence microscope	Olympus	FV-1000