JP2007084393A - Carotenoid including structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new structure for allowing the original characteristics of carotenoid to exhibit in such a manner that carotenoid is stabilized and its chemical change is not made to occur by eliminating influence owing to chemical molecules such as oxygen, light or radicals, and to provide a new structure capable of protecting carbon nanotubes from the circumferential environment and stabilizing the same. <P>SOLUTION: The structure is composed of carotenoid including carbon nanotubes. A carotenoid stabilization-maintaining material is composed of the structure. A carbon nanotube stabilization-maintaining material is composed of the structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure containing carotenoids.

Carotenoid is a general term for pigments widely contained in animals and plants. Besides being widely used as a natural pigment, β-carotene among carotenoids is also known as a powerful provitamin and is widely used for pharmaceuticals.
Carotenoids are generally insoluble in water, dissolved in a solvent that dissolves fats, are easily oxidized, are unstable to acids, and have a chemical property that is inherently susceptible to photoisomerization. Specifically, it is a substance that has the property of reacting with radical species and is easily deteriorated.
It is also known that carotenoids are materials having large third-order nonlinear optical properties (Non-patent Document 1 R. Mader et al., Science 276 (1997) 1233)). The use of carotenoids as nonlinear optical materials has already been proposed (Patent Document 1). However, although it has the characteristics of a nonlinear optical material, it has been difficult to put it into practical use as a nonlinear optical material due to the properties of carotenoids.
Conventionally, as a method for suppressing the degradation of carotenoids, it has been proposed to coat carotenoids with protective substances including gelatin and alginates (Patent Document 2).
However, the coating with these protective substances cannot provide durability enough to be used as an optical device element. In particular, in order to use carotenoids as device materials, it is considered ideal to have a structure that protects the entire carotenoid molecule from the surrounding environment, but such a structure has not yet been developed. .

As a method for stabilizing a chemical substance, it is known to stabilize the structure as a structure protecting the chemical substance.
By encapsulating a photofunctional molecule such as rubrene, which is different from carotenoid, in a dendrimer which is a structure, functional inhibition of the encapsulated molecule is prevented by the active oxygen molecular species (Patent Document 3).
By encapsulating a photofunctional molecule in a dendrimer, it aims to stabilize the photofunctional molecule and use it as an optical device material.
However, it is very expensive to create a dendrimer as a structure, and the dendrimer itself cannot be said to be a robust substance. From this point of view, it can be fully expected as a structure that protects chemical substances. Can not.
In recent years, it has been announced that it is possible to encapsulate a dye inside a carbon nanotube (T. Takenobu et al., Nature materials 2 (2003) 683).
This pigment is different in structure and action from carotenoids. Specifically, this document is as follows.
tetrakis (dimethylamino) ethylene (TDAE),
tetramethyl-tetraselenafulvalene (TMTSF),
Tetrathiafulvalene (TTF),
Pentacene,
Anthracene,
C60,
Tetracyano-p-quinodimethane (TCNQ),
Tetrafluorotetracyano-p-quinodimethane (F4TCNQ) is mentioned.
The purpose of encapsulating the dye inside the carbon nanotube is exclusively used to dope the carbon nanotube. This document does not intend to stabilize dyes or carbon nanotubes.

For this reason, structures that stabilize carotenoids and prevent them from undergoing chemical changes and exhibit their original properties, and carbon nanotubes stabilize and prevent them from undergoing chemical changes. The development of a structure that can be used to achieve this is eagerly desired.
Patent publication: 2000-095754 Patent publication 2002-525090 Patent publication: 2003-95999 R. Maderet al., Science276 (1997) 1233)

  An object of the present invention is to provide a novel structure for causing carotenoids to exhibit their original properties by stabilizing the carotenoid by eliminating the influence of chemical molecules such as oxygen, light or radicals, and preventing chemical changes, and It is to provide a novel structure capable of protecting and stabilizing a carbon nanotube from the surrounding environment.

The present inventors diligently studied the above-mentioned problems and found the following to complete the present invention. The inside of the carbon nanotube is a space in which atoms such as carbon do not exist, and the outside is a structure formed as a tube (cylindrical) shape made of carbon. The carbon nanotube structure encapsulating carotenoids obtained by incorporating carotenoids inside the carbon nanotubes stabilizes the carotenoids by eliminating the influence of chemical molecules such as oxygen, light, or radicals, so that no chemical changes occur. Can be.
As a result, in the case of a carotenoid molecule-containing structure, since the nanotube wall surrounds the carotenoid molecule, it is possible to prevent attacks from oxygen molecules, light, and radical species (such as active oxygen) existing outside. Carotenoid isomerization can also be suppressed by encapsulating the carbon nanotubes. In addition, since the action of carotenoid molecules helps to stabilize the carbon nanotube, the application field of the carbon nanotube can be expanded.

  The carbon nanotube structure encapsulating the carotenoid of the present invention can prevent attacks from ultraviolet light (365 nm), radical species (active oxygen, etc.), oxygen, etc. existing outside because the wall of the nanotube surrounds the carotenoid molecule. It becomes. As a result, the field of application as carotenoid molecules, pigments, nutrients, and nonlinear optical materials can be expanded. In addition, since the action of carotenoid molecules helps to stabilize the carbon nanotube, the application field of the carbon nanotube can be expanded.

  The present invention is a carbon nanotube structure containing carotenoids. This structure is a state in which carotenoids are taken in and encapsulated in carbon nanotubes. Specifically, it is as shown in FIG. 1 and FIG. This structure can be confirmed as follows. By comparing the results of each Raman measurement for carotenoids, carbon nanotubes, and carbon nanotubes incorporating carotenoids, it can be confirmed that the carbon nanotubes incorporate carotenoids.

In the structure, carotenoids are relatively stabilized and present in a space region where no carbon atom or the like exists in the center of the carbon nanotube. Due to the action of the flow of gas and liquid, the carotenoid taken into the carbon nanotube does not jump out of the carbon nanotube from the space region of the carbon nanotube.
Active oxygen does not enter through the carbon nanotubes present around the carotenoid, and the carbon nanotube has a shielding effect, and the carotenoid is stabilized. Moreover, it exists stably in the environment where heat exists. Conversely, carbon nanotubes themselves can be present in a stabilized manner.

The carotenoid means a general term for pigments widely contained in animals and plants (published on June 1, 1998, p492).
It is a yellow, red or purple polyene dye. Many comprising several 40 carbon _{(C 40} - carotenoids). C _30- , C ₄₅ -C _50- and the like. Hydrocarbons include carotene and lycopene. In the case of alcohol, it is generically called xanthophyll. In general, it is insoluble in water, dissolved in a solvent that dissolves fat, easily oxidized, and unstable in acid.
Carotenes are carotenoid hydrocarbons, both of which are known substances. Specific examples of carotenoids are as follows.
α-carotene, β-carotene, γ-carotene, δ-carotene, δ-carotene, ξ-carotene, β, γ-carotene, γ, γ-carotene, lycopene, lutein, astaxanthin and the like.
These exist in various plants and can be separated and removed by solvent extraction.
In order for carotene to be taken into the carbon nanotube, the chemical structure of the carotene needs to be large enough to fit within the carbon nanotube.
β carotene has a length of about 3 nm and a width of about 0.5 nm. Other carotenes are similar in chemical structure to β-carotene and are about this size.

The carbon nanotube (CNT) has a structure having a graphite cylinder having a hollow portion.
Carbon nanotubes may be single-bar single-walled carbon nanotubes or multi-walled carbon nanotubes. In the case of a single-walled carbon nanotube, the diameter is 0.8 to 1.4 nm and the length is about several μm. In the case of multi-walled carbon nanotubes, the diameter is from several nanometers to several tens of nanometers ("Basics of Carbon Nanotubes and the Forefront of Industrialization" NTS Co., Ltd., published on January 11, 2002, page 4).

  Carbon nanotubes can be produced by many known methods such as low-pressure arc discharge method, laser evaporation method, catalytic vapor phase growth method, SiC surface decomposition method, laser ablation method, arc method, etc. page). According to the arc method, an arc is blown between the anode graphite and the rotating cathode, and the deposits deposited on the cathode are removed to take out the product. The conditions are He 450 to 760 Torr, He flow rate 3 to 10 L / min, current 60 to 160 A, voltage 16 to 23 V, gap between cathode and anode of about 1 mm, anode graphite 8, 10, and 15 mmφ (supra 295 pages) ( JP-A-7-216660). In addition, hydrocarbons are thermally decomposed in the presence of a catalyst base to generate carbon nanotubes on the surface of the base, carbon nanotubes are collected, a catalyst solution containing ultrafine catalyst particles is applied to the base surface and dried to form a catalyst. The substrate can be regenerated and again manufactured by a method described in a method for manufacturing carbon nanotubes (Japanese Patent Laid-Open No. 2001-80912).

In order to incorporate carotenoid into the carbon nanotube, the following procedure is used.
(1) A process of removing the ends of the carbon nanotubes for incorporation into the carbon nanotubes.
(2) Carotenoid encapsulation into carbon nanotubes

(1) About the process which deletes the terminal of a carbon nanotube in order to take in in a carbon nanotube The description process says the process which processes a carbon nanotube beforehand and leaves the terminal of a carbon nanotube. There are many ways to do this. One example is as follows. By removing the catalyst metal used for the heat treatment (100 to 1000 ° C.) and nanotube production in the air with an acid or the like, the end can be opened (H. Kataura et al., Appl. Phys. A Vol. 74, (2002) 349, C. Yang et al., Nano letters, Vol. 2 (2002) 385)). According to this method, the end of the carbon nanotube can be opened. It is not necessary to confirm and use this in normal operation.
As a test method for determining whether or not the end of the carbon nanotube is open, there is a method of confirming by a change in the adsorption state of nitrogen atoms (C. Yang et al., Nano letters, Vol. 2 (2002) 385).

(2) Method of encapsulating carotenoids inside carbon nanotubes The method of encapsulating carotenoids inside carbon nanotubes is as follows: (i) Carotenoids and carbon nanotubes that have been treated to open the ends are immersed in a solvent (B) Carotenoid and the terminal are opened under a nitrogen atmosphere in the presence of a solvent for 10 hours under reflux, and (c) Carotenoid and the terminal. There is a method in which the carbon nanotubes after the treatment for opening are left standing in a state immersed in a solvent.
These methods are described below.

(A) Carotenoid and the method of ultrasonically treating the carbon nanotubes after opening the ends in a state of being immersed in a solvent. Carotenoids (β-carotene) and carbon nanotubes with open ends are put in a polar solvent, and then for a certain period of time. Sonicate in slightly warmed condition.
Carotenoids can be included by sonication at a low temperature below this, but the efficiency of the encapsulation is not good.
After completion of the treatment, the carotenoid existing outside the carbon nanotube is washed away with a solvent to form a thin film.
In order to completely remove the carotene present outside the carbon nanotubes, it is dispersed again by sonication in a solvent to form a thin film, and then washed with a solvent. By the above operation, carotenoid can be encapsulated inside the carbon nanotube.

(B) A method of treating the carotenoid and the carbon nanotubes after the end-opening treatment under reflux in a nitrogen atmosphere for 10 hours in the presence of a solvent. Carotenoid (β-carotene) and a carbon nanotube having an open end are treated with a solvent (for example, In a solvent selected from hexane, benzene, and toluene, or a mixture thereof) and refluxed in a nitrogen atmosphere. Thereafter, the carotenoid existing outside the carbon nanotube is washed away with a solvent to form a thin film. In order to completely remove carotenoids existing outside the carbon nanotubes, they are dispersed again in a solvent by ultrasonic treatment, thinned, and washed with a solvent. By the above operation, carotenoid can be encapsulated inside the carbon nanotube.

(C) Carotenoid and a method of leaving the carbon nanotubes after the end-opening treatment immersed in a solvent The carotenoid and the carbon nanotubes having open ends are put in a solvent and left standing overnight.
Thereafter, the carotenoid existing outside the carbon nanotube is washed away with a solvent to form a thin film. In order to completely remove carotenoids (carotene) existing outside the carbon nanotubes, they are dispersed again in a solvent by ultrasonic treatment, thinned, and washed with a solvent. By the above operation, carotenoid can be encapsulated inside the carbon nanotube. However, this stationary treatment method is not good in comparison with the above two methods in terms of efficiency.

  It can be confirmed by the following operation that the structure composed of carbon nanotubes encapsulating carotenoid obtained by the above operation is stabilized against ultraviolet light. The carotenoid dissolved in the solution and the carotenoid encapsulated in the carbon nanotube are irradiated with ultraviolet light, and the irradiation time and photodecomposition are shown. The rate of photolysis can be clarified from changes in absorption intensity. It was revealed that by incorporating carotenoids inside carbon nanotubes, photodegradation can be drastically prevented compared to the situation of a single substance. An example of the results is as shown in Example 5 (FIG. 2) and Example 6 (FIG. 5).

About confirming that carotenoids are encapsulated in carbon nanotubes In order to confirm that carotenoids are encapsulated in carbon nanotubes, Raman measurement is performed on the following. By comparing the results of Raman measurement of carotenoids, carbon nanotubes, and carbon nanotubes in which carotenoids are incorporated, it can be confirmed that the carotenoids are incorporated in the carbon nanotubes in which carotenoids are incorporated.
The result is shown in FIG. The carbon nanotubes used in FIG. 3 were prepared by a laser ablation method and purified at the ends of the tube. 3a, b, and c are Raman spectra of carotenoid, carbon nanotube, and carbon nanotube encapsulating carotenoid, respectively, in an acetone solution. From the above comparison, it can be seen that carotenoids are properly encapsulated inside the carbon nanotubes. Furthermore, in order to make sure that carotenoids are not attached to the outside of the carbon nanotube, but the end of the nanotube is closed (Hipco: nanotube created by the High pressure CO method) and the nanotube. The sample (Hipco after, Hipco-O after) was subjected to the above-described encapsulation process for the sample with the open end (Hipco-O: tube in which the end of Hipco was opened). ) For Raman measurement. The result is shown in FIG. When the carbon nanotube ends are closed, there is no carotenoid-derived Raman peak (see FIG. 4b).
It can be seen that a peak derived from carotene exists only when the ends are opened (see FIG. 4c). This indicates that carotenoids are present not inside the carbon nanotube surface but inside. That is, it was confirmed that the synthesis of the carbon nanotube structure encapsulating carotenoid was successful.

A confirmation method for allowing a structure composed of carbon nanotubes encapsulating carotenoids to be used in an optical device is as follows.
The test is performed in the same manner as a test method using a method for confirming a material that can be used as a normal optical device.
The test method for confirming that it can be used as an optical device material is as follows.
SrTiO3 can be cited as the most optimal Kerr medium used for time-resolved spectroscopy [Rev. Sci. Inst. 75 (2004) 636].
As a characteristic required for the Kerr medium, there is a large third-order optical nonlinearity.
On the other hand, SrTiO3 is a material having a third-order optical nonlinearity about 40 times that of β-carotene [App. Phys. Lett. 23 (1973 178), Rev. Sci. Inst. 75 (2004) 636, Phys. Rev. B 39 (1989) 3337, derived].
By the way, it has been reported that a polar carotenoid having a donor-acceptor functional group introduced into a polyene skeleton has a third-order optical nonlinearity of 35 times that of β-carotene [Science 276 (1997) 1233].
From the above, it can be said that carotenoid is sufficiently usable as a Kerr medium used in time-resolved spectroscopy.
There are two methods for confirming that a structure composed of carbon nanotubes containing carotenoids can be used as an optical device material.

Confirmation that the carbon nanotube structure encapsulating carotenoid can be used as a carbon nanotube stabilizer is performed as follows.
It is clear from the following that carbon nanotubes are susceptible to degradation due to oxidation.
In Japanese Patent Application Laid-Open No. 2004-280028 “Saturable Absorption Tip, Method for Producing the Same, and Device Using the Saturable Absorption Tip”, carbon nanotubes are used as the saturable absorption tip. In this patent, prevention of deterioration due to oxidation is a technical solution. On the other hand, it is widely known that carotenoids react with radical molecules and have an antioxidant effect [Biochem. Biophys. Res. Com., 305 (2003) 754].
It is also known to have a photoprotective action that suppresses the generation of singlet oxygen [Phtosynth. Res. 70 (2001) 249]. The generation of singlet oxygen is caused by the generation of a triplet state by photoexcitation. Carotenoids suppress the generation of singlet oxygen by eliminating this triplet state.
From the above, it is expected that the lifetime can be extended significantly when the carbon nanotube is used as a device.

Confirmation that the structure composed of carbon nanotubes encapsulating carotenoid has thermal stability is performed as follows.
It was confirmed that the carbon nanotubes encapsulating the carotenoid were present in a stable state even when the carbon nanotube encapsulating the carotenoid was heated at 100 ° C. for one hour in a vacuum (10 ⁻⁶ torr).

Confirmation that the structure composed of carbon nanotubes encapsulating carotenoid has light stability is performed as follows.
It can be confirmed that the carbon nanotubes encapsulating the carotenoids are stably irradiated with light and the carbon nanotubes encapsulating the carotenoids are present (Examples 5 and 6).

  Since the structure composed of carbon nanotubes encapsulating carotenoid has the above-mentioned properties, it can be used as a carotenoid stabilization maintenance material and a carbon nanotube stabilization maintenance material. The stabilization maintaining material means that it serves as a stabilizing material and can maintain a stable state.

  A structure composed of carbon nanotubes encapsulating carotenoids having the above characteristics can be used as a drug delivery material for guiding a carotenoid to a site that requires carotenoids in vivo. The carotenoid can be β-carotene.

  Since carotenoids and β-carotene are known to be nonlinear optical materials, carbon nanotubes containing carotenoids and β-carotene can be used as nonlinear optical materials. Moreover, it can use as an optical device material used as a nonlinear optical material.

  Since carotenoids and β-carotene become laser dyes, carbon nanotubes encapsulating carotenoids and β-carotene can be used as the laser dye material.

Since carotenoids and β-carotene can be used as sensitizing dyes, carbon nanotubes encapsulating carotenoids and β-carotene can be used as dye-sensitized solar cell materials.
Hereinafter, production examples of carbon nanotube structures encapsulating carotenoids and examples relating to their use will be described. The present invention is not limited to this.

Treatment for opening ends of carbon nanotubes The ends of unpurified carbon nanotubes (HiPco) were opened by heat treatment (100 to 1,000 ° C.) for 30 minutes in air. Subsequently, it was immersed in hydrochloric acid (18 wt%) at room temperature for about 10 minutes, filtered through a filter, and washed with pure water. This hydrochloric acid treatment was performed twice.

Method of encapsulating carotenoids inside carbon nanotubes ((i) Method of ultrasonically treating carbon nanotubes after carotenoids and the above-mentioned end opening treatment in the presence of a solvent)
15 mg of β-carotene and 1 mg of open carbon nanotubes were immersed in 10 ml of methanol and sonicated at 50-60 ° C. for 60 minutes.
After the treatment, the carotenoid existing outside the carbon nanotube was washed away with 100 ml of THF to form a thin film.
In order to completely remove the carotene present on the outside of the carbon nanotubes, the dispersion treatment was again performed for 5 minutes by ultrasonic treatment in 10 ml of THF, and after thinning, washing was performed with 50 ml of THF. Carotenoids could be encapsulated inside the carbon nanotubes.

A method of encapsulating carotenoids inside carbon nanotubes ((b) A method of treating carotenoids and carbon nanotubes after opening the ends under reflux in a nitrogen atmosphere in the presence of a solvent for 10 hours)
100 mg of β-carotene and 1 mg of carbon nanotubes with open ends were placed in 100 ml of hexane and refluxed for 10 hours in a nitrogen atmosphere. Thereafter, β-carotene present outside the carbon nanotubes was washed away with 100 ml of THF to form a thin film. In order to completely remove β-carotene present on the outside of the carbon nanotube, it was dispersed again in 10 ml of THF by ultrasonic treatment, thinned, and washed with 50 ml of THF. Through the above operation, carotenoids could be encapsulated inside the carbon nanotubes.

Method of encapsulating carotenoids inside carbon nanotubes ((c) Method of allowing carotenoids and carbon nanotubes after treatment to open the ends to stand in the presence of a solvent)
Beta carotene (15 mg) and a terminal carbon nanotube (1 mg) were placed in methanol (10 ml) and allowed to stand overnight.
Thereafter, β-carotene present outside the carbon nanotubes was washed away with 100 ml of THF to form a thin film. In order to completely remove β-carotene present on the outside of the carbon nanotube, it was again dispersed in 10 ml of THF by ultrasonic treatment, thinned, and washed with 50 ml of THF. Through the above operation, carotenoids could be encapsulated inside the carbon nanotubes.

Test to confirm that β-carotene encapsulated in carbon nanotubes is stabilized (1)
The beta carotene dissolved in the DMF solution and the beta carotene (Car @ CN) encapsulated in the carbon nanotube dissolved in the DMF solution are irradiated with ultraviolet light (365 nm), and the irradiation time and the state of photolysis are shown. Show. The ratio after photolysis was observed from the change in absorption intensity. The results are shown in FIG. It is shown that by incorporating carotenoids inside carbon nanotubes, photodegradation can be drastically prevented compared to the situation of β-carotene alone.

Test to confirm that β-carotene encapsulated in carbon nanotubes is stabilized (2)
Changes in absorption spectrum of β-carotene and β-carotene-encapsulated nanotubes (Car @ SWCNT) dispersed in dimethylformamide (DMF) solution and irradiated with ultraviolet light (365 nm, Vilber Lourmat, TFX-20LC) for 30 minutes Was measured. The measurement results are shown in FIG.
Fig. 5 shows the change in the absorption spectrum of carotene, and (b) shows the change in the absorption spectrum of β-carotene encapsulated in the nanotube. In FIG. 5 (b), in order to clarify the absorption band of β-carotene existing in the nanotube, the absorption contribution derived from the nanotube is already removed and displayed. In each figure, the solid line is before ultraviolet light irradiation, and the dotted line is after ultraviolet light irradiation. In FIG. 5 (a), it can be seen that β-carotene is degraded by the irradiation of ultraviolet light, and the absorption band is almost lost. On the other hand, in FIG. 5 (b), it can be seen that the absorption band of β-carotene remains clearly even after irradiation with ultraviolet light. This indicates that the photodegradation of β-carotene encapsulated inside the nanotubes is greatly suppressed.

Test for confirming that carotenoid (β-carotene) is encapsulated in carbon nanotubes In order to confirm that carotenoid (β-carotene) is encapsulated in carbon nanotubes, Raman measurements were performed on the following. The results of Raman measurements were compared for carotenoids, carbon nanotubes, and carbon nanotubes incorporating carotenoids.
The result is shown in FIG. The carbon nanotubes used in FIG. 3 were prepared by a laser ablation method and purified at the ends of the tube. 3a, b, and c are Raman spectra of β-carotene, carbon nanotube, and carbon nanotube encapsulating β-carotene in an acetone solution, respectively. From the above comparison, it was found that β-carotene was properly encapsulated inside the carbon nanotube. Furthermore, in order to make sure that β-carotene is not attached to the outside of the carbon nanotube, but the sample is closed (Hipco: nanotube made by High pressure CO method) The sample (Hipco after, Hipco-O) was obtained by performing the above-described encapsulation process on a sample with a hollow end of a nanotube (Hipco-O: a tube that had been subjected to a treatment for opening the end of Hipco). Raman measurement was performed on after). The results are shown in FIG. When the end of the carbon nanotube is closed, there is no Raman peak derived from β-carotene (see FIG. 4b). It can be seen that a peak derived from carotene exists only when the ends are opened (see FIG. 4c). This indicates that β-carotene is present not inside the carbon nanotube surface but inside. That is, it was confirmed that the synthesis of the carbon nanotube structure containing β-carotene was successful.

The structure schematic diagram of the carbon nanotube structure which included beta carotene. The figure which compares the photodegradability (irradiation of 365 nm ultraviolet light) of the carbon nanotube (Car @ CN) which included beta-carotene in the DMF solvent of beta-carotene. Raman spectra of (a) β-carotene (Car), (b) carbon nanotube (CN), and (c) carbon nanotube (Car @ CN) containing β-carotene in acetone solution. (a) Carbon nanotube with closed end of tube (Hipco), (b) Sample in which Hipoco was encapsulated with carotene (Hipcoafter), (c) Carbon that had been subjected to end opening treatment with Hipco The figure which shows each Raman spectrum of the sample (Hipco-Oafter) which performed the encapsulation process of the carotene with respect to the nanotube (Hipco-O) and (d) Hipco-O. Changes in the absorption spectrum of β-carotene and β-carotene-containing nanotubes (Car @ SWCNT) dispersed in dimethylformamide (DMF) solution and irradiated with ultraviolet light (365 nm, Vilber Lourmat, TFX-20LC) (b) is a diagram showing a change in the absorption spectrum of β-carotene encapsulated in nanotubes. The structure schematic diagram of the carbon nanotube structure which included beta carotene. The structure schematic diagram of the carbon nanotube structure which included beta carotene.

Claims (9)

A structure comprising carbon nanotubes encapsulating carotenoids. A carotenoid stabilizing and maintaining material comprising the structure according to claim 1. A carbon nanotube stabilization maintaining material comprising the structure according to claim 1. A drug delivery material comprising the carotenoid stabilizing agent according to claim 2. The structure according to claim 1, wherein the carotenoid according to claim 1 is β-carotene. A nonlinear optical material comprising the structure according to claim 1. An optical device material comprising the structure according to claim 1. A laser dye material comprising the structure according to claim 1. A dye-sensitized solar cell material comprising the structure according to claim 1.