U.S. patent application number 14/662174 was filed with the patent office on 2015-07-09 for rapid detection and identification of energetic materials with surface enhanced raman spectrometry (sers).
The applicant listed for this patent is LAWRENCE LIVERMORE NATIONAL SECURITY, LLC. Invention is credited to Thomas Yong-Jin Han, Sung Ho Kim, Tammy Y. Olson, Joe H. Satcher, Carlos A. Valdez.
Application Number | 20150192579 14/662174 |
Document ID | / |
Family ID | 45527135 |
Filed Date | 2015-07-09 |
United States Patent
Application |
20150192579 |
Kind Code |
A1 |
Han; Thomas Yong-Jin ; et
al. |
July 9, 2015 |
RAPID DETECTION AND IDENTIFICATION OF ENERGETIC MATERIALS WITH
SURFACE ENHANCED RAMAN SPECTROMETRY (SERS)
Abstract
In one embodiment, a system includes a plurality of metal
nanoparticles functionalized with a plurality of organic molecules
tethered thereto, each organic molecule having a primary face and a
secondary face. The plurality of organic molecules preferentially
interact with the one or more analytes when placed in proximity
therewith. The plurality of organic molecules comprise one or more
of: one or more modifying groups on the primary face in place of
one or more primary hydroxyl groups; and one or more modifying
groups on the secondary face in place of one or more secondary
hydroxyl groups. At least one of the one or more analytes is an
energetic compound. In another embodiment, a method includes
chemically modifying a plurality of cyclodextrin molecules at a
primary hydroxyl moiety to create a chemical handle; and tethering
the plurality of cyclodextrin molecules to a metal nanoparticle
using the chemical handle.
Inventors: |
Han; Thomas Yong-Jin;
(Livermore, CA) ; Valdez; Carlos A.; (San Ramon,
CA) ; Olson; Tammy Y.; (Livermore, CA) ; Kim;
Sung Ho; (Livermore, CA) ; Satcher; Joe H.;
(Patterson, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LAWRENCE LIVERMORE NATIONAL SECURITY, LLC |
Livermore |
CA |
US |
|
|
Family ID: |
45527135 |
Appl. No.: |
14/662174 |
Filed: |
March 18, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12844778 |
Jul 27, 2010 |
9012241 |
|
|
14662174 |
|
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Current U.S.
Class: |
436/525 ;
436/527; 436/528 |
Current CPC
Class: |
G01N 33/551 20130101;
G01N 33/54373 20130101; G01N 21/658 20130101; G01N 33/544 20130101;
G01N 33/552 20130101; G01N 2400/18 20130101; G01N 33/54346
20130101 |
International
Class: |
G01N 33/552 20060101
G01N033/552; G01N 33/551 20060101 G01N033/551; G01N 33/544 20060101
G01N033/544 |
Goverment Interests
[0002] The United States Government has rights in this invention
pursuant to Contract No. DE-AC52-07NA27344 between the United
States Department of Energy and Lawrence Livermore National
Security, LLC for the operation of Lawrence Livermore National
Laboratory.
Claims
1. A system, comprising: a plurality of metal nanoparticles
functionalized with a plurality of organic molecules tethered
thereto, each organic molecule having a primary face and a
secondary face, wherein the plurality of organic molecules are
characterized by preferentially interacting with one or more
analytes when placed in proximity therewith, wherein the plurality
of organic molecules comprise one or more of: one or more modifying
groups on the primary face in place of one or more primary hydroxyl
groups; and one or more modifying groups on the secondary face in
place of one or more secondary hydroxyl groups, wherein at least
one of the one or more analytes is an energetic compound.
2. The system as recited in claim 1, wherein the one or more
analytes are selected from a group consisting of: trinitrotoluene
(TNT), tetrahexamine tetranitramine (HMX),
cyclotrimethylenetrinitramine (RDX), pentaerythritol tetranitrate
(PETN), 2,4,6-trinitrophenylmethylnitramine (Tetryl), and
peroxides.
3. The system as recited in claim 1, wherein at least some of the
plurality of organic molecules are molecules of modified
cyclodextrin.
4. The system of claim 3, wherein the cyclodextrin molecules are
chemically modified at a primary hydroxyl moiety to tether to a
surface of the plurality of metal nanoparticles via a chemical
handle.
5. The system of claim 4, wherein the chemical handle is at least
one of: a thiol functionality and an amine functionality.
6. The system of claim 3, wherein the plurality of modified
cyclodextrin molecules include at least one modifying group on a
primary face in place of one or more primary hydroxyl groups.
7. The system of claim 6, wherein the modifying groups are selected
from a group consisting of: N.sub.3, RSH, ROH, RNH.sub.2,
RO.sup..THETA., RS.sup..THETA., and R.sub.2N.sup..THETA., wherein R
is any carbon containing group, or any modifying group.
8. The system of claim 3, wherein the plurality of modified
cyclodextrin molecules include at least one modifying group on a
secondary face in place of one or more secondary hydroxyl
groups.
9. The system of claim 8, wherein the modifying groups are selected
from a group consisting of: N.sub.3, RSH, ROH, RNH.sub.2,
RO.sup..THETA., RS.sup..THETA., and R.sub.2N.sup..THETA., wherein R
is any carbon containing group, or any modifying group.
10. The system of claim 3, wherein the plurality of modified
cyclodextrin molecules include one or more modifying groups on a
primary face in place of one or more primary hydroxyl groups and
one or more modifying groups on a secondary face in place of one or
more secondary hydroxyl groups.
11. The system of claim 10, wherein the modifying groups are
selected from a group consisting of: N.sub.3, RSH, ROH, RNH.sub.2,
RO.sup..THETA., RS.RTM., and R.sub.2N.sup..THETA., wherein R is any
carbon containing group, or any modifying group.
12. The system as recited in claim 1, further comprising a
substrate, wherein the plurality of metal nanoparticles are
attached to the substrate, and wherein the substrate comprises one
of: silicon, glass, an aerogel having an inorganic matrix, and an
aerogel having an organic matrix.
13. A method, comprising: chemically modifying a plurality of
cyclodextrin molecules at a primary hydroxyl moiety to create a
chemical handle; and tethering the plurality of cyclodextrin
molecules to a metal nanoparticle using the chemical handle.
14. The method of claim 13, wherein the chemical handle is at least
one of: a thiol functionality and an amine functionality.
15. The method of claim 13, further comprising attaching a
plurality of the metal nanoparticles having cyclodextrin molecules
tethered thereto to a substrate.
16. The method of claim 15, wherein the substrate is selected from
a group consisting of: silicon, silicon compounds, glass, and
aerogels.
17. The method of claim 13, further comprising chemically modifying
the plurality of cyclodextrin molecules on a primary face via
monotosylation of at least one primary hydroxyl group followed by
nucleophilic displacement with an appropriate modifying group.
18. The method of claim 13, further comprising chemically modifying
the plurality of cyclodextrin molecules on a primary face via
ditosylation of at least two primary hydroxyl groups followed by
nucleophilic displacement with appropriate modifying groups.
19. The method of claim 13, further comprising chemically modifying
the plurality of cyclodextrin molecules on a secondary face via
alkylation with an alkylating agent which becomes trapped in a
cavity of the cyclodextrin molecule causing preferential reacting
with one or more secondary hydroxyl groups.
20. The method of claim 13, further comprising chemically modifying
the plurality of cyclodextrin molecules on a secondary face by
capping a primary face with tertbutyldimethylsilyl chloride
(TBDMSCl) to form hexasilylated cyclodextrin, followed by
nucleophilic displacement of one or more secondary hydroxyl groups
with an appropriate modifying group.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 12/844,778, filed Jul. 27, 2010 for "Rapid Detection and
Identification of Energetic Materials with Surface Enhanced Raman
Spectroscopy (SERS)," to which priority is claimed.
FIELD OF THE INVENTION
[0003] The present invention relates to Surface Enhanced Raman
Spectroscopy (SERS), and more particularly, to the rapid detection
and identification of energetic materials using SERS.
BACKGROUND
[0004] Rapid detection and identification of energetic materials
such as explosives is one of the cornerstones of the rapidly
evolving war on terrorism, and is used to mitigate emerging
terrorist threats around the world, targeting the United States of
America and its interests, home and abroad. However, due to the
extremely low vapor pressures of many commonly used and available
explosives, rapid detection and identification of trace amounts of
these explosives using conventional analytical tools are limited.
The current state-of-the-art technique for detection and
identification of explosive systems is Surface Enhanced Raman
Spectroscopy (SERS). SERS utilizes bare, roughened metal surfaces
to enhance Raman signals of adsorbed Raman active molecules. The
enhancement of the signals can be by as much as 10.sup.14, thus
allowing for trace amounts to be detected which could not be
detected without the enhancement. However, current use of SERS
technology is somewhat limited due to the specificity of the
explosives to the substrates (i.e., metal nanoparticles, metal thin
films, etc.) used during the collection of explosives. Therefore, a
method and system of overcoming the current limitations of SERS
technologies to be used in detection and identification of
energetic materials would be very beneficial.
SUMMARY
[0005] In one embodiment, a system includes a plurality of metal
nanoparticles functionalized with a plurality of organic molecules
tethered thereto, each organic molecule having a primary face and a
secondary face. The plurality of organic molecules preferentially
interact with the one or more analytes when placed in proximity
therewith. The plurality of organic molecules comprise one or more
of: one or more modifying groups on the primary face in place of
one or more primary hydroxyl groups; and one or more modifying
groups on the secondary face in place of one or more secondary
hydroxyl groups. At least one of the one or more analytes is an
energetic compound.
[0006] In another embodiment, a method includes chemically
modifying a plurality of cyclodextrin molecules at a primary
hydroxyl moiety to create a chemical handle; and tethering the
plurality of cyclodextrin molecules to a metal nanoparticle using
the chemical handle.
[0007] Other aspects and embodiments of the present invention will
become apparent from the following detailed description, which,
when taken in conjunction with the drawings, illustrate by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1A shows a simplified cross-sectional view of a metal
nanoparticle with tethered cyclodextrin molecules, according to one
embodiment.
[0009] FIG. 1B shows a chemical handle binding a metal nanoparticle
to molecules of cyclodextrin, according to one embodiment.
[0010] FIG. 2 shows a chemical representation and a stylized
representation of cyclodextrin, according to one embodiment.
[0011] FIG. 3A shows chemical remodeling of cyclodextrin, according
to one embodiment.
[0012] FIG. 3B shows chemical remodeling of cyclodextrin, according
to one embodiment.
[0013] FIG. 3C shows chemical remodeling of cyclodextrin, according
to one embodiment.
[0014] FIG. 3D shows chemical remodeling of cyclodextrin, according
to one embodiment.
[0015] FIG. 4 is a simplified schematic of a Surface Enhanced Raman
Spectroscopy (SERS) system, according to one embodiment.
[0016] FIG. 5 is a flowchart of a method, according to one
embodiment.
[0017] FIG. 6 is a flowchart of a method, according to one
embodiment.
[0018] FIG. 7 is a SERS system, according to one embodiment.
DETAILED DESCRIPTION
[0019] The following description is made for the purpose of
illustrating the general principles of the present invention and is
not meant to limit the inventive concepts claimed herein. Further,
particular features described herein can be used in combination
with other described features in each of the various possible
combinations and permutations.
[0020] Unless otherwise specifically defined herein, all terms are
to be given their broadest possible interpretation including
meanings implied from the specification as well as meanings
understood by those skilled in the art and/or as defined in
dictionaries, treatises, etc.
[0021] It must also be noted that, as used in the specification and
the appended claims, the singular forms "a," "an" and "the" include
plural referents unless otherwise specified.
[0022] In one general embodiment, a system includes a plurality of
metal nanoparticles functionalized with a plurality of organic
molecules tethered thereto, wherein the plurality of organic
molecules preferentially interact with one or more analytes when
placed in proximity therewith.
[0023] In one general embodiment, a method for detecting analytes
includes contacting a fluid having one or more analytes of interest
therein with a plurality of metal nanoparticles, each metal
nanoparticle having a plurality of organic molecules tethered
thereto, and detecting Raman scattering from an analyte of interest
from the fluid, the analyte interacting with one or more of the
plurality of organic molecules.
[0024] In another general embodiment, a method includes chemically
modifying a plurality of cyclodextrin molecules at a primary
hydroxyl moiety to create a chemical handle, and tethering the
plurality of cyclodextrin molecules to a metal nanoparticle using
the chemical handle.
[0025] According to one embodiment, the current limitations in the
use of SERS to detect and identify energetic materials (explosives)
can be overcome by functionalizing the substrates used in the SERS
techniques with organic molecules specifically designed to bind and
retain molecules of explosives, thereby allowing for greater
retention of target molecules for rapid detection, while
simultaneously lowering the detection limits of explosives
generally.
[0026] In one approach, a device uses metal nanoparticles
functionalized with organic molecules to detect energetic
materials. The metal nanoparticles may be one or more of many
different types of metals, such as gold, silver, platinum, etc.,
and preferably possess unique surface properties which enhance the
Raman signatures of target molecules on their surface when using
Surface Enhanced Raman Spectroscopy (SERS). Particularly applicable
in the current context, explosives also cause the metal
nanoparticles to exhibit this enhanced Raman signature. The
enhanced detection using SERS over contemporary techniques is
achieved, in one approach, by tethering specific organic molecules
which possess unique properties of binding and retaining energetic
materials of interests to the metal nanoparticles, e.g., tethering
cyclodextrin to the metal nanoparticles to test for trinitrotoluene
(TNT). Having these specific organic molecules on the surfaces of
the metal nanoparticles greatly enhances the signals of the target
materials (energetic materials or explosives), in addition to
lowering detection limits when compared to current technologies,
thus allowing for trace amount detection of energetic materials in
solution, solid, and/or vapor forms, a clear advantage over
conventional techniques.
[0027] FIG. 1A shows a simplified cross-sectional schematic diagram
of a cyclodextrin (CD) functionalized metal nanoparticle 100,
according to one embodiment. Of course, a plurality of CD
functionalized (active) metal nanoparticles 100 may be used with
SERS for the detection of trace explosives. Since FIG. 1A is only a
cross-sectional diagram, the additional CDs 104 tethered to the
metal nanoparticle 102 which are not dispersed along the immediate
sides of the metal nanoparticle 102 do not appear in this diagram;
however, the metal nanoparticles 102 may be covered by tethered CDs
104 along some, most, or all surfaces, and the density of the
tethered CDs 104 may be controlled, random, a function of some
other factor, etc., according to some approaches. Also, the metal
nanoparticles 102 may include, but are not limited to, gold,
silver, platinum, etc., and they may be synthesized using
techniques as would be known to one of skill in the art. The size
ranges of the metal nanoparticles 102 may vary from about 5 nm to
about 100 nm without the CDs 104 tethered, in some embodiments.
This size range may be a mean diameter, maximum diameter, minimum
diameter, median diameter, etc.
[0028] As shown in FIGS. 1A-1B, structurally modified CDs 104 may
be tethered to the metal nanoparticles 102 by chemical techniques,
as would be known to one of skill in the art. Particularly, primary
hydroxyl moieties of the CD 104 may be selectively converted to a
thiol functionality 108, an amine functionality 106, etc., thus
providing a useful chemical handle for their subsequent attachment
to the metal nanoparticles 102, as shown in FIG. 1B.
[0029] CDs 104 may also be chemically modified to target specific
analytes 110 of interest, in some embodiments. These analytes
include, but are not limited to, TNT, tetrahexamine tetranitramine
(HMX), cyclotrimethylenetrinitramine (RDX), pentaerythritol
tetranitrate (PETN), 2,4,6-trinitrophenylmethylnitramine (Tetryl),
peroxides, and other common explosives.
[0030] With regard to modifying a CD 104, it is noted that there
are two regions in these toroid-shaped macromolecules that are
subject to chemical manipulation, as shown in FIG. 2, according to
one embodiment. One region is the primary face 202, which
encompasses a rim lined with six primary hydroxyl groups 206 from
the monomeric glucose units, according to a first approach. These
are generally the most reactive sites in the CD 104, and as such
can be subject to several chemical manipulations. The other region
is the secondary face 204, which encompasses a rim decorated with
twelve secondary hydroxyl groups 208 from the glucose units, in a
second approach. These secondary hydroxyl groups 208 are generally
not as reactive as the primary hydroxyl groups 206.
[0031] One of the most useful reactions on the primary face 202 of
the CD 104 is monotosylation, which allows for the activation of
one of the six primary hydroxyl groups 206 for nucleophilic
displacement, as shown in FIG. 3A, according to one embodiment. The
range of nucleophiles that may be utilized for such displacement is
vast, from small azides and thiols to alcohols and amines, among
others, as would be known to one of skill in the art.
[0032] According to one embodiment, primary face 202 modification
of a CD 104 involving up to two hydroxyl groups 206 may be
performed with a high degree of precision via ditosylation,
particularly when making use of reagents designed for this purpose,
as shown in FIG. 3B.
[0033] The second region of the CD 104 is known as its secondary
face 204 and includes the twelve secondary hydroxyl groups 208 (C2
and C3) of the monomeric glucose units comprising the
macromolecule, as shown in FIG. 2. The secondary hydroxyl groups
208 are generally less reactive than the primary hydroxyl groups
206, but they may be selectively modified by using an alkylating
agent that gets encapsulated in the CD 104 cavity 210, thus
allowing the secondary hydroxyl groups 208 to preferentially react
with this reagent mainly as a result of proximity, in some
approaches. As shown in FIG. 3C, one of these reagents is o-Nosyl
chloride, which reacts preferentially with the C2-hydroxyl groups
in the secondary face 204 of a CD 104, leaving the primary hydroxyl
groups 206 and even the C3-hydroxyl groups of the secondary
hydroxyl groups 208 untouched, as shown in one embodiment.
[0034] Additionally, if derivatization of only the secondary
hydroxyl groups 208 is desired, the entire primary face 202 of the
CD 104 may be capped with tertbutyldimethylsilyl chloride (TBDMSCl)
to form a hexasilylated CD, as shown in FIG. 3D. With all the
primary hydroxyl groups 206 temporarily blocked, the secondary face
204 may be modified as desired, and then the primary face 202 may
be unmasked by removing the silyl protecting groups, such as with
acid, fluoride ions, etc. In FIGS. 3A-3D, the modifying group may
be any desired group as would be known to one of skill in the art,
such as N.sub.3, RSH, ROH, RNH.sub.2, RO.sup..THETA.,
RS.sup..THETA., R.sub.2N.sup..THETA., etc., where R may be any
additional group as would be known to one of skill in the art, such
as any organic moieties.
[0035] The chemical remodeling of a CD 104 is shown according to
various embodiments in FIGS. 3A-3D. Of course, additional and/or
altered modifications are also possible, in addition to or in place
of those described in FIGS. 3A-3D. For example, the primary face
202 may be modified via monotosylation as shown in FIG. 3A,
ditosylation as shown in FIG. 3B, etc., followed by nucleophilic
displacement, in some approaches. The secondary face 204 may be
modified using specific reagents such as nosyl chloride followed by
substitution as shown in FIG. 3C, by making use of a more lengthy
route involving the capping of the primary face 202 leaving the
secondary face 204 available for the desired modification as shown
in FIG. 3D, along with many other possible routes in other
approaches. Removal of the protective groups at the primary face
202 after the secondary face 204 modification leads to the
selectively functionalized CD 104, in one embodiment.
[0036] Once the modified metal nanoparticles are synthesized, they
may be placed on a substrate, e.g., silicon wafer, glass slide,
aerogel matrix, etc., according to some embodiments. These
substrates with the modified metal nanoparticles may be used to
detect and identify explosives by SERS, in preferred embodiments,
along with the detection of various analytes of interest, in other
embodiments.
[0037] Referring to FIG. 4, according to one embodiment, a system
400 includes a plurality of metal nanoparticles 102 functionalized
with a plurality of organic molecules 104 tethered thereto. The
plurality of organic molecules 104 preferentially interact with one
or more analytes 406 when placed in proximity therewith. For
example, the organic molecules 104 may be selected such that they
bind to, attract, capture, etc., an analyte 406 of interest. Some
exemplary analytes 406 include, but are not limited to, energetic
compounds and/or materials, such as trinitrotoluene (TNT),
tetrahexamine tetranitramine (HMX), cyclotrimethylenetrinitramine
(RDX), pentaerythritol tetranitrate (PETN),
2,4,6-trinitrophenylmethylnitramine (Tetryl), peroxides, etc.
[0038] In a further embodiment, the system 400 may include a
substrate 402. The plurality of metal nanoparticles 102 may be
attached to the substrate 402 through any mechanism as would be
known to one of skill in the art, such as being bonded to the
substrate 402, adhered to the substrate 402, attracted to the
substrate 402, etc. The substrate 402 may be one of: silicon,
glass, an aerogel having an inorganic matrix, and an aerogel having
an organic matrix, among many other substances. The substrate 402
may also be a mixture of one or more materials.
[0039] In some embodiments, the metal nanoparticles 102 may have a
mean diameter of between about 5 nm and about 100 nm, such as
between about 20 nm and about 50 nm, between about 25 nm and about
40 nm, between about 5 nm and about 15 nm, etc.
[0040] In further approaches, the system 400 may include a Raman
probe 404 for detecting the presence of the one or more analytes
406 interacting with the organic molecules 104.
[0041] In a preferred embodiment, the plurality of organic
molecules 104 may comprise molecules of cyclodextrin, as shown in
FIG. 4.
[0042] In this embodiment, as shown in FIGS. 1B, 3A-3D, the
cyclodextrin molecules may be chemically modified at a primary
hydroxyl moiety 206 to tether to a surface of the plurality of
metal nanoparticles 102 via a chemical handle 108. Also, the
chemical handle 108 may be at least one of: a thiol functionality
and an amine functionality, in some approaches.
[0043] Also in this embodiment, the plurality of cyclodextrin
molecules may include at least one modifying group on a primary
face 202 in place of one or more primary hydroxyl groups 206.
Further, the modifying groups may be selected from a group
including: N.sub.3, RSH, ROH, RNH.sub.2, RO.sup..THETA.,
RS.sup..THETA., and R.sub.2N.sup..THETA., wherein R is a carbon
containing group known in the art, any modifying group or portion
thereof, etc.
[0044] In more embodiments, the plurality of cyclodextrin molecules
may include at least one modifying group on a secondary face 204 in
place of one or more secondary hydroxyl groups 208. Further, the
modifying groups may be selected from a group including: N.sub.3,
RSH, ROH, RNH.sub.2, RO.sup..THETA., RS.sup..THETA., and
R.sub.2N.sup..THETA., wherein R is a carbon containing group known
in the art, any modifying group or portion thereof, etc.
[0045] In more approaches, the plurality of cyclodextrin molecules
may include one or more modifying groups on a primary face 202 in
place of one or more primary hydroxyl groups 206 and one or more
modifying groups on a secondary face 204 in place of one or more
secondary hydroxyl groups 208. Further, the modifying groups may be
selected from a group including: N.sub.3, RSH, ROH, RNH.sub.2,
RO.sup..THETA., RS.RTM., and R.sub.2N.THETA., wherein R is a carbon
containing group known in the art, any modifying group or portion
thereof, etc.
[0046] Now referring to FIG. 5, a method 500 for detecting analytes
is shown according to one embodiment. The method 500 may be
performed in any desired environment, and may include embodiments
and approaches described in FIGS. 1A-4, according to various
embodiments.
[0047] In operation 502, a fluid having one or more analytes of
interest therein is contacted with a plurality of metal
nanoparticles, each metal nanoparticle having a plurality of
organic molecules tethered thereto. The fluid may be a liquid, a
gas, a vapor, a suspension, etc., as would be known to one of skill
in the art. The analytes may be energetic materials, such as
explosives, etc., as described above; toxins; carcinogens; etc.
[0048] In operation 504, Raman scattering from an analyte of
interest is detected from the fluid. The analyte interacts with one
or more of the plurality of organic molecules, for example, by
binding to, being attracted by, being captured by an organic
molecule, etc.
[0049] In one approach, the plurality of metal nanoparticles may be
attached to a substrate through any mechanism as would be known to
one of skill in the art. The substrate may comprise one of:
silicon, glass, an aerogel having an inorganic or organic matrix,
or one of many other possible materials.
[0050] Now referring to FIG. 6, a method 600 is described according
to one embodiment. The method 600 may be performed in any desired
environment, and may include embodiments and approaches described
in FIGS. 1A-4, according to various embodiments.
[0051] In operation 602, a plurality of cyclodextrin molecules are
chemically modified at a primary hydroxyl moiety to create a
chemical handle
[0052] In operation 604, the plurality of cyclodextrin molecules
are tethered to a metal nanoparticle using the chemical handle.
[0053] In one embodiment, the chemical handle may be at least one
of: a thiol functionality and an amine functionality, among many
other possible handles.
[0054] In another embodiment, the method 600 may include attaching
a plurality of the metal nanoparticles having cyclodextrin
molecules tethered thereto to a substrate.
[0055] Any method of attaching the metal nanoparticles to the
substrate may be used, as would be known to one of skill in the
art. In a further embodiment, the substrate may be selected from a
group including: silicon, silicon compounds, glass, and inorganic
or organic aerogels, among many other possible materials.
[0056] In one approach, the method 600 may include chemically
modifying the plurality of cyclodextrin molecules on a primary face
via monotosylation of at least one primary hydroxyl group followed
by nucleophilic displacement with an appropriate modifying
group.
[0057] In one embodiment, the method 600 may include chemically
modifying the plurality of cyclodextrin molecules on a primary face
via ditosylation of at least two primary hydroxyl groups followed
by nucleophilic displacement with appropriate modifying groups.
[0058] In another approach, the method 600 may include chemically
modifying the plurality of cyclodextrin molecules on a secondary
face via alkylation with an alkylating agent which becomes trapped
in a cavity of the cyclodextrin molecule causing preferential
reacting with one or more secondary hydroxyl groups.
[0059] In another embodiment, the method 600 may include chemically
modifying the plurality of cyclodextrin molecules on a secondary
face by capping a primary face with tertbutyldimethylsilyl chloride
(TBDMSCl) to form hexasilylated cyclodextrin, followed by
nucleophilic displacement of one or more secondary hydroxyl groups
with an appropriate modifying group.
[0060] Now referring to FIG. 7, a SERS system 700 is shown
according to one embodiment. Of course, modifications, changes,
alterations, etc., to this system are possible, and this exemplary
embodiment is not meant to be limiting on the application or use of
any embodiments described herein. The system 700 may include an
adaptor sleeve 716 which may act to "focus" analytes 706 towards
the SERS substrate 702, in some embodiments. Also, the sleeve 716
may slide over a Raman probe 708, which may be a fiber-optic Raman
probe and may be connected to a fiber-optic cable 704 for coupling
to a laser and to a spectrograph for reading reflections of the
laser off the SERS substrate 702, and any analytes 706 located
there. The vapor flows through the inlet 712, through the inner
chamber of the sleeve 716, past the SERS substrate 702, and then
out the outlet 714. Additionally, a fan 710 may be used to draw the
vapor, including analytes 706 therein, through the sleeve 716. In
addition, the SERS substrate 702, which may include any of the
embodiments described herein for more effectively detecting
analytes 706 of interest, is positioned at the focal point of the
Raman probe 708 and partially blocks the air flow through the
sleeve 716, creating turbulent flow at the substrate 702 face,
according to one embodiment.
[0061] While various embodiments have been described above, it
should be understood that they have been presented by way of
example only, and not limitation. Thus, the breadth and scope of a
preferred embodiment should not be limited by any of the
above-described exemplary embodiments, but should be defined only
in accordance with the following claims and their equivalents.
* * * * *