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Some century-old chemistry could have a strong impact on important issues in
biosensors and other nanotech devices.

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

Some century-old chemistry
could have a strong impact on important issues in biosensors and other nanotech
devices, according to a Purdue University research group.

A team led by Alexander Wei has shown that amines, a large
and important class of organic molecules, when mixed with carbon disulfide,
can bond to gold more robustly than thiols, which are commonly used materials
for giving new functions to metal surfaces. Gold surfaces are often used
as baseplates of sensors and in nanomaterials, and scientists have been
searching for stable organic coatings they can attach to gold to form an
interface between the organic and inorganic worlds. The group’s findings
suggest that amines may be the best candidate group of such materials.

‘Amines could allow us to expand the range of molecules
which can be incorporated into sensors for the biotech field,’ said Wei,
who is an associate professor of chemistry in Purdue’s College of Science.
‘Amines react with carbon disulfide to form dithiocarbamates (DTCs) and
appear to be better suited for coating surfaces than thiols, which have
been the standard thus far. The DTC chemistry itself has been around for
over 100 years, but we think it can offer many opportunities for current
applications in biosensors and nanotechnology.’

Wei performed the study with his Purdue colleagues Yan
Zhao, Waleska Pérez-Segarra and Qicun Shi. Their work appeared in
this week’s (Vol. 127, No. 20) issue of the Journal of the American Chemical
Society.

Nanotechnologists and other materials scientists use gold
as an interface between electronic components and organic or biomolecular
substances. Gold’s conductivity and resistance to corrosion makes it an
ideal surface for attaching molecules that can detect the presence of proteins
in the blood that indicate disease, for example.

‘Up to this point, the standard practice has been to modify
gold surfaces with thiols, because they are relatively easy to work with
and form coatings quickly,’ Wei said. ‘Thiols are well known to adsorb,
or stick, onto gold surfaces to form highly uniform films with adjustable
surface properties. But a drawback to thiols is their intermittent hold
on the surface, and the relatively weak chemical bond makes them less attractive
for applications that require environmentally durable coatings.’

Wei’s team found that converting amines into DTCs empower
them with an ability to grasp gold surfaces with a strength that thiols
do not possess.

‘As DTCs, the amines are armed with a ‘pincer’ made of
two sulfur atoms,’ Wei said. ‘Thiols are typically bonded to gold by one
sulfur atom, like pins stuck in a gold pincushion. DTCs are more like a
vice grip, so we hope they will last longer on the gold.’

Wei said that although DTCs have been around for a long
time, their application to surface chemistry has been overlooked and is
long overdue. But Wei cautions that further studies are needed to establish
the full scope and limitations of DTCs for various applications.

Wei is associated with Purdue’s Birck Nanotechnology Center,
which will be one of the largest university facilities in the nation dedicated
to nanotechnology research when construction is completed in the summer
of 2005. Nearly 100 groups associated with the center are pursuing diverse
research topics such as nanometer-sized machines, advanced materials for
nanoelectronics and nanoscale biosensors.

Source : www.sciencedaily.com

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