nanodetection platforms [78]. As evoked earlier, glycosylated pyrene derivatives
29 pyrene , 30 pyrene , and 31 pyrene , synthesized via click chemistry, were able to form
π–π stacking interactions with SWNT and graphene surfaces to generate
corresponding SWNT-FET pyrene 29–31 and CCG-FET pyrene 29–31. The general
tendencies suggested that SWNT-FET induced a larger response and better selectivity
than CCG-FET devices, regardless of the glycoconjugate appendages exhibited
through the pyrene or porphyrin framework. Computational modeling revealed that
the one-dimensional SWNT systems provided more flexibility for the sugar termini to
interact with lectin, leading to higher sensitivity than the two-dimensional CCG
systems. More specially, the stacking of pyrene or porphyrin moieties of the
glycoconjugates on the SWNT yielded galactose residues that were accessible for
PA-IL lectin, whereas CCG congener provoked the epitopes’ presentation only in
close proximity to the carbon sheet, reducing their accessibility. Atomic force microscopy (AFM) imaging was performed to obtain evidence for the attachment of
glycoconjugates onto the carbon nanostructures, and showed substantial and progressive increase in height at different stages of functionalization and during specific lectin
interactions. This technique, together with fluorescence microscopy, also allowed
visualization of the continuously high coverage on SWNTs whereas the binding
sites were scattered randomly on the CCG surface with a reduced number of adsorption sites for lectins, in accordance with the previous computer modeling studies.
Finally, these comparative studies confirmed the potential of these carbon
nanomaterial-based FET systems as effective bacteria or virus detection devices in
water, soil, or human fluids.
5 Gold Nanoparticles
Gold NPs are the most stable and studied of the metal-based nanoclusters. Owing to
their exceptional electronic, magnetic, and optical properties that are highly size
dependent, they have been extensively studied in material and biomedical
applications. Even though a large number of methodologies are known for the
preparation of gold NPs, the Brust technique and its variations are still the most
popular for preparing a monolayer of coated gold NPs. The technique is based on
the high affinity of the thiol groups for the gold atoms because of the soft character
of both Au and S atoms [79]. In this method, gold NPs are synthesized through
reduction of gold salt (HAuCl 4 ) by NaBH 4 in the presence of a thiol. Gold NPs
coated with glycan monolayers have been studied extensively in various areas of
biomedical research [80–82]. Since the first report in 2001 [83], gold glyconanoparticles (gold GNPs) have received great attention among glycochemists. Here, we
discuss a few recent examples of gold GNPs that have been used for biomedical
applications related to diagnostics and therapy.
Gold NPs have been used as multivalent and multifunctional platforms for
tumor-associated carbohydrate antigens in combination with suitable immunogenic
carriers to develop carbohydrate-based vaccines. The pioneering group of Penade ´s
was the first to identify gold NPs as potential scaffolds for vaccine preparation [84].
316
N. Kottari et al.
29 pyrene , 30 pyrene , and 31 pyrene , synthesized via click chemistry, were able to form
π–π stacking interactions with SWNT and graphene surfaces to generate
corresponding SWNT-FET pyrene 29–31 and CCG-FET pyrene 29–31. The general
tendencies suggested that SWNT-FET induced a larger response and better selectivity
than CCG-FET devices, regardless of the glycoconjugate appendages exhibited
through the pyrene or porphyrin framework. Computational modeling revealed that
the one-dimensional SWNT systems provided more flexibility for the sugar termini to
interact with lectin, leading to higher sensitivity than the two-dimensional CCG
systems. More specially, the stacking of pyrene or porphyrin moieties of the
glycoconjugates on the SWNT yielded galactose residues that were accessible for
PA-IL lectin, whereas CCG congener provoked the epitopes’ presentation only in
close proximity to the carbon sheet, reducing their accessibility. Atomic force microscopy (AFM) imaging was performed to obtain evidence for the attachment of
glycoconjugates onto the carbon nanostructures, and showed substantial and progressive increase in height at different stages of functionalization and during specific lectin
interactions. This technique, together with fluorescence microscopy, also allowed
visualization of the continuously high coverage on SWNTs whereas the binding
sites were scattered randomly on the CCG surface with a reduced number of adsorption sites for lectins, in accordance with the previous computer modeling studies.
Finally, these comparative studies confirmed the potential of these carbon
nanomaterial-based FET systems as effective bacteria or virus detection devices in
water, soil, or human fluids.
5 Gold Nanoparticles
Gold NPs are the most stable and studied of the metal-based nanoclusters. Owing to
their exceptional electronic, magnetic, and optical properties that are highly size
dependent, they have been extensively studied in material and biomedical
applications. Even though a large number of methodologies are known for the
preparation of gold NPs, the Brust technique and its variations are still the most
popular for preparing a monolayer of coated gold NPs. The technique is based on
the high affinity of the thiol groups for the gold atoms because of the soft character
of both Au and S atoms [79]. In this method, gold NPs are synthesized through
reduction of gold salt (HAuCl 4 ) by NaBH 4 in the presence of a thiol. Gold NPs
coated with glycan monolayers have been studied extensively in various areas of
biomedical research [80–82]. Since the first report in 2001 [83], gold glyconanoparticles (gold GNPs) have received great attention among glycochemists. Here, we
discuss a few recent examples of gold GNPs that have been used for biomedical
applications related to diagnostics and therapy.
Gold NPs have been used as multivalent and multifunctional platforms for
tumor-associated carbohydrate antigens in combination with suitable immunogenic
carriers to develop carbohydrate-based vaccines. The pioneering group of Penade ´s
was the first to identify gold NPs as potential scaffolds for vaccine preparation [84].
316
N. Kottari et al.