Micro- and nano-sized peptidic assemblies prepared via solid-vapor approach: Morphological and spectroscopic aspects

Amaral, Heliane R.; Kogikoski, Sergio; Silva, E.R.; Souza, J. A.; Alves, Wendel A.

doi:10.1016/j.matchemphys.2012.09.067

Cited by 16 publications

(20 citation statements)

References 52 publications

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“…29 Moreover, as aforementioned, in other contexts, where structures have been grown directly onto the substrate, aniline vapor has led to rodlike structures (e.g., nanowires). 16,24,25 To characterize our structures at the crystallographic level, we performed powder diffraction experiments. Figures 2 and 3 show high-resolution XRD patterns of both water-and anilineincubated samples.…”

Section: Resultsmentioning

confidence: 99%

A Nonenzymatic Biosensor Based on Gold Electrodes Modified with Peptide Self-Assemblies for Detecting Ammonia and Urea Oxidation

et al. 2014

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We have developed a nonenzymatic biosensor for the detection of ammonia and urea oxidation based on the deposition of peptide microstructures onto thiolated gold electrodes. FF-MNSs/MCP/Au assemblies were obtained by modifying gold substrates with 4-mercaptopyridine (MCP), followed by coating with l,l-diphenylalanine micro/nanostructures (FF-MNSs) grown in the solid-vapor phase. Benzene rings and amide groups with peptide micro/nanostructures interact with synthetic NH4(+) receptors through cation-π and hydrogen bonding. AuOH clusters on the Au surface provided the catalytic sites. The application of a predetermined concentration of analytes at the peptide interfaces activated the catalytic sites. We observed a relationship between the stability of films and the crystal structure of peptides, and we organized the FF-MNSs into an orthorhombic symmetry that was the most suitable assembly for creation of our biosensors. At 0.1 mol L(-1) NaOH, these FF-MNSs/MCP/Au electrodes have electrocatalytic properties regarding ammonia and urea oxidation that are comparable to those of enzyme-based architectures. Under optimal conditions, the electrocatalytic response is proportional to the ammonia and urea concentration in the range 0.1-1.0 mmol L(-1). The sensitivity was calculated as 2.83 and 81.3 μA mmol L(-1) cm(-2) for ammonia and urea, respectively, at +0.40 V (vs SCE). Our detection method is easy to follow, does not require a mediator or enzyme, and has strong potential for detecting urea via nonenzymatic routes.

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Section: Resultsmentioning

confidence: 99%

A Nonenzymatic Biosensor Based on Gold Electrodes Modified with Peptide Self-Assemblies for Detecting Ammonia and Urea Oxidation

et al. 2014

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“…As an example of this water‐dependent behavior, two of us recently reported on the splitting of the conduction and valence bands in FF nanotubes, likely due to the alignment of individual dipole moments leading to a larger dipole moment of the overall structure . Moreover, when FF‐based assemblies are produced under anhydrous conditions, they are frequently described in terms of orthorhombic groups . Similarly, hydrated FF nanotubes exhibit a hexagonal → orthorhombic phase transition when incubated at temperatures above 150 °C.…”

Section: Introductionmentioning

confidence: 99%

The role of water and structure on the generation of reactive oxygen species in peptide/hypericin complexes

Souza

Silva

Jaques

et al. 2014

Journal of Peptide Science

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Hybrid associates formed between peptide assemblies and fluorophores are attractive mainly because of their unique properties for biomedical applications. Recently, we demonstrated that the production of reactive oxygen species (ROS) by hypericin and their stability in excited states are enhanced upon conjugation with l,l-diphenylalanine microtubes (FF-MNTs). Although the detailed mechanisms responsible for improving the photophysical properties of ROS remain unclear, tentative hypotheses have suggested that the driving force is the growth of overall dipolar moments ascribed either to coupling between aligned H2O dipoles within the ordered structures or to the organization of hypericin molecules on peptide interfaces. To provide new insights on ROS activity in hypericin/FF-MNTs hybrids and further explore the role of water in this respect, we present results obtained from investigations on the behavior of these complexes organized into different crystalline arrangements. Specifically, we monitored and compared the photophysical performance of hypericin bound to FF-MNTs with peptides organized in both hexagonal (water-rich) and orthorhombic (water-free) symmetries. From a theoretical perspective, we present the results of new molecular dynamics simulations that highlight the distinct hypericin/peptide interaction at the interface of FF-MNTs for the different symmetries. As a conclusion, we propose that although water enhances photophysical properties, the organization induced by peptide structures and the availability of a hydrophobic environment surrounding the hypericin/peptide interface are paramount to optimizing ROS generation. The findings presented here provide useful basic research insights for designing peptide/fluorophore complexes with outstanding technological potential.

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“…36 Modification with MP11 and PAH result in some small differences, more noticeably for the orthorhombic material ( Figure 2D). A shoulder at 1640 cm -1 , and new bands around 1550 and 1400 cm -1 are observed.…”

Section: Spectroscopic Characterizationmentioning

confidence: 97%

“…A similar result was observed for the orthorhombic structure modified with the conductive polyaniline forming a core-shell hybrid material. 35,36 …”

Section: Morphological Characterizationmentioning

confidence: 99%

Multifunctional biosensors based on peptide–polyelectrolyte conjugates

Kogikoski

Sousa

Liberato

et al. 2016

Phys. Chem. Chem. Phys.

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A novel enzymatic platform for the sensing of H2O2 and glucose that uses L,L-diphenylalanine micro/nanostructures (FF-MNSs) as an enzyme support is shown. This platform is obtained by the self-assembly of poly(allylamine hydrochloride) (PAH), FF-MNSs, and microperoxidase-11 (MP11) anchored onto the peptide matrix, in two different crystal structures of FF-MNSs: hexagonal (P61) and orthorhombic (P22121). The electroactive area of the electrodes increases in the presence of FF-MNSs. We also demonstrate via theoretical calculations that the valence band energy of the orthorhombic structure allows it to be doped, similarly to p-type semiconductors, where PAH acts as a doping agent for the orthorhombic peptide structure, decreasing the band-gap by around 1 eV, which results in a smaller charge transfer resistance. These results are consistent with electrochemical impedance spectroscopy measurements, which further elucidate the role of the band structure of the orthorhombic FF-MNSs in the conductivity and electron transfer rates of the hybrid material. An effective communication between the electrode and the active site of a glucose oxidase enzyme through MP11-protein complexes occurs, paving the way for FF-MNSs in the orthorhombic phase for the future development of bioelectronics sensing devices.

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Micro- and nano-sized peptidic assemblies prepared via solid-vapor approach: Morphological and spectroscopic aspects

Cited by 16 publications

References 52 publications

A Nonenzymatic Biosensor Based on Gold Electrodes Modified with Peptide Self-Assemblies for Detecting Ammonia and Urea Oxidation

A Nonenzymatic Biosensor Based on Gold Electrodes Modified with Peptide Self-Assemblies for Detecting Ammonia and Urea Oxidation

The role of water and structure on the generation of reactive oxygen species in peptide/hypericin complexes

Multifunctional biosensors based on peptide–polyelectrolyte conjugates

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