Electric Field Tunability of Photoluminescence from a Hybrid Peptide–Plasmonic Metal Microfabricated Chip

Abstract

Enhancement of fluorescence through the application of plasmonic metal nanostructures has gained substantial research attention due to the widespread use of fluorescence-based measurements and devices. Using a microfabricated plasmonic silver nanoparticle–organic semiconductor platform, we show experimentally the enhancement of fluorescence intensity achieved through electro-optical synergy. Fluorophores located sufficiently near silver nanoparticles are combined with diphenylalanine nanotubes (FFNTs) and subjected to a DC electric field. It is proposed that the enhancement of the fluorescence signal arises from the application of the electric field along the length of the FFNTs, which stimulates the pairing of low-energy electrons in the FFNTs with the silver nanoparticles, enabling charge transport across the metal–semiconductor template that enhances the electromagnetic field of the plasmonic nanoparticles. Many-body perturbation theory calculations indicate that, furthermore, the charging of silver may enhance its plasmonic performance intrinsically at particular wavelengths, through band-structure effects. These studies demonstrate for the first time that field-activated plasmonic hybrid platforms can improve fluorescence-based detection beyond using plasmonic nanoparticles alone. In order to widen the use of this hybrid platform, we have applied it to enhance fluorescence from bovine serum albumin and Pseudomonas fluorescens . Significant enhancement in fluorescence intensity was observed from both. The results obtained can provide a reference to be used in the development of biochemical sensors based on surface-enhanced fluorescence.

Thermally‐controlled spherical peptide gel architectures prepared using the pH switch method

“…The observed increase in a lifetime could be due to a semiconductor‐induced charge transfer process, allowing extended lifetime for the excited singlet state between Fmoc‐FF and TMPyP. [ 43 ] Our findings are in agreement with previous studies [ 38 ] reporting that charge transfer from peptide‐based materials can stabilize the excited state of the photosensitizer or dye molecules.…”

“…The increase in PL intensity could be attributed to the fact that both heat and water change the hydrophobic interactions and hydrogen bonding, affecting intermolecular interaction and hence enhancing the PL intensity. [38,42] Similar results were observed when using CV (Figure S19).…”

“…The UV-vis spectra lose their structure and become flat. The bandgap was determined from UV-vis data following previous reports [37,38] to decrease from 4.8 ± 0.1 (control samples) to 3.9 ± 0.1 eV at 1:6 ratio. Studies have shown that the presence or addition of ddH 2 O leads to changes in the electronic properties of peptide-based materials that reduce the bandgap and lead to increased conductivity.…”

Structural Transition-Induced Raman Enhancement in Bioinspired Diphenylalanine Peptide Nanotubes

“…The variation in PSERS from MB on FFNTs annealed at 150 °C was determined from multiple locations per sample to be 15, 17, and 19% of MB at concentrations of 10 –4 , 10 –6 , and 10 –7 M, respectively (Figure S13), indicating that the FFNT template provides reproducible results. , …”

“…The variation in PSERS from MB on FFNTs annealed at 150 °C was determined from multiple locations per sample to be 15, 17, and 19% of MB at concentrations of 10 −4 , 10 −6 , and 10 −7 M, respectively (Figure S13), indicating that the FFNT template provides reproducible results. 35,36 Enhancement Mechanism. Theoretical calculations of an absorbed probe molecule on an FFNT demonstrate that changes in the electronic states occur.…”