Electric Field-Induced Chemical Surface-Enhanced Raman Spectroscopy Enhancement from Aligned Peptide Nanotube–Graphene Oxide Templates for Universal Trace Detection of Biomolecules

Abstract

Semiconductor-graphene oxide-based surface enhanced Raman spectroscopy substrates represent a new frontier in the field of surface enhanced Raman spectroscopy (SERS). However, the application of graphene oxide has had limited success due to the poor Raman enhancement factors achievable compared to noble metals. In this work, we report chemical SERS enhancement enabled by the application of electric field to aligned semiconducting peptide nanotube-graphene oxide composite structures during Raman measurements. The technique enables nanomolar detection sensitivity of glucose and nucleobases with up to 10-fold signal enhancement compared to metal-based substrates, which, to our knowledge, is higher than previously reported for semiconductor-based SERS substrates. The increased Raman scattering is assigned to enhanced charge-transfer resonance enabled by work function lowering of the peptide nanotubes. The substrate presented here is easy to make, low cost, sensitive, stable, highly reproducible, and can be used as an excellent platform for biomolecular sensing. These results provide insight into how semiconductor organic peptide nanotubes interact with graphene oxide, which may facilitate chemical biosensing, electronic devices, and energy harvesting applications.

Flexing Piezoelectric Diphenylalanine–Plasmonic Metal Nanocomposites to Increase SERS Signal Strength

“…Such blinking-based processes potentially arise from charging of the FF-PNT. [25][26][27][28][29] These results further support the assertion that the FF-PNTs become piezoelectrically charged during substrate bending.…”

“…This is distinct but not easily disentangled from the additional chemical enhancement mechanism. [25][26][27][28][29] Electron accumulation on the surface of the FF-PNT yields a predicted (Fig. 3(c)) electromagnetic reduction in SERS signal intensity (relative to simulations where the Ag NP is absent).…”

“…Ag NPs can be observed to aggregate in localized regions on and around the FF-PNTs due to strong chemical and electrostatic interactions. 22,[25][26][27][28][29] Additionally, the template remains intact following the addition of the probe molecule solution (Fig. S1).…”

“…23,24 The wettability difference between the polyvinyl surface (contact angle (CA) of 68.3 ± 1.8°) and the resulting oxide layer (CA = 4.3 ± 1.2°) promotes FF-PNT alignment during selfassembly. 22,[25][26][27][28][29] Scanning electron microscopy (SEM) was used to characterize the aligned FF-PNT/Ag NP template (Figs. 1(a) and S1-S2).…”

3D-Printed Peptide-Hydrogel Nanoparticle Composites for Surface-Enhanced Raman Spectroscopy Sensing

“…[3][4][5][6][7][8][9][10] Peptide-metal NP composites, in particular, have been used for drug delivery and electrochemical biosensing applications, [11][12][13] and more recently, in surface-enhanced Raman spectroscopy (SERS)-based sensing applications using FF-nanotube-metal NP composites. [14][15][16] Although nanoparticles and organic-nanoparticle composites that may facilitate cellular and biomolecular sensing applications have been assembled through bio-templating and self-assembly routes, 14,16,[25][26][27][28][29][30][31][17][18][19][20][21][22][23][24] few of these have been used for SERS, 14,[16][17][18][19]25,28,29,31 and none are based on Fmoc-FF.…”