Surface-Enhanced Raman Spectroscopy and Electrochemistry: The Ultimate Chemical Sensing and Manipulation Combination

Unveiling the Dual-Enhancing Mechanisms of Kinetically Controlled Silver Nanoparticles on Piezoelectric PVDF Nanofibers for Optimized SERS Performance

Noble metal nanoparticle (NMP)-based composite substrates have garnered significant attention as a highly promising technique for surface-enhanced Raman scattering (SERS) in diverse scientific disciplines because their remarkable ability to amplify and functionalize Raman signals has positioned them as valuable tools for molecular detection. However, optimizing the size and distribution of NMPs has not received sufficient emphasis because of challenges associated with the precise control of deposition and the modulation of reducing rates during growth. In this research, we achieved the optimized size and spatial patterns of AgNWs on electrospun poly(vinylidene fluoride) (PVDF) nanofibers by utilizing a polydopamine (PDA) layer as a mild and controllable reduction mediator, by which the size and density of the AgNWs could be relatively precisely manipulated, achieving a dense distribution of effective "hot spots". On the other hand, harnessing the inherent piezoelectric properties of the electrospun PVDF nanofibers further boosted the LSPR effect during the SERS test, forming a flexible dual-enhancing composite SERS substrate with excellent sensitivity. In addition to addressing structural aspects, exploiting synergistic systems capable of transferring external energy or forces to enhance the SERS performances presents a compelling avenue to broaden the practical applications of SERS. The dual-enhanced substrate achieved an exceptional enhancement factor (EF) of 1.05 × 108 and a low detection limit (LOD) of 10-10 M during the SERS test. This study focuses on integrating NMPs with electrospun piezoelectric polymer nanofibers to develop a dual-enhancing SERS substrate with excellent sensitivity and practicality. The findings provide valuable insights into controllably depositing NMPs on electrospun polymer fibers and hold significant implications for the development of highly sensitive and practical SERS substrates across various applications.

Molecular Plasmonic Silver Forests for the Photocatalytic-Driven Sensing Platforms

Structural electronics, as well as flexible and wearable devices are applications that are possible by merging polymers with metal nanoparticles. However, using conventional technologies, it is challenging to fabricate plasmonic structures that remain flexible. We developed three-dimensional (3D) plasmonic nanostructures/polymer sensors via single-step laser processing and further functionalization with 4-nitrobenzenethiol (4-NBT) as a molecular probe. These sensors allow ultrasensitive detection with surface-enhanced Raman spectroscopy (SERS). We tracked the 4-NBT plasmonic enhancement and changes in its vibrational spectrum under the chemical environment perturbations. As a model system, we investigated the sensor's performance when exposed to prostate cancer cells' media over 7 days showing the possibility of identifying the cell death reflected in the environment through the effects on the 4-NBT probe. Thus, the fabricated sensor could have an impact on the monitoring of the cancer treatment process. Moreover, the laser-driven nanoparticles/polymer intermixing resulted in a free-form electrically conductive composite that withstands over 1000 bending cycles without losing electrical properties. Our results bridge the gap between plasmonic sensing with SERS and flexible electronics in a scalable, energy-efficient, inexpensive, and environmentally friendly way.