Plasmonic Retrofitting of Membrane Materials: Shifting from Self‐Regulation to On‐Command Control of Fluid Flow

Abstract

This work calls for a paradigm shift in order to change the operational patterns of self-regulated membranes in response to chemical signals. To this end, the fabrication of a retrofitting material is introduced aimed at developing an innovative generation of porous substrates endowed with symbiotic but fully independent sensing and actuating capabilities. This is accomplished by transferring carefully engineered plasmonic architectures onto commercial microfiltration membranes lacking of such features. The integration of these materials leads to the formation of a coating surface proficient for ultrasensitive detection and "on-command" gating. Both functionalities can be synergistically modulated by the spatial and temporal distribution of an impinging light beam offering an unprecedented control over the membrane performance in terms of permeability. The implementation of these hybrid nanocomposites in conventional polymeric porous materials holds great potential in applications ranging from intelligent fluid management to advanced filtration technologies and controlled release.

Preventing Memory Effects in Surface-Enhanced Raman Scattering Substrates by Polymer Coating and Laser-Activated Deprotection

“…Photodegradation was achieved by first embedding gold nanorods (Au NRs) within the polymeric material so that PLGA was disrupted upon photothermal heating when Au NRs were irradiated with a resonant laser . Other studies have demonstrated that the photothermal effect can be exploited to alter the permeability of different polymers, such as poly­( N -isopropylacrylamide) (pNIPAM), upon NIR irradiation …”

“…22 Other studies have demonstrated that the photothermal effect can be exploited to alter the permeability of different polymers, such as poly(Nisopropylacrylamide) (pNIPAM), upon NIR irradiation. 23 We hypothesized that the deposited PLGA layer should protect the SERS substrate by preventing adsorption of analyte molecule(s) from solution. Upon laser irradiation at a sufficiently high fluence, the plasmonic photothermal effect would lead to formation of a micron-sized hole in the PLGA layer, while the plasmonic substrate itself remains intact.…”

Analysis of the factors controlling performances of Au-modified TiO 2 nanotube array based photoanode in photo-electrocatalytic (PECa) cells

“…In photonic crystals, due to the periodically structured electromagnetic medium, light cannot propagate through the structure and thus is localized and trapped, creating an intense local electromagnetic field which may interact with other incoming photons, allowing the generation of some hot-electrons (injected into the valence band of the semiconductor) [51] . The mechanism, although less efficient, is similar to that present in plasmonic materials (for example, gold NPs deposited on TiO 2 ), where two mechanisms of hot-electron generation exist [52][53][54] : (i) plasmon-induced resonant energy transfer and (ii) direct electron transfer. The first consists in the non-radiative dipole-dipole coupling between the plasmon of the metal and the electron-hole pairs in the semiconductor.…”

Prospects of Surface-Enhanced Raman Spectroscopy for Biomarker Monitoring toward Precision Medicine

“…Laser irradiation at high fluence induces plasmonic heating of the underlying nanoparticles, so the sheathing layer degrades under high local temperature and opens a measurement window at the selected measurement time and location. Depending on the nature of the polymer layer, this process can be applied in a reversible (poly- N -isopropylacrylamide, pNIPAm) 187 or an irreversible (poly(lactic-glycolyc acid), PLGA) 186 manner. As soon as a micrometer-sized window is created in the polymer layer, the molecules in solution can reach the plasmonic surface and can be registered by SERS ( Figure 5 d).…”