H³ (Hydrogel‐Based, High‐Sensitivity, Hybrid) Plasmonic Transducers for Biomolecular Interactions Monitoring (Adv. Mater. Technol. 9/2022)

Abstract

Plasmonic Transducers In article number 2101425, Bruno Miranda, Carlo Forestiere, and co‐workers report on hydrogel‐based, high‐sensitivity, hybrid plasmonic transducers for monitoring biomolecular interactions. The hydrogel network physically stabilizes gold nanoparticles, which act as biochemical optical transducers both in spectroscopy and fluorescence.

Hollow Microneedle‐based Plasmonic Sensor for on Patch Detection of Molecules in Dermal Interstitial Fluid

“…The chemical modifications of the AuNPs were monitored, after accurate washing steps, by measuring the absorption spectra of the single HMNs ( n ≥ 15) on a minimum of three different HMNs arrays ( n ≥ 3). Differently from what was reported elsewhere, [ 40 ][ 40 ] cysteamine‐modified AuNPs exhibited a redshift in the LSPR absorption peak from about 541.3 ± 1.4 nm to 543.6 ± 1.0 nm. The redshift observed herein is justified by a novel concept: “confined” swelling.…”

“…Thin film nanocomposite transducers (patches) were fabricated to study the stability and compatibility of the newly fabricated AuNPs within the hydrogel network. [ 39,40 ] By following the protocol reported in our previous work, [ 39,40 ] AuNPs aqueous solution was added to a prepolymer solution of high Mw PEGDA (10 kDa), containing the photoinitiator. The resulting mixture was cast between two coverslips and exposed to UV light for a few minutes until complete polymerization, to obtain a plasmonic patch (Figure 2c).…”

“…In fact, it has already been shown that hydrophilic molecules such as cys cause high Mw PEGDA/AuNPs nanocomposites absorption decrease due to an increase in the swelling ratio equilibrium, without significant redshift of the LSPR. [ 40 ] In high Mw PEGDA hydrogels embedding AuNPs, no significant redshift was observed after cysteamine functionalization. This does not mean that cys molecules had not capped the AuNPs.…”

“…This means that the redshift caused by the capping of cys molecules on the AuNPs is counterbalanced by the blue shift caused by the enhanced swelling of the nanocomposites. [ 40 ] Differently, when the nanocomposite is not free but confined in an MN, it is possible to observe the redshift caused by the cysteamine since the amount of water that effectively permeates the hydrogel is physically limited by the MNs. In this case, high Mw PEGDA was confined within a sub‐millimetric cavity and exhibited a swelling up to the complete filling of the HMN cavity.…”

“…The capability of PEGDA to retain the physical and chemical stability of AuNPs, which act as optical transducers in both label‐free and label‐based modes, has been already reported in previous works. [ 39,40 ] The combination of plasmonic transducers and MNs has been already reported in the literature, [ 5,41 ] as a promising optical alternative to electrochemical transducers. However, in the proposed platforms, the plasmonic transducers are arranged outside the MNs arrays.…”