Plasmon‐Induced Photopolymerization of Molecularly Imprinted Polymers for Nanosensor Applications

Abstract

A new simple, fast, and versatile method is developed to functionalize gold nanoparticles (AuNPs) via nanoscale layers of molecularly imprinted polymers (MIPs). The key step is based on near‐field radical photopolymerization of the MIP prepolymerization mixture. This enables the fabrication of AuNPs@MIPs hybrid nanoparticles, which are used as substrates for localized surface plasmon resonance and surface‐enhanced Raman spectroscopy (SERS) analysis with excellent sensitivity and specificity. To demonstrate the performance of AuNPs@MIPs, methylene blue‐specific MIPs are prepared. The sensitivity of SERS detection is in the range of 10 nm. Specificity is demonstrated by comparing the response to a non‐imprinted control polymer and by interference testing with two analogs (Rhodamine 6G and Rhodamine 110). This fabrication method allows to obtain robust and reusable sensor surfaces with high sensitivity and selectivity. The nanometric thickness of the MIP allows for shorter analysis times (10 min), thereby improving the performance of MIP‐based sensors and opening up new perspectives for the detection of molecules at very low concentrations.

Sol–Gel TiO2 Thin Film on Au Nanoparticles for Heterogeneous Plasmonic Photocatalysis

“…The AuNPs used in this work were synthesized by thermal dewetting of a gold film deposited on a glass slide, following a protocol described elsewhere − (Figure ). In the present work, the thickness of the deposited gold film was 4 nm.…”

“…A 50 μL drop of 125 μM MB (99%, Sigma-Aldrich) in ethanol was deposited and left to dry on the nanostructures. Drop drying is a method typically used to simply deposit organic molecules on the surface of substrates. ,, It should be noted that the Raman signatures of MB and TH are very similar, but they differ from two peaks (namely, 447 and 475 cm –1 ). As explained in more detail in the Results and Discussion section, the degradation of MB and TH can occur in parallel with the ND reaction, making the monitoring of the ND reaction via peak intensity less meaningful.…”

Synthesis and Integration of Hybrid Metal Nanoparticles Covered with a Molecularly Imprinted Polymer Nanolayer by Photopolymerization

“…Due to their localized surface plasmon (LSPR) properties, metallic nanoparticles (MNPs) are nanoobjects of great interest in many fields such as photonics, molecular detection [1][2][3] or photocatalysis for various reactions [4,5]. Due to the nanometric size of nanoparticles (NPs), resonance phenomena cause an exaltation of the electromagnetic field in the vicinity of metallic nanostructures (optical near field, ONF), which considerably increases the coupling with molecules present on their surface and thus amplifies their optical response [6]. This principle allows the significant increase of the Raman signal by offering surface-exalted Raman spectrometry (SERS) [7,8].…”

“…Another interesting property is the sensitivity of the optical properties of MNPs towards changes in the refractive index of their environment. This allows probing target molecules that accumulate in the vicinity, for example, upon their recognition by specific sites or cavities in the sensing layer [4,6,10], thus providing opportunities for applications in the sensor field.…”

“…Crosslinker monomers are added and copolymerized using a suitable initiator, thus 'freezing' the 3D complex in space. Finally, the resulting polymer is processed in order to weaken the interactions between the template and the polymer to liberate the binding cavities that have formed [6,[15][16][17]. The MIP is now able to specifically bind its target molecule.…”