Real-Time Monitoring of the In Situ Microfluidic Synthesis of Ag Nanoparticles on Solid Substrate for Reliable SERS Detection

Abstract

A sharpened control over the parameters affecting the synthesis of plasmonic nanostructures is often crucial for their application in biosensing, which, if based on surface-enhanced Raman spectroscopy (SERS), requires well-defined optical properties of the substrate. In this work, a method for the microfluidic synthesis of Ag nanoparticles (NPs) on porous silicon (pSi) was developed, focusing on achieving a fine control over the morphological characteristics and spatial distribution of the produced nanostructures to be used as SERS substrates. To this end, a pSi membrane was integrated in a microfluidic chamber in which the silver precursor solution was injected, allowing for the real-time monitoring of the reaction by UV–Vis spectroscopy. The synthesis parameters, such as the concentration of the silver precursor, the temperature, and the flow rate, were varied in order to study their effects on the final silver NPs’ morphology. Variations in the flow rate affected the size distribution of the NPs, whereas both the temperature and the concentration of the silver precursor strongly influenced the rate of the reaction and the particle size. Consistently with the described trends, SERS tests using 4-MBA as a probe showed how the flow rate variation affected the SERS enhancement uniformity, and how the production of larger NPs, as a result of an increase in temperature or of the concentration of the Ag precursor, led to an increased SERS efficiency.

Application of Surface-Enhanced Raman Spectroscopy Combined with Immunoassay for the Detection of Adrenoceptor Agonists

“…During trace analysis, the Raman reporter molecules adsorbed on monometallic nanosubstrates are susceptible to environmental interference, resulting in inaccurately detected signals [ 55 ]. In recent years, with the development of nanosynthesis technology, multicomponent nanostructures have become promising substrates for SERS [ 56 ]. Nanocomposite substrates are increasingly being investigated as SERS substrates due to their greater signal enhancement and better biocompatibility.…”

Recent advances of Au@Ag core–shell SERS‐based biosensors

“…Due to extremely effective performance of SERS for morphological characteristics of NPs, the development of novel metallic nanoscale materials has increased with focus on their basic features with respect to their role as SERS active substrates. [ 107 ] The focus and development on the base of basic features like shapes and sizes of the metallic nanoscale materials have elevated the degree of applications in domain of nanophotonic. The tunability and adaptability of the localized resonance bands can be achieved by variations in these basic features and ultimately improving SERS efficiency.…”

Facile production of quercetin nanoparticles using 3D printed centrifugal flow reactors

“…For this reason, the RIAC is less suitable than other reported techniques for studying nanoparticle formation mechanisms or observing the transport of fluids and chemical species within microchannels. 47–51…”

“…For this reason, the RIAC is less suitable than other reported techniques for studying nanoparticle formation mechanisms or observing the transport of uids and chemical species within microchannels. [47][48][49][50][51] Building upon our previous study, in the present work we aimed to determine whether the RIAC can be employed as a tool for rapid, reliable and facile production of API nanocrystals. In particular, we report on the design and manufacturing of two different RIAC prototypes, the development of a method for API nanoparticle production using these devices, and a comparison of nanoparticles obtained through this method with those reported in the literature.…”