Microfluidic In Situ Patterning of Silver Nanoparticles for Surface-Enhanced Raman Spectroscopic Sensing of Biomolecules

Abstract

This work integrates the advantages of microfluidic devices, nanoparticle synthesis, and on-chip sensing of biomolecules. The concept of microreactors brings new opportunities in chemical synthesis, especially for metallic nanoparticles favorable in surface-enhanced Raman spectroscopy (SERS) for high-resolution and low-limit detection of biomolecules. However, still missing is our understanding of reactions at the microscale and how microsystems can be exploited in biosensing applications via precise control of nanomaterial synthesis. We investigate how microfluidic geometry affects nanoparticle patterning for high-resolution SERS-based sensing and propose a spiral-shaped microchannel that can achieve enhanced mixing, rapid reaction at room temperature, and uniform in situ patterning. The roles of channel geometry as the key parameter on patterning have been studied systematically to provide insight into the rational design of continuous microfluidic systems for SERS applications. We also demonstrate potential applications of this integrated system in label-free on-chip detection of 1 pM rhodamine B (enhancement factor, ∼4.3 × 1011) and a 1 nM 41-base single-stranded deoxyribonucleic acid (DNA) sequence (enhancement factor, ∼1.5 × 108). Our ready-to-use multifunctional system provides an alternative strategy for the facile fabrication of SERS-active substrates and promotes system integration, miniaturization, and on-site biological applications.

Plasmonic nanosensors for point-of-care biomarker detection

“…Being the technique to precisely manipulate fluids at the microscale, microfluidic technology is capable of implementing bioreaction with minimized reagent and shortened span, thus can significantly reduce the cost and time of detection [ [24] , [25] , [26] ]. Compared with traditional platforms, integrating microfluidic systems with plasmonic microsensors offer a bunch of advantages in cost, sensitivity, and adaptability.…”

“…Next, Section 4 reviews sandwich-, microfluidic-, chip-, and paper-based biosensors with plasmonic mechanism. Microfluidic system is an emerging tool to precisely control nanoparticles geometry and size by confining the chemical reaction in micro channels [ [24] , [25] , [26] ]. Paper-based devices are lightweight, small, easily portable, and are therefore extremely suitable for POC diagnosis.…”

Raman Scattering-Based Biosensing: New Prospects and Opportunities

“…To date, such analytical devices are successfully adapted for the detection of a wide range of analytes, including medicines and drugs [ 185 , 187 ], pesticides [ 188 , 189 ], hormones [ 190 ], antibiotics [ 191 ], disease markers [ 184 , 192 , 193 , 194 ], nucleic acids [ 195 ], whole cells [ 196 ], and others [ 186 ]. Figure 6 , drawn in the review, represents the basic principle of measurements that is used in the listed above developments and its application to multi-analysis cases.…”

Catalytically active silver nanoparticles stabilized on a thiol-functionalized metal–organic framework for an efficient hydrogen evolution reaction

“…Silver nanoparticles (Ag NPs) have gained pre-eminence in the contemporary scientific community by virtue of their unique properties like localized surface plasmon behaviour, luminescence, antimicrobial activity, high surface area to volume ratio and coordinatively unsaturated environments. Hence, Ag NPs are advocated in sensing, [1][2][3] nanomedicine, [4][5][6][7] electronics, [8][9][10] catalysis, [11][12][13] etc. Their properties are strongly correlated with the size, morphology and nature of ligands associated with the structure.…”