Advances in Plasmonic Technologies for Point of Care Applications

Abstract

Figure 7. Recent advances in surface functionalization methods and materials. (A) Lipid-supported surface functionalization and applications: (i) Schematic of a gold nanorod coated with a biotinylated lipid membrane and interactions with streptavidin. Adapted with permission from ref 146.

Particle-by-Particle Charge Analysis of DNA-Modified Nanoparticles Using Tunable Resistive Pulse Sensing

“…The functionalization of DNA onto nanoparticle surfaces is now a common practice, and within the field of biosensors alone the number of strategies for immobilization, type of nanomaterial, and detection platform are varied enough to fill several reviews [13][14][15][16][17][18][19] . One family of nanomaterials favoured with purification strategies is Superparamagnetic Particles, SPPs.…”

Surface enhanced Raman spectroscopy (SERS) for in vitro diagnostic testing at the point of care

“…It is defined as a group of metabolic diseases where ultimately the body's pancreas does not produce enough insulin or does not properly respond to insulin produced, resulting in high blood sugar levels over a prolonged period. Glucose meters and other POC devices utilize an assortment of methods for detecting and monitoring biomarkers including electrochemical [16][17][18][19][20], magnetic [21][22][23][24][25][26][27][28][29][30], optical [31][32][33][34], label-free spectroscopic analysis [35][36][37][38][39][40][41][42][43], colorimetric [44][45][46][47][48][49], and plasmonic nanoparticle based sensors [50][51][52]. Generally, electrochemical detection uses potentiometric, amperometric, and impedimetric measurements in conjunction with electroactive tags or free flowing electroactive analytes [17][18][19][20] [15,53,54] are examples of electrochemical and colorimet...…”

“…Indirect sensing through the identification of optically active molecules, including chromophores and fluorophores or other reporter molecules, has improved the sensitivity and multiplexing capabilities of techniques like Raman or fluorescence spectroscopy while simultaneously lowering the limits of detection (LODs) and broadening the dynamic range of spectroscopic analysis [31,90]. This has led to fluorescence-based POC devices, in particular, as being one of the most widely explored and currently utilized optical modalities for the detection of multiple analytes on a single test.…”

“…SERS signal enhancement is achieved through two distinct mechanisms: electromagnetic enhancement and chemical enhancement [100,[102][103][104]. For both mechanisms to occur simultaneously, an analyte must be adsorbed onto or reside very close to a dielectric (often metallic) surface [90]. Electromagnetic enhancement utilizes metallic nanostructures with local surface plasmon resonance (LSPR) wavelengths in resonance with the Raman excitation source.…”

“…Due to the difficulty in reproducibly preparing nanostructures, many planar SERS substrates must be synthesized using a variety of sequential complex photolithographic techniques borrowed from the silicon wafer industry. These methods include techniques such as using electron beam deposition (EBD) to create the nanorough surface itself [90,119], using EBD to produce "nanostamps" [120], combining nanoimprint and copolymer lithographic techniques [121], using selfassembled nanoparticles (SAMs) [122,123], and many others using non-spherical particles such as Au-and Agcoated nanorod arrays [124,125]. These techniques, specifically EBD, produce high-resolution nanostructures that are reproducible within a wafer; however, there is a tradeoff with high reproducibility and low enhancement factor (10 2 - 10 4 ) [126].…”