Rational design and synthesis of SERS labels

Abstract

SERS labels are a new class of nanotags for optical detection based on Raman scattering. Central advantages include their spectral multiplexing capacity due to the small line width of vibrational Raman bands, quantification based on spectral intensities, high photostability, minimization of autofluorescence from biological specimens via red to near-infrared (NIR) excitation, and the need for only a single laser excitation line. Current concepts for the rational design and synthesis of SERS labels are summarized in this review. Chemical constituents of SERS labels are the plasmonically active metal colloids for signal enhancement upon resonant laser excitation, organic Raman reporter molecules for adsorption onto the metal surface for identification, and an optional protective shell. Different chemical approaches towards the synthesis of rationally designed SERS labels are highlighted, including also their subsequent bioconjugation.

SERS Nanoparticles in Medicine: From Label-Free Detection to Spectroscopic Tagging

“…123,236 PEG is a biocompatible polymer able to prevent nonspecific adsorption of proteins and other cellular components, leading to prolonged blood circulation lifetimes in vivo. 14,237,238 The great ability of PEG to prevent the biofouling of particles is attributed to a combination of flexibility and strong interaction with water molecules where protein adsorption would lead to an unfavorable increase in free energy. 239 PEG ligands can be anchored to noble metal surfaces through a distal thiol functional group.…”

SERS Nanotags and Their Applications in Biosensing and Bioimaging

“…SERS nanotags, as an alternative label, provide unique optical properties and potential for simultaneous and multiple detection due to the advantages of SERS nanotags over the fluorescent labels including the multiplexing capability for simultaneous target detection, quantification using the SERS fingerprint and the need for only a single laser excitation wavelength, and high photostability [21,22]. Typically, SERS nanotags (as shown in Fig.…”

“…1a), (ii) a few atoms and/or high symmetry, resulting in a minimal number of Raman bands for multiplexing (Fig. 1b), (iii) low or no photobleaching for the stability of signal, and (iv) surface groups for binding the metal colloid surface with target molecules [22]. As an typical example, Graham et al reported the use of either custom-built benzotriazoles [67] or commercially available dyes (BODIPY, Cy5.5, etc.)…”

“…Based on this concept, SERS-active substrates have usually been made to support plasmonic field and enhance the Raman signal with exquisite sensitivity. In regards to the application of SERS in biosensing and bioimaging, the unique advantages of SERS include: (i) the great multiplexing capacity for simultaneous detection and imaging of the targets, which is due to the narrow width of the vibrational Raman bands; (ii) quantification based on a specific SERS fingerprint of the corresponding molecules, conformation and structural studies of the targets; (iii) high photostability and optimal contrast with the red or nearinfrared (NIR) excitation, which will minimize the fluorescence background, in particularly the autofluorescence from biological samples, such as blood, urine and tissue [20][21][22].…”

Development of point-of-care and multiplex diagnostic methods for the detection of plant pathogens

“…[213][214][215] With its narrow and distinct spectral peaks, SERS could potentially be better suited than standard fluorescent-based methods for highly multiplexed applications. [216][217][218] Indeed, SERS particles labelled with various Raman reporters have enabled various multiplex detection applications 219 especially in clinical applications. 220,221 However, to the best of our knowledge, SERS has not been applied to any multiplex RPA applications in agriculture.…”