Waveguiding and SERS Simplified Raman Spectroscopy on Biological Samples

Abstract

Biomarkers detection at an ultra-low concentration in biofluids (blood, serum, saliva, etc.) is a key point for the early diagnosis success and the development of personalized therapies. However, it remains a challenge due to limiting factors like (i) the complexity of analyzed media, and (ii) the aspecificity detection and the poor sensitivity of the conventional methods. In addition, several applications require the integration of the primary sensors with other devices (microfluidic devices, capillaries, flasks, vials, etc.) where transducing the signal might be difficult, reducing performances and applicability. In the present work, we demonstrate a new class of optical biosensor we have developed integrating an optical waveguide (OWG) with specific plasmonic surfaces. Exploiting the plasmonic resonance, the devices give consistent results in surface enhanced Raman spectroscopy (SERS) for continuous and label-free detection of biological compounds. The OWG allows driving optical signals in the proximity of SERS surfaces (detection area) overcoming spatial constraints, in order to reach places previously optically inaccessible. A rutile prism couples the remote laser source to the OWG, while a Raman spectrometer collects the SERS far field scattering. The present biosensors were implemented by a simple fabrication process, which includes photolithography and nanofabrication. By using such devices, it was possible to detect cell metabolites like Phenylalanine (Phe), Adenosine 5-triphosphate sodium hydrate (ATP), Sodium Lactate, Human Interleukin 6 (IL6), and relate them to possible metabolic pathway variation.

Human metabolite detection by surface-enhanced Raman spectroscopy

“…For applications that integrated the primary sensors with other devices (e.g., flasks, microfluidic devices), the transmission of optical signals might be difficult. To overcome this spatial constraint, a waveguide could be considered to drive optical signals near plasmonic surfaces [ 128 ]. Pretreatment.…”

Raman Spectroscopy and Its Modifications Applied to Biological and Medical Research

“…The method of RS is becoming increasingly popular in biological research. Valpapuram et al [82] proposed a new technique combining optical biosensing and Raman micro spectroscopy. The particular advantage of this method is its ability to reduce the background signal and thus improve the signal-to-noise ratio.…”

Detection of Hypertension-Induced Changes in Erythrocytes by SERS Nanosensors

“…The development of novel methods and techniques has expanded our understanding of the molecular mechanisms underlying many pathologies and paved the way for the creation of novel diagnostic tools [ 1 , 2 , 3 ]. Cardiovascular diseases remain the leading cause of death around the world.…”

“…Surface-enhanced Raman spectroscopy (SERS) has been successfully applied to detect different disease biomarkers in blood and other body fluids [ 3 , 10 , 11 ]. We have proposed an approach for the selective study of the Hb mb in erythrocytes with SERS using a colloidal solution of silver nanoparticles [ 12 ] and silver nanostructured surfaces (AgNSS) [ 13 , 14 ].…”