LI-SERS . technology capabilities

In a new post in optoelectronic advanceJapanese researchers discuss the label-free detection of biomolecules by liquid interface enhanced Raman scattering (SERS) using a microfluidic chip.

SERS has attracted attention in biotechnology. This is due to its high sensitivity to localized surface plasmon resonance for nanostructured metals.

Trace detection of large molecular weight biomolecules remains a challenge because treatment of the SERS substrate with coupling or cross-linking agents is required. The researchers applied SERS with the help of a liquid interface to achieve label-free trace detection of biomolecules. The results indicate that they are promising for early detection of viral infection And the Alzheimer’s disease.

SERS, based on the optical near-field effect caused by the surface plasmon of noble metal nanoparticles or nanostructures excited by laser radiation, amplifies Raman signals up to 1,014 times compared to normal Raman. Due to its enhanced intensity, SERS technology continues to attract increasing interest in trace-level detection and analysis of biomaterials. Interest has increased in areas such as imaging of single-cell organelles, tracking of tumor cells, and identification of biomarkers.

early diagnosis

SERS technology can be used in the field of biomedicine disease diagnosis In the early stage as well as in the treatment of tumors. Although the optimization factor for SERS usually ranges from 106 to 108 due to the use of novel SERS substrates and methods, single molecule detection by label-free SERS is impractical due to SERS flash. The origin of this phenomenon is due to the escape of analyte particles from hot spots. Biomolecules, including DNA and proteins, are difficult to detect directly by SERS. Additional treatments using a SERS substrate are required to bind biomolecules.

researchers, from Advanced laser treatment research teamRIKEN Center for Advanced Photonics, in Wakō and Nano Lab for Medical Engineering, the RIKEN group for pioneering research in Wakō LI-SERS proposed, which achieves a SERS improvement factor greater than 1,014, higher than the normal SERS method. The microfluidic SERS chip features an Ag-Cu SERS substrate embedded in a small, compact glass channel. The femtosecond (fs) hybrid laser treatment created the micro-turf canal.

fs hybrid laser processing enables the creation of more complex 3D structures with enhanced functionality for biochips, sensors and microelectronic devices. When the interface between analyte solution and air on a SERS substrate in a microfluidic channel was irradiated by a Raman excitation laser, the intensity of LI-SERS was increased by six orders of magnitude compared to normal SERS.

The researchers said the study showed that the LI-SERS method is applicable for further practical use. It is particularly useful for the detection of trace-free label-free biomolecules with large molecular masses, including DNA bases, DNA sequences, and amyloid beta (Aβ). Due to the superior sensitivity and self-stabilization of LI-SERS, discrimination of DNA bases and DNA sequences was obtained with a detection limit of 1 fM without the need for additional treatments featuring coupling or cross-linking means.

Early detection of Alzheimer’s disease

Also, LI-SERS technology can detect unlabeled Aβ, a biomarker of Alzheimer’s disease, at levels below 1 PM. The label-free biosensing capability of LI-SERS offers great potential for early diagnosis of disease in the clinic.