Method for detecting a biomolecule by surface-enhanced Raman spectroscopy

A method for detecting SARS-CoV-2 by surface-enhanced Raman spectroscopy, comprising the steps of:

• preparing a target substrate by depositing nanoparticles of a metal on a substrate of silicon nanowires, wherein the metal is selected from the group consisting of silver, gold, and a combination thereof;
• obtaining far-field Raman spectra of at least one biomolecule associated with SARS-CoV-2;
• applying a biological fluid sample on the target substrate;
• obtaining surface-enhanced Raman spectroscopy spectra of the biological fluid sample on the target substrate;
• comparing the far-field Raman spectra of the biomolecule against the surface-enhanced Raman spectroscopy spectra of the biological fluid sample on the target substrate;
• and
• determining a presence of the SARS-CoV-2 in the biological fluid sample when the Raman bands associated with the at least one biomolecule are found in the surface-enhanced Raman spectroscopy spectra of the biological fluid sampler, wherein step of preparing the target substrate comprises the steps of:
• cleaning a p-doped silicon substrate;
• rinsing the cleaned p-doped silicon substrate in piranha solution;
• rinsing the cleaned p-doped silicon substrate in deionized water;
• immersing the cleaned and rinsed p-doped silicon substrate in an aqueous solution of hydrofluoric acid and silver nitrate to produce an etched substrate comprising silicon nanowires;
• removing silver dendrites from the etched substrate;
• and
• depositing the nanoparticles of the metal on the etched substrate using the magnetron sputtering.