Methods to detect trace levels of genetic materials using colloidal gold nanoparticles on quartz paper or metamaterial substrates and surface-enhanced Raman scattering

1. A method of Surface Enhanced Raman Scattering testing for 1 to 10 ppm analyte using refrigerated 1 mL solutions of prepared colloidal gold nanoparticles having a position of the surface plasmon peak at 540 nm and said analyte testing on substrates in blood comprising:

mixing 20-30 μL of said prepared colloidal gold nanoparticles with 0.6-1 μL 20 mM NaCl and 5 μL of this mixture is pipetted onto a substrate and allowed to dry;

placing a non-metalized porous substrate on top of said metallized substrate containing aggregated colloidal gold nanoparticles as a filter for the red blood cells;

then dissolving 10 μL of said analyte of interest in blood at a concentration <60 mg/dL creating a solution and pipetting said solution on top of the non-metalized porous substrate;

drying said solution on said sandwiched substrate and non-metalized porous substrate before removing a top filter substrate from said non-metalized porous substrate; and,

then interrogating the sample with 785 nm laser excitation and Raman instrumentation at a power density of approximately 100 W/cm 2 .

2. The method of claim 1 wherein the preparation of said prepared colloidal gold nanoparticles is comprising:

soaking A 250 mL Erlenmeyer flask in a base bath solution;

rinsing said flask with purified water and creating a solution by adding 200-300 mL of purified water and 0.05 to 0.06 grams HAuCl 4 ;

preventing any light interaction with gold salt;

bringing said solution to a boil with magnetic stirring on a hot plate;

once boiling, the stirring is increased until a vortex is achieved in said solution;

then adding 0.05 to 0.06 grams sodium citrate to said solution, and continue boiling with stirring for 14 minutes;

removing said flask from the hot plate and cooling said solution to room temperature;

cooling said resulting solution containing colloidal gold nanoparticles in a refrigerator; and,

once cooled, measuring said colloidal gold nanoparticles solution with absorption spectroscopy to confirm the position of the surface plasmon peak at 540 nm.

3. The method of claim 1 wherein said analyte is Phenylalanine.