Dual functional substrates and methods of making the same

1. A substrate for use in surface enhanced Raman spectroscopy and surface enhanced infrared absorption spectroscopy, the substrate comprising:

a flexible polymeric membrane comprising one or more polymers that are insoluble in water;

a plurality of metal oxide nanoparticles disposed on 50% to 100% of the surface area of a first surface of the polymeric membrane; and

a plurality of metallic nanoparticles directly disposed on a portion of the plurality of metallic nanoparticles together forming an external surface of the substrate, wherein

the plurality of metal oxide nanoparticles are configured to work synergistically with metal nanoparticles upon exposure of the substrate surface to at least one of visible light or infrared radiation.

2. The substrate of claim 1 , wherein the one or more polymers range from about 50 wt % to about 100 wt % of the polymeric membrane.

3. The substrate of claim 2 , wherein the one or more polymers are chosen from polyvinylidene fluoride, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polytetrafluoroethylene, thermoplastic polyurethane, cellulose, copolymers thereof, and mixtures thereof.

4. The substrate of claim 3 , wherein the polymer is polyvinylidene fluoride.

5. The substrate of claim 1 , wherein the membrane is porous and comprises a plurality of pores independently ranging in size from about 100 nm to about 900 nm.

6. The substrate of claim 1 , wherein the plurality of nanoparticle covers about 80% of surface area to about 100% of surface area of a first surface of the polymeric membrane.

7. The substrate of claim 1 , wherein the plurality of metal oxide nanoparticles are configured to transfer one or more electrons to at least one of the metallic nanoparticles upon exposure of the plurality of metal oxide nanoparticles to at least one of visible light or infrared radiation.

8. The substrate of claim 7 , wherein the plurality of metal oxide nanoparticles comprise TiO 2 , Cu 2 O, CuO, Bi 2 O 3 , SnO 2 , SnS 2 , ZnO, mixtures thereof, or combinations thereof.

9. The substrate of claim 1 , wherein individual nanoparticles of the plurality of metallic nanoparticles comprise Ag 2 O, elemental silver, elemental gold, elemental copper, elemental platinum, mixtures thereof, alloys thereof, or combinations thereof.

10. The substrate of claim 9 , wherein the plurality of metallic nanoparticles are a mixture of elemental silver nanoparticles and elemental gold nanoparticles.

11. The substrate of claim 1 , wherein at least one of the metallic nanoparticles comprise a surface coating.

12. The substrate of claim 11 , wherein the surface coating is on about 5% of surface area to about 100% of surface area of the at least one metallic nanoparticle.

13. The substrate of claim 11 , wherein the surface coating comprises an antibody, an analyte specific targeting group, a compound having an end group, or a combination thereof, wherein the compound having an end group comprises at least one of a nucleophilic end group, electrophilic end group, a hydrophobic end group, a hydrophilic end group, or a combination thereof.

14. A substrate for use in both surface enhanced Raman spectroscopy and surface enhanced infrared spectroscopy, the substrate comprising:

a flexible porous water insoluble membrane comprising polyvinylidene fluoride;

a coating comprising TiO 2 nanoparticles disposed on 50% to 100% of the surface area of a first surface of the membrane; and

at least one of

a plurality of Ag 2 O nanoparticles directly disposed on a portion of the coating comprising TiO 2 nanoparticles,

a first plurality of elemental silver nanoparticles and a second plurality of elemental gold nanoparticles directly disposed on a portion of the coating comprising TiO 2 nanoparticles, and

an alloy comprising elemental silver nanoparticles and elemental gold nanoparticles directly disposed on a portion of the coating comprising TiO 2 nanoparticles.