Method of fabrication of photonic biosensor arrays

A method for the fabrication of a biosensor array for plasmon resonance-based sensing of a plurality of different biological targets simultaneously, the method comprising:

• (i) providing a transparent substrate;
• (ii) providing seed metallic nanoparticles in the form of a colloid;
• (iii) depositing said colloid as discrete metallic islands on the transparent substrate, each of said metallic islands comprising a plurality of metallic nanoparticles;
• (iv) washing the substrate in order to remove unadhered material;
• (v) developing the substrate in a growth solution, which solution comprises a salt of the same metal which is present in the form of discrete metallic islands on the substrate, a reducing agent, a capping agent and optionally a surfactant;
• (vi) washing the developed substrate;
• and
• (vii) functionalising each of said metallic islands with a different functionalising molecule using a common chemical process to attach said different functionalising molecules to said metallic islands.

A method for controlling the size distribution of nanoparticles grown in accordance with the following steps:

• (i) provision of a transparent substrate;
• (ii) provision of seed metallic nanoparticles in the form of a colloid;
• (iii) deposition of said colloid as discrete metallic islands on the transparent substrate, each of said metallic islands comprising a plurality of metallic nanoparticles;
• (iv) washing of the substrate in order to remove unadhered material;
• (v) development of the substrate in a growth solution, which solution comprises a salt of the same metal which is present in the form of discrete metallic islands on the substrate, a reducing agent, a capping agent and optionally a surfactant;
• which method comprises adding metal ions to the growth solution of development step (v), wherein these additional metal ions are different to the metal forming the plurality of metallic islands on the substrate.

A method of plasmon resonance-based sensing of a plurality of different biological targets simultaneously, the method comprising:

• coupling light of at least one wavelength into a biosensor array as claimed in claim 15 such that total internal reflection of said light at said surface generates an evanescent wave field which excites plasmons in said functionalised metallic nanoparticles and scatters said light;
• flowing a fluid carrying a plurality of said biological targets for analysis over said array;
• imaging said scattered light from said array to generate image data for said biological targets carried by said fluid;
• and
• analysing said image data to determine levels of said biological targets carried by said fluid.

A method of analysing a plurality of different biological targets simultaneously, the method comprising:

• fabricating an array according to the method of claim 1;
• passing a fluid carrying a plurality of said biological targets for analysis over said array;
• and
• detecting said biological targets carried by said fluid by imaging light scattered by plasmon resonance at said functionalised metallic islands.