Gold Nano-urchin Biosensor for Cancer Biomarker Detection

The patent introduces an APTES self-assembled monolayer as an intermediary between the gold surface and antibodies. This monolayer provides specific chemical groups that enable controlled orientation of antibodies through their Fc region, preventing random orientation and ensuring Fab regions face outward for optimal biomarker binding. The intermediary layer mediates the conjugation process to achieve both attachment and proper orientation.

The patent modifies specific regions of the antibody-conjugation system to achieve uniform orientation. By functionalizing the gold surface with APTES and controlling the conjugation chemistry at the Fc region specifically, the system creates local chemical environments that guide antibody orientation. This localized modification ensures that only the Fc region binds to the surface while Fab regions remain accessible.

The patent employs gold nano-urchins with unique spiky surface morphology as composite structures. These nano-urchins combine the plasmonic properties of gold with a high-surface-area spiky architecture, creating a composite material that enhances both signal amplification and antibody loading capacity. The composite structure provides multiple binding sites per nanoparticle, increasing the effective concentration of antibodies available for detecting low-abundance biomarkers.

The spiky surface structure of gold nano-urchins creates a porous-like high-surface-area morphology that increases the capacity for antibody conjugation. The numerous spikes provide extensive surface area for attaching antibodies, effectively increasing the density of detection sites without increasing the overall particle size, thereby enhancing sensitivity for low-abundance biomarkers.