Diamond and Carbon Materials

Biography

Biography: Pedro Alpium

Abstract

The importance of bio sensing systems in biomedical research is steadily increasing, as they became pervasive in a large range of health applications, from prognosis and diagnosis to personalized medicine. Graphene is a material of choice for sensing applications, with its highly conjugated, high mobility, zero bandgap 2D electronic system providing extreme sensitivity to charges and electric fields in its vicinity, combined with a high chemical stability and ease of processing. However, specific target biorecognition on graphene requires surface functionalization. We developed a general process for immobilization of probe molecules on graphene surfaces, based on π-π interactions with a pyrenic linker (PBSE). Electrolyte-gated field-effect transistors (FETs), with receded integrated gate architecture were fabricated at the 200 mm wafer scale followed by functionalization of the graphene channel for detection of antigens and DNA.

A graphene immuno-FET is designed to detect the biomarkers of the hemorrhagic transformation of ischemic stroke. The probe is immobilized by reaction of the PBSE succinimidyl ester groups with a primary amine from the antibody protein. The device is able to detect the biomarker (MMP-9) in concentrations down to 0.01 ng/mL, in a range up to 10 ng/mL. Compared with existing MMP-9 immunoassays, ours has a much shorter time to diagnostic since it is based on a simpler label-free protocol. The nucleic acid sensor is made by immobilization of single-stranded DNA (25 nucleotides long) on the PBSE-functionalized graphene transistor channel. Hybridization with complementary DNA was detected down to 1 aM, with a saturation attained at 100 fM and sensitivity to single nucleotide polymorphism. These results show that the fabrication of graphene sensors using standard clean-room technology, with high sensitivity and low cost, is possible.