Oligomeric 2-aminothiophenol decorated carboxyl graphene: A new surface enhanced Raman reporter and its application in immunosensing

• Oligomeric 2-aminothiophenol (OATP) was synthesized via a one-step reaction and contact the carboxyl graphene (OACG).
• The OACG showed a significant SERS activity, and can be directly used as Raman reporter to construct SERS tags for immunoassay.
• This model of immunosensor could be widely applied as Raman reporter for other SERS-based immunoassay.

Herein, a simple wet-chemical pathway has been demonstrated for the synthesis of oligomeric 2-aminothiophenol (OATP) where ammonium peroxydisulfate ((NH)4S2O8) is judiciously employed as an efficient oxidizing agent, hydrochloric acid (HCl) as stabilizing agent via a one-step reaction. Then, carboxyl graphene was conjugated reduced by OATP to form the oligomeric 2-aminthiophnol-carboxyl graphene (OACG) composite. Importantly, the OACG showed a significant surface enhanced Raman scattering (SERS) activity, and then the composite material has been exploited as an intriguing Raman reporter to construct SERS tags. Based on the promising properties, an ultrasensitive SERS-based immunosensing platform was developed. The human immunoglobulin (h-IgG) was used as the model target analyte in the proposed method. Under optimal condition, the response of the label-free immunosensor had a linear range from 100 fg mL−1 to 100 ng mL−1 with a detection limit of 22.18 fg mL−1 (S/N = 3). Its response is much better than the reported studies using routine Raman reporters.

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