(265d) Protein Detection with Peptoid-Functionalized Carbon Nanotube Optical Sensors

A primary limitation to real-time imaging of small molecule metabolites and proteins has been the selective detection of biomolecules that have no naturally-occurring molecular recognition counterpart.¹ We present recent developments in the design of synthetic non-photobleaching fluorescent sensors, ‘synthetic antibodies’, to detect protein analytes, based on the near-infrared fluorescence modulation of single-walled carbon nanotubes (SWNT). Bio-mimetic peptoids, or N-substituted glycine polymers, are electrostatically pinned to the surface of SWNT to create peptoid-SWNT sensors sensitive and selective for the lectin protein wheat germ agglutinin.² We show the sensor to remain functional in Dulbecco’s Modified Eagle’s Medium, suitable for mammalian cell experimentation. The protein sensor is characterized with near-infrared spectroscopy and microscopy to extract protein-sensor interaction parameters and kinetic binding constants. We further show ternary selective interactions of the lectin with its conjugate sugars, through the near-infrared modulation of the peptoid-SWNT. This peptoid-SWNT sensor is a notable demonstration of a synthetic peptoid-nanoparticle biosensor with sugar recognition, and informs us of design considerations for developing synthetic molecular recognition elements to detect proteins and complex biomolecules.

1. Landry, M. P. et al. Single-molecule detection of protein efflux from microorganisms using fluorescent single-walled carbon nanotube sensor arrays. Nat. Nanotechnol. (2017). doi:10.1038/nnano.2016.284
2. Olivier, G. K. et al. Antibody-mimetic peptoid nanosheets for molecular recognition. ACS Nano 7, 9276–9286 (2013).