L-phenylalanine (Phe) is an amino acid prevalent in human metabolism and is a building block of peptides. Detection of Phe has seen relevance in the clinical diagnosis of the disorder phenylketonuria (PKU), where a defect in the phenylalanine hydroxylase gene leads to elevated levels in the bloodstream. A detection method utilizing a capture agent with Phe detection could also be applied to Phe-terminal peptides, such as insulin, for diagnosis and treatment of diabetes. Curcurbit[n]uril (CB[n]) is a macrocycle which exhibits the proper Phe affinity for such an assay, as it’s known to bind with Phe and Phe-terminal peptides. CB[n]s are particularly advantageous in SERS schemes, given their surface-affinity for noble metal substrates and increased sensitivity due to hotspot formation. We report SERS detection of Phe through formation of a CB[7]-Phe complex. The CB[7]-guest interaction improves the detection limit 5-25 times greater than Phe on Ag nanoparticle (Ag NP) aggregates, with the ability to use a portable Raman system. We further extend the CB[7]-Phe detection scheme to Phe-terminal peptides, namely insulin and the insulin B-chain peptides to prove this method’s utility for SERS detection of biomolecules. Through this CB[7]-Phe SERS assay, we present a sensitive, field-deployable method for detection of Phe and Phe-terminal peptides.

Surface-enhanced Raman scattering of a cucurbituril-phenylalanine complex with applications in peptides

ACS Fall 2020 Virtual Meeting

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