Porphyrin-conjugated silver-coated gold nanostars for ultrasensitive detection and multiplexing

BENAVIDES, L.N.; MORENO, M.S.; MURGIDA, D.H.; CASTRO, M.A.

JOURNAL OF RAMAN SPECTROSCOPY

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2020

0377-0486

Here, we propose the use of silver-coated gold nanostars as the basis for a multiplex sensing system based on SERS/SERRS ultrasensitive detection of porphyrins using a 532 nm laser excitation. By modifying the synthetic parameters, we were able to shift the plasmon peak to an optimized position for SERS enhancement of 540 nm for silver-coated gold nanostars, estimating a SERS enhancement factor around 4.6x105. Furthermore, we show HR-TEM images and EELS spectra of silver coated gold nanostars which provide solid experimental proof on the proposed silver coating mechanism. Finally, we compare the multiplex performance of common reporters such as cyanines and malachite green with the performance of covalently bound porphyrins and show the superiority of the latter. We studied the multiplex detection capabilities of the system with three different porphyrins. By deconvoluting a mixture spectrum into individual porphyrin spectra we were able to determine the relative concentration of porphyrins with an average error of 3.1%.