resumo
A series of hydrogel samples composed of Ag nanoparticles dispersed in carrageenan gels have been prepared and used in SERS studies. These studies demonstrate the dependence of the enhancement of the SERS signal on the strength of the Ag/polysaccharide hydrogel. 2,2'-Dithiodipyridine was used as the analyte probe. Several strategies were employed in order to vary the gel strength. These include the increase of the polysaccharide content in the gel, the addition of KCl as cross-linker, and the variation of the type of carrageenan (kappa, l, lambda) network. An increase in the gel strength originates an increase in the SERS enhancement observed. The results have been interpreted considering hot spots increase due to the formation of Ag particles nanojunctions as the biopolymer matrix tends to rearrange into stronger gels. This is the first report showing that there is a direct correlation between the gel strength of a hydrogel composite used as substrate and its analytical SERS sensitivity.
palavras-chave
KAPPA-CARRAGEENAN; SILVER NANOPARTICLES; TEMPERATURE-DEPENDENCE; HOT-SPOTS; SCATTERING; SPECTROSCOPY; NANOCOMPOSITES; ADSORPTION; 2,2'-DITHIODIPYRIDINE; PARTICLES
categoria
Chemistry; Science & Technology - Other Topics; Materials Science
autores
Fateixa, S; Daniel-da-Silva, AL; Nogueira, HIS; Trindade, T
nossos autores
Ana Luísa Daniel da Silva
Investigador Principal
Helena Isabel Seguro Nogueira
Professor Auxiliar com Agregação
Sara Fateixa
Investigador Júnior
Tito Trindade
Professor CatedráticoProjectos
agradecimentos
S.F. thanks Fundacao para a Ciencia e Tecnologia (FCT/FEDER) for the Grant SFRH/BPD/93547/2013. The authors acknowledge FCT/FEDER (PTDC/CTM-NAN/120668/2010, Pest-C/CTM/LA0011/2011), FSE and POPH for funding.