Time Dependence of SERS Enhancement for Pyrimidine Nucleosides

Abstract

The effects of chemical components in a SERS sample preparation on the time scale of the SERS enhancement process have not previously been examined in detail. In this report the effects of the nature and concentration of aggregating agent as well as the concentration of both colloid and analyte on the time dependence of SERS enhancement and on the spectral profiles observed for the pyrimidine nucleosides cytidine and uridine are characterized. In conjunction with hydrodynamic diameter and ζ-potential measurements the differences in SERS enhancement profile with time observed for the aggregating agents studied (KCl and K2SO4) are ascribed to two competing processes affecting the SERS substrate nanoparticles. The first being the conventional aggregation process and the second being an equilibrium between smaller and larger aggregates which is influenced by the presence of Cl− ions.

Absolute Quantification of Uric Acid in Human Urine Using Surface Enhanced Raman Scattering with the Standard Addition Method

“…For the latter, this meant using a different colloidal batch for each replicate performed (see Figure S5). In general, batch-to-batch variation and reproducibility of SERS enhancements is a key discussion point within the Raman community. − Groups report noticeable discrepancies in results due to variations in colloidal batches, colloid concentrations, and nanoparticle aggregation, all of which can result in inconsistent enhancements. However, we have demonstrated that the use of this optimized set of conditions for uric acid detection in urine can produce consistent, reliable results that are in good agreement and they are comparable to HPLC results, the “gold standard” in this case and used for benchmarking (see Table ).…”

On‐site detection of phosgene agents by surface‐enhanced Raman spectroscopy coupled with a chemical transformation approach

“…‘Hot spots’ is the gap region of a pair of strongly coupled nanoparticles, and the highest Raman response of above 10 6 usually occurs at the inter‐particle ‘hot spot’ in which the electromagnetic optical fields are highly concentrated . The assembly of nanoparticles to aggregation is a very efficient way to obtain the ‘hot spot’, and various ways have been reported, among them the inorganic salt induction way is the most convenient . Here, ten kinds of potassium salts, including KF, KCl, KBr, KI, KNO 3 , KHCO 3 , K 2 CO 3 , K 2 SO 4 and K 3 PO 4 , were used to induce the Au NPs particles aggregation .…”

SERS study of methylated and nonmethylated ribonucleosides and the effect of aggregating agents

“…The average sizes and size distributions of typical preparations of these colloidal systems with nucleosides have been recently reported. [19] All spectra were collected using a ChiralRAMAN spectrometer (BioTools Inc., Jupiter FL, USA) operating in the Raman backscattering mode with a spectral resolution of 7 cm −1 . All spectra were collected at 532 nm using a laser power of 75 mW at the sample and a data collection time of 30 s. In all cases the raw data are shown with no normalisation or baseline correction functions applied.…”

“…[22] In the spectrum presented in Fig. 2, two bands are present at ∼1586 and Cytidine in nucleic acid chains, [20] ring breathing in uracil [5,20] 867 863 867 863 864 866 C-O and C-C vibrations in cytidine, [19] C4-C5 deformations and C-H wagging in uracil [5] 902 898 902 936 927 955 951 952 1030 1030 1017 1021 1033 1033 Cytosine base ring vibrations, [19] C C and N3-C4 stretching in uracil [5] 1104 1104 1142 1148 1190 N1-C1 bond vibrations [19] 1220 1220 C4-NH 2 vibrations [19] 1239 1236 1242 1242 C4-N4 vibrations in cytidine, [19] ring stretching in uracil [21] 1303 1301 1290 1283 C-H vibrations in cytosine ring, [19] C-H and N-H bending in uracil [5] [19] C O, C-H and N-H vibrations in uracil [5] wileyonlinelibrary.com/journal/jrs 1626 cm −1 , which could, therefore, be associated with the two C O bonds also present in uridine. However, in the spectrum for thymine these bands are both strong and relatively equal in intensity, [22] which is not the case for uridine.…”