Surface-enhanced Raman spectroscopic sensing of glucose
The small normal Raman cross-section of glucose is a major challenge in its detection by surface enhanced Raman spectroscopy (SERS) for medical applications, such as blood glucose level monitoring of diabetic patients and evaluation of patients with other medical conditions, since glucose is a marker for many human diseases. Here we will discuss the use of commercially available multilayer graphene sheets as substrates on which gold nanoparticles are chemically assembled by reduction of sodium citrate.
approximate assignments at: 919 (O-C1-H1 bend), 1,340 (C-C-H bend), 1,270, 1,164, 1,116 (C-C + C-O stretch), 860 (C-C stretch), and 1,070 (C1-OH stretch). SERS on a gold/graphene substrate of 1M glucose showing the key Raman lines is displayed in Figure 3 in agreement with the conventional Raman data in Figure 2.
Scanning electron microscope (SEM) images of pristine and gold-coated graphene sheets were obtained with a VP-1530 Carl Zeiss LEO field-emission SEM. A high magnification image of a gold-coated graphene sheet is shown in Figure 4. The figure shows that gold nanoparticles on the graphene sheet surface which appear with lighter contrast is uniform, with an average concentration of 4.6% determined by energy dispersive x-ray (EDX) analysis.
Figure 5 shows how the Raman intensities of the key Raman line of glucose at 1,340cm-1 vary with concentration down to the 10-8M concentration level of the analyte. This essentially linear variation shows that gold/graphene can be an excellent substrate for glucose detection by SERS. Another feature observed is a small shift of the glucose SERS frequencies on graphene relative to those from free glucose, suggesting the presence of an EM field between the gold particles mediated by the graphene substrate that can provide additional enhancement of the Raman signal.15,16 The results presented suggest the potential of the gold-graphene system as a flexible, highly efficient glucose sensor, particularly for medical applications.
- Fleischmann M, Hendra PJ, McQuillan AJ. Raman spectra of pyridine adsorbed at a silver electrode. Chemical Physics Letters. 1974;26(2):163-166.
- Jeanmaire DL, Van Duyne RP. Surface Raman spectroelectrochemistry: Part I. Heterocyclic, aromatic, and aliphatic amines adsorbed on the anodized silver electrode. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry.1977;84(1):1-20.
- Albrecht MG, Creighton JA. Anomalously intense Raman spectra of pyridine at a silver electrode. Journal of the American Chemical Society. 1977;99(15):5215-5217.
- Moskovits M. Surface roughness and the enhanced intensity of Raman scattering by molecules adsorbed on metals. The Journal of Chemical Physics. 1978;69(9):4159-4161.
- Creighton JA, Blatchford CG, Albrecht MG. Plasma resonance enhancement of Raman scattering by pyridine adsorbed on silver or gold sol particles of size comparable to the excitation wavelength. Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics. 1979;75:790-798.
- Le Ru E, Blackie E, Meyer M, Etchegoin PG. Surface enhanced Raman scattering enhancement factors: a comprehensive study. The Journal of Physical Chemistry C. 2007;111(37):13794-13803.
- Cialla D, März A, Böhme R, Theil F, Weber K, Schmitt M, Popp J. Surface-enhanced Raman spectroscopy (SERS): progress and trends. Analytical and Bioanalytical Chemistry. 2012;403(1):27-54.
- Li W, Camargo PH, Lu X, Xia Y. Dimers of silver nanospheres: facile synthesis and their use as hot spots for surface-enhanced Raman scattering. Nano Letters. 2008;9(1):485-490.
- Sharma B, Frontiera RR, Henry A-I, Ringe E, Van Duyne RP. SERS: materials, applications, and the future. Materials Today. 2012;15(1):16-25.
- Yonzon CR, Haynes CL, Zhang X, Walsh JT, Van Duyne RP. A glucose biosensor based on surface-enhanced Raman scattering: improved partition layer, temporal stability, reversibility, and resistance to serum protein interference. Analytical Chemistry. 2004;76(1):78-85.
- Xu W, Mao N, Zhang J. Graphene: A Platform for Surface-Enhanced Raman Spectroscopy. Small. 2013;9(8):1206-1224.
- Novoselov KS, Geim AK, Morozov SV, Jiang D, Zhang Y, Dubonos SV, Grigorieva IV, Firsov AA. Electric field effect in atomically thin carbon films. Science. 2004;306(5696):666-669.
- Turkevich J. Colloidal gold. Part II. Gold Bulletin. 1985;18(4):125-131.
- Frens G. Controlled nucleation for the regulation of the particle size in monodisperse gold suspensions. Nature. 1973;241(105):20-22.
- Schedin F, Lidorikis E, Lombardo A, Kravets VG, Geim AK, Grigorenko AN, Novoselov KS, FerrariAC. Surface-enhanced Raman spectroscopy of graphene. ACS Nano. 2010;4(10):5617-5626.
- Hao Q, Morton SM, Wang B, Zhao Y, Jensen L, Jun Huang T. Tuning surface-enhanced Raman scattering from graphene substrates using the electric field effect and chemical doping. Applied Physics Letters. 2013;102(1):011102.
LAILA AL-QARNI completed her Master’s degree in Chemistry from King Abdul Aziz University in Saudi Arabia in 2009, where she started as a Teaching Assistant in 2008 and was promoted to Lecturer in 2009. Since 2015 she has been researching and studying at the New Jersey Institute of Technology, where she expects to receive her PhD in Physical Chemistry under the direction of Prof Zafar Iqbal for the use of SERS as a biosensor.
ZAFAR IQBAL is a Research Professor in Chemistry at the New Jersey Institute of Technology (NJIT), and President of CarboMet, a company founded to commercialise nanotechnologies from his laboratory. Before joining NJIT Dr Iqbal was Senior Principal Research Scientist and Project Manager at AlliedSignal. Prior to that, he spent 10 years as a Research Scientist at the US Army’s Research and Development Centre in New Jersey. Dr Iqbal has been awarded the Army’s Paul A Siple Medal, an Alexander von Humboldt Fellowship, and is a Fellow of the American Physical Society. He has published over 225 papers in peerreviewed journals and been awarded 25 US patents on topics ranging from energetics to sonar sensors.