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Issue 6, 2007
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Drop coating deposition Raman spectroscopy of protein mixtures

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The technique of drop coating deposition Raman (DCDR) spectroscopy has been shown to be a highly reproducible and sensitive method of obtaining Raman spectra from low concentration protein solutions. This study assesses the ability of DCDR to analyse changes in the relative protein concentrations of aqueous tertiary protein mixtures, with protein levels similar to that found in human tear fluid. The three proteins used to make the mixtures were lysozyme, lactoferrin and albumin. The combination of DCDR spectroscopy and principal components analysis is found to be sensitive enough to detect small changes in the relative protein concentrations, from very small sample volumes (1.5 µl). With certain mixtures it was found that the deposition of proteins was not homogeneous across the width of the ring, but averaging spectra taken at different positions could compensate for this. Principal components regression was able to predict the protein concentrations of test solutions with a good degree of accuracy (root-mean-square errors of prediction of 0.083, 0.112, and 0.082 mg ml−1 or 8.3, 11.2 and 8.2% of the mean concentration value, for lysozyme, lactoferrin and albumin concentrations respectively). The results of this study suggest that DCDR spectroscopy could be a simple, fast, near-patient technique capable of assisting the diagnosis of ocular infection.

Graphical abstract: Drop coating deposition Raman spectroscopy of protein mixtures

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Publication details

The article was received on 31 Jan 2007, accepted on 10 Apr 2007 and first published on 23 Apr 2007

Article type: Paper
DOI: 10.1039/B701541K
Citation: Analyst, 2007,132, 544-550
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    Drop coating deposition Raman spectroscopy of protein mixtures

    J. Filik and N. Stone, Analyst, 2007, 132, 544
    DOI: 10.1039/B701541K

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