Drop coating deposition Raman (DCDR) spectroscopy of biologically important molecules

• Published in: Journal of Raman spectroscopy 2023-07, Vol.54 (7), p.694-705
• Main Authors: Kuižová, Alžbeta, Kočišová, Eva
• Format: Article
• Language: English
• Subjects: Anthrax; biomolecule; Biomolecules; Coffee; Contaminants; DCDR; Deposition; drop coating deposition Raman; Drying; Food contamination; hydrophobic substrate; Hydrophobic surfaces; Hydrophobicity; Lipids; Porphyrins; Raman spectroscopy; Spectroscopy; Spectrum analysis
• ISSN: 0377-0486; 1097-4555
• DOI: 10.1002/jrs.6524

Drop coating deposition Raman (DCDR) spectroscopy introduces a simple and easily accessible approach to studying biologically important molecules and their mixtures. The method is based on drying a small drop of solution or suspension of studied molecules deposited on a special hydrophobic surface. The drying process efficiently accumulates the molecules in the ‘coffee‐ring’ or any small pattern from which the Raman spectrum can be measured. In this way, a significant (several orders of magnitude) improvement of the Raman detection sensitivity compared with Raman measurement from solution can be reached. Therefore, a small sample volume (several microliters), as well as a low initial concentration of studied molecules in deposited droplets, are important advantages of the DCDR method over the normal Raman one. Recently, many relevant DCDR applications on biomolecules and related molecules have been reported. The mini‐review covers a brief overview of the DCDR method (principle, short history, suitable hydrophobic surfaces and state‐of‐the‐art). It will be followed by a summary of the studies over the last 15–20 years on different biologically important molecules, including proteins, lipids (in the form of liposomes) and small molecules (e.g., porphyrins, anthrax marker dipicolinic acid and food and environmental contaminants). Finally, the application potential and further perspectives of the DCDR method for biomolecular studies will be discussed. DCDR spectroscopy is a simple and powerful approach to studying biologically important molecules and complex samples, such as real body fluids. The method is based on drying of small liquid sample drop on a hydrophobic substrate, leading to the preconcentration of studied material into the dried pattern from which high‐quality Raman spectra are measured. This enables study samples in low initial concentrations and from small initial volumes. The DCDR method has sensitivity both in terms of detection limit and chemical information content.