Nanostructured Plasma Polymerized Fluorocarbon Films for Drop Coating Deposition Raman Spectroscopy (DCDRS) of Liposomes.

Alžbeta Kuižová,Eva Kočišová,Anna Kuzminova,Ondřej Kylián

doi:10.3390/polym13224023

Abstract

Raman spectroscopy is one of the most used biodetection techniques. However, its usability is hampered in the case of low concentrated substances because of the weak intensity of the Raman signal. To overcome this limitation, the use of drop coating deposition Raman spectroscopy (DCDRS), in which the liquid samples are allowed to dry into well-defined patterns where the non-volatile solutes are highly concentrated, is appropriate. This significantly improves the Raman sensitivity when compared to the conventional Raman signal from solution/suspension. As DCDRS performance strongly depends on the wetting properties of substrates, we demonstrate here that the smooth hydrophobic plasma polymerized fluorocarbon films prepared by magnetron sputtering (contact angle 108°) are well-suited for the DCDRS detection of liposomes. Furthermore, it was proved that even better improvement of the Raman signal might be achieved if the plasma polymer surfaces are roughened. In this case, 100% higher intensities of Raman signal are observed in comparison with smooth fluorocarbon films. As it is shown, this effect, which has no influence on the profile of Raman spectra, is connected with the increased hydrophobicity of nanostructured fluorocarbon films. This results in the formation of dried liposomal deposits with smaller diameters and higher preconcentration of liposomes.

Highlights

The wetting of polymeric surfaces plays a crucial role in different sectors such as the textile industry [1], ink-jet printing [2], metallization of polymers [3], and last but not least in biomedical applications [4,5]
The great advantage of this approach is the possibility of detecting biological samples at biologically relevant concentrations, which is not possible by conventional Raman spectroscopy
Two distinct types of surfaces for the drop coating deposition Raman spectroscopy (DCDRS) measuresigned to the subspectra can be used, where the significant drop in the value is crucial

Summary

Introduction

The wetting of polymeric surfaces plays a crucial role in different sectors such as the textile industry [1], ink-jet printing [2], metallization of polymers [3], and last but not least in biomedical applications [4,5]. The latter is connected with the fact that the surface wettability governs the interaction of polymers with surrounding media, including the biological suspensions or solutions. A prominent example of this is the formation of the so-called “coffee-ring”, i.e., the ring-shaped pattern where the edge part comprises accumulated non-volatile solutes [13] Such structures are highly advantageous, especially for biodetection, as the substances to be detected are highly preconcentrated in well-defined surface locations. The great advantage of this approach is the possibility of detecting biological samples at biologically relevant concentrations, which is not possible by conventional Raman spectroscopy (measurement from solutions or suspensions at a standard concentration from cuvette)

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