Drop‐coating deposition Raman spectroscopy of liposomes

Abstract

Drop-coating deposition Raman (DCDR) spectroscopy was tested as a potential technique for studying liposomes at very low sample concentrations. We used model liposomes prepared either from 1,2-distearoyl-sn-glycero-3-phospocholine or from soybean asolectin, which is composed of various lipids and thus represents a good model of natural membranes. In both cases, deposited samples formed a dried drop with a circular shape with a ring of concentrated liposomes at the edge. Spectral mapping showed that maximum Raman intensity originated from the inner part of the edge ring, while Raman signal gradually decreased in both radial directions. The Raman spectra exhibited excellent reproducibility of spectral characteristics at different locations in the drop, indicating similar conformation and ordering of hydrocarbon lipid chains in the sample. Our results suggest that DCDR spectroscopy can be used for studying lipids in situ, and sensitivity of this technique is at least two orders of magnitude higher than that of conventional Raman microscopy.

Sensitive Raman spectroscopy of lipids based on drop deposition using DCDR and SERS

“…b) demonstrate that DMTAP holds its solution properties, including the phase, after drying. It confirms our previous conclusions for other lipids on DCDR plates . There is no trace of remaining water (see water bands at 1642 and >3000 cm −1 in the solution spectrum, Fig.…”

“…Moreover, impurities of different sizes can be partially separated this way . Recently, Raman spectra of dried samples of proteins (~1 μM in the deposited solution) and liposomes (~300 μM in the deposited solution) were obtained. Apart from improved sensitivity, a big advantage of DCDR is that proteins and liposomes retain their solution properties .…”

“…Recently, Raman spectra of dried samples of proteins (~1 μM in the deposited solution) and liposomes (~300 μM in the deposited solution) were obtained. Apart from improved sensitivity, a big advantage of DCDR is that proteins and liposomes retain their solution properties . Drying of the droplet on hydrophobic surface is not straightforward; it depends on both properties of the surface and the size, charge and initial concentration of deposited molecules.…”

Rapid and nondestructive method for evaluation of embryo culture media using drop coating deposition Raman spectroscopy

“…[20][21] Here, we demonstrate a simple and rapid method to speed up evaporation to achieve fast drying by increasing the sample temperature (see Sec. 2).…”

Raman spectroscopy combined with multivariate analysis techniques as a potential tool for semen investigation

“…In addition, numerous efforts based on biophysical, biochemical and spectroscopic methods [7][8][9] have been taken to search for biomarkers for evaluating fertility potential. Spectroscopic methods such as infrared spectroscopy and Raman spectroscopy offer advantages of providing unique molecular and biochemical information by characterizing the spectral properties of biomolecules such as proteins [10] , nucleic acids [11] , lipids [12,13] , and carbohydrates [14] . Recently Gamulin and co-workers have reported the application of utilizing Fourier transform infrared spectroscopy (FTIR) to evaluate spermatozoa and seminal plasma [15] .…”