Aleksandra Jaworska

Simultaneous intracellular redox potential and pH measurements in live cells using SERS nanosensors

Intracellular redox potential is a highly regulated cellular characteristic and is critically involved in maintaining cellular health and function. The dysregulation of redox potential can result in the initiation and progression of numerous diseases. Redox potential is determined by the balance of oxidants and reductants in the cell and also by pH. For this reason a technique for quantitative measurement of intracellular redox potential and pH is highly desirable. In this paper we demonstrate how surface enhanced Raman scattering (SERS) nanosensors can be used for multiplexed measurement of both pH and redox potential in live single cells.

Raman microscopy as a novel tool to detect endothelial dysfunction

Raman microscopy, a label-free method with high spatial resolution, shows growing potential in various fields of medical diagnostics. Several proof-of-concept studies related to the application of Raman microscopy to detect endothelial dysfunction are summarized in this work. Both ex vivo measurements of the tissues in the murine models of endothelial pathologies, as well as in vitro investigations of the cell cultures in the context of cellular transport, drug action and inflammation processes are discussed. The future directions in application of Raman spectroscopy-based methods in such studies are also described.

A comparison between adsorption mechanism of tricyclic antidepressants on silver nanoparticles and binding modes on receptors. Surface-enhanced Raman spectroscopy studies.

A series of the tricyclic antidepressants known as a surface-active drugs, has been used as a model for an evaluation of their adsorption mechanism on the metal substrate and its relationship to pharmacological action of the chosen drugs. In these studies, six antidepressants were adsorbed on the metal substrate in a form of silver nanoparticles (ca. 30 nm in diameter) and afterwards their interactions have been examined in terms of surface-enhanced Raman spectroscopy (SERS). An analysis of SERS spectra has revealed that the dibenzopine moiety is a primary site of the adsorption with some differences in the orientation with respect to the metal among the studied molecules. The spectral changes due to the interactions with the silver particles also appear in the region typical for vibrations of the side chain. These observations are consistent with a model, in which the tricyclic ring is docked in the outer vestibule of biogenic amine transporters whereas the dimethyl-aminopropyl side chain is pointed to the substrate binding site. This work sheds a light on a potential of SERS technique in predicting a key functional group responsible for drug action.

SERS-based monitoring of the intracellular pH in endothelial cells

The intracellular pH plays an important role in various cellular processes. In this work, we describe a method for monitoring of the intracellular pH in endothelial cells by using surface enhanced Raman spectroscopy (SERS) and 4-mercaptobenzoic acid (MBA) anchored to gold nanoparticles as pH-sensitive probes. Using the Raman microimaging technique, we analysed changes in intracellular pH induced by buffers with acid or alkaline pH, as well as in endothelial inflammation induced by tumour necrosis factor-α (TNFα). The targeted nanosensor enabled spatial pH measurements revealing distinct changes of the intracellular pH in endosomal compartments of the endothelium. Altogether, SERS-based analysis of intracellular pH proves to be a promising technique for a better understanding of intracellular pH regulation in various subcellular compartments.

An impact of the ring substitution in nicorandil on its adsorption on silver nanoparticles. Surface-enhanced Raman spectroscopy studies.

The substituent effect on structure and surface activity of biologically active nicorandil was investigated by means of surface-enhanced Raman spectroscopy (SERS). Vibrational characterization was a basis for investigation of the adsorption profile of nicorandil and 1-methylnicorandil on silver nanoparticles. An assignment of SERS bands was performed by the comparison of the Raman spectra of both compounds in the solid state and in solutions, complemented by DFT calculations. Even though the nitro group was found to be the most attractive to the silver surface, the strong impact of the methyl substituent changed this preferable adsorption mechanism in 1-methylnicorandil. Protonation of the nitrogen atom in the pyridinium ring was also found to have an impact on absorption mechanism.

(-)-R-mevalonolactone studied by ROA and SERS spectroscopy.

Here we present for the first time the experimental and theoretical (DFT/B3LYP/6-311++G**) Raman optical activity (ROA) spectra of (-)-R-mevalonic acid as the δ-lactone form in neat liquid and in the aqueous solution. Quantum chemical calculations show the conformational diversity of (-)-R-mevalonolactone originated from small energy differences between the various conformation of the six-membered ring and the arrangement of the hydroxyl group. According to calculations, the investigated compound takes predominantly the chair conformation with the hydroxyl group in axial position, but the contribution of the other chair and boat conformers in the equilibrium at room temperature is not negligible. Additionally, we present normal Raman and the surface enhanced Raman (SERS) spectra of (-)-R-mevalonolactone adsorbed on the colloidal silver.

The uptake of gold nanoparticles by endothelial cells studied by surface-enhanced Raman spectroscopy

BACKGROUND: The SERS imaging of the intracellular microenvironment may provide valuable insight into the chemical composition and distribution of a cellular biological system. OBJECTIVE: In order to develop the SERS-based methodology for the cellular uptake of gold nanoparticles conjugated with the fluorescent dye (rhodamine 6G) was investigated in endothelial EA. hy. 926 cell line. A few timeframes were chosen to assess an effect of particles accessibility on their distribution in the cells. METHODS: Confocal Raman imaging was employed to evaluate the distribution of SERS response within the cells incubated with labelled Au nanoparticles. A cluster K-means analysis was used in the construction of SERS maps. RESULTS: The cellular uptake of the gold nanoparticles labelled with rhodamine 6G occured up to 12 h of the incubation. Along with the SERS signal of the dye, the bands originating mainly from aromatic amino acid residues and nucleobases were found in the spectra. CONCLUSIONS: The optimal accumulation of label-nanoparticles is found for up to 6 h incubation of the particles, confocal SERS imaging of labelled endothelial cells can serve as a powerful tool for further examination of the physiological and pathological changes in endothelial intracellular microenvironment.