EnSpectr modern technologies enable accurate analysis of particular microorganism’s parts using an optical microscope and a SERS substrate. Raman-luminescent microscope Rammics M532 is empowered with a digital camera that allows focusing the laser beam on the object quickly and easily; the signal is written down and analyzed by EnSpectr Professional software.
In the picture on the left the spectra of P. aeruginosa (blue) and S. aureus (red) are presented. These bacteria are characterized by pigment presence so they are easily found in Raman spectral range. You can see the individual Raman lines of S.aureus at 959, 1006, 1160, 1284, 1530 cm-1; for P. aeruginosa the peaks are at 675, 1353, 1404, 1605, 1630 cm-1.
Also, Raman spectra of E.coli (red), Proteus mirabilis (green) and Acinetobacter baumannii (blue) were studied. These bacteria do not contain pigments. Their Raman peaks are produced by various individual structures of membranes and near-membranous sites that react to the enhancement of local electromagnetic field of the nanostructured SERS-substrate.
The experiments provide the evidence of the presence of individual and distinctive Raman lines for different bacteria; besides one can observe a spread in Raman lines intensities that can quantitatively reflect the concentrations of different substances found in membranes of different microorganisms. Based on the fact that the accuracy of SERS technology implementation is about 100% it is possible to found a database of microorganisms with electronic “passports” for every element.
Analysis of blood plasma and single DNA molecules
Raman spectra of blood plasma may vary significantly and depends on the person: in the picture, we can see the Raman signal of blood samples of an ordinary donor, a professional sportsman after a hard workout and a pregnant woman suffering from preeclampsia.
EnSpectr instruments allow to study a variety of human biological liquids for diagnosis of diseases and pathologies. It is still an extremely complicated task to detect, recognize and determine a concentration of any pathogenetic bacterium or a virus since most biological liquids are multicomponent mixtures. Special sample preparation has to be done first for this kind of measurement e.g. cascade plasma filtration.
In the picture on the left, we can see Raman spectra of oligonucleotide chains – adenine, cytosine, guanine and thymine. Each of presented nucleotides has a unique Raman spectra.
This information allows developing a new-age DNA sequenator that will scan along the chain and obtain the Raman spectra of each nucleobase separately thus decoding the DNA sequence.
Analysis of fullerenes
Water-soluble fullerene derivatives have intense recognizable SERS spectra which allow reliable detection of their water solutions in concentration of 10-6 – 10-5 М. The covalent bonding of fullerene derivative of dye enables detection of such hybrid molecule structures due to the strong SERS peak of dye in concentration of about 10-8 – 10-5 М.
This fact will mostly lead to widespread use of SERS methods for examination of interaction between the fullerene derivatives and various biological structures.
The decrease of hydroxyapatites (Raman line 963 см-1) intensity along with caries development implicates the decrease of enamel demineralization.
Photoluminescence spectra of healthy and caries teeth. There is strong red-range luminescence in the caries teeth spectra.
Oncology and cancer analysis
A peculiarity of angiomyolipoma spectrum is a number of narrow Raman lines associating with benign tumor fat tissue. Malignant tumor (kidney cancer) spectra are mainly single dome-shaped peak of luminescence. The spectrum of healthy kidney features double peak luminescence (this is unspecific feature of the pathology absence for all studied tissues) regardless of a sample or a point of spectral measurement.