Applications of Raman spectroscopy to skin research

Raman Spectroscopy: Incorporating the Chemical Dimension into Dermatological Diagnosis

Raman spectroscopy provides chemical analysis of tissue in vivo. By measuring the inelastic interactions of light with matter, Raman spectroscopy can determine the chemical composition of a sample. Diseases that are visually difficult to visually distinguish can be delineated based on differences in chemical composition of the affected tissue. Raman spectroscopy has successfully found spectroscopic signatures for skin cancers and differentiated those of benign skin growths. With current and on-going advances in optics and computing, inexpensive and effective Raman systems may soon be available for clinical use. Raman spectroscopy provides direct analyses of skin lesions, thereby improving both disease diagnosis and management.

Application of Raman spectroscopy in Andrology: non-invasive analysis of tissue and single cell

As a fast, label-free and non-invasive detection method, Raman spectroscopy has been widely used for the interrogation of biological tissues, any alterations of molecular structure and chemical components during pathological processes would be identified and revealed via the differences on Raman spectrum. In clinics, the Raman spectroscopy has great potentials to provide real-time scanning of living tissues and fast diagnosis of diseases, just like discrimination of various carcinomas. A portable Raman spectroscopy which combined Raman system with an optical fiber probe has also been developed and proved to be able to provide intraoperative assistance in both human study and animal models. In Andrology, interests in Raman spectroscopy had just emerged. In this review, we summarized the progress about the utility of Raman spectroscopy in Andrology, the literatures were gathered from PubMed and Ovid database using MeSH terms associated with prostate, testis, seminal plasma and single sperm cell. We also highlighted the serious challenges as to the final clinical application of Raman technique. In conclusion, research in Raman spectroscopy may herald a new era for Andrology.

Percutaneous penetration modifiers and formulation effects: thermal and spectral analyses

The study investigated the formulation effects of laurocapram and iminosulfurane derived penetration modifiers on human stratum corneum using thermal and spectral analyses. Firstly, formulations of penetration modifiers were assessed as enhancers/retardants using the model permeant, diethyl-m-toluamide followed by investigation of their mechanisms of action using differential scanning calorimetry (DSC) and attenuated total reflectance Fourier-transform infra-red spectroscopy. The penetration modifiers investigated were laurocapram, 3-dodecanoyloxazolidin-2-one (N-0915), S,S-dimethyl-N-(4-bromobenzoyl) iminosulfurane (DMBIS), S,S-dimethyl-N-(2-methoxycarbonylbenzenesulfonyl) iminosulfurane (DMMCBI) and tert-butyl 1-dodecyl-2-oxoazepan-3-yl-carbamate (TBDOC) that were formulated in either water, propylene glycol (PG), ethanol or polyethylene glycol 400 (PEG 400). The results explain the mechanism for the first time why an enhancer can become a retardant or vice versa depending upon the vehicle in which it is applied to the skin. DSC indicated that penetration modifier formulations enhanced permeation of active mainly by disruption and fluidization of the stratum corneum lipid bilayers while IR data indicated characteristic blue shifts with decreases in peak intensity. On the other hand, DSC of penetration modifier formulations showing retardation depicted elevated T (m2) with a strengthening of lipid-protein complex while IR results indicated formation of multiple peaks around 1,738 cm(-1) transition in stratum corneum spectra suggesting retardation may be caused by organization of SC lipids by increased H-bonding.

Vibrational spectroscopy for molecular characterisation and diagnosis of benign, premalignant and malignant skin tumours

Understanding the molecular, cellular and tissue changes that occur during skin carcinogenesis is central to cancer research in dermatology. The translational aspects of this field--the development of clinical applications in dermatology from the laboratory findings--aim at improving clinical diagnosis, monitoring and treatment of skin cancer. Vibrational spectroscopy, both infrared (IR) and Raman spectroscopy, would be helpful in achieving those goals, since it has been shown to have potential in characterising and discriminating tumour and dysplastic tissue from normal tissue. Clinically differential diagnosis of skin tumours is often difficult and a histopathologic analysis of skin biopsies remains the standard for diagnostic confirmation. We review and update the literature on the subject, demonstrating that the IR and Raman spectra of skin tissues provide valid and useful diagnostic information about a number of skin tumours. We also include a survey of introduced sampling methods for IR and Raman spectroscopy in dermatology, and additionally describe the differences between microscopic, macroscopic and fibreoptic diagnosis of skin cancer. Although in its early stages, we remain optimistic that vibrational spectroscopy has the potential to be fully accepted as a rapid screening tool with sufficient sensitivity and specificity for non-destructive in vitro, ex vivo and in vivo analyses by the dermatological community. Further progress toward molecular characterisation of skin cancer by vibrational spectroscopy would have important research and clinical benefits in dermatology.

Fiber optic near-infrared Raman spectroscopy for clinical noninvasive determination of water content in diseased skin and assessment of cutaneous edema

Currently, measuring Raman spectra of tissues of living patients online and in real time, collecting the spectra in a very short measurement time, and allowing diagnosis immediately after the spectrum is recorded from any body region, are specific advantages that fiber optic near-infrared Raman spectroscopy (NIR RS) might represent for in vivo clinical applications in dermatology. We discuss various methodological aspects and state of the art of fiber optic NIR RS in clinical and experimental dermatology to outline its present advantages and disadvantages for measuring skin in vivo, particularly its water content. Fiber optic NIR Fourier transform (FT) RS has been introduced to dermatological diagnostics to obtain information regarding the molecular composition of the skin up to several hundred micrometers below the skin surface in a relatively fast nondestructive manner. This has been especially important for probing for in vivo assessment of cutaneous (intradermal) edema in patients patch test reactions. Fiber optic NIR FT Raman spectrometers still require further technological developments and optimization, extremely accurate water concentration determination and its intensity calculation in skin tissue, and for clinical applications, a reduction of measurement time and their size. Another promising option could be the possibility of applying mobile and compact fiber optic charge-coupled device (CCD)-based equipment in clinical dermatology.

Skin imaging: is it clinically useful?

Non-invasive skin imaging techniques have proliferated over the last decade. Whilst most have a research role, some are routinely used in dermatology clinics. Of these, the skin surface microscope (dermatoscope), a diagnostic aid for pigmented lesions, has had most clinical impact. Such devices, when linked to a videomicroscope for computer analysis, have been dubbed as 'mole scanners'. Mole scanners are increasingly available on a commercial basis even though computer diagnosis of pigmented lesions is currently no better than diagnosis by human experts. Meanwhile, other imaging techniques, such as high-resolution ultrasonography, spectroscopy and optical coherence tomography, may yet find a role in diagnosis and disease monitoring.

Water and protein structure in photoaged and chronically aged skin

Changes in the structural proteins and hydration during aging is responsible for altered skin morphologic and mechanical properties manifested as wrinkling, sagging, loss of elasticity, or apparent dryness. To gain insight into the age-related alterations in protein conformation and water structure, we obtained Raman spectra from the sun-protected buttock skin representing chronologic aging and the sun-exposed forearm skin representing combined effects of photoaging and chronologic aging. Ten aged individuals (five men, five women; age range 74-87) and 10 control young individuals (five men, five women; age range 22-29) entered the study. In the photoaged forearm skin the positions of protein-specific amide I, amide III, and CH stretching bands were shifted, suggesting increased protein folding. In contrast, major changes were seen only in the amide I peak in chronologically aged skin. The intensity of the 3250 cm(-1) OH stretching band was increased in photoaged skin (but not in chronologically aged skin) indicating an increased water content. R(v) representation of the low-frequency region of Raman spectra was applied to determine water structure. In the young skin and chronologically aged skin water was mostly present in the bound form. In the photoaged skin, however, an increase in intensity at 180 cm(-1) was noted, which reflects an increase in the not-protein bound water (tetrahedron water clusters). In conclusion, it seems that proteins in the photoaged skin are more compact and interact with water to limited degree. Impairment in protein hydration may add to the understanding of ultrastructural, mechanical, and biochemical changes in structural proteins in the aged skin.