Fluorescence spectroscopy

Introduction
Fluorescence spectroscopy (also known as fluorometry or spectrofluorometry) is a type of electromagnetic spectroscopy which analyzes fluorescence from a sample. It involves using a beam of light, usually ultraviolet light, that excites the electrons in molecules of certain compounds and causes them to emit Light (typically, but not necessarily, visible Light). The devices that measure fluorescence are called fluorometers. Fluorescence spectroscopy is used in, among others, biochemical, medical, and chemical research fields for analyzing organic compounds.

Importance in clinical medicine
Flurescence spectroscopy is an important diagnostic and research tool in medical microbiology field with high sensitivity and specificity. At the present, Fluorescence spectroscopy is being applied in medical microbiology field for various purposes, such as pseudomonad taxonomic purpose at species and genus level, diagnosis of fungal infection and detection of virus. This is due with the high sensitivity and specifity of the fluorescence spectrometry technique. There are many studies which indicate that Fluorescence spectroscopy is promising diagnostic technique with high sensitivity and specificity for microorganisms associated diseases diagnosis with the help of spectroscopic fingerprints. Also, may be applied to understand various pathophysiological steps of various microorganisms. Another medical use of this technique is in low dosage drug formulations containing less than 1 mg per dose unit and biological samples (blood, urine, etc...) containing low concentration of the drugs, because this may require the high sensitivity of spectrofluorimetry, thus the spectrofluorimetric method is of choice for the determination of many hormones, alkaloids and vitamins in formulations and biological fluids.

Advantages and Disadvantages
One of the most important advantage of this technique is due to its high sensitivity and specifity. Another is its fast and rapid diagnosis ability. The main disvantage is that not all compounds fluoresce.

Instrumentation
Two types of instruments exist: Filter fluorometers and spectrofluorometers. Filter fluorometers use filters to isolate the incident light and fluorescent light. Spectrofluorometers use diffraction grating monochromators to isolate the incident light and fluorescent light. Process Both types of intruments use the following scheme: The light from an excitation source passes through a filter or monochromator, and strikes the sample. A proportion of the incident light is absorbed by the sample, and some of the molecules in the sample fluoresce. The fluorescent light is emitted in all directions. Some of this fluorescent light passes through a second filter or monochromator and reaches a detector, which is usually placed at 90° to the incident light beam to minimize the risk of transmitted or reflected incident light reaching the detector.

Conclusion
At present, nearly all the diagnostic techniques and methods used for microorganism's diagnosis have some limitations. There is great need for a diagnostic technique which can overcome limitations and drawbacks of commonly used microbiological techniques and methods. Studies indicate that Fluorescence spectroscopy have great potential to become an excellent and perfect diagnostic technique for microorganisms. Even though, in the future this technique may be automatized which can then process many diagnostic samples at the same time. Also, fiber optic systems may be integrated with this spectroscopic technique to diagnose microorganisms in vivo.