Transcript Presentation

Department of Dermatology and Allergy
Charité - Universitätsmedizin Berlin
Overview of noninvasive methods for
determination of carotenoid concentrations in
mammalian skin
M.E. Darvin, J. Lademann
Charité-Universitätsmedizin Berlin, Center of Experimental and Applied Cutaneous
Physiology, Department of Dermatology, Venerology and Allergology, Berlin, Germany
Carotenoids are known to be powerful antioxidants acting
effectively against reactive oxygen species. The ability of
carotenoids to quench oxygen radicals (including singlet
oxygen) is related to the conjugated carbon double-bond
system, and maximum protection is provided by those having
nine or more double bonds.
Most prominent carotenoids being accumulated in human skin
are beta-carotene (9 double bonds) and lycopene (11 double
bonds) and their isomers.
High-performance liquid chromatography (HPLC) is a widely
used „gold standard“ method for determination of carotenoids.
This method is highly invasive, time-consuming and expansive.
Moreover, the oxidation of carotenoids during the sample
preparation cannot be excluded.
For analyzing the kinetics of carotenoids in the skin
noninvasive methods are irreplaceable and should be
performed.
Carotenoids cannot be detected in the skin using fluorescence
analyses because their fluorescence efficiency is very low (104-10-5).
Optical methods for noninvasive determination
of carotenoids in mammalian skin:
1. resonance Raman spectroscopy
2. Raman microscopy
3. reflection spectroscopy
4. skin color measurements
Resonance Raman spectroscopy
1 – Ar+ laser; 2 – lens system; 3 – filter (488nm/514.5nm);
4, 9 – optical fiber; 5 – excitation channel; 6 – optical imaging system;
7 – skin; 8 – receiving channel; 10 – spectrometer; 11 – CCD;
2 – computer; 13 – photo detector
Darvin et al. J. Biomed. Opt. 18(6), 061230, 2013
Fiber optic-based
resonance Raman spectroscopy
for endoscopic measurement of carotenoid
oxidative breakdown in living tissue
Excitation wavelength 488 nm
Brandon et al. Cancer Prev. Res. 3(4): 529-538, 2010
Resonance Raman spectroscopy
Advantages:
- measurement quickness
- high sensitivity
- selectivity between beta-carotene and lycopene
- increasing the measurement accuracy using photobleaching
effect
- measurement stability
- transportability
Limitations:
- influence of other carotenoids
- reabsorption of Raman signal at 527.2 nm by lycopene
Darvin et al. J. Biomed. Opt. 18(6), 061230, 2013
Raman microscopy
1 – laser (NIR or VIS); 2 – short-pass filter; 3 – objective; 4 – mirrors;
5 – skin; 6 – laser rejection filter; 7 – lens; 8 – optical fiber; 9 – spectrometer;
10 – CCD; 11 – computer
Darvin et al. J. Biomed. Opt. 18(6), 061230, 2013
Raman microscopy
Advantages:
- measurement of axial distribution of carotenoids in the skin
Limitations:
- low and very low carotenoid concentrations are not detectable
under non-resonant excitation
- bulky size
- high price
Darvin et al. J. Biomed. Opt. 18(6), 061230, 2013
Reflectance spectroscopy
1 – LED (440 - 490 nm); 2 – skin; 3 – focusing system;
4 – replicated holographic grating spectrometer; 5 – Bluetooth
Darvin et al. J. Biophotonics 5(7): 550-558, 2012
„Scanner“ in use
Reflectance spectroscopy
Advantages:
- low price
- measurement stability
- compact size (easy to transport)
- independence from electric mains
Limitations:
- low carotenoid concentrations are not detectable
- could be applied only on thenal and plantar skin areas where the
epidermis is thick enough and influence of melanin and blood
chromophores is less pronounced
Darvin et al. J. Biophotonics 5(7): 550-558, 2012
Darvin et al. J. Biomed. Opt. 18(6), 061230, 2013
Skin color measurements
b*-value characterizing yellowness
of the skin serves as a measuring
parameter for epidermal carotenoids
Bersha. Master Thesis, University of Eastern Finland, 21 June 2010
b*-value was found to correlate
with concentration of carotenoids
in human epidermis
Alaluf et al. Journal of Nutrition 132(3), 399-403, 2002
Skin color measurements
Advantages:
- low price
- compact size (easy to transport)
- independence from electric mains
Limitations:
- low carotenoid concentrations are not detectable
- could be applied only on thenal and plantar skin areas where the
epidermis is thick enough and influence of melanin and blood
chromophores is less pronounced
- measurement stability is not high enough
Darvin et al. J. Biomed. Opt. 18(6), 061230, 2013
Conclusions
Comparison of optical methods
for measurement of carotenoids in human skin
Resonance Raman
spectroscopy
Raman microscopy
Skin color measurements
Reflection
spectroscopy
Size/weight
compact to bulky
bulky
compact
compact
Transportability
yes
no
yes
yes
Price
middle to high
high
low
low to middle
3 to 90 sec
around 60 seconds
around 30 sec
around 60 sec
better than 10%
better than 10%
no data
better than 10%
laser, LED
laser
lamp, LED
LED
up to 200 µm
up to 40 µm
up to 200 µm
up to 200 µm
Selectivity
to lycopene
no
no
no
Electric mains
needed
needed
don’t needed
don’t needed
Personal rating
1
3
4
2
Measurement time
Measurement stability
Light source
Measurement depth
Thank you for your attention