Does anyone know the plasmonic resonant frequencies for the following metals: Fe, Al, Mg, Ti?

Anming Hu 41.77

This parameter is critical to determine light coupling efficiencies.

 Serge Grabtchak · 60.35 · 96.9 · University of Prince Edward Island

Mg=10.6 eV
Al=15.3 eV
(Kittel, Solid State Physics, any latest editions)

May 24, 2014

 Christin David · 18.15 · 43.35 · Spanish National Research Council

You can calculate wp for metals from the electron density given in e.g. Ashcroft and Mermin (Solid State Physics), see also link given for a web source. You simply find wp from wp^2= e^2/m_e n.

• http://hyperphysics.phy-astr.gsu.edu/hbase/tables/fermi.html#c2

• http://hyperphysics.phy-astr.gsu.edu/hbase/organic/gencode.html#c1

Fermi Energies, Solid Properties

Free Electron Number Densities

Element	N/V x10^28/m^3
Cu	8.47
Ag	5.86
Au	5.90
Be	24.7
Mg	8.61
Ca	4.61
Sr	3.55
Ba	3.15
Nb	5.56
Fe	17.0
Mn*	16.5
Zn	13.2
Cd	9.27
Hg**	8.65
Al	18.1
Ga	15.4
In	11.5
Sn	14.8
Pb	13.2

*alpha form **at 78K

Numerical data from N. W. Ashcroft and N. D. Mermin,

http://hyperphysics.phy-astr.gsu.edu/hbase/tables/ttab.html#c1

ndex of Refraction

Material	Index
Vacuum	1.00000
Air at STP	1.00029
Ice	1.31
Water at 20 C	1.33
Acetone	1.36
Ethyl alcohol	1.36
Sugar solution(30%)	1.38
Fluorite	1.433
Fused quartz	1.46
Glycerine	1.473
Sugar solution (80%)	1.49
Typical crown glass	1.52
Crown glasses	1.52-1.62
Spectacle crown, C-1	1.523
Sodium chloride	1.54
Polystyrene	1.55-1.59
Carbon disulfide	1.63
Flint glasses	1.57-1.75
Heavy flint glass	1.65
Extra dense flint, EDF-3	1.7200
Methylene iodide	1.74
Sapphire	1.77
Rare earth flint	1.7-1.84
Lanthanum flint	1.82-1.98
Arsenic trisulfide glass	2.04
Diamond	2.417

Optical Glasses

The most common types of glasses used in optics are crown glasses and flint glasses, designations based on their dispersions. Flint glasses contain lead. These designations are further subdivided by composition and have letter designations and number designations called "glass numbers".

Example data for glasses: Glass Glass Number Density gm/cm^3 Borosilicate BK7 517642 2.51 Crown K5 522595 2.59 Dense barium crown SK4 618551 3.57 Dense flint SF6 805254 5.18

Common crown glasses have indices of refraction around 1.5-1.6, while extra dense flint glass may have an index as high as 1.75 . Lenses of crown and flint glasses are often used in multi-component lenses because of their complementary properties. For example, a strong positive crown lens with its low dispersion may be used in a doublet with a weaker negative lens of flint glass (high dispersion) to correct for chromatic aberration.

The design of multi-component lenses requires very exacting specifications for the glasses used. Professional optics books have detailed tables of glasses with their glass numbers, densities, softening temperatures, etc. For example, Table 11.6a in Waynant & Ediger.

Does anyone have experience with photonic biosensors for cancer biomarkers?

Peter Rolfe 46.30 OBH Ltd

Cancer biomarkers are being sought urgently to allow earlier detection of cancers such as prostate, pancreas, breast and lung, where current technologies (PSA, mammography, etc) are failing in many patients to provide sufficiently timely detection to allow successful treatment. Biosensors, based on photonics, plasmonics, opto-acoustics, electrochemistry, impedance spectrometry, may provide convenient, cheap, safe, and reliable screening if, and only if, the right biomarkers can be discovered. So, do we have sufficiently proven cancer biomarkers yet? How are the miRNA biomarkers performing at present? What about heat shock proteins? Are there other serious contenders, such as volatile organic compounds in breath, or urine headspace? Do we have enough effort looking for better biomarkers and are biosensors being developed to at least test them in realistic ways?

 Serge Grabtchak · 60.35 · 96.9 · University of Prince Edward Island

Due to the nature of the question(s), I think it would be very useful if somebody can also provide references to comprehensive critical or topical reviews pertinent to the subject.

1 / 0 · Jun 7, 2014

 Aleksandr Aleksandrovsky · 38.37 · 74.52 · Russian Academy of Sciences

It seems that experts in biomarkers are still out of RG.....Peter, do you mean suchbiosensors as hematoporphirine which produce characteristic luminescence?

1 / 0 · Jun 7, 2014

 Serge Grabtchak · 60.35 · 96.9 · University of Prince Edward Island

Personally, I've found very informative the following review:
https://www.researchgate.net/publication/262862926_Review_of_Animal_Models_of_Prostate_Cancer_Bone_Metastasis?ev=prf_pub
The fact that we use animal models and probably continue using them for quite a while speaks for itself. I have to add that this is cancer models& biomarkers review and NOT biophotonics applications.

1 / 0 · Jun 7, 2014

Peter Rolfe

Thanks for the reference, Serge, which is helpful and thanks, Aleksandr for your comments; maybe RG is not attracting the cancer biomarker colleagues yet.

My real concern is that biosensors for cancer biomarkers are being developed, at a substantial cost, without there necessarily being solid proof that such biomarkers have the discriminant performance to allow accurate diagnoses to be made. If good cancer biomarkers do exist then there is a strong case for developing low-cost, convenient, point-of-care biosensor systems. These would then allow quick screening to be carried out in the Doctor's office, or even with, say, a Raman test strip interfaced with a smart phone. Blood, urine or saliva are the samples of choice in this kind of scenario, although breath analysis is showing promise and can also be approached with photonic systems.

From my perspective the work on microRNAs and on heat shock proteins are perhaps the current front runners to give us useful, verified, cancer biomarkers.

1 / 0 · Jun 7, 2014

Serge Grabtchak ·

In my opinion, for developing any generic photonics-based cancer biosensor the best of two (at least) worlds has to be combined: optics and molecular biology. Hence, it would require joint efforts of two or more scientists with strong expertise in corresponding areas. (A single person equally proficient in both is an an exception from the rule rather than a standard, unfortunately.) Thus, saying "optics" may not resonate well in the biomarkers community in the same way as asking a photonics researcher about the best biomarkers for a particular case. Of course, there is an overlap in communities driving strong research in the area of biosensors! I also know however, that there are experts in cancer biomarkers on RG...

Please get me right. Being educated and knowledgeable in a complementary field is a must but it doesn't makes one an expert capable of advancing it. Perhaps, I'm changing slightly the subject of the question but I've been in these shoes:)

1 / 0 · Jun 7, 2014

 Peter Rolfe ·

Yes I agree, Serge, multidisciplinary grouping is essential for the effective development of technologies that are appropriate for the intended biomedical purpose. In the biosensor sector it is becoming increasingly important, as the target molecule becomes more complex and number of potentially important molecules increases.

In the early days of sensor research for biomedical applications there were only a few targets, oxygen, pH, carbon dioxide, glucose, plus one or two other ions, such as potassium, chloride, sodium and calcium. The importance of each of these molecules was uncontentious. Now there is no short list, only a very large and growing number of complex biological compounds that are of interest in biomedical research and which might be of value in clinical medicine. Photonics-based sensors are also being produced at an increasing rate for more and more esoteric targets, often without there being a clear need, at least for clinical purposes.

Although I have kicked off this question about cancer biomarkers, it has a broader relevance in biology and medicine, including in inflammatory diseases, neurological diseases, and even in food safety and environmental monitoring. No doubt photonics will continue to play its part in the teams that are rightly being assembled to bring relevance to the efforts.