@article {1614,
	title = {Facile size-controlled synthesis of fucoidan-coated gold nanoparticles and cooperative anticancer effect with doxorubicin},
	journal = {Journal of Materials Chemistry B},
	year = {2017},
	author = {Jang, H and et al.}
}
@article {1611,
	title = {A force for Egyptian science},
	journal = {Proceedings of the National Academy of Sciences},
	year = {2017},
	author = {El-Sayed, Mostafa A. and Zewail, Ahmed}
}
@article {1076,
	title = {Following Charge Separation on the Nanoscale in Cu(2)O-Au Nanoframe Hollow Nanoparticles},
	journal = {Nano Letters},
	volume = {11},
	number = {8},
	year = {2011},
	note = {A. Mahmoud, Mahmoud Qian, Wei El-Sayed, Mostafa A.},
	month = {Aug},
	pages = {3285-3289},
	abstract = {Cu(2)O-Au nanoframes with different nanolayer thicknesses of Cu(2)O were prepared, and their photocatalytic properties in aqueous solutions were studied. Cu(2)O semiconductor excitation leads to electron-hole separation. In aqueous solution, the hole is known to oxidize water to produce hydroxyl radicals whose concentration (and that of the holes) can be monitored by the rate of the degradation of dissolved methylene blue dye. The exciton lifetime is determined by femtosecond techniques and is determined by electron-hole recombination which depends on the rates of a number of competing processes such as, electron or hole transfer to an acceptor such as a gold nanoframe and/or the electron or hole trapping processes at the Cu(2)O-Au nanoframe interface. We measured the exciton lifetime as a function of the average Cu(2)O-Au layer separation. A good correlation was found between the rate of the photocatalytic degradation of methylene blue and the exciton lifetime. The exciton lifetime is found to increase as the Cu(2)O thickness is increased. This leads to an increase in the electron-hole separation time and thus an increase in the hole (and so the hydroxyl radical) concentration leading to an observed enhanced rate of the dye degradation.},
	isbn = {1530-6984},
	doi = {10.1021/nl201642r},
	author = {Mahmoud, M A and Qian, Wei and El-Sayed, Mostafa A}
}
@inbook {816,
	title = {Fluorescent Quenching Gold Nanoparticles: Potential Biomedical Applications},
	booktitle = {Metal Enhanced Fluorescence},
	year = {2010},
	month = {06/2010},
	pages = {573-599},
	publisher = {Wiley Online Library},
	organization = {Wiley Online Library},
	chapter = {20},
	keywords = {biomedical applications, fluorescent quenching, gold nanoparticles, Raman spectroscopy, surface plasmon resonance},
	doi = {10.1002/9780470642795.ch20},
	url = {http://dx.doi.org/10.1002/9780470642795.ch20},
	author = {Huang, Xiaohua and El Sayed, I.H. and El-Sayed, Mostafa A}
}
@article {1161,
	title = {Femtosecond excitation dynamics in gold nanospheres and nanorods},
	journal = {Physical Review B},
	volume = {72},
	number = {23},
	year = {2005},
	note = {Varnavski, OP Goodson, T Mohamed, MB El-Sayed, MA},
	month = {Dec},
	abstract = {Femtosecond visible photoluminescence is detected from gold nanoparticles using time-resolved fluorescence upconversion spectroscopy. We directly compared this fast luminescence from gold nanospheres (subset of 25 nm) with that obtained from nanorods (subset of 15x40 nm, subset of 15x27 nm) under vis (3.02 eV) and UV(4.65 eV) excitation. A fast (similar to 50 fs) decay was obtained for the nanoparticles and the emission was depolarized. Degenerate femtosecond pump-probe experiments in the low excitation intensity regime demonstrated much slower electron thermalization and/or equilibration dynamics on the time scale of a few hundred femtoseconds. These features strongly indicate a d-hole-conduction electron recombination process as the origin of this photoluminescence. A direct comparison of the fast emission spectra from nanorods and nanospheres is used to discuss the emission enhancement mechanism. These results suggest that the classical local field enhancement theory describes quantitatively well many of the emission features of nanorods with respect to those for nanospheres without invoking more complex models.},
	isbn = {1098-0121},
	doi = {10.1103/PhysRevB.72.235405},
	author = {Varnavski, O. P. and Goodson, T. and Mohamed, MB and El-Sayed, Mostafa A}
}
@article {1166,
	title = {FTIR study of the mode of binding of the reactants on the Pd nanoparticle surface during the catalysis of the Suzuki reaction},
	journal = {Journal of Physical Chemistry B},
	volume = {109},
	number = {10},
	year = {2005},
	note = {Narayanan, R El-Sayed, MA},
	month = {Mar},
	pages = {4357-4360},
	abstract = {In the Suzuki reaction between phenylboronic acid and iodobenzene catalyzed by palladium nanoparticles, our previous studies suggested that the phenylboronic acid adsorbs on the nanoparticle surface and then interacts with the iodobenzene that is present in solution. In the present study, FTIR is used to examine the change in the vibrational frequencies of phenylboronic acid in films with and without the addition of palladium nanoparticles. The large change in the B-O stretching frequency of phenylboronic acid from 1348 to 1376 cm(-1) in the presence of sodium acetate and palladium nanoparticles strongly suggests that the mode of binding of phenylboronic acid to the Pd nanoparticle surface involves a B-O-Pd type of bonding. Shifts in the B-C stretching mode and the out-of-plane phenyl C-C ring deformation bands associated with phenylboronic acid provide additional confirmations of the binding process. It is also shown that the phenylboronic acid needs to be in the deprotonated form in the presence of sodium acetate (phenylboronate anion) to bind to the palladium nanoparticle surface. No changes in the characteristic bands of iodobenzene were observed in films made in the presence of the palladium nanoparticles. The FTIR studies provide proof of the mode of binding that occurs in the nanoparticle Surface for the first time and also confirms the mechanism of the Suzuki reaction that we proposed previously.},
	isbn = {1520-6106},
	doi = {10.1021/jp044659t},
	author = {Narayanan, Radha and El-Sayed, Mostafa A}
}
@article {846,
	title = {FTIR study of the adsorption of the capping material to different platinum nanoparticle shapes},
	journal = {The Journal of Physical Chemistry A},
	volume = {107},
	year = {2003},
	pages = {8371-8375},
	publisher = {ACS Publications},
	abstract = {FTIR spectroscopy has been used to study the binding geometry of polyacrylate capping material on cubic and tetrahedral platinum nanoparticles. It is proposed that the capping material forms an ester-like linkage to the Pt surface on the tetrahedral shapes through the hydroxyl oxygen atom of the carboxylic acid moiety of the polyacrylate (linear adsorption configuration). On the cubic particle the adsorption is through both of the carboxylic oxygen atoms (bridge adsorption configuration). These shaped nanoparticles are synthesized by changing the starting ratio of the capping material to that of the Pt salt. The results are discussed in terms of the effect of changing the concentration of the polyacrylate capping material on the mode of bonding to the surface. This might be a factor in determining the final shape formed.},
	isbn = {1089-5639},
	doi = {10.1021/jp0300694},
	url = {http://dx.doi.org/10.1021/jp0300694},
	author = {Petroski, J. M. and El-Sayed, Mostafa A}
}
@article {851,
	title = {Fourier transform infrared study of the effect of different cations on bacteriorhodopsin protein thermal stability},
	journal = {Biophysical journal},
	volume = {82},
	year = {2002},
	pages = {1598-1606},
	publisher = {Elsevier},
	abstract = {The effect of divalent ion binding to deionized bacteriorhodopsin (dI-bR) on the thermal transitions of the protein secondary structure have been studied by using temperature-dependent Fourier transform infrared (FT-IR) spectroscopy. The native metal ions in bR, Ca2+, and Mg2+, which we studied previously, are compared with Mn2+, Hg2+, and a large, synthesized divalent organic cation, ((Et)3N)2Bu2+. It was found that in all cases of ion regeneration, there is a pre-melting, reversible conformational transition in which the amide frequency shifts from 1665 to 1652cm-1. This always occurs at \~{}80{\textdegree}C, independent of which cation is used for the regeneration. The irreversible thermal transition (melting), monitored by the appearance of the band at 1623cm-1, is found to occur at a lower temperature than that for the native bR but higher than that for acid blue bR in all cases. However, the temperature for this transition is dependent on the identity of the cation. Furthermore, it is shown that the mechanism of melting of the organic cation regenerated bR is different than for the metal cations, suggesting a difference in the type of binding to the protein (either to different sites or different binding to the same site). These results are used to propose specific direct binding mechanisms of the ions to the protein of deionized bR.},
	isbn = {0006-3495},
	doi = {10.1016/S0006-3495(02)75511-2},
	url = {http://dx.doi.org/10.1016/S0006-3495(02)75511-2},
	author = {Heyes, C D and Wang, Jianping and Sanii, L. S. and El-Sayed, Mostafa A}
}
@article {1212,
	title = {Formation of quantum-dot quantum-well heteronanostructures with large lattice mismatch: ZnS/CdS/ZnS},
	journal = {Journal of Chemical Physics},
	volume = {114},
	number = {4},
	year = {2001},
	note = {Little, RB El-Sayed, MA Bryant, GW Burke, S},
	month = {Jan},
	pages = {1813-1822},
	abstract = {Two-dimensional heterostructures have been exploited extensively in the synthesis of optoelectronic devices. Structures with small lattice mismatch can be synthesized readily. Large lattice mismatch in II-VI film heterostructures makes synthesis of devices with these materials more difficult. However, these large mismatch heterostructures usually have useful optical properties. One such heterostructure is the ZnS/CdS system with a large exciton binding energy and a large band gap useful for blue-green emitting devices. In this work, small II-VI nanoparticles are studied. We show that II-VI heterostructures can be made in quantum dots, despite the large bulk lattice mismatch. Two well-known techniques are combined to synthesize first very small ZnS and CdS seed nanoparticles and then do nanoepitaxy on them to produce ZnS/CdS core/shell quantum-dot quantum-well heteronanostructures. These structures are characterized by UV visible absorbance. Measured spectra are compared with electronic level structures calculated for the fabricated heteronanostructures with a tight-binding model. The consistency of the observed spectra with the predicted transitions indicates that the desired core/shell and core/shell/clad structures were grown. The metastability of the ZnS/CdS/ZnS heteronanostructures is attributed to low-temperature construction and small crystal size (<3 nm). The small particle size should produce large surface forces and ZnS core contraction. Also, the small particle size should accommodate strain, as a result of the ZnS/CdS interfacial curvature, which is not possible for planar systems. Furthermore, this new structure is kinetically stabilized against alloying by the large size difference between the Cd2+ ion and Zn2+ ions. We suggest that all of these factors contribute to the formation of quantum-dot quantum-well ZnS/CdS/ZnS heteronanostructures. (C) 2001 American Institute of Physics.},
	isbn = {0021-9606},
	doi = {10.1063/1.1333758},
	author = {Little, Reginald and El-Sayed, Mostafa A and Bryant, G. W. and Burke, S.}
}
@article {1233,
	title = {Femtosecond dynamics of a simple merocyanine dye: Does deprotonation compete with isomerization?},
	journal = {Journal of the American Chemical Society},
	volume = {122},
	number = {28},
	year = {2000},
	note = {Burda, C Abdel-Kader, MH Link, S El-Sayed, MA},
	month = {Jul},
	pages = {6720-6726},
	abstract = {The primary photochemistry of the trans isomer of a simple merocyanine dye of the stilbazolium betaine type 1-methyl-4-(4{\textquoteright}-hydroxytyryl)pyridinium betaine (M-trans) and its conjugate acid MHtrans+ in aqueous solution is studied by femtosecond time-resolved pump probe spectroscopy. The measured rate of the primary photodynamics is determined to be k = 1.1 x 10(12) s(-1) for M-trans at pH 10 and 0.8 x 10(12) s(-1) for MHtrans+ at pH 6. This was assigned to either conformational changes or a simple vibrational relaxation before the actual isomerization takes place. Wavelength excitation studies give support for the former assignment. These results an discussed in terms of the recent results found for the primary processes of retinal in bacteriorhodopsin. Time-resolved transient measurements show that no excited-state deprotonation of MHtrans+ occurs in aqueous solutions at pH 6 or pH 0, suggesting that the deprotonation occurs on a longer time scale than the picosecond time domain. This is in agreement with present theories of intermolecular proton-transfer reactions, which require solvent reorganization as well as the time of deprotonation estimated from the pK(a) value of this molecule in the excited state. The results of our MO calculations on the electronic structure of these two compounds could account for the fact that, while MHtrans+ photoisomerizes, its deprotonated form does not.},
	isbn = {0002-7863},
	doi = {10.1021/ja993940w},
	author = {Burda, Clemens and Abdel-Kader, M. H. and Link, Stephan and El-Sayed, Mostafa A}
}
@article {1229,
	title = {Femtosecond transient-absorption dynamics of colloidal gold nanorods: Shape independence of the electron-phonon relaxation time},
	journal = {Physical Review B},
	volume = {61},
	number = {9},
	year = {2000},
	note = {Link, S Burda, C Mohamed, MB Nikoobakht, B El-Sayed, MA},
	month = {Mar},
	pages = {6086-6090},
	abstract = {We studied the femtosecond dynamics of colloidal gold nanorods encapsulated in micelles after excitation with 400 nm pulses of 100 fs duration. It is found that the laser heating of the electron gas of gold nanorods with an average aspect ratio of 3.8 leads to the bleaching of both the transverse and longitudinal mode of the surface plasmon oscillation at 520 and 750 nm. The bleach recovers with the same time constant for both the transverse and longitudinal oscillation, for gold nanodots prepared by photothermal reshaping of the rods as well as for nanodots synthesized chemically by citrate reduction (and known to have twin boundaries and surface defects). Since the bleach recovery on the 3 ps time scale is assigned to electron-phonon relaxation processes, these results suggest that phonon dependent relaxation processes in gold nanoparticles are independent of the shape, size, type of the surfaces, or the mode of the surface plasmon, oscillation excited. The fact that the mean free path of the electron in metallic gold is in the nanometer length scale (similar to 50 nm) raised the question of the importance of surface scattering to the electron-phonon relaxation process in gold nanoparticles. Our previous studies showed little dependence of the relaxation rate of the size of gold nanodots (from 9 to 48 nm). In the present study, the electron-phonon relaxation is measured in gold nanorods, which have different facets from those of gold nanodots.},
	isbn = {1098-0121},
	doi = {10.1103/PhysRevB.61.6086},
	author = {Link, Stephan and Burda, Clemens and Mohamed, MB and Nikoobakht, Babak and El-Sayed, Mostafa A}
}
@article {1292,
	title = {Femtosecond Interfacial Electron Transfer Dynamics of CdSe Semiconductor Nanoparticles },
	journal = {MRS Proceedings},
	volume = {43},
	year = {1998},
	pages = {419-424},
	abstract = {The effect of the adsorption of an electron donor (thiophenol, TP) on the surface of CdSe nanoparticles (NPs) on the emission and electron-hole dynamics is studied. It is found that while the emission is completely quenched, the effect on the transient bleach recovery of the band gap absorption is only slight. This is explained by a mechanism in which the hole in the valence band of the NP is rapidly neutralized by electron transfer from the TP. However, the excited electron in the conduction band is not transferred to the TP cation, i. e. the electron does not shuttle via the organic moiety as it does when naphthoquinone is adsorbed [1]. The excited electron is rather trapped by surface states. Thus the rate of bleach recovery in the CdSe NP system is determined by the rate of electron trapping and not by hole trapping. Comparable conclusions resulted previously [2] for the CdS NP when the CdS-MV2+ system is studied. A comparative discussion of the electron-hole dynamics in these systems (CdSe-NQ, CdS-MV2+ and CdSe-TP) is given.},
	doi = {10.1557/PROC-536-419 },
	author = {Burda, Clemens and Green, T.C. and Link, Stephan and El-Sayed, Mostafa A}
}
@article {856,
	title = {Femtosecond time-resolved two-photon photoemission studies of electron dynamics in metals},
	journal = {Progress in surface science},
	volume = {56},
	year = {1997},
	pages = {239-310},
	publisher = {Elsevier},
	abstract = {Electron-hole excitation and relaxation in the bulk, at interfaces, and surfaces of solid state materials play a key role in a variety of physical and chemical phenomena that are important for surface photochemistry, particle-surface interactions, and device physics. Information on charge carrier relaxation in metals can be obtained through analysis of linewidths measured by photoemission and related techniques, which give an estimate of the upper limit for electron and hole relaxation; however, many factors can contribute to spectral broadening, thus it is difficult to extract specific information on electronic relaxation processes. With femtosecond lasers it is possible to probe directly in a time-resolved fashion the charge carrier dynamics in metals by a variety of linear and nonlinear optical techniques. Femtosecond time-resolved two-photon photoemission has attracted particularly strong interest because it incorporates many of the surface analytical capabilities of photoemission and inverse photoemission {\textemdash} the traditional probes for surface and bulk band structures of solid state materials {\textemdash} with time-resolution that is approaching the fundamental response of electrons to optical excitation. Advances in the direct measurements of electron-hole excitation, charge carrier relaxation, and dynamics of intrinsic and adsorbate induced surface states are reviewed. With femtosecond lasers it also is possible to probe a variety of coherent phenomena, and even to control the charge carrier dynamics in metals through the optical phase of the excitation light. Pioneering experiments in this new field also are discussed.},
	isbn = {0079-6816},
	doi = {10.1016/S0079-6816(98)00002-1},
	url = {http://dx.doi.org/10.1016/S0079-6816(98)00002-1},
	author = {Petek, H. and Ogawa, S.}
}
@article {875,
	title = {Fluorine Substitution Effects on the Photodissociation Dynamics of Iodobenzene at 304 nm},
	journal = {The Journal of Physical Chemistry },
	volume = {100},
	year = {1996},
	note = {doi: 10.1021/jp952662u},
	month = {1996},
	pages = {7989 - 7996},
	publisher = {American Chemical Society},
	abstract = {The photodissociation dynamics of pentafluoroiodobenzene are investigated by state-selective one-dimensional translation spectroscopy at 304 nm. We have determined the one-dimensional recoil distribution and the spatial distribution in the form of the anisotropy parameter, ?, as well as the photodissociation relative yields of both ground-state I(3P3/2) and excited-state I*(2P1/2) iodine photofragments. The results are compared to those observed for iodobenzene at 304 nm. As in iodobenzene, two velocity distributions were observed for the dissociation channel which gives ground-state iodine:? a sharp, high recoil velocity peak assigned previously to n,σ* excitation and a slow recoil velocity distribution peak assigned previously to π,π* excitation. Unlike in C6H5I, the I* distribution is relatively strong and its spatial anisotropy can be measured. The fluorine perturbation has led to a number of different observations that can be summarized as follows:? (1) The high velocity distribution has a lower average value and much broader width, suggesting more rapid energy redistribution to the fluorinated phenyl ring prior to and during the dissociation process, resulting from stronger coupling between the n,σ* and π,π* states and/or a longer excited-state lifetime; (2) the slow distribution is weaker and has an almost isotropic spatial distribution (the anisotropy parameter ? ≈ 1.0), while in the iodobenzene spectrum ? is correlated with the recoil velocity; (3) the I* quantum yield for C6F5I is 14 times larger than that for iodobenzene; and (4) ? is correlated with the velocity in the I* spectrum found for C6F5I which is not observed for iodobenzene. These observed fluorine perturbations are attributed to an increased mixing between the charge-transfer state (resulting from electron transfer from the iodine nonbonding electrons to the π* orbitals of the fluorinated benzene ring) and both the n,σ* and the ring π,π* states. This leads to two effects:? (1) a decrease in the nonbonding electron density on the iodine, which decreases the spin-orbit interaction between the n,σ* states themselves, resulting in a decrease in the curve-crossing probability (thus increasing the I* yield) and (2) an increase in the coupling between the repulsive n,σ* states and the fluorinated phenyl π,π* states, leading to an increase in the rate of energy redistribution.The photodissociation dynamics of pentafluoroiodobenzene are investigated by state-selective one-dimensional translation spectroscopy at 304 nm. We have determined the one-dimensional recoil distribution and the spatial distribution in the form of the anisotropy parameter, ?, as well as the photodissociation relative yields of both ground-state I(3P3/2) and excited-state I*(2P1/2) iodine photofragments. The results are compared to those observed for iodobenzene at 304 nm. As in iodobenzene, two velocity distributions were observed for the dissociation channel which gives ground-state iodine:? a sharp, high recoil velocity peak assigned previously to n,σ* excitation and a slow recoil velocity distribution peak assigned previously to π,π* excitation. Unlike in C6H5I, the I* distribution is relatively strong and its spatial anisotropy can be measured. The fluorine perturbation has led to a number of different observations that can be summarized as follows:? (1) The high velocity distribution has a lower average value and much broader width, suggesting more rapid energy redistribution to the fluorinated phenyl ring prior to and during the dissociation process, resulting from stronger coupling between the n,σ* and π,π* states and/or a longer excited-state lifetime; (2) the slow distribution is weaker and has an almost isotropic spatial distribution (the anisotropy parameter ? ≈ 1.0), while in the iodobenzene spectrum ? is correlated with the recoil velocity; (3) the I* quantum yield for C6F5I is 14 times larger than that for iodobenzene; and (4) ? is correlated with the velocity in the I* spectrum found for C6F5I which is not observed for iodobenzene. These observed fluorine perturbations are attributed to an increased mixing between the charge-transfer state (resulting from electron transfer from the iodine nonbonding electrons to the π* orbitals of the fluorinated benzene ring) and both the n,σ* and the ring π,π* states. This leads to two effects:? (1) a decrease in the nonbonding electron density on the iodine, which decreases the spin-orbit interaction between the n,σ* states themselves, resulting in a decrease in the curve-crossing probability (thus increasing the I* yield) and (2) an increase in the coupling between the repulsive n,σ* states and the fluorinated phenyl π,π* states, leading to an increase in the rate of energy redistribution.},
	isbn = {0022-3654},
	url = {http://dx.doi.org/10.1021/jp952662u},
	author = {Griffiths, Jennifer A. and Jung, Kwang-Woo and El-Sayed, Mostafa A}
}
@article {1287,
	title = {Fourier Transform Infrared Spectroscopic Studies of the Effect of Ca2+ Binding on the States of Aspartic Acid Side Chains in Bacteriorhodopsin},
	journal = {The Journal of Physical Chemistry},
	volume = {99},
	year = {1995},
	note = {doi: 10.1021/j100019a066},
	month = {1995},
	pages = {7776 - 7781},
	publisher = {American Chemical Society},
	abstract = {View http://dx.doi.org/10.1021/j100019a066 for article{\textquoteright}s front page in lieu of an abstract},
	isbn = {0022-3654},
	doi = {doi: 10.1021/j100019a066},
	url = {http://dx.doi.org/10.1021/j100019a066},
	author = {Masuda, Satoshi and Nara, Masayuki and Tasumi, Mitsuo and El-Sayed, Mostafa A and Lanyi, Janos K.}
}
@article {1274,
	title = {A Fourier-transform infrared spectroscopic comparison of cultured human fibroblast and fibrosarcoma cells: a new method for detection of malignancies},
	journal = {Journal of clinical laser medicine \& surgery},
	volume = {13},
	year = {1995},
	pages = {55-59},
	abstract = {Infrared vibration spectroscopy appears to be a more powerful technique for tumor diagnosis than visible or UV spectroscopy. In the present work, Fourier-transform infrared (FTIR) spectroscopy was used to compare cultured normal fibroblast and fibrosarcoma cells. Significant differences were observed by comparing the spectra of the normal human cells with that of the cancer cells. The PO2 symmetric stretching mode at 1082 cm-1 is shifted to a higher frequency in the cancer cell and a broad band, whose center is located at 1064 cm-1 in the cancer cell is reduced in intensity. In addition, the decrease in intensity of the CH2 bending mode relative to that of CH3 mode is detectable only in the fibrosarcoma cell. This FTIR difference between fibroblast and fibrosarcoma cells suggests that either fatty acid chains or protein side chains of the cancer cells are partially degraded resulting in more terminal carbon (e.g., CH3). It is also possible that changes in the environment upon carcinogenesis induces a change in the relative absorption cross section for CH3 and CH2 bending vibrations. These results suggest that FTIR spectroscopy may become a promising and sensitive technique for tumor identification.},
	isbn = {1044-5471},
	author = {Yang, Difei and Castro, D. and El Sayed, I.H. and El-Sayed, Mostafa A and SAXTON, R.E. and ZHANG, N.Y.I.}
}
@article {1284,
	title = {Fourier-transform infrared spectroscopic comparison of cultured human fibroblast and fibrosarcoma cells},
	journal = {Proceedings of SPIE},
	volume = {2389},
	year = {1995},
	month = {1995},
	pages = {543},
	publisher = {SPIE},
	abstract = {Infrared vibration spectroscopy appears to be a more powerful technique for diagnosis than visible or UV spectroscopy. Advantages of IR spectra include: 1) vibrational motion has a smaller tissue absorption coefficient than electronic motion, 2) scattering of infrared radiation has a lower cross section than visible or UV light, (these two facts allow deeper penetration of IR radiation) and 3) vibration spectra provide a better fingerprint of chemical groups present in cells than the unresolved broad electronic spectrum of biological molecules. In the present work, Fourier-transform IR spectroscopy was used to compare cultured human fibroblast and malignant fibrosarcoma cells. Significant differences were observed by comparing the spectra of the normal cells with that of the cancer cells. the PO2 symmetric stretching mode at 1082cm-1 in the cancer cell is reduced in intensity. These observations are similar to those reported previously by Wong et al in comparing the IR spectra of pairs of normal and cancerous cells from the colon and cervix. However, the observed increase in the relative intensity of the symmetric to antisymmetric CH3 bending mode are only found in fibrosarcoma and basal cell carcinoma. The decrease in intensity of the CH2 bending mode relative to that of CH3 mode was observed only for fibrosarcoma cells. This finding with paired human fibroblast and fibrosarcoma cells suggests that fatty acid chains or side chains of protein in the cancer cells are partially degraded leading to more terminal carbon. It is also possible that changes in the environment upon carcinogenesis induces a change in the relative absorption cross sections for the CH3 and CH2 bending vibrations.
},
	doi = {10.1117/12.210030},
	url = {http://dx.doi.org/10.1117/12.210030},
	author = {Yang, Difei},
	editor = {Castro, D. and El Sayed, I.H. and El-Sayed, Mostafa A and Saxton, R. and Zhang, N.}
}
