We report femtosecond Laser-induced Breakdown Spectroscopy (fs-LIBS) measurements on several amino acids (Serine, Glutamine, and Cysteine) and Albumin protein solutions mixed with Ficoll polysaccharide at different proportions. The goal is to assess the effects of a host matrix on the identification and spectral characterization of amino acids by fs-LIBS. fs-LIBS utilizes an intense short laser pulse to obliterate a sample into basic constituents and to record the emission spectrum of atoms, ions, and molecules in the cooling down of the plasma plume. Several spectral peaks associated primarily with elemental composition of a sample were observed in the fs-LIBS spectra in a range from 200 to 950 nm. In addition, some molecular information associated with diatomic vibrational modes in certain molecules such as C-C and C-N were also obtained. The presence of Ficoll affects the relative intensity and broadening of the CN band, which could be considered as signatures of the amino acids. The fs-LIBS data and their analysis compare favorably with those derived from Fourier Transform Infrared Spectroscopy (FTIR). Interpretation of the spectral information enclosed in the emission of the diatomic molecules during laser ablation may lead to a better understanding of plume chemistry with a direct consequence on chemical analysis of complex samples such as amino acids. Altogether, the results demonstrate the potential of fs-LIBS technique as a detection method of biomolecules and for probing interactions of these biomolecules with a host matrix.
We report on pump-probe mode-mismatched photothermal lens experiments of metallic nanoparticles water solutions.
We show that metallic nanoparticles colloids exhibit nonlinear absorption effects related to attraction or repulsion forces
that result from the interaction with the electromagnetic radiation. Gold and iron oxide nanoparticles show a double
peak Z-scan shape that is associated to the presence of attraction forces. We calibrate the experiment using the linear
absorption values of the samples obtaining their corresponding nonlinear absorption coefficients.
We report on a new application of laser induced breakdown spectroscopy (LIBS) for the diagnosis of diseases such as
ovarian cancer. We perform detection of ovarian cancer biomarker CA 125 based on LIBS measurements. Immunoconjugated
Silicon particles are incubated with the affinity agarose beads carrying CA125 molecules. In the competitive
affinity method Si particles carrying IgG molecules are pre-incubated with CA125. This pre-incubation decreases the
numbers of free IgG molecules available for consequent interaction with the affinity beads. Thus less Si particles are
attached to the agarose beads and consequently smaller Si peak area is measured by LIBS. We demonstrate a limit-ofdetection
about 30 ppb for model protein avidin. We use two-element coded micro-particles to yield spectroscopic
emission code using LIBS. We show that LIBS-based data collecting technique provides methodology for identification
of biomarkers and cost-effective device for future clinical applications.
We report on Fourier transform spectra of deuterated proteins: Bovine Serum Albumin, Leptin, Insulin-like Growth
Factor II, monoclonal antibody to ovarian cancer antigen CA125 and Osteopontin. The spectra exhibit changes in
the relative amplitude and spectral width of certain peaks. New peaks not present in the non-deuterated sample are
also observed. Ways for improving the deuteration of proteins by varying the temperature and dilution time are
discussed. We propose the use of deuterated proteins to increase the sensitivity of immunoassays aimed for early
diagnostic of diseases most notably cancer.