No effect of femtosecond laser pulses on M13,E. coli, DNA, or protein

Abstract

Data showing what appears to be nonthermal inactivation of M13 bacteriophage (M13), Tobacco mosaic virus, Escherichia coli (E. coli), and Jurkatt T-cells following exposure to 80-fs pulses of laser radiation have been published. Interest in the mechanism led to attempts to reproduce the results for M13 and E. coli. Bacteriophage plaque-forming and bacteria colony-forming assays showed no inactivation of the microorganisms; therefore, model systems were used to see what, if any, damage might be occurring to biologically important molecules. Purified plasmid DNA (pUC19) and bovine serum albumin were exposed to and analyzed by agarose gel electrophoresis (AGE) and polyacrylamide gel electrophoresis (PAGE), respectively, and no effect was found. DNA and coat proteins extracted from laser-exposed M13 and analyzed by AGE or PAGE found no effect. Raman scattering by M13 in phosphate buffered saline was measured to determine if there was any physical interaction between M13 and femtosecond laser pulses, and none was found. Positive controls for the endpoints measured produced the expected results with the relevant assays. Using the published methods, we were unable to reproduce the inactivation results or to show any interaction between ultrashort laser pulses and buffer/water, DNA, protein, M13 bacteriophage, or E. coli.

Advanced multimodal laser imaging tool for urothelial carcinoma diagnosis (AMPLITUDE)

“…The ability of light to penetrate tissue is highly dependent on tissue composition, with optical scattering profoundly affecting the penetration depth. With an unmet and increasing demand for deeper tissue imaging, the use of near-infrared instead of visible-or UV-light, is increasingly appealing, in particular when the wavelengths fall within 'biological windows' where light has much deeper penetration [12,13]. Within these windows, four distinctive wavelength regions have been identified: the first biological window spans the wavelength range from 700-950 nm, the second biological window spans the region from 1000-1350 nm, the third biological window covers 1550-1870, and the fouth biological window is within 2100-2300 nm, with each window providing increased transparency with respect to biological matter.…”

“…However, the third biological window wavelength range offers several potential highly appealing advantages for deep tissue imaging that are not currently fully exploited. Firstly, the longer wavelength decreases Rayleigh scattering (which varies as the inverse fourth power of the wavelength) and due to Mie scattering (which varies as 1⁄λ n with n ≥ 1) (we can expect much less scattering (five times in comparison with a 1 µm wavelength for soft tissue) [13,14] and higher contrast images (SNR =~5 dB at 1700 nm compared to SNR = 0 dB at 1300 nm for 1.1 mm penetration depth [15]) than the first or second biological windows due to the nonlinear effect based on discrepancy of scattered and signal light absorption by the tissue [16]. Taking into account the possible penetration depth and reduced effect of optical scattering, the use of these longer wavelengths for both excitation and emission are therefore, in principle, highly favourable for photonics imaging systems.…”

<p>Preparation Of Nanobubbles Modified With A Small-Molecule CXCR4 Antagonist For Targeted Drug Delivery To Tumors And Enhanced Ultrasound Molecular Imaging</p>

“…Ultrasound contrast agents with a nanoscale particle size and strong permeability can pass through tumor blood vessels and accumulate in tumor extravascular tissues. [14][15][16][17] Lipid nanobubbles (NBs) represent a common nanoscale ultrasound contrast agent with strong permeability and high stability that can not only enhance extravascular ultrasound imaging of tumors but also allow ultrasound-assisted focused delivery of drugs or genes to tumor parenchymal cells. Moreover, specific antibodies or ligands that target tumor tissue can be conjugated to the surface of drug-or gene-loaded NBs, thereby improving the aggregation ability of NBs in tumor extravascular tissue and in turn improving the outcome of extracellular ultrasound molecular imaging and targeted therapy.…”

Interaction of near-infrared femtosecond laser pulses with biological materials in water

“…16 In those experiments, the irradiation times are on the order of 1 h, while the individual laser pulse energy is only on the order of 1 nJ (100 MW∕cm 2 on target power density). The integrated incident laser energy for that experiment is ∼288 J∕mL (2-mL total irradiated volume), which is almost 600 times higher than the total dose in our experiment (0.5-J∕mL, 50-μL sample volume).…”

“…15 Interestingly, an independent study of the interactions of 90-fs laser pulses (850 or 425 nm) with buffer/water, DNA, protein, M13 bacteriophage, or Escherichia coli could not confirm these observations. 16 Very recently, the application of intense ultra-short infrared laser pulses for cancer radiotherapy has been discussed. 17 With this technique, a large energy density can be deposited at unprecedented dose rates precisely in a microscopic volume without exposing the adjacent tissue.…”