Custom designed acoustic pulses

Probing protein misfolding and dissociation with an infrared free-electron laser

Misfolding is observed in the mutant proteins that are causative for neurodegenerative disorders such as polyglutamine diseases. These proteins are prone to aggregate in the cytoplasm and nucleus of cells. To reproduce cells with the aggregated proteins, gene expression system is usually applied, in which the expression construct having the mutated DNA sequence of the interest is transfected into cells. The transfected DNA is finally converted into the mutant protein, which is gradually aggregated in the cells. In addition, a simple method to prepare the cells having aggregates inside has been recently applied. Peptides were first aggregated by incubating them in water. The aggregates are spontaneously taken up by cells because aggregated proteins generally transfer between cells. Peptides with different degrees of aggregation can be made by changing the incubation times and temperatures, which enables to examine contribution of aggregation to the toxicity to the recipient cells. Moreover, such cells can be used for therapeutic researches of diseases in which aggregates are involved. In this chapter, we show methods to induce aggregation of peptides. The functional analyses of the cells with aggregates are also described. Then, experimental dissociation of the aggregates produced using this method by mid infrared free electron laser irradiation and its theoretical support by molecular dynamics simulation are introduced as the therapeutic research for neurodegenerative disorders.

Degradation of Lignin by Infrared Free Electron Laser

Lignin monomers have attracted attention as functional materials for various industrial uses. However, it is challenging to obtain these monomers by degrading polymerized lignin due to the rigid ether linkage between the aromatic rings. Here, we propose a novel approach based on molecular vibrational excitation using infrared free electron laser (IR-FEL) for the degradation of lignin. The IR-FEL is an accelerator-based pico-second pulse laser, and commercially available powdered lignin was irradiated by the IR-FEL under atmospheric conditions. Synchrotron-radiation infrared microspectroscopy analysis showed that the absorption intensities at 1050 cm⁻¹, 1140 cm⁻¹, and 3400 cm⁻¹ were largely decreased alongside decolorization. Electrospray ionization mass chromatography analysis showed that coumaryl alcohol was more abundant and a mass peak corresponding to hydrated coniferyl alcohol was detected after irradiation at 2.9 μm (νO-H) compared to the original lignin. Interestingly, a mass peak corresponding to vanillic acid appeared after irradiation at 7.1 μm (νC=C and νC-C), which was supported by our two-dimensional nuclear magnetic resonance spectroscopy analysis. Therefore, it seems that partial depolymerization of lignin can be induced by IR-FEL irradiation in a wavelength-dependent manner.

Nuclear transport by laser-induced pressure transients

PURPOSE

Control of the transport of molecules into the nucleus represents a key regulatory mechanism for differentiation, transformation, and signal transduction. Permeabilization of the nuclear envelope by physical methods can have applications in gene therapy. Laser-induced pressure transients can produce temporary aqueous pores analogous to those produced by electroporation and that the cells can survive this procedure. In this study, we examine the role of the pressure transients in creating similar pores in the nuclear envelope.

METHODS

The target human peripheral blood mononuclear cells in a 62 microM 72 kDa fluoresceinated dextran solution were exposed to the pressure transients generated by laser ablation. An in vitro fluorescence confocal microscope was used to visualize and quantify the fluoresceinated dextran in the cytoplasmic and nuclear compartments.

RESULTS

In contrast to electroporation, the pressure transients could deliver 72 kDa fluoresceinated dextrans, which are normally excluded by the nucleus, across the nuclear envelope into the nucleus. In addition to creating pores in the plasma membrane, temporary pores were also created in the nuclear envelope following exposure to pressure transients.

CONCLUSION

The production of temporary nuclear pores could provide a unique resource for drug-delivery and gene therapy.

Photomechanical transdermal delivery: the effect of laser confinement

BACKGROUND AND OBJECTIVE

Photomechanical waves can transiently permeabilize the stratum corneum and facilitate the delivery of drugs into the epidermis and dermis. The present study was undertaken to assess the effect of pulse characteristics to the penetration depth of macromolecules delivered into the skin.

STUDY DESIGN/MATERIALS AND METHODS

Photomechanical waves were generated by confined ablation with a Q-switched ruby laser. Fluorescence microscopy of frozen biopsies was used to assay the delivery of macromolecules through the stratum corneum and determine the depth of penetration.

RESULTS

Photomechanical waves generated by confined ablation of the target have a longer rise time and duration than those generated by direct ablation. Confined ablation required a lower radiant exposure (from approximately 7 J/cm(2) to approximately 5 J/cm(2)) for an increase in the depth of delivery (from approximately 50 microm to approximately 400 microm).

CONCLUSIONS

Control of the characteristics of the photomechanical waves is important for transdermal delivery as they can affect the depth of drug penetration into the dermis.