In pharmaceutical development, more and more drugs are classified as poorly water-soluble or insoluble. Particle size reduction is a common way to fight this trend by improving dissolution rate, transport characteristics and bioavailability. Pulsed laser ablation is a ground-breaking technique of drug particle generation in the nano- and micrometer size range. Meloxicam, a commonly used nonsteroidal anti-inflammatory drug with poor water solubility, was chosen as the model drug. The pastille pressed meloxicam targets were irradiated by a Ti:sapphire laser (τ = 135 fs, λc = 800 nm) in air and in distilled water. Fourier transform infrared and Raman spectroscopies were used for chemical characterization and scanning electron microscopy to determine morphology and size. Additional particle size studies were performed using a scanning mobility particle sizer. Our experiments demonstrated that significant particle size reduction can be achieved with laser ablation both in air and in distilled water without any chemical change of meloxicam. The size of the ablated particles (~50 nm to a few microns) is approximately at least one-tenth of the size (~10–50 micron) of commercially available meloxicam crystals. Furthermore, nanoaggregate formation was described during pulsed laser ablation in air, which was scarcely studied for drug/organic molecules before.

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Ablation and plasma mirror characteristics of Borofloat, BK7, and B270 glasses processed with 34 fs pulses of 800 nm central wavelength are compared in the 10 14-10 15 W/cm 2 intensity domain. With thresholds of 1.7-1.9 × 10 14 W/cm 2 , higher than those of fused silica, and depths saturating above 5×10 14 W/cm 2 , the three glasses behave similarly from the point of view of ablation. With reflectivity enhancements comparing favorably with that of fused silica, the glasses prove to be good plasma mirror hosts. With the steepest increase in time integrated transient reflectivity with intensity, Borofloat is the most promising candidate.

The material response of Borofloat, BK7, and B270 glass targets to 34 fs pulses of 800 nm central wavelength is analyzed in the 1–30 J/cm2 fluence domain. The contours of the craters change with the fluence very much the same for all three glasses up to approximately 20 J/cm2, above which the Borofloat and BK7 continue behaving similarly, while bump formation sets on for the B270 glass. Analyzing the contours single-shot ablation thresholds are determined by applying both the conventional diameter regression technique and a multiphoton absorption-based fit to depth data. The ablation threshold values are equal within the 6.1 ± 0.55 J/cm2 domain for the three glasses as well as the three-photon absorption coefficients, which lie in the same magnitude (10–25 cm3/W2). Above the ablation threshold, the diameter values follow logarithmic dependence in the fluence range investigated, reaching similar values around 45 µm at 30 J/cm2 with 51 ± 1 µm 1/e2 beam diameter on the target surface as derived from the diameter regression technique. The onset of plasma formation derived from the changes in the energy reflected from the processed surface is also found to be similar for the three glasses (9.5, 10, and 8.0 J/cm2) in good correlation with the ablation threshold values.

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